Org. Divers. Evol. 6, Electr. Suppl. 8: 1 - 20 (2006)
© Gesellschaft für Biologische Systematik
URL: http://www.senckenberg.de/odes/06-08.htm
URN: urn:nbn:de:0028-odes0608-9
The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in southern
Luzon, Philippines
Samuel W. James
Natural History Museum and Biodiversity Research Center, Dyche Hall, 1345 Jayhawk Drive, University of Kansas,
Lawrence, KS 66045, USA
e-mail: [email protected]
Received 2 December 2004 • Accepted 11 August 2005
Abstract
An earthworm biodiversity survey of the Philippines has yielded 14 new species of the perichaetine megascolecid genus Pleionogaster,
previously known from only a few species from scattered Philippine locations. Bicol, the southern peninsula of Luzon, has intact forests on
several isolated volcanic peaks and other remote areas. Collections made in these forests yielded the following new species, here presented
by type location: Mt. Malinao, Pleionogaster albayensis, P. bicolensis, P. castilloi, P. malinaoensis, P. tiwiensis; Mt. Isarog, P. ffitchae, P.
isarogensis; Mt. Bulusan, P. bulusanensis, P. hongi, P. sorsogonensis; Catanduanes Island, P. nautsae, P. viracensis; Caramoan Peninsula,
P. caramoanensis, P. nillosae. Most of the species were found only in the neighborhood of the type locality, but P. bicolensis occurs in two
locations in northern Bicol. Intraspecific variation in P. castilloi was observed between northern and southern flanks of Mt. Malinao. The importance of several previously overlooked Pleionogaster traits is demonstrated by their homogeneity within species reported here.
Keywords: Pleionogaster; Megascolecidae; Clitellata; Philippines; Luzon; Bicol
Introduction
The perichaetine megascolecid genus Pleionogaster
Michaelsen, 1892 has long been known from a few isolated collections made in the Philippines during the last
two centuries (Easton 1979; James 2004), but its range
and diversity remained unknown. In early 2001 the author and a field team set out to conduct the first organized collecting of earthworm material from the Philippines, and discovered many species of Pleionogaster
in all parts of the island of Luzon, including Catanduanes, an island united with Luzon at Pleistocene low
sea levels (Heaney 1985; 1993). This paper is one of
a series planned on new earthworm species discovered by the Philippines Terrestrial Annelid and Gastropod Survey (PTAGS). Here I report the Pleionogaster
species found in Bicol, a long southern peninsula of
Luzon,plus Catanduanes Island, composed of lowland
plains dotted with dormant and active volcanoes.
Pleionogaster is an interesting group of earthworms,
from the standpoint of the systematics of the Pheretima complex (sensu Sims and Easton 1972) of the Megascolecidae. Several of its characteristics are unique
among the genera of the complex, raising questions
about its placement in that group. Its members have
a reduced esophageal gizzard in viii, all the anterior
septa are present, and these are generally muscular anterior of 9/10 or 10/11. There are paired meganephridia in the intestinal segments, but not elsewhere; these
are connected to paired longitudinal ducts flanking the
dorsal blood vessel. In addition there are regular ranks
of micronephridia opening to corresponding rows of
nephridiopores, again in the intestinal segments. Micronephridia are present in the anterior segments but
are placed differently. The intestine is supplied with
several gizzards posterior to xxiv, followed by an atyphlosolate section of intestine up to 25 segments long,
at the end of which is a constriction and the typhlosolar
origin, if a typhlosole is present. The supra-esophageal
vessel extends posteriorly past the heart segments to
xvii in most cases, and the vessels returning blood from
the clitellar region (posterior latero-parietals) are from
one to four pairs in segments xiv–xvii. In some cases
the posteriormost pair of these vessels is connected to
paired longitudinal vessels extending many segments
back on the body wall. Most of these features have
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
been noted in older works on the genus, but some are
reported here for the first time.
No other genera in the Pheretima complex share any
of the unusual features of Pleionogaster, and neither
do any other megascolecid genera found in the region comprising the Philippine and Indonesian archipelagoes and mainland Southeast Asia west through
Thailand. This poses a biogeographic and systematic
puzzle, the solving of which will require additional exploration. For now, the most likely location of related
genera seems to be Australia, where Anisogaster Blakemore, 2000, Eastoniella Jamieson, 1977, Gastrodrilus
Blakemore, 2000, Hickmaniella Jamieson, 1974, Pseudocryptodrilus Jamieson, 1972, and Pseudonotoscolex
Jamieson, 1971 share some characteristics with Pleionogaster (Jamieson 2000). The Indian genus Lampito
Kinberg, 1866 has a similar arrangement of post-clitellar meganephridia and ducts (Gates 1972)
Ecologically, members of Pleionogaster are mostly
endogeic, with generally long and slender, rarely pigmented bodies, and always found in the soil, never in
litter or arboreal habitats. Some of the larger species in
which the anterior ends are darkly pigmented may be
anecic.
Methods and material
On the upper slopes of the Bicol volcanoes lie the remaining primary montane and mossy forests of the area,
and these were given priority in collecting. Collections
were also carried out in two low-elevation sectors in
some relatively undisturbed forest on Catanduanes Island and the nearby Caramoan Peninsula. Earthworms
were collected by digging and handsorting soil, searching organic soil and root mats from the tops of boulders, logs, roots and branches, dissecting epiphytes,
primarily arboreal ferns, and searching the leaf axils of
palms and Pandanaceae. All specimens examined for
this paper were recovered from mineral soil, not from
organic soil horizons, organic mats or other suspended
soils, or plants.
Photographs were taken live of as many different
species as could be distinguished in the field by inspection with the unaided eye. Additional photomicrographs were taken in the laboratory using a Nikon
Coolpix 995 digital camera fitted to an adapter mounted on the phototube of a Leica M5 stereomicroscope. Specimens were killed in 50% ethanol and fixed in
10% formaldehyde in the field. After at least 48 hours
fixation they were rinsed in three changes of tap water
with at least 12 hours between changes, and transferred
to 80% ethanol. This removes residual formaldehyde,
reduces health hazards to those working with the specimens, and may reduce DNA degradation. Duplicate
sets of specimens were preserved in 95% ethanol for
2
molecular phylogenetic studies, and were archived at
–20 ºC. All material was scored for external characters,
drawings made by way of a drawing tube, and internal anatomy studied by dorsal dissection. Setal counts
were made over 1 mm each of a dorsal, lateral and
ventral segmental equator arc, averaging these counts,
and multiplying the average by the estimated circumference of the segment. This was necessary due to the
extremely large numbers of setae (up to 300) crowded
into the anterior setal rings.
Collecting site data include the acronym PTAGS
(Philippine Terrestrial Annelid and Gastropod Survey)
followed by a location number that uniquely identifies a
location in the survey. Latitude and longitude are given
in degrees and decimal minutes. Elevations were read
from a GPS unit (Magellan Map410) if sufficient satellites were detectable, or from an altimeter. The map
datum used in the GPS readings was Luzon. Collectors
listed are those working at the respective site.
Holotypes of the new species are deposited in the
National Museum of the Philippines Annelid Collection (NMA), P. Burgos St., Manila, Philippines. Additional depositories: KUNHM = Kansas University
Natural History Museum, Lawrence, Kansas USA;
UPLBMNH = University of the Philippines Los Baños
Museum of Natural History, College, Laguna, Philippines.
Taxonomic section
Clitellata: Megascolecidae Rosa, 1891
Genus Pleionogaster Michaelsen, 1892
Perichaeta Beddard, 1886: 298 (in part).
Pleionogaster Michaelsen, 1892: 247; Beddard
(1895: 433), Michaelsen (1896: 198), Easton (1979:
114), James (2004).
Plionogaster Michaelsen, 1900: 210; Stephenson
(1930: 840), Stephenson (1933: 923), Gates (1943:
105), Jamieson (1971: 82).
Type species. Pleionogaster jagori Michaelsen,
1892 (Easton 1979).
Diagnosis. Perichaetine Megasolecidae with larger
numbers of setae in the head segments than in post–clitellate segments, a reduced esophageal gizzard in viii,
intestinal gizzards in the region xxiv–xxx, paired enteroic stomate meganephridia and regular ranks of exoic
micronephridia in post-clitellate segments, and a single
pair of racemose prostates whose ducts are united with
the vasa deferentia near the ental end of the duct. All
known species have paired spermathecae in segments
viii and ix.
Remarks. James (2004) discussed synonymy issues
raised by Easton (1979) and made some changes to the
genus definition in Easton (1979).
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
Pleionogaster tiwiensis n. sp.
(Fig. 1A, B)
Etymology. Named after Tiwi, the municipality closest to the type locality.
Type material. Holotype (NMA004134): adult,
PTAGS 055, Albay Province, near Tiwi, montane forest on north ridge of Mt. Malinao, 13° 25.98’ N, 123°
37.63’ E, 850m asl, 10 May 2001, leg. S.W. James & A.
Castillo. Paratypes (KUNHM 002175): 4 adults, collecting data as for holotype.
Description. Unpigmented, body 94–103 mm x 3.1–
3.5 (vii), 2.7–3.7 mm (xv), 3.3–3.9 mm (xxv); 215–285
segments, some specimens with regenerated segments;
body cylindrical in cross-section; segments x–xiii biannulate, postclitellar segments faintly biannulate in anterior half of body. First dorsal pore 11/12 or 12/13; spermathecal pores paired in 7/8, 8/9, 0.08 circumference
apart, female pore single in xiv, male pores crescentic
paired in xviii on raised porophores, 0.12 circumference apart, 5–6 setae between male pores. Setae regularly distributed around segmental equators; estimated
at 210 setae on vii, 114 setae on xxv; in vii no dorsal
gap, in xx ZZ:YZ = 2–3, ventral gap AA:AB = 2. Clitellum annular 1/2xiii, xiv–1/2xvii; genital markings
midventral broad pad xvii, paired presetal in line with
male pores on xviii, narrow elongate midventral over
equator, presetal portion of xx, xxi, midventral epidermal thickenings of xxii–xxiv (Figure 1A). Body wall
slightly depressed between male pores. Nephridiopores
visible as gaps in setal rings of postclitellar segments,
apparently 6–10 pores per segment but not always in
regular rows.
