Zoological Journal of the Linnean Society, 2002, 136, 199–216. With 5 figures
New taxa of Japanese and New Zealand Eurystomellidae
(Phylum Bryozoa) and their phylogenetic relationships
DENNIS P. GORDON1 FLS, SHUNSUKE F. MAWATARI2 and HIROSHI KAJIHARA2*
1
National Institute of Water & Atmospheric Research (NIWA), PO Box 14-901 Kilbirnie, Wellington,
New Zealand and 2Division of Biological Sciences, Graduate School of Science, Hokkaido University,
Sapporo 060, Japan
Received November 2001; accepted for publication April 2002
As presently recognized, the small cheilostome bryozoan family Eurystomellidae (superfamily Catenicelloidea) comprises just two genera: Eurystomella Levinsen, 1909, with three Recent species, and Selenariopsis Maplestone, 1913;
with one Recent and two fossil species. Within Eurystomella sensu lato, colonies range from uni-/biserial to multiserial and the smooth gymnocystal frontal shields of zooids may be entire or have one to several large foramina.
Here we describe seven new Recent species of encrusting eurystomellids from New Zealand and Japan. Including
species of Selenariopsis, a cladistic analysis was carried out on 11 eurystomellid species and five outgroup species,
the latter representing the families Cribrilinidae, Euthyroididae, Petalostegidae, and Catenicellidae. The results of
the analysis support restricting Eurystomella to multiserial species with large frontal foramina, median suboral
sutures, and basal pore-chambers. Two new genera, both with imperforate frontal shields and uniporous mural
septula, are segregated from Eurystomella: uni-/biserial Zygopalme, with a median suboral suture and accssory perforations in the ovicellular kenozooid, and multiserial Integripelta, lacking the suture and accessory perforations.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216.
ADDITIONAL KEYWORDS: Cheilostomata – Catenicelloidea – Eurystomella – new genera – new species –
cladistic analysis – biogeography
INTRODUCTION
As recognized in recent literature, the cheilostome
family Eurystomellidae Levinsen, 1909 comprises only
two described genera and six Recent and fossil species,
but their zooidal characters are distinctive and
members of the family are easily recognized. Levinsen
(1909), in fact, based the family on just two species –
Lepralia foraminigera Hincks, 1883 from New
Zealand and L. bilabiata Hincks, 1884 from British
Columbia, both of which he attributed to his new
genus Eurystomella. The generic name alludes to one
of the characters, namely the broad primary orifice
with the general outline of a hat – the anter is high-
Correspondence to: Dennis P. Gordon. E-mail:
[email protected].
*Present address: Biological Resources and Informatics,
Laboratory for Intellectual Fundamentals for Environmental
Studies, National Institute for Environmental Studies, 16-2
Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
arched and rounded, and the poster is broader, nearly
straight-rimmed proximally, and extended at each
proximolateral corner, adjacent to shallow excavations
in the gymnocystal calcification. Levinsen (1909) also
mentioned the lack of a “covering membrane”, i.e.
an outer epidermis associated with an underlying
hypostegal coelom. The calcareous frontal shield is a
gymnocyst with only an outer cuticle. Other characters noted by Levinsen included an ‘ooecium enclosed
in a kenozooecium’ and the lack of other polymorphs
like spines and avicularia. Also E. foraminigera has
basolateral pore-chambers, whereas E. bilabiata has
groups or rows of uniporous mural septula.
For the next seven decades, Eurystomella was the
only known genus in the family until Cook &
Chimonides (1981) examined samples of the littleknown genus Selenariopsis Maplestone, 1913 (a senior
synonym of Australiana Powell, 1966) and concluded
that it is confamilial. Whereas species of Eurystomella
are encrusters of hard substrata, living and fossil
species of Selenariopsis are lunulitiform and rooted in
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
199
200
D. P. GORDON ET AL.
soft sediment (Wass & Yoo, 1983; Bock & Cook, 1996).
Zooidal characters are very similar to those of
Eurystomella, except that autozooidal orifices tend to
be longer than wide. There are no foramina in the
frontal shield and the rootlets arise from basal porechambers separated from the autozooidal chamber by
multiporous septula.
Cook & Chimonides (1981) discussed the two
described species of Eurystomella, giving brief diagnoses of each and an extensive commentary on the significant features of the family and genus, especially
the gymnocystal frontal shield, orificial and opercular
characters, the ancestrula, and the kenozooid associated with the maternal zooid. Gordon (1984) added
a biserial third species, E. crystallina from the
Kermadec Ridge, north-eastern New Zealand, that
resembles E. bilabiata in lacking frontal foramina in
the autozooidal gymnocyst and in having mural septular pores instead of basolateral pore-chambers. In
their remarks on E. bilabiata, Cook & Chimonides
(1981) noted that some Japanese populations show
character states differing from those along the Pacific
coast of North America. Our studies not only confirm
this distinction but also show that the Japanese forms
represent three new nonforaminate species. Concurrent studies of E. foraminigera in New Zealand similarly show that two new foraminate species may
be segregated from this species. Further, two new
imperforate species have also recently been found in
northern New Zealand waters.
When Levinsen (1909) introduced his new genus
Eurystomella he remarked: “There may possibly be
reason . . . to form a special genus for E. bilabiata”,
noting the lack of basolateral pore-chambers as
significant in this regard. Now that we have several
frontally foraminate species as well as several
frontally imperforate species, it is possible to evaluate
the taxonomic significance of frontal foramina and
basal pore-chambers in the Eurystomellidae. Similar
foramina in the Catenicellidae are certainly important at genus level (see Gordon (1984, 1989). In this
paper we describe the new species of Eurystomellidae
from Japan and New Zealand and introduce two
new genera for the nonforaminate species. Using
cladistic analysis we consider relationships within
Eurystomella sensu lato and the relationship of the
Eurystomellidae to some other gymnocystal-shielded
ascophorans. These taxonomic and phylogenetic clarifications are necessary for the forthcoming revision of
the cheilostome bryozoan volume in the Treatise on
Invertebrate Palaeontology.
MATERIAL AND METHODS
New specimens of Japanese eurystomellids were
obtained in September 1998 from dredgings made by
staff of the Seto Marine Laboratory, Shirahama,
Honshu (courtesy of Professor Y. Shirayama,
Laboratory Director) and sorted by D. Gordon. A new
intertidal species from Hokkaido was collected by S.F.
Mawatari. New specimens of New Zealand eurystomellids were obtained in 1999 during a NIWA
survey of the impact of scallop dredging in Spirits and
Tom Bowling Bays, off the northernmost point of
mainland North Island. Additional material was furnished from the NIWA marine biology collection,
Wellington. Selected specimens were soaked in liquid
domestic bleach (sodium hypochlorite solution) to
remove organic tissues from the zooid skeletons. These
were washed thoroughly in water and dried prior to
metal-coating and scanning electron microscopy.
