PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY
54
Monogenean Parasites of Costa Rican Fishes. II. Proposal of
Palombitrema heteroancistrium n. gen., n. sp.1
C. E. PRICE- AND W. A. BUSSING:!
Prior to the present investigation, only
four freshwater monogenetic trematodes were
known from Central America, all described
from Costa Rican hosts. E. W. Price (1938)
described two species of Cleidodiscus Mueller,
1934 from the gills of Rhamdia rogersi (Regan),
the host taken from the San Pedro Montes de
Oca. Price (in press) has given reasons why
these two parasites should be transferred to
the genus Urocleidus Mueller, 1934.
In a study recently completed (Price and
Bussing, 1967), two species of Cleidodiscus
were removed from the gills of Astyanax
fasciatus (Cuvier) and subsequently described
as the first valid Cleidodiscus forms from
Central America.
This paper is concerned with the description and classification of Palombitrema, a new
genus of Monogenea, recovered from the gills
of Astyanax fasciatus (Cuvier) from Costa Rica.
Materials and Methods
Host specimens utilized in this study were
collected in Costa Rica, immediately frozen
for several hours, and preserved in 3.5% formalin prior to shipment to the United States.
Gill trematodes were recovered and treated
as prescribed by Price (1966). Appropriate
measurements and illustrations were made with
the aid of a calibrated filar micrometer ocular
and a camera lucida, respectively. All measurements are expressed in microns; average measurements are given first, followed by minimum
and maximum values enclosed in parentheses.
Palombitrema n. gen.
GENERIC DIAGNOSIS: Dactylogyridae, Ancyrocephalinae. A form of moderate size provided with a thin cuticle. Two pairs of eyespots, members of posterior pair larger. Haptor
well set off from body proper. Two pairs of
1 This study was supported jointly by the Departamento
de Biologia, Universidad de Costa Riea and by the Department of Biology, Augusta College.
- Department of Biology, Augusta College, Augusta,
Georgia 30904.
3 Departamento de Biologia, Universidad de Costa Rica,
Central America.
dissimilar anchors, one pair located ventrally
in haptor, the other dorsally. Rases of each
anchor pair connected by a separate transverse bar. Hooks 14 (7 pairs), greatly variable
in both size and shape. Cirrus provided with
a basally articulated accessory piece, the latter
of two distinct pieces joined by connective
tissue. Vagina opening near left body margin.
Vitellaria well developed, often arranged in
patches. Intestinal crura apparently confluent
posteriorly.
TYPE SPECIES: Palombitrema heteroancistrium.
TYPE HOST: Astyanax fasciatus (Cuvier).
TYPE LOCALITY: Guanacaste Province, Rio
Montenegro; 23 km NW of Canas (on Interamerican Highway), Costa Rica, Central
America.
Palombitrema heteroancistrium n. sp.
HOST AND LOCALITY: Asttjanux fasciatus
(Cuvier); Guanacaste Province, Rio Montenegro, 23 km NW of Canas (on Interamerican Highway), Costa Rica, Central
America.
BODY REGION OCCUPIED BY PARASITE:
Gill
filaments.
SPECIMENS STUDIED: Ten.
TYPES: Holotype deposited in USNM Helm.
Coll. (No. 62987), Washington, D. C. First
paratype deposited in Museo de Zoologia (No.
UCR-1), Departamento de Biologia, Universidad de Costa Rica, Central America. Remaining paratypes in authors' collections.
DESCRIPTION: A robust dactylogyrid of moderate size, provided with a thin cuticle; length
502 (454-529). Greatest body width 100
(88-105), usually near midlength. Two pairs
of eyespots, members of posterior pair larger
and spaced farther apart than members of
other pair. A few eyespot granules scattered
in cephalic region. Peduncle short and stout,
setting haptor off well from body proper. Well
developed anterior cephalic lobes; lateral cephalic lobes vestigial. Pharynx muscular, subspherical in ventral view (whole mount: Fig. 1).
Copyright © 2011, The Helminthological Society of Washington
OF WASHINGTON, VOLUME 35, NUMBER 1, JANUARY 1968
55
8
0. 04 mm
Figures 1-13. Camera lucida illustrations of Palombitrema heteroancistriwn n. gen., n. sp. 1. Entire
worm (ventral view); 2. Ventral anchor; 3. Dorsal anchor; 4. Ventral bar; 5. Dorsal bar; 6-9. Hooks;
10. Vagina; 11. Seminal receptacle; 12. Cirrus; 13. Accessory piece. All illustrations except Figure 1
drawn to same scale.
Copyright © 2011, The Helminthological Society of Washington
56
PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY
Two pairs of dissimilar anchors. Ventral
anchor without prominent roots and with a
hollow base (Fig. 2 ) ; length 33 (30-34),
width of base 15 (14-17). Dorsal anchor
smaller, of a shape unusual for the Ancyrocephalinae: the deep root, shaft, and point
form a solid structure, whereas the superficial
root is thin and extremely flexible, appearing
to be a membranous appendage of the baseshaft region (Fig. 3); length 23 (21-25),
width of base 11 (10-12). Ventral bar of
simple construction (Fig. 4); length 38 (3640). Dorsal bar unusual for subfamily: main
shaft is in form of a "V," the ends in form of
poorly developed sclerotized discs (Fig. 5);
length 36 (34-37).