Septa 5/6–8/9 thick, muscular, 9/10 thinner, remainder membranous. Weak gizzard in viii with typical iridescent outer wall but flaccid, esophagus vascularized,
with low villous discontinuous vertical folds xiii–xvii,
valvular xviii, intestinal origin xix, no caeca; thick intestinal gizzards xxvii–xxx (4), xxv–xxviii (1); typhlosole xlvii–lxx, simple fold, 0.1–0.15 lumen diameter.
Intestine heavily vascularized xx–xxvii, less vascularized xxxi–xlv, xlvi; internal texture changes from rugose to smooth xlv, xlvi.
Hearts x–xiii esophageal, commissural vessels v–ix
lateral. Supra-esophageal vessel x–xvii, efferent parieto-esophageal vessels lacking, but vessels connecting
extraesophageal vessel to body wall present in each of
xiv–xvii, extra- esophageal vessels from vi to xiii, in
xiii fuse to single midventral vessel on ventral esophageal wall, entering esophageal wall xviii.
Nephridia present as peptonephridia on anterior
faces of 4/5, 5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 6–10 micronephridia per segment, 2
meganephridia per segment from xix posteriorly, the-
3
se attached to tubules adherent to either side of dorsal
vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca
with club-shaped ampulla, ampulla not sharply demarked from duct; simple club-shaped diverticulum joins
duct near body wall (Figure 1B). Male sexual system
holandric, testes and funnels enclosed in annular sacs
in x, xi, these sacs encompass hearts, seminal vesicles;
seminal vesicles xi, xii small, acinous; vasa deferentia very small, travel up prostatic ducts, adherent to
surface thereof until entering duct at most half-way to
male pore; each prostate racemose two- to four-lobed,
occupying xviii; with muscular duct; copulatory bursae
lacking.
Remarks. The efferent latero-parietal vessels of
most Megascolecidae are formed from the coalescence
of small vessels on the body wall of clitellar segments
to a single pair of vessels that join the extraesophageal
vessels or the esophageal wall, usually in the region of
segments xiii–xvi. In P. tiwiensis this arrangement is
not found, but instead there are four such paired connections to the extra-esophageals from the body wall of
clitellar segments xiv–xvii.
Pleionogaster tiwiensis is one of many species with
four intestinal gizzards in xxvii–xxx (Table 1). Among
those it has similar numbers of micronephridia in the
intestinal segments to P. viracensis and P. isarogensis.
However, P. viracensis is pigmented and has a more
posterior intestinal constriction, P. isarogensis lacks
paired genital markings, has a more posterior intestinal origin, a more anterior intestinal constriction, and
a single pair of latero-parietal vessels in xv rather than
four pairs.
Pleionogaster albayensis n. sp.
(Fig. 1 C, D)
Etymology. Named after the province of Albay in
which the species was found.
Type material. Holotype (NMA 004135): adult,
PTAGS 055, Albay Province, near Tiwi, montane forest on north ridge of Mt. Malinao, 13° 25.98’ N, 123°
37.63’ E, 850m asl, 10 May 2001, leg. S.W. James &
A. Castillo.
Description. Slight purplish-brown anterior-dorsal
tint, dusky strip along mid-dorsal line, otherwise unpigmented, body 94 mm x 2.7–3.2 mm (vii), 2.6–2.9
mm (xv), 3.0–3.7 mm (xxv); 159 + > 60 regenerated
segments, regenerates very small and asetal, thus hard
to count; body cylindrical in cross-section; segments
viii, ix biannulate, x–xiii triannulate, anterior half of
postclitellar segments triannulate. First dorsal pore
12/13; spermathecal pores paired in 7/8, 8/9, 0.2 circumference apart; female pore single in xiv, male pore
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
openings crescentic, paired in xviii on porophores tilted posteriorly, 0.18 circumference apart, 12 setae between male pores. Setae regularly distributed around
segmental equators; estimated at 148 setae on vii, 85
setae on xxv; no dorsal or ventral gaps. Clitellum annular xiv–xvii; genital markings paired presetal xvii,
paired 17/18, paired 18/19 in depression posterior to
male pores, paired 19/20, paired presetal xix, xx, unpaired midventral presetal xix (Figure 1C). Nephridiopores visible as gaps in setal rings and longitudinal
musculature of postclitellar segments, 12 pores per
segment in regular rows.
Septa 5/6–8/9 thick, muscular, 9/10 thinner, remainder membranous. Weak gizzard in viii with typical
iridescent outer wall but flaccid, esophagus valvular
xix, intestinal origin xx, no caeca; thick intestinal gizzards xxvii–xxx; typhlosole xlvii–lxxiii, simple low
fold. Intestine internal texture changes from rugose to
smooth xlv, coelomic fluid rich in oil within intestinal
segments.
Hearts x–xiii esophageal, commissural vessels v–ix
lateral. Supra-esophageal vessel xi–xvii, efferent parieto-esophageal vessels lacking, but vessels connecting
extraesophageal vessel to body wall present in each of
xiv–xvii, extra- esophageal vessels from vi to xiii, in
xiii fuse to single midventral vessel on ventral esophageal wall, entering esophageal wall xviii.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 12 micronephridia per segment, 2
meganephridia per segment from xix posteriorly, these attached to paired tubules adherent to either side of
dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca
with elongate club-shaped ampulla; simple club-shaped
diverticulum joins duct near body wall on medial side
rather than usual lateral side, slightly shorter than ampulla; no differentiation of duct from ampulla within
coelom. (Figure 1D). Male sexual system holandric,
testes and funnels enclosed in annular sacs in x, xi, these sacs encompass hearts, seminal vesicles; sacs formed of membranes connecting septa 9/10 and 10/11,
10/11 and 11/12; seminal vesicles xi, xii large, dense,
acinous; vasa deferentia small, adherent to ental half of
prostatic duct, then fuse with duct; few micronephridia surrounding duct-body wall contact; each prostate
racemose four-lobed, occupying xviii; with muscular
duct; copulatory bursae lacking.
Remarks. Other species with four intestinal gizzards
in xxvii–xxx and with dark pigmentation are P. bicolensis, P. ffitchae and P. viracensis. All of these have
more setae per segment, a more posterior intestinal
4
constriction, a more anterior intestinal origin, and the
first two lack midventral genital markings (Table 1).
Pleionogaster bicolensis n. sp.
(Fig. 1E, F)
Etymology. Named after the province of Bicol in
southern Luzon, because the species was collected in
several locations in this region.
Type material. Holotype (NMA 004136): adult,
PTAGS 056, Albay Province, Barangay Jarod, upper
montane forest on south ridge of Mt. Malinao, 13°
23.96’ N, 123° 37.16’ E, 1030m asl, 11 May 2001, leg.
S.W. James & A. Castillo. Paratypes: one adult (KUNHM 002176), one adult (UPLBMHN Z-NS-0083); collecting data as for holotype.
Other material. KUNHM 002177: 1 adult, PTAGS
055., Albay Province, near Tiwi, montane forest on
north ridge of Mt. Malinao, 13° 25.98’ N, 123° 37.63’
E, 850m asl, 10 May 2001, leg. S.W. James & A. Castillo. UPLBMNH Z-NS-0084: 1 adult, PTAGS 121,
Camarines Norte Province, Caramoan Peninsula, lowelevation forest on karst, 13° 44.40’ N, 123° 54.38’ E,
245m asl, 21 May 2001, leg. Y. Hong, M. Levi, P. Nillos. KUNHM 002178: 2 adults, PTAGS 122, Camarines Norte Province, Caramoan Peninsula, low-elevation forest on karst, 13° 45.29’ N, 123° 53.81’ E, 346m
asl, 22 May 2001, leg. Y. Hong, M. Levi, P. Nillos.
Description. Deep brown anterior dorsal pigmentation, body 155–293 mm x 5.5–6 mm (vii), 5.6–6.6
mm (xv), 5.6–6.8 mm (xxv); 340–370 segments, most
specimens amputees; body cylindrical in cross-section;
segment xi biannulate, triannulate xii–xxx exclusive of
clitellum. First dorsal pore 12/13; spermathecal pores
paired in 7/8, 8/9, 0.17 circumference apart, asetal sections ventrally near spermathecal pores viii, ix; female
pore single in xiv, male pore openings paired in xviii
on porophores tilted posteriorly into sunken male field
zone, 0.17 circumference apart, 8–10 setae between
male pores. Setae regularly distributed around segmental equators; estimated at 130–220 setae on vii,
132–140 setae on xxv; no ventral gaps, dorsal gaps ZZ:
YZ 2:1. Clitellum annular xiv–1/2xvii; genital markings paired presetal xvii, xix; paired 17/18 (Figure 1E).
Nephridiopores visible as gaps in setal rings and longitudinal musculature of postclitellar segments, 12 pores
per segment in regular rows.
Septa 5/6–9/10 thick, muscular, others membranous.
Weak gizzard in viii with typical iridescent outer wall
but flaccid; esophagus valvular xviii, intestinal origin
xix or xx, no caeca; thick intestinal gizzards xxvii–xxx;
typhlosole lacking. Intestine internal texture changes
from rugose to smooth at intestinal constriction lvii.