Measurements of zooids and other optically resolvable
features were made using a calibrated eyepiece graticule in a binocular microscope. Type specimens of new
species have been deposited in the collections of the
National Institute of Water & Atmospheric Research,
Wellington (collection code NZOI, pertaining to the
former N.Z. Oceanographic Institute), Seto Marine
Biological Laboratory of Kyoto University (ZMBL),
and the Zoological Institute, Hokkaido University
(ZIHU). Phylogenetic analysis was carried out as
described below.
SYSTEMATICS
In this section we fully redescribe the type species of
Eurystomella, E. foraminigera (Hincks) from New
Zealand, then describe new species from New Zealand
and Japan. Measurements of autozooids are given as
ranges, with means and standard deviations in parentheses for 20 zooids.
FAMILY EURYSTOMELLIDAE LEVINSEN, 1909
EURYSTOMELLA LEVINSEN, 1909
Diagnosis
Colony encrusting, multiserial. Autozooids with
smooth gymnocystal frontal shield perforated by one
to several large foramina. Zooidal orifices with proximolateral indentations, and shallow excavations in
the adjacent gymnocyst; proximal rim of orifice with
median suture. No spines or avicularia. Maternal
orifice usually slightly larger than autozooidal orifice,
or obviously so; brooding internal, with a distal ovicelllike kenozooid with a central perforation; kenozooid
extending to basal wall. Ancestrula with membranous
frontal wall only, no spines. Interzooidal communications via basal pore-chambers.
Type species: Lepralia foraminigera Hincks, 1883,
by original designation.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
EURYSTOMELLA
FORAMINIGERA
(HINCKS, 1883)
(FIG. 1A, B)
Lepralia foraminigera Hincks, 1883: 200, pl. 7, fig. 1;
not Waters 1887: 62; Hincks 1893: 180; Hamilton
1898: 195, 198; Waters 1925: 542, pl. 28, fig. 12.
Eurystomella foraminigera: Levinsen 1909: 36, 41,
314, pl. 18, fig. 14a-c; Canu & Bassler 1923: 141, fig.
26D-F; Brown 1952: 286 (part), fig. 215 (not fig. 216);
Macken 1958: 105; Powell 1967: 310 (part), not fig.
66a-b; Gordon 1967: 59, fig. 33; Gordon 1970: 315;
Whitten 1979: 159, pl. 7, fig. 12; Cook & Chimonides
1981: 113, fig. 5E, F; Gordon 1984: 65 (part), not pl.
21F; 1989: 17 (part), not pl. 4 A-C; Stevens et al.
1996: 324, pl. 4C.
Material examined
Colonies from Goat Island Bay, Leigh; Auckland
Harbour; Greta Point, Wellington Harbour, New
Zealand (unregistered, all DPG Collection); NZOI
Stns Z9669, Z9670, Z9677, Z9684, Z9685, Z9687,
Z9700, Z9701, Z9710.
Description
Colony encrusting, multiserial, unilaminar, circular
on clean substrata, attaining c. 38 mm diameter.
Self-overgrowth not usual, but possible from loci of
damaged zooids through reparative budding, or on
small pebbles where lateral expansion is restricted.
Colony pink in newly forming zooids to red in fully
formed and ephebic zooids, the pigment residing in
epithelial tissues in foramina, under the operculum,
and in the cells of the pharynx and oesophagus,
thus imparting colour to the introvert, whereas the
tentacles are colourless. Polypide with 14–17 tentacles. Autozooids contiguous, quincuncially arranged,
0.39–0.68 mm long (0.51 ± 0.08 mm), 0.22–0.47 mm
wide (0.37 ± 0.07 mm). Gymnocystal frontal shield
scarcely elevated, perforated by 3–7, rarely only 2,
large oval to circular foramina; these with inwardly
sloping sides, inner diameters of each foramen
smaller than outer diameters; foramina covered in life
with an epitheca. Orifice having a somewhat hatshaped outline, the anter high-arched and rounded
with the proximal corners somewhat condyle-like;
poster wider than anter, the proximal rim nearly
straight though tending to sinuous, extended at the
corners where there are lateral indentations. No peristome, umbones, spines, or avicularia. Maternal
zooids with internal brooding of embryos, the distal
zooidal wall strongly convex, overarched by a distal
kenozooidal chamber whose extensive frontal wall
resembles an ovicell; this perforated by a relatively
large circular foramen with inwardly sloping
walls, the foramen covered in life with an epitheca.
201
Maternal orifice slightly broader (0.24–0.26 mm wide
at the proximal margin) than that of autozooids
(0.15–0.22 mm). Zooids communicating by 1–2 distal
and 2–3 basolateral pore-chambers. Ancestrula
subcircular with entire frontal area membranous,
0.40–0.42 ¥ 0.32–0.38 mm, larger than immediate
daughter zooids; no spines; operculum with narrow
subperipheral sclerite; ancestrular polypide with
13–15 tentacles. First daughter zooid budded
mid-distally.
Remarks
As originally described, autozooids of E. foraminigera
sensu stricto have several frontal foramina — Hincks
(1883) illustrated 3–5. Very rarely, zooids may have
only two, especially if they are constrained in their
growth. At least one other New Zealand species (E.
biperforata sp.nov.) has been consistently confused
with E. foraminigera. Its zooids have only a pair of
oval to circular foramina (rarely one) (see Brown,
1952; Powell, 1967; Gordon, 1984, 1989). A rarer,
second new biperforate species (E. aupouria sp. nov.)
has narrowly crescentic foramina. These three species
also share a feature first noted, and illustrated, by
Brown (1952), namely a median triradiate suture in
the proximal rim of the orifice. His observations are
germane to the phylogenetic relationships of eurystomellids: “the proximal lip of the orifice closely
resembles the ‘apertural bar’ of Figularia . . . for it
appears to be formed by the coalescence of a pair of
lateral, spiny processes, and, as in that genus, often
shows a tiny median notch where the primitive spines
have joined”. Scanning electron microscopy has
allowed close examination of this feature, lending
strong support for Brown’s interpretation. Gordon
(1989), for example, interpreted the triradiate suture
as indicating the boundaries between contiguous vestigial costae, noting similar features in the orificial
rims of some catenicellids.
Ryland (1975) gave parameters of the lophophore
in E. foraminigera from Goat Island Bay, Leigh, on
the north-east coast of North Island (36°16¢S,
specimens collected November 1971). The number of
tentacles varied from 14 to 16 (mean 15.17). Mean
tentacle length was 0.504 mm (SD 0.053 mm) and
mean funnel diameter 0.530 mm (SD 0.028 mm).
These figures accord with specimens freshly collected
(February 2001) from Greta Point, Wellington
(41°18¢S) which have the same range in tentacle
number. Tentacle length and lophophore diameter can
attain 0.566 mm and introvert length (measured from
the plane of the orifice to the base of the lophophore)
0.415 mm. Faecal pellets measure 0.134 ¥ 0.068 mm,
are circular in cross section, and rounded at each
end.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
202
D. P. GORDON ET AL.
Figure 1. A, B, Eurystomella foraminigera. Greta Point, Wellington, intertidal. A, group of zooids, ¥65. B, suboral rim,
showing triradiate suture, ¥803. C-E, Eurystomella biperforata sp. nov. C,E, NZOI Stn Z9700. C, group of autozooids,
¥53. D, NZOI Stn Z9677, maternal zooid with distal foraminate kenozooid, ¥95. E, rare zooid with a single foramen, ¥163.
F, Eurystomella aupouria sp. nov. NZOI Stn Z9716, ¥63.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
Distribution
Eurystomella foraminigera is endemic to New
Zealand. Its exact geographical and depth distributions are uncertain owing to previous confusion of this
species with E. biperforata. It certainly occurs from
Spirits Bay at the far north of North Island, along the
north-east coast of Northland, and from Wellington
Harbour, at depths of 0–76 m. Whitten (1979) reported
living colonies from the intertidal to 21 m depth, and
transported colonies to 82 m depth in the vicinity of
the outer Hauraki Gulf. Eurystomella foraminigera is
among the more commonly encountered bryozoans
of the middle to lower shore around New Zealand,
encrusting shells, plastic, broken glass, brown algal
holdfasts (Carpophyllum maschalocarpum (Turner)
Grev., Ecklonia radiata (C.Agardh) J.Agardh, and the
undersides of boulders (Gordon, 1967; Stevens et al.,
1996). The reddish coloration of the colonies makes
them conspicuous.
EURYSTOMELLA BIPERFORATA
(FIG. 1C–E)
SP. NOV.
Eurystomella foraminigera: Brown 1952: 286 (part),
fig. 216 (not fig. 215); Powell 1967: 310 (part), fig.
66a–b; Uttley & Bullivant 1972: 47; Gordon 1984:
65 (part), pl. 21f; 1989: 17 (part), pl. 4 a–c.
Material examined
Holotype: NZOI H-748, from NZOI Stn B230,
46°40.0¢S, 168°02.5¢E, 26 m, Foveaux Strait, New
Zealand.
Paratype: NZOI P-1217, from NZOI Stn Z9697,
34°21.06¢S, 172°42.53¢E, 57 m, Spirits Bay, New
Zealand.
Other material: NZOI Stns B220, B221, B224, B230,
B235, D273, K837, Z9671, Z9677, Z9678, Z9687,
Z9695, Z9697, Z9700, Z9708, Z9710, Z9716. Chatham
Islands 1954 Expedition Stn 24, 69 m (see Uttley &
Bullivant, 1972).
Description
Form of colony and colony colour as in E. foraminigera. Autozooids contiguous, quincuncially arranged,
0.37–0.74 mm long (0.53 ± 0.10 mm) and 0.28–0.53 mm
wide (0.36 ± 0.079 mm). Gymnocystal frontal shield
scarcely elevated, perforated by 2, exceptionally 1 (or
3 in proximally elongated zooids), large oval to circular foramina; if oval, often with the long axes directed
obliquely away from each other; shield surface smooth
proximal to foramina. Orifice as in E. foraminigera,
the proximolateral corners also having a slight excavation of the gymnocystal surface beyond the indentations of the orifice. No peristome, umbones, spines,
203
or avicularia; low bosses may be on the frontal shield
between the orifice and foramina in some zooids.
Maternal zooids and kenozooids as in E. foraminigera,
including the size of the kenozooid and its foramen,
except that the maternal orifice is more consistently
broader (0.23 mm wide at the proximal margin) than
that of other zooids (0.16–0.19 mm). Zooids likewise
communicating by distal and lateral pore-chambers
and the ancestrula (0.38 ¥ 0.34 mm) has the same
form.
Etymology
From bi- (L) two, and perforatus (L) bored through,
alluding to the two perforations of the kenozooid distal
to the maternal zooid.
Remarks
Eurystomella biperforata is so similar to E. foraminigera that it must be asked if the number of gymnocystal foramina is a sufficiently reliable character for
segregating a new species. It is now clear, from the
examination of many colonies of both species, that
foramen number is indeed consistent, but, beyond this
externally obvious character, there is an important
internal feature as well. Whereas the interior of the
frontal shield in E. foraminigera is uniformly smooth
and featureless (apart from the foramina), that of E.
biperforata has an abrupt demarcation in its angle of
slope, creating a line that curves around the proximal
margins of the foramina. Additionally, in some zooids,
the ascus roof is partially calcified.
Distribution
Eurystomella biperforata is endemic to New Zealand,
where it ranges from 30°15¢S (Macauley Island,
Kermadec Ridge) to 46°30¢S (Foveaux Strait) at
26–125 m depth. In the field, live colonies of E. biperforata are probably indistinguishable from those of E.
foraminigera.
EURYSTOMELLA AUPOURIA
(FIG. 1F)
SP. NOV.
Material examined
Holotype: NZOI H-749, from NZOI Stn Z9716,
34°21.69¢S, 173°00.06¢E, 100 m, Tom Bowling Bay,
New Zealand.
Paratype: NZOI P-1218, same locality as holotype.
Other material: NZOI Stns Z9077, Z9679, Z9713.
Description
Form of colony and autozooidal orifice as in E.
foraminigera; colony colour not known. Autozooids
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
204
D. P. GORDON ET AL.
contiguous, quincuncially arranged, 0.37–0.58 mm
long (0.46 ± 0.056 mm), 0.28–0.51 mm wide (0.37 ±
0.006 mm). Gymnocystal frontal shield not elevated,
perforated by 2 large, nearly crescentic foramina;
these very broad, extending almost to the zooidal
margins, the inwardly sloping walls broad and shelflike, the inner distal foramen edge generally concealed
by the outer distal foramen rim which overlaps it,
giving the foramina a slit-like appearance frontally;
shield surface smooth proximal to foramina. Orifice
as in E. foraminigera. No peristome, umbones, bosses,
spines, or avicularia. Maternal zooids and kenozooids
as in E. foraminigera, including the size of the kenozooid and its foramen, except that the plane of the
foramen opening slopes distad. Zooids communicating
by distal and lateral pore-chambers. Ancestrula not
known.
Etymology
From aupouri (Maori) alluding to the marine biotic
province (Aupourian) in which the species occurs, in
turn named after the long NW-trending Aupouri
Peninsula at the north of North Island.
Remarks
When frontal membranes and cuticle are removed,
Eurystomella aupouria is readily distinguished from
E. biperforata by its much broader, narrower foramina
that extend almost to the zooidal margins, and in
which the inner distal edge is generally concealed.
Distribution
Eurystomella aupouria is endemic to New Zealand,
where it is known only from the Three Kings
Islands (~34°08¢S) to Spirits Bay (34°25¢S) at depths
of 27–100 m.
ZYGOPALME
GEN. NOV.
Diagnosis
Colony encrusting, uni- to biserial. Autozooids with
smooth gymnocystal frontal shield lacking foramina.
Zooidal orifices with minute proximolateral indentations and a median suboral suture; no excavations in
adjacent gymnocyst. No spines or avicularia. Maternal
orifice slightly larger than autozooidal orifice; brooding internal, with a distal ovicell-like kenozooid with
a large central perforation; two tiny accessory pores
frontally. Ancestrula with membranous frontal wall
only, no spines. Interzooidal communications via
uniporous mural septula.