Hearts xi–xiii esophageal, x lateral, commissural
vessels v–ix lateral. Supra-esophageal vessel xi–xvii,
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
efferent parieto-esophageal vessels from body wall of
xv–xviii, intestinal segments to extraesophageal vessels in xv, segmental parietal vessel from body wall of
xiv to extraesophageal vessels xiv; extra- esophageal
vessels ventral-lateral to gut vi–xii, ventral to esophagus xiii–xviii, fuse to one midventral vessel xviii, enters esophageal wall at esophageal valve.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–xi, on body wall thereafter; from xviii 12 micronephridia per segment,
these connected to tubular sinus with connections to
nephridiopores; 2 meganephridia per segment from xix
posteriorly, these attached to paired tubules adherent to
either side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca with horn-shaped ampulla thinner-walled than stout
muscular duct; simple club-shaped diverticulum joins
duct near body wall, slightly shorter than spermathecal
duct (Figure 1F). Male sexual system holandric, testes and funnels enclosed in horseshoe-shaped sacs in
x, xi, these sacs encompass hearts, seminal vesicles;
sacs formed of membranes connecting septa 9/10 and
10/11, 10/11 and 11/12; seminal vesicles xi, xii small,
acinous; vasa deferentia slender, non-muscular; each
prostate racemose rounded mass occupying xviii; with
thick muscular duct; copulatory bursae lacking.
Remarks. Among Pleionogaster with four intestinal
gizzards in xxvii–xxx and dark pigmentation, P. bicolensis is most similar to P. ffitchae (Table 1). The lack
of a typhlosole, the more posterior intestinal constriction, and the different array of latero-parietal vessels
distinguish it from P. ffitchae. Distinction from P. albayensis is discussed under that species.
Pleionogaster bulusanensis n. sp.
(Fig. 1G, H)
Etymology. Named after the mountain on which the
species was discovered.
Type material. Holotype (NMA 004137): preclitellate adult, PTAGS 051, Sorsogon Province, Bulusan
National Park, dipterocarp forest at Bulusan Lake, 12°
45.32’ N, 124° 05.34’ E, 360m asl, 3 May 2001, leg.
S.W. James, A. Castillo, K. James, P. James. Paratype
(KUNHM 002179): 1 juvenile; collecting data as for
holotype.
Description. Unpigmented, body 105 mm X 4.6
mm (vii), 4.6 mm (xxv); 220 segments (anterior plus
posterior fragments of same worm), 317 segments in
complete juvenile; body cylindrical. First dorsal pore
11/12; spermathecal pores paired in 7/8, 8/9, 0.15 circumference apart; female pore single, male pore openings crescentic, paired in xviii on small porophores,
5
0.17 circumference apart, 20 setae between male pores;
clitellum not developed. Setae regularly distributed
around segmental equators; estimated 200 setae on vii,
144 setae on x, 120 setae on xxv; no dorsal, ventral
gaps. Genital markings paired presetal xvii, postsetal
xvii, paired presetal xix–xxi, all just medial to line of
male pores (Figure 1G). Nephridiopores visible as gaps
in setal rings, longitudinal musculature of postclitellar
segments, 14 pores per segment in regular rows.
Septa 5/6–8/9 thick, muscular, 9/10 thinner, muscular, remainder membranous. Weak gizzard in viii with
typical iridescent outer wall but flaccid, esophagus
valvular xix, intestinal origin xx, no caeca; thick intestinal gizzards xxvii–xxx; typhlosole lacking; intestine
constricted lv, thereafter coated with brown chloragogen layer.
Hearts x–xiii lateral-esophageal with very small connections to dorsal vessel, commissural vessels vii–ix
lateral; supra-esophageal vessel x–xvii, extra-esophageal vessels not traceable past viii.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 14 micronephridia per segment, two
meganephridia per segment from xix posteriorly, these
attached to paired ureters adherent to either side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca blunt lanceolate ampulla, poorly differentiated duct;
narrow digitate diverticulum half or less length of main
spermathecal axis joins duct near body wall (Figure
1H). Male sexual system holandric, testes and funnels
enclosed in annular sacs in x, xi, these sacs encompass
hearts, dorsal vessel, seminal vesicles; sacs formed of
membranes connecting septa 9/10 and 10/11, 10/11 and
11/12; seminal vesicles xi, xii slender arcs; each prostate racemose four- to five-lobed occupying xviii; duct
muscular; vas deferens slender, non-muscular, joins
ental end of prostatic duct but visible within duct wall
over ental 2/3; copulatory bursae lacking.
Remarks. The arc-shaped seminal vesicles are unusual. This species has a very large number of micronephridia per segment, relative to its body size. Other
small-bodied species reported here tend to have low
numbers of micronephridia (4–6 per segment), whereas
large numbers (10–12) have been found in large-bodied species such as P. bicolensis. This indicates that the
number of micronephridia may be size-related in most
but not all species. The genital markings are more numerous and placed farther back in P. bulusanensis than
in most other species encountered so far. Of those unpigmented Pleionogaster with four intestinal gizzards
in xxvii–xxx, it is the only species without a typhlosole
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
and has the posteriormost intestinal constriction (Table
1).
Pleionogaster hongi n. sp.
(Fig. 1I, J)
Etymology. Named after Dr. Hong Yong, a Korean
earthworm specialist who is part of the PTAGS research team.
Type material. Holotype (NMA 004138): adult,
PTAGS 051, Sorsogon Province, Bulusan National
Park, dipterocarp forest at Bulusan Lake, 12° 45.32’ N,
124° 05.34’ E, 360m asl, 3 May 2001, leg. S.W. James,
A. Castillo, K. James, P. James. Paratype (KUNHM
002180): adult; collecting data as for holotype.
Description. Faint pink anterior dorsal pigment,
body 84, 87 mm x 3–3.5 mm (vii), 2.9–3.2 mm (xv),
3–3.4 mm (xxv); 190, 189 + 49 regenerated segments;
body cylindrical. First dorsal pore 11/12; spermathecal
pores paired in 7/8, 8/9, 0.18–0.19 circumference apart;
female pore single, male pore openings crescentic,
paired in xviii on small porophores facing posteriorly
in sunken male field, 0.18–0.19 circumference apart,
10–12 setae between male pores; clitellum xiv–1/2xvii,
annular. Setae regularly distributed around segmental
equators; estimated 176 setae on vii, 104 setae on x,
80 setae on xxv; no dorsal, ventral gaps. Genital markings paired presetal xvii, 17/18, xix–xxi (Figure 1I).
Nephridiopores visible as gaps in setal rings, longitudinal musculature of postclitellar segments, 12 pores per
segment in regular rows.
Septa 5/6–8/9 thick, muscular, 9/10, 10/11 thinner,
muscular, remainder membranous. Weak gizzard in
viii with typical iridescent outer wall but flaccid, esophagus valvular xix, intestinal origin xx, no caeca; intestine vascularized xx–xxvi, thick intestinal gizzards
xxvii–xxx; typhlosole simple fold ¼ lumen diameter
xlvi–lxviii; intestine constricted 44/45, thereafter coated with brown chloragogen layer.
Hearts x–xiii esophageal, commissural vessels vi–ix
lateral; supra-esophageal vessel x–xvii, extra-esophageal vessels not traceable past viii, vessels from ventral
esophagus xiv to body wall xv–xvii, paired longitudinal vessels on body wall xviii–xxiv.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 12 micronephridia per segment, two
stomate meganephridia per segment from xix posteriorly, these attached to paired ureters adherent to either
side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca cylindrical ampulla, poorly differentiated duct;
club-shaped diverticulum half or less length of main
spermathecal axis joins duct near body wall (Figure
6
1J). Male sexual system holandric, testes and funnels
enclosed in annular sacs in x, xi, these sacs encompass
hearts, dorsal vessel, seminal vesicles; sacs formed of
membranes connecting septa 9/10 and 10/11, 10/11 and
11/12; seminal vesicles xi, xii slender arcs; each prostate racemose five-lobed occupying xviii; ectal 1/3 duct
muscular; vas deferens slender, non-muscular, joins
ental end of prostatic duct but visible within duct wall
over ental 2/3; copulatory bursae lacking.
Remarks. The closest morphologically is P. bulusanensis, but P. hongi has pink pigmentation (versus
brown in the other pigmented Bicol species), half as
many setae between the male pores, an intestinal transition anterior to that of P. bulusanensis, and a typhlosole (Table 1).
Pleionogaster ffitchae n. sp.
(Fig. 2A, B)
Etymology. Named after Jana ffitch, who as an undergraduate student participated in the fieldwork and
initial cataloguing of the 2001 expedition collections.
Type material. Holotype (NMA 004139): adult,
PTAGS 060, Camarines Sur Province, montane forest
on Mt. Isarog, 13° 39.90’ N, 123° 21.89’ E, 1100m asl,
14 May 2001, leg. Y. Hong, M. Levi, J. ffitch, P. Nillos,
R. Abiada. Paratype (KUNHM 002181): adult; collecting data as for holotype.
Other material. UPLBMNH Z-NS-0085: adult,
PTAGS 066, Camarines Sur Province, lower montane
forest soils on Mt. Isarog, 13° 40.02’ N, 123° 21.16’
E, 920m asl, 17 May 2001, leg. S.W. James, Y. Hong,
M. Levi, J. ffitch, P. Nillos, D. Franke, R. Abiada, R.
Lazaro. KUNHM 002182: adult, PTAGS 069, Catanduanes Province, low-elevation forest north of Barangay Summit, Buradan, 13° 46.0’ N, 124°16.0’ E, 275m
asl, 22 May 2001, leg. S.W. James, P. James, J. James,
K. James, J. ffitch, A. Castillo.
Description. Medium milky brown dorsal pigment,
fading gradually towards tail, body 194, 170, 142 (amputee) mm x 4.5–6 mm. (vii), 4.7–4.9 mm (xv), 4.6–5.8
mm (xxv); 285, 352, 210 (amputee) segments; body
cylindrical. First dorsal pore 11/12, 12/13; spermathecal pores paired in 7/8, 8/9, 0.18–0.19 circumference
apart bordered by thick lips on trailing edges of vii, viii,
smaller lips on leading edges of viii, ix; female pore
single, male pore openings crescentic, paired in xviii
on small porophores facing posteriorly in sunken male
field, 0.16–0.17 circumference apart, 8 setae between
male pores; clitellum xiv–1/2xvii, annular. Setae regularly distributed around segmental equators; estimated
212–226 setae on vii, 150–170 setae on x, 100–110 setae on xxv; dorsal gaps variable ZZ = YZ, up to 2.5
YZ, ventral gaps AA:AB 1.5:1. Genital markings oval,
paired, presetal xvii, rectangular paired 17/18, oblong,
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
paired presetal xix–xxi (Figure 2A). Nephridiopores
visible as gaps in setal rings, longitudinal musculature
of postclitellar segments, 12 pores per segment in regular rows.