Type species: Eurystomella crystallina Gordon
(1984).
Etymology
From zygas (Greek) pair, and palme (f. Greek) shield,
alluding to the linear colonial morphology in which
zooids may be biserial.
Remarks
Cladistic analysis has tended to highlight the differences between Zygopalme crystallina and other
encrusting eurystomellids. Two characters are unique
for this species and considered synapomorphies for
this monotypic genus. These are the scarcely differentiated proximal corners of the orificial anter, and three
kenozooidal foramina (one central, plus two small
frontal pores) (see also Cladistic Analysis, below).
Autapomorphic characters include the linear colony
form and absence of gymnocystal foramina but retention of the median suboral suture. At present the
genus is known only from a single station on the
southern half of the Kermadec Ridge (33°S), on scleractinian coral at 350 m depth. It was fully described
and illustrated by SEM by Gordon (1984).
INTEGRIPELTA
GEN. NOV.
Diagnosis
Colony encrusting, multiserial. Autozooids with
smooth gymnocystal frontal shield lacking foramina.
Zooidal orifices with proximolateral indentations, and
shallow excavations in the adjacent gymnocyst; oral
rim lacking median suboral suture. No spines or avicularia. Maternal orifice usually slightly larger than
autozooidal orifice, or obviously so; brooding internal,
with a distal ovicell-like kenozooid with a central perforation. Ancestrula with membranous frontal wall
only, no spines. Interzooidal communications via uniporous mural septula.
Type species: Lepralia bilabiata Hincks 1884.
Etymology
From integer (L.) whole, and pelta (f. L.) a small shield.
Remarks
A new genus is established here for encrusting eurystomellids with imperforate frontal shields and communicating via uniporous mural septula instead of
basal pore-chambers. In the diagnosis, the ancestrula
is described as having a membranous frontal wall only.
This is based on the description of I. bilabiata by Soule
et al. (1995), who described it as resembling the adult
zooid “but with cuticular frontal wall”; there are no
spines (D. Soule, pers. comm. 2001). This accords with
the form of the ancestrula in Eurystomella, which has
no frontal shield and the distal rim and operculum are
like those of later zooids. The ancestrula has not yet
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
been encountered in any of the new species described
below. Integripelta bilabiata was fully described and
illustrated by SEM by Soule et al. (1995).
INTEGRIPELTA NOVELLA
(FIG. 2A, B)
SP. NOV.
Material examined
Holotype: ZIHU 02034, from 43°3¢N, 140°35¢E, 0 m,
the rocky tidal flat of Kamekawa, Kikonai-cho,
Shirabeshi Prefecture, Hokkaido.
Paratype: ZIHU 02035, same locality as holotype.
Description
Colony
encrusting,
multiserial,
unilaminar.
Autozooids contiguous, quincuncially arranged, 0.39–
0.75 mm long (0.52 ± 0.08 mm), 0.33–0.45 mm wide
(0.39 ± 0.03 mm). Gymnocystal frontal shield smoothsurfaced, somewhat convex, no umbo or carina,
lacking fenestrae. Orifice somewhat hat-shaped, the
anter high-arched with the proximal embayments
rounded, the proximal rim of the poster gently and
evenly concave or straight; the lateral excavations of
the gymnocyst very well developed, occurring adjacent
to the embayments and extending proximally, on one
or both sides, for a considerable distance, often equivalent to half the zooid length. Orifice of maternal
zooids dimorphic, though not always obviously so
(0.26–0.31 mm wide at the proximal margin compared
to that of autozooids 3/4 0.20–0.26 mm); distal kenozooidal chamber forming a somewhat triangular cap,
with a transverse to circular sloping shelf of interior
wall and a small circular foramen. No basal porechambers, interzooidal communications comprising a
row of uniporous septula along each lateral wall.
Ancestrula not seen.
205
Hincks (1882, 1884), Robertson (1908), O’Donoghue &
O’Donoghue (1925, 1926), Osburn (1952), and Banta
(1973). Soule et al. (1995) gave its range as Nootka
Island, Alaska, through British Columbia to southern
California and to Navidad Head, Mexico, at depths of
168–237 m, but it has also been recorded intertidally
(McBeth, 1971). It is also known from the Pleistocene
of southern California (Soule & Duff, 1957). Robertson
(1908) described the operculum of I. bilabiata in some
detail — it appeared to be two-layered and, together
with the distal rim of the orifice, the whole structure
appeared to be superficially bilabiate. Judging from
observations on I. sextaria (below) the ‘bilabiate’
appearance obtains in dried material, in which the
distal vestibular wall may be accentuated if slightly
protruding. While the operculum proper may be thin,
a descending cuticular rim around its periphery can
give the appearance of thickness. The orificial structure of I. japonica (below) is not known.
Distribution
Known with certainty only from the intertidal zone at
the type locality in Hokkaido.
INTEGRIPELTA JAPONICA
(FIG. 2C, D)
SP. NOV.
Eurystomella bilabiata: ?Kataoka 1960: 396, pl. 41, fig.
3; ?Hayami 1970: 330, pl. 36, fig. 3; ?Hayami 1974:
222, pl. 69, fig. 2a, b; ?Seo 1996: 301.
Etymology
From novellus (L.), diminutive of novus, new.
Material examined
Holotype: SMBL Type no. 399, 34°50.568¢N,
131°05.554¢E, 89–94 m, near the island of Mi-shima,
north of south-west Honshu (Yamaguchi Prefecture)
[Seto Marine Biological Laboratory Station 13-1, 29
September 1998].
Paratypes: SMBL Type no. 400, and NIWA P-1218,
same locality as holotype.
Remarks
Integripelta novella closely resembles the type species,
I. bilabiata, which, however, is much larger in size.
According to Soule et al. (1995), autozooids of I. bilabiata are 0.60–0.65 mm long and 0.50–0.55 mm
wide with an orifice width of 0.30–0.32 mm (hence the
widths of zooids and orifices do not even overlap in
the two species). Additionally, the shallow gymnocystal excavations in I. novella are proportionately
very much longer whereas the kenozooidal foramen is
tiny and surrounded by a broader area of interior
wall.