Septa 5/6–9/10 thick, muscular, 10/11–16/17 tough
but transparent, remainder membranous. Weak gizzard in viii with typical iridescent outer wall but flaccid, esophagus valvular xviii, intestinal origin xix, no
caeca; intestine vascularized xix–xxvi, thick intestinal
gizzards xxvii–xxx; typhlosole simple fold 1/6 lumen
diameter 50/51 (1), liv (1)–lxxvii; intestine constricted
xlix (1), 52/53 (1), thereafter coated with brown chloragogen layer.
Hearts x–xiii esophageal, commissural vessels vi–ix
lateral; supra-esophageal vessel x–xvii, extra-esophageal vessels traced from iii–ix, then on ventral esophageal surface x–xvi, segmental paired vessels from
ventral esophagus xiii to body wall xiv–xvi, those of
xvi connect to paired longitudinal vessels on body wall
xviii–cv.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 12 micronephridia per segment, two
stomate meganephridia per segment from xix posteriorly, these attached to paired ureters adherent to either
side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca long lanceolate ampulla, duct of similar structure;
short basally-attached diverticulum (Figure 2B). Male
sexual system holandric, testes and funnels enclosed
in annular sacs in x, xi, these sacs encompass hearts,
dorsal vessel, seminal vesicles; some individuals with
U-shaped dorsally open sac in x; sacs formed of membranes connecting septa 9/10 and 10/11, 10/11 and
11/12; seminal vesicles xi, xii, thick ventral half, upper portion slender arc; prostates racemose five-lobed
occupying xviii; duct muscular; vas deferens slender,
non-muscular; copulatory bursae lacking. Genital marking glands sessile, dense xvii–xxi corresponding in
placement to external markings.
Remarks. Pleionogaster ffitchae is most similar to
P. bicolensis; differences are discussed under the latter
species.
Pleionogaster viracensis n. sp.
(Fig. 2C, D)
Etymology. Named after Virac, the capitol city of
Catanduanes Province and the large town nearest to the
type locality.
Type material. Holotype (NMA 004140): adult,
PTAGS 068, Catanduanes Province, low-elevation
forest near Barangay Summit, Buradan, 13° 43.60’
7
N, 124° 17.14’ E, 210m asl, 21 May 2001, leg. S.W.
James, P. James, J. James, K. James, J. ffitch, A. Castillo. Paratype (KUNHM 002183): adult; collecting data
as for holotype.
Other material. UPLBMNH Z-NS-0086: adult,
PTAGS 069, Catanduanes Province, low-elevation forest north of Barangay Summit, Buradan, 13° 46’ N,
124°16’ E, 275m asl, 22 May 2001, leg. S.W. James,
P. James, J. James, K. James, J. ffitch, A. Castillo.
UPLBMNH Z-NS-0087: adult, PTAGS 071, Catanduanes Province, lower riparian forest near Barangay
San Miguel, Pangabinan, 13° 54.50 N, 124° 11 E,
212m asl, 23 May 2001, leg. S.W. James, J. ffitch, A.
Castillo.
Description. Medium brown anterior dorsal pigment, diminishing to mid-dorsal stripe in post-clitellar
segments, body 107–140 mm x 4–4.6 mm (vii), 3.1–3.8
mm (xv), 4.2–4.5 mm (xxv); 260–279 segments; body
cylindrical. First dorsal pore 11/12; spermathecal pores
paired in 7/8, 8/9, 0.13 circumference apart surrounded
by thickened area about 2 mm wide from 1/2vii–1/2ix;
female pore single, male pore openings crescentic,
paired in xviii on small porophores facing posteriorly
in sunken male field, 0.16–0.17 circumference apart,
10 setae between male pores; clitellum xiv–1/2xvii,
annular. Setae regularly distributed around segmental
equators; estimated 182–226 setae on vii, 150–160 setae on x, 138–146 setae on xxv; dorsal gaps variable ZZ
= YZ, up to 1.5 YZ, no ventral gaps. Genital markings
oval, paired, presetal xvii, rectangular paired 17/18,
oblong, paired presetal xix–xxi, midventral at equator
xviii (Figure 2C). Nephridiopores visible as gaps in setal rings, longitudinal musculature of postclitellar segments, 10 pores per segment in regular rows.
Septa 5/6–7/8 thick, muscular, 8/9 thinly muscled,
9/10–16/17 membranous. Weak gizzard in viii with
typical iridescent outer wall but flaccid, esophagus
valvular xviii, intestinal origin xix, no caeca; intestine
vascularized xix–xxvi, thick intestinal gizzards xxvii–
xxx; typhlosole very low fold lii–lxcii, full size by lvi;
intestine constricted lii (1), lvi (2), thereafter coated
with brown chloragogen layer.
Hearts x–xiii esophageal, commissural vessels vi–ix
lateral; supra-esophageal vessel x–xvii, extra-esophageal vessels traced from iii–ix, then on ventral esophageal surface x–xvii, segmental paired vessels from
body wall to extra-esophageal vessels xiv; posterior latero-parietals to extra-esophageals xv, these connect to
paired longitudinal vessels on body wall xviii–cv.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 10 micronephridia per segment, two
stomate meganephridia per segment from xix posteri-
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
orly, these attached to paired ureters adherent to either
side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca broad club-shaped ampulla with very short slightly
differentiated muscular duct; short basally-attached
diverticulum (Figure 2D). Male sexual system holandric, testes and funnels enclosed in annular sacs in x,
xi, these sacs encompass hearts, seminal vesicles; slender arcuate seminal vesicles xi, xii; prostates racemose
three- to four-lobed occupying xviii; duct muscular;
vas deferens slender, non-muscular; copulatory bursae
lacking.
Remarks. Among the brown-pigmented Pleionogaster with four intestinal gizzards in xxvii–xxx (Table 1),
P. viracensis is most similar to P. albayensis and P.
ffitchae. Pleionogaster albayensis has a lower number
of setae and more anterior locations of the intestinal
origin and constriction; P. ffitchae lacks mid-ventral
genital markings, has more micronephridia per intestinal segment, and three pairs of latero-parietal vessels
rather than two.
Pleionogaster isarogensis n. sp.
(Fig. 2E, F)
Etymology. Named for Mt. Isarog, on which the species was found over a wide elevational range.
Type material. Holotype (NMA 004141): adult,
PTAGS 065, Camarines Sur Province, upper montane
forest soils on Mt. Isarog, 13° 39.75’ N, 123° 21.98’ E,
1500m asl, 16 May 2001, leg. S.W. James, Y. Hong, M.
Levi, J. ffitch, P. Nillos, R. Abiada, R. Lazaro. Paratypes:
3 adults (KUNHM 002184), 4 adults (UPLBMNH ZNS-0088); collecting data as for holotype.
Other material. UPLBMNH Z-NS-0089: 2 adults,
PTAGS 059, Camarines Sur Province, soils of montane forest on Mt. Isarog, 13° 39.79’ N, 123° 21.79’ E,
1330m asl, 13 May 2001, leg. S.W. James, Y. Hong,
M. Levi, J. ffitch, D. Franke, P. Nillos, R. Abiada, R.
Lazaro. KUNHM 002186: 2 adults, PTAGS 060, Camarines Sur Province, montane forest on Mt. Isarog,
13° 39.90’ N, 123° 21.89’ E, 1100m asl, 14 May 2001,
leg. Y. Hong, M. Levi, J. ffitch, P. Nillos, R. Abiada.
UPLBMNH Z-NS-0090: 1 adult, PTAGS 061, Camarines Sur Province, mossy forest soils at summit of Mt.
Isarog, 13° 39.65’ N, 123° 22.28’ E, 1987m asl, 15
May 2001, leg. S.W. James, Y. Hong, M. Levi, J. ffitch,
P. Nillos, R. Abiada, R. Lazaro. KUNHM 002187: 1
juvenile, PTAGS 062, Camarines Sur Province, in organic mats in mossy forest at summit of Mt. Isarog, 13°
39.65’ N, 123° 22.28’ E, 1987m asl, 15 May 2001, leg.
S.W. James, Y. Hong, M. Levi, J. ffitch, P. Nillos, R.
Abiada, R. Lazaro. UPLBMNH Z-NS-0091: 2 adults,
PTAGS 064, Camarines Sur Province, upper montane
8
forest soils on Mt. Isarog, 13° 39.70’ N, 123° 22.07’ E,
1745m asl, 16 May 2001, leg. S.W. James, Y. Hong,
M. Levi, J. ffitch, D. Franke, P. Nillos, R. Abiada, R.
Lazaro. KUNHM 002188: 2 adults, PTAGS 066, Camarines Sur Province, lower montane forest soils on
Mt. Isarog, 13° 40.02’ N, 123° 21.16’ E, 920m asl, 17
May 2001, leg. S.W. James, Y. Hong, M. Levi, J. ffitch,
P. Nillos, D. Franke, R. Abiada, R. Lazaro.
Description. Unpigmented, body 75–165 mm x
2.7–3.2 mm (vii), 2.2–3.0 mm (xv), 2.8–3.3 mm (xxv);
275–294 segments; body cylindrical. First dorsal pore
12/13; spermathecal pores paired in 7/8, 8/9, 0.09–0.11
circumference apart deep in furrows; female pore single, male pore openings crescentic, paired in xviii on
small porophores, 0.11–0.12 circumference apart, 4–8
setae between male pores; clitellum xiv–1/2xvii, annular. Setae regularly distributed around segmental equators; estimated 170–186 setae on vii, 110–120 setae on
x, 72–84 setae on xxv; asetal zones midventral in one
or more of vii–ix. Genital markings oval, midventral,
presetal xvii, xix, xx (all), some with additional midventral GM xviii, epidermal thickenings ventral xxi,
xxii; (Figure 2E). Nephridiopores visible as gaps in setal rings, longitudinal musculature of postclitellar segments, 6 pores per segment in regular rows.
Septa 5/6–8/9 thick, muscular, 9/10 thinner, remainder membranous. Weak gizzard in viii with typical iridescent outer wall, esophagus valvular xviii, intestinal
origin xx, no caeca; intestine vascularized xx–xxvi,
thick intestinal gizzards xxvii–xxx with small vascular network on anterior thin-walled half of gut in each
giceriate segment; typhlosole simple fold 1/3 lumen
diameter for first ten segments, then only 1/6 lumen
diameter from xli, xliii–lxxviii; intestine constricted
40/41 or 41/42.
Hearts x–xiii esophageal, commissural vessels
vii–ix lateral; supra-esophageal vessel x–xvii, extraesophageal with branch from body wall of xiv, efferent posterior latero-parietal vessels travel up 15/16
to extra-esophageal vessel in xvi, these connected to
paired longitudinal vessels on body wall xviii–lviii; not
always visible past xxx.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 6–8 micronephridia per segment, two
stomate meganephridia per segment from xix posteriorly, these attached to paired ureters adherent to either
side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca ovate ampulla; short basally-attached diverticulum
(Figure 2F). Male sexual system holandric, testes and
funnels enclosed in annular sac in x, U-shaped sac
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
open dorsally in xi, these sacs encompass hearts, dorsal vessel, seminal vesicles; sacs formed of membranes
connecting septa 9/10,10/11; 10/11, 11/12; seminal
vesicles xi, xii, loosely acinous; prostates racemose
three- to four-lobed occupying xviii; ectal 1/3 duct
muscular; vas deferens slender, non-muscular; copulatory bursae lacking.
Remarks. Compared to other unpigmented Pleionogaster with four intestinal gizzards in xxvii–xxx, P.
isarogensis has fewer setae per segment than P. bulusanensis and P. tiwiensis, more narrowly spaced
male and spermathecal pores than P. bulusanensis,
and consistently fewer micronephridia in the intestinal segments as well as a more anterior location of the
intestinal constriction than both those species (Table
1). While P. tiwiensis has both midventral and paired
genital markings, and P. bulusanensis has only paired
markings, P. isarogensis has only midventral genital
markings.
Pleionogaster malinaoensis n. sp.
(Fig. 2G, H)
Etymology. Named after the mountain on which the
material was collected.
Type material. Holotype (NMA 004142): adult,
PTAGS 055, Albay Province, near Tiwi, montane forest on north ridge of Mt. Malinao, 13° 25.98’ N, 123°
37.63’ E, 850m asl, 10 May 2001, leg. S.W. James & A.
Castillo. Paratype (KUNHM 002189): adult; collecting
data as for holotype.
Other material. KUNHM 002190: 2 adults, PTAGS
056, Albay Province, Barangay Jarod, upper montane forest on south ridge of Mt. Malinao, 13° 23.96’
N, 123° 37.16’ E, 1030m asl, 11 May 2001, leg. S.W.
James and A. Castillo.
Description. Unpigmented, body 97–110 mm x
2.8–3.2 mm (vii), 2.6–3.4 (xv), 3.5–4 mm (xxv); 227
segments, most specimens amputees; body cylindrical
in cross-section; segments x–xiii triannulate, postclitellar segments faintly triannulate in anterior half. First
dorsal pore 12/13; spermathecal pores paired in 7/8,
8/9, 0.10 circumference apart, female pores single in
xiv, male pores crescentic paired in xviii on raised porophores, 0.09 circumference apart, 2–4 setae between
male pores. Setae regularly distributed around segmental equators; estimated at 150–160 setae on vii, setal
density drops in ix, 100 setae on xxv; in vii no dorsal
or ventral gaps, in xxv ZZ:YZ = 2, no ventral gap. Clitellum annular 1/2xiii, xiv–1/2xvii; genital markings
broad midventral ix (1), x slightly wider than spermathecal pore spacing; midventral round white area xv
(1) triangular pad xvi, paired presetal in line with male
pores xix–xxii, or in less well developed specimens
midventral epidermal thickenings on xxii–xxiii (Fig-
9
ure 2G). Nephridiopores visible as gaps in setal rings
and longitudinal musculature of postclitellar segments,
apparently 10–12 pores per segment but not always in
regular rows.
Septa 5/6–8/9 thick, muscular, 9/10 thinner, remainder membranous. Weak gizzard in viii with typical
iridescent outer wall but flaccid, esophagus valvular
xviii, intestinal origin xix or xx (1), no caeca; thick intestinal gizzards xxv–xxix; typhlosole xlv, xlvii–lxiii,
lxvii, lxxv simple fold, 0.1 lumen diameter. Intestine
internal texture changes from rugose to smooth xliii,
43/44, xlvi.
Hearts x–xiii esophageal, commissural vessels v–ix
lateral. Supra-esophageal vessel x–xvi, efferent parieto-esophageal vessels lacking, but vessels connecting
extraesophageal vessel to body wall present in each of
xiv–xvii, extra- esophageal vessels from vi to xiii, in
xiii fuse to single midventral vessel on ventral esophageal wall, entering esophageal wall xviii.
Nephridia present as peptonephridia on anterior
face septum 5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 10–12 micronephridia per segment, 2
meganephridia per segment from xix posteriorly, these attached to tubules adherent to either side of dorsal
vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca
with ovate ampulla differentiated from narrower duct;
simple club-shaped diverticulum joins duct near body
wall, slightly longer than spermathecal duct (Figure
2H). Male sexual system holandric, testes and funnels
enclosed in annular sacs in x, xi, these sacs encompass
hearts, seminal vesicles; sacs formed of membranes
connecting septa 9/10 and 10/11, 10/11 and 11/12; seminal vesicles xi, xii small, acinous; vasa deferentia
slender, non-muscular; each prostate racemose multilobed, occupying xviii; with slender muscular duct;
copulatory bursae lacking.
Remarks. Other species with five gizzards in xxv–
xxix are P. sorsogonensis and potentially P. castilloi from the same mountain (Table 2). Pleionogaster
malinaoensis has more intestinal micronephridia and
more narrowly spaced male and spermathecal pores
than those two species. Pleionogaster castilloi (see
below) lacks paired genital markings; P. sorsogonensis has preclitellar genital markings. The former has a
more posterior intestinal origin, the latter a more anterior typhlosolar origin and spermathecal ampullae
undifferentiated from the ducts. One individual from
PTAGS055 had large numbers of small yellow nematodes under the peritoneum on the inner body wall surface from xii and posteriorly.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
Pleionogaster castilloi n. sp.
(Fig. 2I, J)
Etymology. Named after Augusto Castillo, one of
the PTAGS logistics coordinators, who discovered unknown reserves of strength climbing the crater wall of
Mt. Malinao.
Type material. Holotype (NMA 004143): adult,
PTAGS 055, Albay Province, near Tiwi, montane forest on north ridge of Mt. Malinao, 13° 25.98’ N, 123°
37.63’ E, 850m asl, 10 May 2001, leg. S.W. James & A.
Castillo. Paratype (KUNHM 002191): adult; collecting
data as for holotype.
Other material. KUNHM 002192: 3 adults, PTAGS
056, Albay Province, Barangay Jarod, upper montane forest on south ridge of Mt. Malinao, 13° 23.96’
N, 123° 37.16’ E, 1030m asl, 11 May 2001, leg. S.W.
James and A. Castillo.
Description. Unpigmented, body 93–113 mm x
2.7–3.2 mm (vii), 2.6–2.9 mm (xv), 3.0–3.7 mm (xxv);
220–234 segments, most specimens amputees; body
cylindrical in cross-section; segments x–xiii biannulate,
anterior half of postclitellar segments triannulate. First
dorsal pore 11/12, 12/13; spermathecal pores paired
in 7/8, 8/9, 0.17 circumference apart, surrounded by
thickened lips; female pores paired in xiv, male pore
openings crescentic, paired in xviii on porophores tilted posteriorly, slightly depressed, 0.17 circumference
apart, 6–8 setae between male pores. Setae regularly
distributed around segmental equators; estimated at
160–166 setae on vii, 70–80 setae on xxv; no dorsal or
ventral gaps. Clitellum annular 1/3xiii–1/2xvii; genital
markings broad midventral 17/18, 18/19, 19/20; long
shallow indentations in raised areas, somewhat like
the fusion of paired indented genital markings; midventral epidermal thickenings on xxi–xxii (Figure 2I).
Nephridiopores visible as gaps in setal rings and longitudinal musculature of postclitellar segments, 6 pores
per segment in regular rows.
Septa 5/6–8/9 thick, muscular, 9/10 thinner, remainder membranous. Weak gizzard in viii with typical iridescent outer wall but flaccid, esophagus valvular xix,
intestinal origin xx, no caeca; thick intestinal gizzards
xxv–xxix, xxv–xxxi, xxvi–xxx, xxvi–xxx, xxvi–xxxi;
typhlosole xlvii, xlviii–lxviii, lxx, lxvii, lxxv simple
fold, 0.16 lumen diameter. Intestine internal texture
changes from rugose to smooth xlvii, 45/46 (3), 47/48
(2); intestinal wall vascularized xxxii–xlvii.