Apart from those sources already mentioned, Integripelta bilabiata has been recorded or described by
Description
Colony encrusting, multiserial, unilaminar. Dried
colonies hyaline. Autozooids contiguous, quincuncially
arranged, 0.47–0.75 mm long (0.62 ± 0.07 mm),
0.32–0.57 mm wide (0.45 ± 0.07 mm). Gymnocystal
frontal shield not elevated, no umbo or carina, smoothsurfaced, lacking fenestrae. Orifice somewhat more Dshaped than hat-shaped, the anter high-arched with
the proximal corners bluntly condyle-like, the proximal rim of the poster straight or scarcely concave, the
lateral corners curving obliquely distad towards the
short indentations and adjacent excavations. Orifice of
maternal zooids mostly not dimorphic, more or less
identical in size and shape (0.30–0.36 mm wide at the
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
206
D. P. GORDON ET AL.
Figure 2. A, B. Integripelta novella sp. nov. Hokkaido, intertidal. A, autozooids and two maternal zooids, the kenozooid distal to the one at left lacking a foramen, ¥89. B, maternal zooid with distal foraminate kenozooid, ¥121. C, D,
Integripelta japonica sp. nov. Mi-shimi, Honshu. C, autozooids and maternal zooids, ¥53. D, maternal orifice and kenozooid, ¥211. E, F, Integripelta sextaria sp. nov. NZOI Stn Z9700. E, autozooids and maternal zooids, ¥48. F, autozooidal
orifice, ¥181.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
proximal margin) to that of autozooids (0.24–
0.30 mm); distal kenozooidal chamber very small, not
extending to the basal wall, the central foramen tiny,
rounded or slit-like. No basal pore-chambers, interzooidal communications comprising a row of uniporous
septula along each lateral wall. Ancestrula not seen.
Etymology
From japonica (L.) Japanese.
Remarks
Integripelta japonica has almost certainly previously
been confused with I. bilabiata. The two species
appear similar, but published SEM micrographs (Cook
& Chimonides, 1981) allow comparison of the key taxonomic features, permitting ready discrimination of
the two species. In I. bilabiata the autozooidal orifice
is proportionately larger than in I. japonica (almost
half the size of the zooid) with larger proximolateral
excavations on the edge of the gymnocyst (see Cook &
Chimonides, 1981; fig. 5D, arrows), the maternal
orifice is dimorphic, a low umbo and/or carina is often
present, and the ‘ooecial kenozooid’ is larger with a
larger foramen. In his original description, Hincks
(1882) noted that the zooids in I. bilabiata were ‘short’
and that the ‘ooecium’ had a ‘large foramen’ (see also
Hincks, 1884). The above synonymy is suggested by
the published illustrations of specimens described by
Kataoka (1960) and Hayami (1970, 1974). We have not
examined these specimens, but the relative proportions of the orifice in relation to the entire zooid
strongly indicate that they were I. japonica, not I.
novella, which is somewhat intermediate between I.
bilabiata and I. japonica in the zooid length:orifice
length ratio.
Distribution
Southern Japan Sea off south-western Honshu,
89–94 m (Seto Marine Biological Laboratory Collection). ?Also Japan Sea, western Honshu, 151 m
(Kataoka, 1960), and Early Miocene of south-west
Hokkaido and central Honshu (Hayami, 1970, 1974).
INTEGRIPELTA SHIRAYAMAI
(FIG. 3A–C)
SP. NOV.
Lepralia bilabiata: Okada 1929: 24, fig. 10, pl. 2,
fig. 3; Sakakura 1935: 25, fig. 7.
Eurystomella bilabiata: Mawatari 1952: 280.
Material examined
Holotype: SMBL Type no. 401, 33°02.326¢N,
132°05.608¢E, 80–86 m, off the island of Saiki-wan,
207
Oita Prefecture, eastern Kyushu [Seto Marine
Laboratory Stn 5, 26 September 1998].
Paratypes: SMBL Type no. 402, and NIWA P-1219,
same locality as holotype.
Description
Colony encrusting, unilaminar, multiserial. Self-overgrowth not seen. Colony colour unknown. Autozooids
contiguous, quincuncially arranged, 0.47–0.75 mm
long (0.58 ± 0.07 mm), 0.28–0.55 mm wide (0.41 ±
0.06 mm). Gymnocystal frontal shield flat, centrally
smooth and imperforate. Orifice longer than wide,
somewhat dumbbell-shaped, the anter high-arched
and rounded with the proximal corners somewhat
condyle-like; poster not wider than anter, the proximal
rim gently and evenly concave. Conspicuous crescentic slits curve proximolaterally from corners of poster;
below the outer edge of each slit is a narrow shelf.
Traces of these slits, paired or distally continuous,
occur in incompletely formed autozooids, i.e. kenozooids. No peristome, umbones, spines, or avicularia.
Orifice of maternal zooids larger overall than in autozooids, the distal kenozooid with a large, transversely
elongate foramen sloping distad. Interzooidal communication via tiny uniporous mural septula. Ancestrula
not known.
Etymology
After Professor Yoshihisa Shirayama, director of the
Seto Marine Laboratory, Shirahama, Kii Peninsula, in
recognition of his contributions to biodiversity appreciation in Japan.
Remarks
This is a very striking species, easily recognizable by
the crescentic lateral slits, which are very conspicuous
in dead zooids. Okada (1929) attributed specimens
in his collection from Mutsu Bay to Eurystomella
bilabiata but illustrated the slits and, in one zooid, a
spine-like umbo, described in the text as keel-like or
carinate and restricted to older zooids. None of the
specimens we have examined show this latter feature.
Eurystomella shirayamai is also distinguished on
the basis of the ‘ooecial kenozooid’, the foramen
of which is larger and more bean-shaped than in E.
bilabiata.
Cook & Chimonides (1981) noted the crescentic
lateral slits illustrated by Okada (1929) and Sakakura
(1935) and also discovered them in a specimen in
The Natural History Museum, London (BMNH
1885.8.29.1) from “Sio-u-whu Bay”. [This name, not
found in modern atlases, refers to a locality south of
Vladivostok, Russia, in the Japan Sea. The coordinates on the label give the following data: “Sio-u-
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
208
D. P. GORDON ET AL.
Figure 3. A–C, Integripeltra shirayamai sp. nov. Saiki-wan, Honshu. A, autozooids, x, 70. B, maternal zooids with
foraminate kenozooids distally, ¥116. C, autozooidal orifice with proximal rim partly removed to show how the long crescentic slits are merely the frontal expressions of the proximolateral embayments of the orifice, ¥201. D, E, Integripelta
umbonata sp. nov. NZOI Stn Z9697. F, autozooids and a maternal zooid with foraminate distal kenozooid, ¥106. G, proximolateral corner of an autozooidal orifice, ¥930.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
whn(u) Bay, Gulf of Tartary, 42°N, 133°S”.] Cook &
Chimonides (1981) wrote: “Some of the Japanese populations have been reported to show characters [sic]
states which vary somewhat from those of the eastern
Pacific specimens. [The slits] are covered by brown
cuticle which appears to be continuous distally with
that of the operculum”. This observation accords with
our interpretation that the slits are lateral extensions
of the indentations seen at the proximolateral corners
of most eurystomellids (see Cook & Chimonides,
1981). Unfortunately, the specimens available to us
were all dead and lacked opercula and membranes.
The narrow shelf below the outer edge of each slit is
clearly homologous with the excavations that occur in
the gymnocysts of species like I. novella sp. nov. and
I. sextaria sp. nov. (cf. Figs 2A, B, F and 3C). One other
possibility is that the slits represent frontal foramina
that have migrated laterally; this is suggested by their
presence in kenozooids lacking orifices, but, in one
instance, the kenozooidal slits are distally continuous
and the distal part of the inverse U-shaped slit is suggestive of aborted orificial development. Further, the
distalmost parts of the frontal gymnocyst merely abut,
and do not fuse, with the proximal corners of the
‘ooecial kenozooid’, such that organic continuity
between the operculum and the slits is possible just at
or under the loci of abutment.