Hearts x–xiii esophageal, commissural vessels v–ix
lateral. Supra-esophageal vessel x–xviii, efferent parieto-esophageal vessels lacking, but vessels connecting
extraesophageal vessel to body wall present in each of
xiv–xvii, extra- esophageal vessels from vi to ix where
they enter dorsal esophageal wall, in xiii fuse to single
10
midventral vessel on ventral esophageal wall, entering
esophageal wall xviii.
Nephridia present as peptonephridia on anterior faces
septa 4/5/6, micronephridia preseptal clustered around
commissural vessels vi–ix, on body wall thereafter;
from xix 6 micronephridia per segment, 2 meganephridia per segment from xix posteriorly, these attached to
tubules adherent to either side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca
with sagittate ampulla thinner-walled than duct; simple club-shaped diverticulum joins duct near body wall,
slightly shorter than spermathecal duct (Figure 2J).
Male sexual system holandric, testes and funnels enclosed in annular sacs in x, xi, these sacs encompass
hearts, seminal vesicles; sacs formed of membranes
connecting septa 9/10 and 10/11, 10/11 and 11/12; seminal vesicles xi, xii small, acinous; vasa deferentia
slender, non-muscular, adherent to ental 2/3 or more of
prostatic duct, then fuse with duct; patch of micronephridia surrounding duct-body wall contact; each prostate
racemose rounded mass, occupying xviii; with muscular duct entering small muscular bulge at body wall;
copulatory bursae lacking.
Remarks. This species is characterized by six micronephridia per segment, at the low end of the range, and
relatively many intestinal gizzards, the number ranging
from 5 to 7. The PTAGS 055 specimens from the north
ridge of Mt. Malinao all had 5 gizzards and the intestinal transition at 45/46, rather than 6 or 7 gizzards and
the intestinal transition at 47/48 as seen in the south
ridge material (PTAGS 056). I have chosen to include
these in one species based on the common number of
micronephridia and the similarity in male field genital
marking pattern. Distinction between P. castilloi and P.
malinaoensis has been discussed under the latter species. The next most similar species is P. sorsogonensis,
from which P. castilloi can be distinguished by the lack
of preclitellar and paired postclitellar genital markings,
the more posterior intestinal constriction, and a greater
number of setae (Table 2).
Pleionogaster nillosae n. sp.
(Fig. 3A, B)
Etymology. Named after Portia Nillos, one of the
PTAGS logistics coordinators.
Type material. Holotype (NMA 004144): preclitellate adult, PTAGS 122, Camarines Norte Province,
Caramoan Peninsula, low-elevation forest on karst,
13° 45.29’ N, 123° 53.81’ E, 346m asl, 22 May 2001,
leg. Y. Hong, M. Levi, P. Nillos. Paratype (KUNHM
002193): juvenile; collecting data as for holotype.
Description. Unpigmented, body 250 mm (extended) x 5 mm (vii), 4.5 mm (xxv); 330 segments; body
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
cylindrical in cross-section; postclitellar segments triannulate. First dorsal pore 12/13; spermathecal pores
paired in 7/8, 8/9, 0.2 circumference apart; female pore
not seen, male pore openings crescentic, paired in xviii
on small flat porophores, 0.18 circumference apart, no
setae between male pores. Setae regularly distributed
around segmental equators; estimated at 314 setae on
vii, 140 setae on xxv; no dorsal or ventral gaps. Genital
markings faint, paired presetal xvii, xix; slight thickening of epidermis over ventral surface of vii–ix (Figure
3A). Nephridiopores visible as gaps in setal rings of
postclitellar segments, 10 pores per segment in regular
rows.
Septa 5/6–9/10 thick, muscular, 10/11, 11/12 thinner,
remainder membranous. Weak gizzard in viii with typical iridescent outer wall but flaccid, esophagus valvular
xix, intestinal origin xx, no caeca; six thick intestinal
gizzards xxiv–xxix; typhlosole lacking. Intestinal transition obscured by poor preservation, in l–lv region.
Hearts xi–xiii esophageal, commissural vessels v–x
lateral. Supra-esophageal vessel xi–xvii, efferent parieto-esophageal vessels not seen due to damage; segmental parietal vessel from body wall of xiv to extraesophageal vessels xiv; extra-esophageal vessels not seen
anteriorly, fused mid-ventral below esophagus xiii–xx.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 8–10 micronephridia per segment, 2
meganephridia per segment from xix posteriorly, these
attached to paired ureters adherent to either side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca with elongate horn-shaped ampulla, muscular duct;
simple club-shaped diverticulum joins duct near body
wall, much shorter than ampulla (Figure 3B). Male sexual system holandric, testes and funnels enclosed in
annular sacs in x, xi, these sacs encompass hearts, seminal vesicles; sacs formed of membranes connecting
septa 9/10 and 10/11, 10/11 and 11/12; seminal vesicles
xi, xii slender arches; each prostate racemose hemispherical mass occupying xviii; with muscular S-curved
duct; copulatory bursae lacking, slight glandular development posterior to prostatic duct unions with body
wall, suggestive of genital marking glands.
Remarks. Better characterization of this large, unpigmented species was prevented by the poor state of
preservation and by immaturity of the limited material
obtained. For the time being it can be distinguished by
its large size, comparable to P. bicolensis but lacking
pigmentation, having fewer micronephridia per segment, more setae per segment but none between the
male pores, more gizzards (6) more anteriorly placed,
11
more anterior intestinal constriction, and different testes sacs (Table 2). The faint genital markings may be
due to immaturity.
Pleionogaster caramoanensis n. sp.
(Fig. 3C, D)
Etymology. Named for the Caramoan Peninsula on
the eastern side of Bicol.
Type material. Holotype (NMA 004145): adult,
PTAGS 123, Camarines Norte Province, Caramoan
Peninsula, low-elevation forest on karst, 13° 41.77’ N,
123° 54.02’ E, 350m asl, 23 May 2001, leg. Y. Hong,
M. Levi, P. Nillos. Paratype (KUNHM 002194): adult;
collecting data as for holotype.
Other material. UPLBMNH Z-NS-0092: 2 adults,
PTAGS 121, Camarines Norte Province, Caramoan
Peninsula, low-elevation forest on karst, 13° 44.40’ N,
123° 54.38’ E, 245m asl, 21 May 2001, leg. Y. Hong,
M. Levi, P. Nillos. KUNHM 002195: 1 adult, PTAGS
128, Camarines Norte Province, Caramoan Peninsula,
low-elevation forest on karst 13° 46.09’ N, 123° 55.08’
E, 31m asl, 24 May 2001, leg. Y. Hong, M. Levi, P.
Nillos.
Description. Unpigmented, body 35–52 mm x
2–2.2 mm (vii), 2.1–2.4 mm (xv), 2.1–2.6 mm (xxv);
123–206 segments; body cylindrical to slightly oval
in cross-section. First dorsal pore 12/13; spermathecal
pores paired in 7/8, 8/9, 0.13 circumference apart; female pore single, male pore openings crescentic, paired
in xviii on small flat porophores, 0.15 circumference
apart, 6 setae between male pores; clitellum annular
xiv–xvii. Setae regularly distributed around segmental
equators; estimated 170–250 setae on vii, 110–160 setae on x, 82–100 setae on xxv; no dorsal gaps, ventral
gaps AA:AB = 2.5:1. Genital markings paired presetal,
lateral to male pores xix, thickened white areas across
ventral surface xix–xxi (Figure 3C). Nephridiopores
visible as gaps in setal rings, longitudinal musculature
of postclitellar segments, 4 pores per segment in regular rows.
Septa 5/6–9/10 thick, muscular, 10/11 thinner, remainder membranous. Weak gizzard in viii with typical iridescent outer wall but flaccid, esophagus valvular
xviii (4), xix (1), intestinal origin 1/2xix (1), xix (4),
no caeca; thick intestinal gizzards xxvii–xxix (1) or
xxvi–xxviii (4); typhlosole low fold xxxix, xl–lviii. Intestine vascularized xix–xxvi, constricted xxxviii (1),
xxxix (4).
Hearts x–xiii esophageal, commissural vessels ix
lateral; vii, viii divide into several small vessels, apparently none reaching ventral vessel. Supra-esophageal
vessel x–xvi, extra-esophageal vessels form from several smaller vessel in iii, iv, branches dorsally to supra-esophageal vessel in ix, other branch along ventral
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
esophageal wall to connect with efferent parieto-esophageal vessels from body wall of xvi, xvii.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 4–6 micronephridia per segment, 2
meganephridia per segment from xix posteriorly, these
attached to paired ureters adherent to either side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca with blunt cylindrical ampulla, clearly differentiated
muscular duct; simple club-shaped diverticulum half or
more length of main spermathecal axis joins duct near
body wall via differentiated stalk, (Figure 3D). Male
sexual system holandric, testes and funnels enclosed in
annular sacs in x, xi, these sacs encompass hearts, dorsal vessel, seminal vesicles; sacs formed of membranes
connecting septa 9/10 and 10/11, 10/11 and 11/12; seminal vesicles xi, xii loosely acinous; each prostate racemose four-lobed occupying xviii; duct not muscular;
vas deferens join prostatic duct one third distance from
gland to body wall; copulatory bursae lacking.
Remarks. Pleionogaster caramoanensis is a smallbodied species with only three intestinal gizzards and
only four micronephridia per intestinal segment. The
other species with low numbers of nephridia are P. sorsogonensis and P. isarogensis; both have many fewer
setae per segment, and more gizzards (Tables 1, 2). The
former has preclitellar genital markings, the latter only
postclitellar midventral markings, whereas P. caramoanensis has only postclitellar paired markings.
Pleionogaster sorsogonensis n. sp.
(Fig. 3E, F)
Etymology. Named after the province that includes
the type locality.
Type material. Holotype (NMA 004146): adult,
PTAGS 051, Sorsogon Province, Bulusan National
Park, dipterocarp forest at Bulusan Lake, 12° 45.32’ N,
124° 05.34’ E, 360m asl, 3 May 2001, leg. S.W. James,
A. Castillo, K. James, P. James.
Description. Unpigmented, body 46 mm x 2.3 mm
(vii), 2.6 mm (xxv); 117 segments (amputee); body cylindrical. First dorsal pore 13/14; spermathecal pores
paired in 7/8, 8/9, 0.11 circumference apart; female
pore not seen, male pore openings crescentic, paired
in xviii on small porophores, 0.15 circumference apart,
2 setae between male pores; clitellum not developed.
Setae regularly distributed around segmental equators;
estimated 120 setae on vii, 114 setae on x, 72 setae on
xxv; no dorsal, ventral gaps. Genital markings midventral 10/11, 11/12, xvi, xx–xxii; paired xvii, xix (Figure
3E). Nephridiopores visible as gaps in setal rings, lon-
12
gitudinal musculature of postclitellar segments, 4 pores
per segment in regular rows.
Septa 5/6–9/10 thick, muscular, 10/11–12/13 thinner, remainder membranous. Weak gizzard in viii with
typical iridescent outer wall but flaccid, esophagus
valvular xviii, intestinal origin xix, no caeca; thick intestinal gizzards xxv–xxix, gizzards occupy posterior
half of each segment as usual but anterior half of gut
wall xxv–xxix somewhat iridescent, also covered with
dense segmental network of blood vessels connected to
dorsal and ventral vessels; typhlosole low fold xl–xlvii,
one fourth lumen diameter. Intestine constricted 38/39,
thereafter coated with brown chloragogen layer.
Hearts x–xiii esophageal, commissural vessels vii–ix
lateral; supra-esophageal vessel x–xiv, extra-esophageal vessels not traceable; paired large longitudinal vessels mid-lateral on body wall from xviii posteriorly.
Nephridia present as peptonephridia on anterior face
septa 5/6, micronephridia preseptal clustered around
commissural vessels vi–ix, on body wall thereafter;
from xix four micronephridia per segment, two clearly
stomate meganephridia per segment from xix posteriorly, these attached to paired ureters adherent to either
side of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca
club-shaped ampulla, poorly differentiated duct; simple
club-shaped diverticulum half or more length of main
spermathecal axis joins duct near body wall (Figure
3F). Male sexual system holandric, testes and funnels
enclosed in annular? or ventrally separated? sacs in x,
xi, these sacs encompass hearts, dorsal vessel, seminal
vesicles; sacs formed of membranes connecting septa 9/10 and 10/11, 10/11 and 11/12; seminal vesicles
xi, xii loosely acinous; each prostate racemose two to
three-lobed occupying xviii; duct slightly muscular;
vas deferens slender, non-muscular; copulatory bursae
lacking.
Remarks. Pleionogaster sorsogonensis appears to be
related to P. caramoanensis, with which it shares the
same body size, pigmentation, and number of micronephridia (Table 2). Pleionogaster sorsogonensis has
two more intestinal gizzards, fewer setae in the anterior
segments, fewer setae between the male pores, different genital marking patterns on the male field and in the
spermathecal segments, and spermathecae whose ducts
and ampullae are not greatly differentiated.
Pleionogaster nautsae n. sp.
(Fig. 3G, H)
Etymology. Named after Phyllis Nauts of Connecticut, USA, as a gift from her husband.
Type material. Holotype (NMA 004147): adult,
PTAGS 071, Catanduanes Province, lower riparian for-
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
est near Barangay San Miguel, Pangabinan, LMK039,
13° 54.5’ N, 124° 11.0’ E, 212m asl, 23 May 2001, leg.
S.W. James, J. ffitch, A. Castillo. Paratypes (KUNHM
002196): 2 adults; collecting data as for holotype.
Other material. UPLBMNH Z-NS-0093: 2 adults,
PTAGS 068, Catanduanes Province, low-elevation
forest near Barangay Summit, Buradan, 13° 43.60’
N, 124° 17.14’ E, 210m asl, 21 May 2001, leg. S.W.
James, P. James, J. James, K. James, J. ffitch, A. Castillo. KUNHM 002197: 1 adult, PTAGS 070, Catanduanes Province, lower montane forest near Barangay
San Miguel, Pangabinan, no GPS data, 305m asl, 23
May 2001, leg. S.W. James, J. ffitch, A. Castillo.
Description. Unpigmented, body 158–295 mm x
3.3–4.6 mm (vii), 3.1–4.0 mm (xv), 3.5–4.3 mm (xxv);
286–343 segments; body cylindrical. First dorsal pore
12/13; spermathecal pores paired in 7/8, 8/9, 0.13 circumference apart deep in furrows; female pore single,
male pore openings crescentic, paired in xviii on small
porophores, 0.12–0.15 circumference apart, 0–7 setae
between male pores; pore orientation rotated so that
crescent concavity directed antero-laterally rather than
straight toward anterior; clitellum xiv–1/2xvii, annular.
Setae regularly distributed around segmental equators;
estimated 170–264 setae on vii, 150–196 setae on x,
92–106 setae on xxv; asetal zones midventral in one
or more of vii–ix. Genital markings narrow transverse
midventral extending to male pore lines presetal xvii,
xix, latter with embedded paired marks, paired indented
markings 17/18, broad epidermal thickenings ventral
presetal, equatorial annuli of xx, xxi; ventral epidermal
thickenings presetal ½ vii, viii to ½ ix, x (Figure 3G).
Nephridiopores visible as gaps in setal rings, longitudinal musculature of postclitellar segments, 8 pores per
segment in regular rows.
Septa 5/6–8/9 thick, muscular, 9/10/11 thinner, remainder membranous. Weak gizzard in viii with typical iridescent outer wall, esophagus valvular xix or xx,
intestinal origin xx or xxi, no caeca; intestine slightly
vascularized xxi–xxiv, thick intestinal gizzards xxiv–
xxix; typhlosole simple fold from liii, liv; intestine
constricted 50/51 or 51/52.
Hearts x–xiii esophageal, commissural vessels
vii–ix lateral; supra-esophageal vessel xi–xvii, extraesophageal with branch from body wall of xiv, efferent
posterior latero-parietal vessels travel up 15/16 to extra-esophageal vessel in xv, these connected to paired
longitudinal vessels on body wall xviii–xl; not always
visible past xxx.
Nephridia present as peptonephridia on anterior
faces septa 4/5/6, micronephridia preseptal clustered
around commissural vessels vi–ix, on body wall thereafter; from xix 8 micronephridia per segment, two stomate meganephridia per segment from xix posteriorly,
13
these attached to paired ureters adherent to either side
of dorsal vessel.
Ovaries and funnels free in xiii, spermathecae paired
in viii, ix without nephridia on ducts; each spermatheca
club-shaped ampulla not differentiated from duct; short
basally-attached diverticulum of similar shape (Figure
3H). Male sexual system holandric, testes, funnels enclosed in annular sacs in x, xi, these sacs encompass
hearts, dorsal vessel, seminal vesicles; sacs formed of
membranes connecting septa 9/10,10/11; 10/11, 11/12;
seminal vesicles xi, xii, slender arcs with large dorsal
block; prostates racemose occupying xviii; duct muscular; vas deferens slender,non-muscular, adheres to
prostatic duct from duct-gland junction but visible on
duct surface over ental one-third to one-half of duct;
copulatory bursae lacking.
Remarks. Compared to P. nillosae, the other species with six intestinal gizzards in xxiv–xxix (see Table
2), P. nautsae has fewer setae and micronephridia per
segment, more narrowly placed male and spermathecal pores, a typhlosole, and little or no differentiation
of the spermathecal duct and ampulla. It is one of two
species in Bicol with preclitellar midventral genital
markings, the other being P. sorsogonensis which has
half as many micronephridia, a more anterior intestinal
constriction and paired post-clitellar genital markings.
Discussion
Among those species for which many individuals were
available for study, relative homogeneity of somatic
and sexual characters is the rule. This is in contrast to
the definition of P. horsti generated by synonymizing
several species under this name (Easton 1979). Even
so, the species described here would fall well outside
that wide net.
In the course of this study, several characters not
generally recorded in previous work proved useful in
distinguishing species. In the post-giceriate intestine
there is always a constriction, either side of which both
internal and external intestinal surfaces differ. The internal surface typically changes from rough and corrugated anterior of the constriction to smooth posterior
of it. The external intestinal surface is more densely
covered with tan or brown chloragogen posterior of the
constriction. In addition, the typhlosole (if present) always begins after the constriction, whereas among the
caecate genera of the Pheretima complex the typhlosole
(if present) begins just after the caeca (range xxii–xxvii) and thus many segments anterior to the typhlosoles of Pleionogaster species. No other known member
of the Pheretima complex of genera (Sims and Easton
1972; Easton 1979) has these intestinal features, or the
intestinal gizzards of Pleionogaster.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
Along the body wall in the anterior intestinal segments there is generally a longitudinal vessel on each
side, extending from the region of segments xv–xviii
back for 20–30 or even more segments. Sometimes this
is not visible, probably due to lack of blood at fixation. Frequently this long vessel is clearly connected to
a posterior latero-parietal vessel, which usually brings
blood from the clitellar body wall to the extra-esophageal vessel (s) located on the ventral side of the esophagus. More rarely, this same vessel is seen to also
connect to the prostate gland circulation. Among the
Pheretima group of genera, I have seen this longitudinal vessel on the body wall of the intestinal segments
in Pleionogaster only. Gates (1972) reports a similar
vessel in Lampito, and I have seen a similarly placed
vessel in a Honduran Ramiellona (James, unpublished
data).
All Pleionogaster possess an arrangement of nephridia unique within the perichaetine Megascolecidae.