Distribution
Integripelta shirayamai is endemic to east Asian
waters. It has been reported (as Eurystomella bilabiata) from numerous localities in Mutsu Bay, northern
Honshu (Okada, 1929), from south-eastern Honshu
(Mawatari, 1952), and south of Vladivostok in the
Japan Sea. Pleistocene material was illustrated by
Sakakura (1935), who found specimens to be very rare
to common in the Dizôdô beds of the Bôsô Peninsula,
eastern Honshu. Specimens examined for this paper
were collected off Saiki-wan, eastern Kyushu (courtesy
of the Seto Marine Laboratory).
INTEGRIPELTA UMBONATA
(FIG. 3D, E)
SP. NOV.
Material examined
Holotype: NZOI H-751, from NZOI Stn Z9697,
34°21.06¢S, 172°42.53¢E, 57 m, Spirits Bay, New
Zealand.
Paratype: NZOI P-1219, same locality as holotype.
Other material: NZOI Stns Z9667, Z9678, Z9684,
Z9687.
Description
Colony encrusting, unilaminar. Autozooids 0.33–0.60
mm long (0.45 ± 0.006 mm), 0.22–0.49 mm wide (0.35
209
± 0.008 mm). Frontal shield smooth with a conspicuous umbo in its centre. No gymnocystal foramina; no
peristome, spines, or avicularia. Autozooidal orifice
broad, not very high-arched, the proximal rim gently
and evenly concave, not sinuous; lateral corners
slightly indented and excavated. Incompletely developed autozooids are kenozooidal, with a central
foramen and cuticular structure that appears to be a
nonfunctional operculum. Maternal zooids obviously
dimorphic, broader than autozooids with broader,
somewhat D-shaped orifice (0.25–0.30 mm wide at
the proximal margin; cf. 0.16–0.24 mm in autozooids).
Ooecium-associated kenozooid moderately well developed frontally, with a single large foramen facing
distad. Interzooidal communications via rows of tiny
uniporous septula. Ancestrula unknown.
Etymology
From umbo (L.) boss, protuberance, alluding to the
umbonate frontal shield.
Remarks
Integripelta umbonata is the second-known frontally
imperforate New Zealand species, the other being Z.
crystallina, from the Kermadec Ridge, which is biserial and its zooids lack umbones. Both species lack
basolateral pore-chambers but the proximolateral rim
of the orifice in Z. crystallina is somewhat elevated
and has a median suture.
Distribution
Endemic to New Zealand – known only from Spirits
Bay, northernmost North Island, 29–57 m depth.
INTEGRIPELTA SEXTARIA
(FIG. 2E, F)
SP. NOV.
Material examined
Holotype: NZOI H-750, from NZOI Stn Z9700,
34°22.88¢S, 172°39.71¢E, 54 m, Spirits Bay, New
Zealand.
Paratype: NZOI P-1220, separated part of holotype
colony, same locality.
Description
Colony
encrusting,
multiserial,
unilaminar.
Autozooids contiguous, quincuncially arranged, 0.47–
0.75 mm long (0.62 ± 0.07 mm), 0.32–0.57 mm wide
(0.45 ± 0.07 mm). Gymnocystal frontal shield smoothsurfaced, somewhat convex, no umbo or carina,
lacking fenestrae. Orifice somewhat hat-shaped, the
anter high-arched with the proximal embayments
rounded, the proximal rim of the poster gently and
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
210
D. P. GORDON ET AL.
evenly concave; the lateral excavations of the gymnocyst well developed, occurring on either side of the
embayments and extending proximally a short distance. Orifice of maternal zooids obviously dimorphic
(0.30–32 mm wide at the proximal margin) compared
to that of autozooids (0.20–0.28 mm); distal kenozooidal chamber well developed, with a conspicuous
transverse or circular foramen. No basal pore-chambers, interzooidal communications comprising a row of
uniporous septula along each lateral wall. Ancestrula
not seen.
Etymology
From sextarius (L.) sixth, alluding to the discovery
of a sixth species of eurystomellid in New Zealand
waters.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Remarks
Integripelta sextaria resembles I. bilabiata but has
smaller zooids and a proportionately broader ‘ooecial
kenozooid’ with a relatively very large foramen. The
gymnocystal excavations are often relatively long, as
in I. novella, but again, the ‘ooecial kenozooid’ and
foramen are significantly larger in I. sextaria.
14.
15.
16.
17.
Distribution
Endemic to New Zealand; known only from Spirits
Bay, North Island, 54 m.
18.
19.
CLADISTIC ANALYSIS
A cladistic analysis of eurystomellids was carried
out to clarify relationships within the family and
among putatively related catenicelloidean families
and genera. Characters and character states of
selected species are given in the table below. As
Grischenko et al. (2000) pointed out, the application
of cladistic methodologies for understanding phylogenetic relationships among bryozoans is in its infancy.
The relatively few, but morphologically distinctive,
eurystomellids that are known, along with good
prospective outgroups, constitute a useful cluster of
taxa for cladistic analysis.
CHARACTER
20.
21.
22.
23.
24.
25.
rim lacking in proximal half (1); not tatiform
(2).
Autozooid proximally tapering (with cauda): no
(0); yes (1).
Autozooids separated by uncalcified joints: no (0);
yes (1).
Gymnocystal foramina (windows): absent (0);
present (1).
Gymnocystal pores: absent (0); present (1).
Well-formed costae: present (0); absent (1).
Costal lumen pore: present (in autozooids or/and
female zooids) (0); absent (1).
Umbo and carina: absent (0): present (1).
Position of autozooidal orifice in frontal shield:
distal (0); central (1).
Depth of zooid: less than zooidal length (0);
greater than zooidal length (1).
Proximal corners of orificial anter: undifferentiated (0); condyle-like (1).
Separate condyles: present (0); absent (1).
Proximolateral corners of orificial poster: not or
scarcely indented, or poster narrower than anter
(0); clearly indented (1).
Excavations in gymnocystal surface associated
with postal indentations: none (0); vestigial (1);
small (2); well-developed (3).
Postal indentations expressed as lateroproximal
slits: no (0); yes (1).
Medial suture in proximal rim of orifice: present
(0); absent (1).
Maternal orifice dimorphic, i.e. broader than autozooidal orifice: obviously so (0); slightly/sometimes
(1); never (2).
Brooding of embryos: extrazooidal in ovicell (0);
endozooidal (1).
Kenozooid distal to maternal ooecium/ovicell: no
(0); yes (1).
Kenozooidal foramen or depressed area: not
applicable (0); one, central (1); two either side of
median suture (2); one central, plus two small
pores frontally, no obvious suture (3).
Adventitious avicularia: present (0); absent (1).