Their micronephridia are arranged in regular rows with
externally visible pores in the intestinal segments, and
in clusters along the anterior septal faces and commissural vessels in the head segments. The nephropores interrupt the setal rings and longitudinal musculature, and
so are easily seen. The number of micronephridia per
segment appears to be relatively constant within a species, only P. tiwiensis varying by more than a pair, and
varies among species (range 4–14). While it is generally true that larger species have more micronephridia per
segment, there are exceptions, notably P. bulusanensis
with 14 though not being particularly large-bodied. All
species have a pair of stomate meganephridia in each
intestinal segment, connected via tubules to ureters parallel to either side of the dorsal vessel.
The testes sacs of Pleionogaster are often different
from other perichaetine megascolecids in that some are
composed of membranes joining the septa enclosing
the testicular segments. In most other Pheretima group
genera, and in the remaining Pleionogaster, the sacs do
not enclose all the segmental contents, and usually only
the testes and funnels. The Pleionogaster sacs are most
often annular, but in some cases they are U-shaped,
and open dorsally; in others the U is open ventrally, in
which case I have described them as horseshoe-shaped.
Annular sacs also occur in Philippine Pithemera and
Polypheretima (James, unpublished data) but in these
genera the sacs are never attached to both neighboring
septa.
Upon consideration of these apparent synapomorphies Pleionogaster has little in common with the genera of the Pheretima complex, other than being perichaetine and having the same male terminalia. Even the
latter show some variation from the common plan, as
Pleionogaster have a vas deferens that remains separa-
14
te from and visible on the surface of the prostatic duct
over the ental half or more of the duct, before it merges and dives in to unite with the prostatic duct lumen.
In the other genera, such as Pheretima and Amynthas,
the vas deferens lumen joins the prostatic duct near the
branching point of the prostatic duct as it receives the
ductlets of the glandular lobes.
Pleionogaster is so far known only from the Philippines, and no closely similar genera have been discovered in other parts of SE Asia or the Australian region, including New Guinea. How, and whence, it or its
ancestor arrived on the Philippines and spread throughout the major islands without ending up anywhere else
remains a mystery.
Even though the collecting teams made prodigious
efforts at each site visited, only a few species were collected from more than one area. Pleionogaster bicolensis seems to be widely distributed across the Bicol
region, except for the extreme south where it was not
found on Mt. Bulusan. Pleionogaster caramoanensis is
abundant and widespread on the Caramoan Peninsula.
This low-elevation limestone karst area was unsuitably dry at the time of our visit, thus we have probably not found all the species present at the Caramoan
collection sites. Pleionogaster isarogensis was found
at many collecting stations spanning a wide range of
elevations within primary forest on Mt. Isarog, but not
at any other location. Therefore, like most of the species described here, it is probably endemic to its own
particular mountain. It is worth recalling here that even
within the Mt. Malinao massif there is geographical
variation of intestinal features in P. castilloi. The extensive deforestation of the Philippines renders impossible any educated guesses about the original ranges
of Bicol’s native earthworm species. It is possible that
some survive in scattered spots of older secondary forest or other areas with low disturbance frequency, but
due to time and permit constraints we focused our efforts on easily defined locations where primary forest
remains.
Acknowledgements
This research was supported by the United States National Science Foundation through grant DEB-0072764
to the author and Maharishi University of Management. John Stimson prepared the illustrations. Hendon
Chubb made a contribution to the author’s research
budget on behalf of his wife Phyllis Nauts. Thanks are
due to the Philippine Department of Environment and
Natural Resources, particularly to the Protected Areas
and Wildlife Bureau staff who issued our permits, and
numerous DENR provincial offices and their employees who worked with us in the field or simply provided good information on access points and contacts
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
for the collecting sites. The National Power Corporation (NAPOCOR) provided access to the Mt. Malinao
area within their geothermal development zone. Hong
Yong, Augusto Castillo, Portia Nillos, Matthew Levi,
Jana ffitch, Dorothy Franke, Joy James, Pearl James,
15
Katharine James and David James provided assistance
in the field. Finally, we thank the people of Barangay
Summit, Catanduanes, for opening their homes to us
during our stay there.
References
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Pleionogaster and Polypheretima. Bull. Brit. Mus.
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Michaelsen, W., 1896. Oligochäten Kükenthal—Ergebnisse
einer zoologischen Forschungsreise in den Molukken
und in Borneo. Abh. Senckenb. Ges. 23, 192–243.
Sims, R.W., Easton, E.G., 1972. A numerical revision of
the earthworm genus Pheretima auct. (Megascolecidae:
Oligochaeta) with the recognition of new genera and
an appendix on the earthworms collected by the Royal
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Stephenson, J., 1930. The Oligochaeta. Clarendon Press,
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Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
16
tiwiensis
albayensis
bicolensis
bulusanensis
hongi
ffitchae
viracensis
isarogensis
Pigmentation
none
brown
brown
none
pink
brown
brown
none
Setae vii, xxv
210, 114
148, 85
130–220,
140
200, 120
176, 104
220, 160
200, 140
180, 76
Spermathecal pore
spacing
0.08
0.20
0.17
0.15
0.18
0.18
0.13
0.10
Male pore spacing
0.12
0.18
0.17
0.17
0.18
0.16
0.16
0.11
Setae betw. male
pores
5, 6
12
8–10
20
10–12
8
10
4–8
Midventral genital
marks
yes
yes
none
none
none
none
yes
yes
Paired genital
marks
yes
yes
yes
yes
yes
yes
yes
none
Nephridia/seg.
6–10
12
12
14
12
12
10
6
Intestinal orgin
xix
xx
xix or xx
xx
xx
xix
xix
xx
Typhlosolar origin
xlvii
xlvii
none
none
xlvi
l
lii
xli
annular
annular
open ventral
annular
annular
annular
annular
annular x, Ushaped xi
Spermath. duct
differentiated
no
no
yes
no
no
no
yes
yes
Latero-parietal
vessels
xiv–xvii
xiv–xvii
xiv, xv
xiv–xvi
xiv–xvii
xiv–xvi
xiv, xv
xv
Testes sacs
Table 1: Pleionogaster species with four intestinal gizzards in xxvii–xxx.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
17
Table 2. Pleionogaster species with three, five, or six intestinal gizzards.
malinaoensis
castilloi
nillosae
caramoanensis
sorsogonensis
nautsae
Pigmentation
none
none
none
none
none
none
Setae vii, xxv
160, 100
160, 80
314, 140
170–250,
110–160
120, 72
170–260,
100
Spermathecal pore
spacing
0.10
0.17
0.20
0.13
0.11
0.13
Male pore spacing
0.09
0.17
0.18
0.15
0.15
0.13
Setae betw. male
pores
2–4
6–8
0
6
2
0–7
Midventral genital
marks
yes
yes
?
none
yes
yes
Paired genital marks
yes
none
yes
yes
yes
none
Nephridia/seg.
10–12
6
10
4
4
8
Intestinal orgin
xix
xx
xx
xix
xix
xx, xi
Typhlosolar origin
xlv
xlv or
xlviii
none
xl
xl
liii
5
5–7
6
3
5
6
annular
annular
annular
annular
annular
annular
Spermath. duct
differentiated
yes
yes
yes
yes
no
no
Latero-parietal
vessels
xiv–xvii
xiv–xvii
xiv, ?
xvi, xvii
?
xv
Gizzards
Testes sacs
Table 2: Pleionogaster species with three, five, or six intestinal gizzards.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
A
E
C
F
1 mm
sp
D
3 mm
B
18
sp
5 mm
5 mm
1 mm
sp
10 mm
xviii
xviii
xviii
G
H
I
sp
J
sp
5 mm
1 mm
5 mm
2 mm
xviii
xviii
Fig. 1: A, B. Pleionogaster tiwiensis sp.n.; (A) ventral view, (B) spermatheca. C, D. Pleionogaster albayensis sp.n.; (C)
ventral view, (D) spermatheca. E, F. Pleionogaster bicolensis sp.n.; (E) ventral view, (F) spermatheca. G, H. Pleionogaster bulusanensis sp.n.; (G) ventral view, (H) spermatheca. I, J. Pleionogaster hongi sp.n.; (I) ventral view, (J) spermatheca. Abbreviation: sp=spermathecal pores.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
A
B
19
C
E
F
sp
2 mm
2 mm
sp
sp
5 mm
10 mm
5 mm
2 mm
D
xviii
xviii
xviii
G
I
1 mm
sp
J
H
sp
5 mm
1 mm
5 mm
xviii
xviii
Fig. 2: A, B. Pleionogaster ffitchae sp.n.; (A) ventral view,. (B) spermatheca. C, D. Pleionogaster viracensis sp.n.; (C)
ventral view,. (D) spermatheca. E, F. Pleionogaster isarogensis sp.n.; (E) ventral view,. (F) spermatheca. G, H. Pleionogaster malinaoensis sp.n.; (G) ventral view,. (H) spermatheca. I, J. Pleionogaster castilloi sp.n.; (I) ventral view,. (J)
spermatheca. Abbreviation: sp=spermathecal pores.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)
James: The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in S Luzon, Philippines
20
C
A
D
sp
sp
B
5 mm
1 mm
10 mm
3 mm
xviii
xviii
G
H
E
sp
3 mm
F
5 mm
1 mm
sp
5 mm
xviii
xviii
Fig. 3: A, B. Pleionogaster nillosae sp.n.; (A) ventral view,. (B) spermatheca. C, D. Pleionogaster caramoanensis sp.n.;
(C) ventral view,. (D) spermatheca. E, F. Pleionogaster sorsogonensis sp.n.; (E) ventral view,. (F) spermatheca. G, H.
Pleionogaster nautsae sp.n.; (G) ventral view,. (H) spermatheca. Abbreviation: sp=spermathecal pores.
Org. Divers. Evol. 6, Electr. Suppl. 8 (2006)