Vicarious avicularia: present (0); absent (1).
Lateral interzooidal communications: rows of
uniporous mural septula (0); pore-chambers
with multiporous septula (1); no communications
(2).
LIST
1. Colony form: encrusting (0); lunulitiform (1); erect
(2).
2. Ancestrular attachment: cementation of entire
basal wall (0); no cementation (basally budded
rootlet) (1); proximal cementation at end of
tapered cauda (2).
3. Ancestrular frontal wall: tatiform, with entire
gymnocystal margin (0); subtatiform, gymnocystal
A matrix of 25 skeletal characters was assembled for
nine living and two fossil species of Eurystomellidae,
including some of the new species described here
(some were excluded because they coded identically to
others in the matrix), plus five out-group species
(Table 1). The outgroup taxa chosen for the analyses
were: Figularia mernae Uttley & Bullivant, 1972
(Cribrilinidae), Euthyroides episcopalis (Busk, 1852)
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
211
Table 1. Data used in the phylogenetic analysis. Characters 4, 7, 10, 11, 14, and
24 are parsimony-uninformative and thus were not employed in the analysis
Characters
Taxa
1
5
1
0
5
2
0
5
E. foraminigera
E. biperforata
Z. crystallina
I. bilabiata
I. japonica
I. sextaria
I. shirayamai
I. umbonata
S. gabrieli
S. macgillivrayi
S. marginata
F. mernae
E. jellyae
P. bicornis
C. bicuspis
O. innominata
0000
0000
0000
0000
0000
00?0
0000
0000
1110
11?0
11?0
0000
2??0
2221
2220
2220
01011
01011
00011
00011
00011
00011
00011
00011
00011
00011
00011
00000
00000
10001
11A00
11011
00011
00011
00001
00011
00011
00011
00011
10011
0A111
00111
0A111
00000
00001
00011
00011
00011
12001
12000
11001
13010
12011
13011
1B111
12010
01010
0A010
0A010
00000
00000
00000
10000
10000
11111
11111
11311
11111
11111
11111
11111
11111
11211
11211
11211
00010
00011
01101
01101
01101
1
1
0
0
0
0
0
0
0
0
0
?
?
2
0
0
A = (0,1); B = (2,3).
(Euthyroididae), Petalostegus bicornis (Busk, 1884)
(Petalostegidae), and Costaticella bicuspis (Gray,
1843) and Orthoscuticella innominata Gordon, 1989)
(Catenicellidae). These are all either acanthostegans
(cribrimorphs) or derived acanthostegans. Most are
Recent species found in the New Zealand region and
their character states are based on examination of
actual specimens.
We analysed the data with PAUP* 4.0b8 (Swofford,
2001). MacClade 3.08a (Maddison & Maddison, 1999)
was used for character mapping, and for character
handling in general. All characters were unordered and
given equal weight. Characters 4, 7, 10, 11, 14, 17 and
24 are parsimony-uninformative and were not included
in the analysis. Character optimization was executed
under accelerated transformation (ACCTRAN)
(Swofford & Maddison, 1987). The heuristic search
option was used in PAUP* with random addition
sequence (100 replicates) and tree-bisectionreconstruction (TBR) branch swapping, holding 10
trees at each step. This analysis was followed by a
successive weighting (base weight 1), based on the
rescaled consistency index (Farris, 1969, 1989).
RESULTS
The initial analysis with equal weighting yielded 174
most parsimonious trees (MPT), each 39 steps, with a
consistency index (CI) of 0.744 and a retention index
(RI) of 0.828. One round of successive weighting
resulted in 39 MPTs (Fig. 4), each 24 steps, with a CI
of 0.848 and a RI of 0.907. One more round did not
change the topology or number of trees, but only
the character weights and thus the indices. All MPTs
were distributed on a single island, which means
that the problem of multiple islands of MPTs
(Maddison, 1991) does not jeopardise the present
study. The tree-length distribution skewness (g1 statistic) is –1.066 (estimated from 100 000 randomly
selected trees) and thus well below the 1% significance
level given by Hillis & Huelsenbeck (1992). This supports a presence of phylogenetic information in the
data. Figure 5 shows the strict consensus tree (Rohlf ’s
consistency index of 0.896) of the final 39 trees. The
consensus tree was well resolved except for two basal
polytomies, among Integripelta and Selenariopsis
species, respectively.
DISCUSSION AND CONCLUSIONS
Gordon (1984, 1989) included the family Eurystomellidae in the superfamily Catenicelloidea. Although all
members of the Catenicellidae are erect and jointed,
comprising long chains of uni- to multizooidal segments, autozooids of several genera share a number
of features with Eurystomella. For example, species of
Orthoscuticella are characterized by smooth gymno-
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
212
D. P. GORDON ET AL.
Figure 4. One of the 39 most parsimonious trees obtained from the final analysis carried out by
tions of all 25 skeletal characters are mapped (cf. Character List).
cystal shields perforated by large foramina. These are
covered by an epidermal epitheca and have sloping
internal walls that effectively constitute cryptocystal
surfaces; the chambers of these foramina, sealed
below by the ascus roof, effectively constitute tiny
hypostegal coeloms (Banta & Wass, 1979). The ascus
roof is commonly partly calcified in many catenicellids
(Banta & Wass, 1979), as is the case in at least
one species of Eurystomella (E. biperforata), Some
other catenicellid genera have what appear to be
vestigial costae comprising the proximal oral rim
(see Banta & Wass, 1979; Gordon, 1984, 1989), resembling the condition in the foraminate species of
Eurystomella.
PAUP*.
The transforma-
The cladistic analyses consistently linked the two
catenicellid species; these in turn were part of a clade,
containing Petalostegus, that was sister to the eurystomellids, consistent with the concept of superfamily
Catenicelloidea (Gordon, 1984; Gordon & d’Hondt,
1991). Basalwards were Euthyroides, sister to the
Catenicelloidea, and Figularia, sister to Euthyroides +
Catenicelloidea. Gordon & d’Hondt (1991) and Gordon
(2000) have argued that eurystomellids evolved from
a cribrimorph ancestor by increasing the area of gymnocystal frontal shield at the expense of the costal
field. Banta (1973) noted the similarity of the frontal
shield in Integripelta bilabiata and the cribrilinid
Figularia hilli Osburn (1950). The earliest-occurring
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
NEW EURYSTOMELLID TAXA
213
Figure 5. The strict consensus of 39 final trees. Synapomorphies for each clade in the ingroups are indicated by solid
bars: lunulitiform colony (1), encrusting colony (1¢), ancestrular attachment without cementation (2), subtatiform ancestrular frontal wall (3), gymnocystal foramina (6), lack of well-formed costae (8), zooid deeper than length (12), undifferentiated proximal corners of orificial anter (13), indented proximolateral corners of orificial poster (15), vestigial
excavations in gymnocystal surface (16), small excavations in gymnocystal surface (16¢), lack of medial suture in proximal
rim or orifice (18), maternal orifice slightly dimorphic (19), endozooidal brooding of embryos (20), two kenozooidal
foramina (22), one central plus two small kenozooidal foramina (22¢), interzooidal communications with pore-chambers
(25).
eurystomellids are Miocene species of Selenariopsis,
which lack any trace of costae (Bock & Cook, 1996),
and a Miocene Japanese species of Integripelta (probably I. japonica). In lacking gymnocystal foramina and
a median suboral suture, the frontal shield in both
Integripelta and Selenariopsis appears to be more
derived than that of Eurystomella, but this genus is
not known before the Pliocene (Brown, 1952), in
New Zealand. Indeed Eurystomella is crownward of
Selenariopsis in the cladograms.
Cladistic analyses tended to highlight the morphological distinctiveness of the biserial Kermadec species
Eurystomella crystallina Gordon 1984. In the consensus tree of the final 39 MPRs this species appears as
a sister taxon to all Eurystomella sensu lato species
with multiserial colonies. We hereby recognize this
species as the type of a new genus, Zygopalme, characterized not only by uni-/biseriality, but by frontally
imperforate autoozoidal shields that nevertheless
have a median suboral suture, and by maternally
associated kenozooids with one large foramen and two
small pores.
We anticipate that encrusting eurystomellids should
be found in the Paleogene with definite costae. The
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216
214
D. P. GORDON ET AL.
question arises – in which part of the world? As mentioned, the earliest-known encrusting species is from
the Japanese Miocene, but the greatest diversity of
Recent eurystomellid species is in Australasia. Six
species occur in New Zealand waters and one (Selenariopsis gabrieli) in Australia. Japan now has three
recognized species of eurystomellid, and one is found
along the western coast of North America from southern Alaska to Baja California, Mexico. No eurystomellids are yet known from the tropical western
Pacific between New Zealand and Japan (though some
should be expected) and none is known from western
South America or the Indian Ocean. The larger
number of species and genera in Australasia is possibly suggestive of an austral origin for the family.
It is remarkable that five of the six New Zealand
species co-occur in Spirits and Tom Bowling Bays at
the far north of New Zealand’s North Island.
Indeed, three of the four new New Zealand species
(Eurystomella aupouria, Integripelta sextaria and I.
umbonata) are known only from this area of the Three
Kings Shelf. Zygopalme crystallina is restricted, as
mentioned, to the southern part of the Kermadec
Ridge, a volcanic arc that was probably initiated in the
earliest Miocene (Wright, 1997).
The occurrence of a specific biological association
between Integripelta bilabiata and the opisthobranch
Hopkinsia rosacea MacFarland, 1905 in southern
California is interesting in this regard, however. This
mollusc feeds exclusively on I. bilabiata, is often
observed with the bryozoan in the intertidal zone, and
consumes it readily in the laboratory (McBeth, 1971).
Hopkinsia rosacea is a suctorial nudibranch that feeds
in the same way as other dorids that consume bryozoans. It first rasps a hole in the frontal area
(whether the frontal shield or operculum has not been
recorded) via radular action, then sucks out the soft
parts by contractions of the buccal bulb. The distinctive pinkish red pigmentation of both the bryozoan
and its prey are imparted by a unique carotenoid, hopkinsiaxanthin. A similar predator-prey relationship is
unknown in any other eurystomellid. Clearly, a not
insignificant period of geological time must have
elapsed for the association to develop, being behaviourally exclusive and involving the same pigments.
Only two other species of Hopkinsia are known (Willan
pers. comm. 2001), both undescribed. They are
obligate predators of the euthyrisellid bryozoan
Pleurotoichus clathratus on the Great Barrier Reef
and elsewhere in tropical to subtropical Australia
(Marshall & Willan, 1999). Both P. clathratus and the
predator are pigmented (generally maroon, but the
dorids can also have pink and crimson body parts) but
the nature of the pigment is not known. Euthyrisellid
bryozoans are quite unrelated to eurystomellids,
however, having an interior-walled frontal shield.
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APPENDIX
National Institute of Water & Atmospheric Research Station Data (NZOI
Stations)
B220: 21 May 1960, 46°40¢S, 168°09.8¢E, 37 m, Foveaux Strait
B221: 21 May 1960, 46°40.0¢S, 168°16.79¢E, 31 m, Foveaux Strait
B224: 21 May 1960, 46°45¢S, 168°16.8¢E, 32 m, Foveaux Strait
B230: 22 May 1960, 46°40.0¢S, 168°02.5¢E, 26 m, Foveaux Strait
B235: 23 May 1960, 46°34.99¢S, 167°55.00¢E, 49 m, Foveaux Strait
D273: 6 October 1964, 40°45.0¢S, 173°49.5¢E, 75 m, Cook Strait
K837: 28 July 1974, 30°15.5¢S, 178°24.2¢W, 110–125 m, Macauley Island,
Kermadec Ridge
Z9077: 5 May 1998, 34°24.6¢S, 172°44.7¢E, 27 m, Spirits Bay, NI
Z9667: 24 January 1999, 34°24.31¢S, 172°49.95¢E, 29 m, Spirits Bay, NI
Z9669: 24 January 1999, 34°23.12¢S, 172°46.36¢E, 35 m, Spirits Bay, NI
Z9670: 25 January 1999, 34°22.68¢S, 172°45.61¢E, 46 m, Spirits Bay, NI
Z9671: 25 January 1999, 34°19.98¢S, 172°45.79¢E, 63 m, Spirits Bay, NI
Z9677: 25 January 1999, 34°2.14¢S, 172°49.5¢E, 55 m, Spirits Bay, NI
Z9678: 26 January 1999, 34°21.6¢S, 172°43.19¢-E, 48 m, Spirits Bay, NI
Z9684: 26 January 1999, 34°23.55¢S, 172°51.72¢E, 40 m, Spirits Bay, NI
Z9685: 26 January 1999, 34°22.58¢S, 172°49.25¢E, 49 m, Spirits Bay, NI
Z9687: 27 January 1999, 34°2.68¢-S, 172°42.66¢E, 48 m, Spirits Bay, NI
Z9695: 27 January 1999, 34°22.0¢S, 173°00.01¢E, 89 m, Tom Bowling Bay, NI
Z9697: 28 January 1999, 34°21.06¢S, 172°42.53¢E, 57 m, Spirits Bay, NI
Z9700: 28 January 1999, 34°22.88¢S, 172°39.71¢E, 54 m, Spirits Bay, NI
Z9701: 28 January 1999, 34°17.90¢S, 172°47.55¢E, 76 m, Spirits Bay, NI
Z9708: 29 January 1999, 34°20.34¢S, 172°44.46¢E, 59 m, Spirits Bay, NI
Z9710: 29 January 1999, 34°21.15¢S, 172°45.92¢E, 54 m, Spirits Bay, NI
Z9713: 29 January 1999, 34°22.5¢S, 172°5.7¢E, 65 m, Spirits Bay, NI
Z9716: 29 January 1999, 34°21.69¢S, 173°00.06¢E, 100 m Tom Bowling Bay, NI
NI = North Island.
© 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216