Seven pairs of hooks, five pairs located
ventrally on haptor, remaining two pairs
located dorsally. Ranges of both size and
shape of hooks constitute unusual features.
Pairs one to five (ventrally located) somewhat
similar to each other (Fig. 9); dorsal members
(pairs six and seven), however, are diverse in
comparison. Members of pair No. 6 each composed of a base tapering uniformly to a sickleshaped termination, exhibiting little or no shaft
region (Fig. 8). Members of pair No. 7 relatively large and very flexible (Fig. 6 , 7 ) . Hook
lengths: No. 1, 13 (11-14); No. 2, 17 (1618); No. 3, 19 (18-20); No. 4, 18 (17-19);
No. 5, 14 (13-15); No. 6, 17 (15-18); No. 7,
38 (37-40).
Cirrus arising from an expanded base, tapering to a tube of narrow diameter (Fig. 12);
estimated length 42. Accessory piece articulated to cirrus base and complex in construction: composed of two distinct portions joined
together by connective tissue (Fig. 13); overall length 27 (25-30). Vagina heavily sclerotized (Fig. 10), opening ventrally in left body
half; vaginal tube opens into a thin-walled
seminal receptacle (Fig. 11). Ovary pretesticular in position, compact, and somewhat
elongate; testis relatively small, subspherical
to elongate in outline. Prostatic reservoir
single, folding back upon itself.
Vitellaria well developed, composed of small
granules of essentially uniform size and density;
tends to form lateral bands in two specimens,
whereas there is a tendency toward formation
of irregular patches in remaining specimens. Intestinal crura apparently confluent posteriorly.
Discussion
This form was originally considered to be
a deviant species of Cleidodiscus Mueller,
1934. Further study indicated that this parasite possesses sufficient atypical features to
prevent its inclusion in Cleidodiscus.
Palombitrema is morphologically close to
Cleidodiscus. The ventral bar and ventrally
located hooks (Nos. 1—5) are similar to those
possessed by Cleidodiscus species. The major
features for differentiation of the two genera
are: (1) the two-piece construction of the
accessory piece of Palombitrema is not present
in any member of Cleidodiscus, (2) the dorsal
hooks of the latter genus are quite similar in
both shape and size, whereas those of the
former are grossly different both in morphology
and in size, and (3) the large, irregularly
shaped, and heavily sclerotized vagina present
in this new form is lacking in all known species
of Cleidodiscus.
DERIVATION OF SCIENTIFIC NAME: The generic name is chosen to honor Professor Arturo
Palombi of Napoli, Italy, in recognition of past
work performed on the Monogenea of Europe
and also in personal appreciation of the senior
author for recent help and encouragement extended by Professor Palombi. The species
name is derived from the Greek HETERO- ("different") and from the Greek ANCISTR- ("hook"
or "spine"); this designation is chosen to indicate discrepancies in hook morphology and
Summary
Ten specimens of a new genus of Monogenea, Palombitrema, were recovered from the
gills of a Costa Rican teleost, Asti/anax fasciatus
(Cuvier).
This parasite was originally considered to
be a deviant species of Cleidodiscus Mueller,
1934. Further study indicated that the form
presently studied was well differentiated from
Cleidodiscus, although the two genera are apparently related.
The type species, Palombitrema heteroancistrium, is described.
Literature Cited
Price, C. E. 1966. Urocleidus cavanaughi, a
new monogenetic trematode from the gills of
Copyright © 2011, The Helminthological Society of Washington
OF WASHINGTON, VOLUME 35, NUMBER 1, JANUARY 1968
the keyhole cichlid, Aeqtiidens rnaroni (Steindachner). Bull. Georgia Acacl. Sci. 24: 117120.
. In press.
Synonymy in the genus
Cleidodiscus with the description of a new
species. Qtrly. J. Florida Acad. Sci.
—-, and W. A. Bussing. 1967. Monogenean
57
parasites of Costa Rican fishes. Part 1. Descriptions of two new species of Cleidodiscus
Mueller, 1934. Riv. Parass. 25: 81-86.
Price, E. W. 1938. The monogenetic trematodes of Latin America. ( I n ) Livro Jubilar
Prof. Travassos, Rio de Janeiro, Brazil. 3:
407-413.
A Soil Population Study of Ditylenchus dipsaci (Kuhii)
Filipjev in an Alfalfa Field1
SHU-TEN TSENG, KEITH R. ALLRED, AND GERALD D. GRIFFINIntroduction
Materials and Methods
There have been several studies made on
the relationship of the environment to Ditylenchus dipsaci in the soil. Lewis and Mai
(1960) found most specimens of this nematode
species in the top 6 inches of fallowed soil.
This agrees with the observations of Wallace
(1962) who observed more D. dipsaci in the
first 10 cm of soil than at lower depths in an
infested oat field. Wallace further stated that
the number of nematodes increased greatly
after a rain and decreased during the following
dry period. Wallace (1961) also found that
horizontal as well as vertical movements of
D. dipsaci were related to the moisture and
temperature gradients in the soil. Seinhorst
(1956) found that heavy soils maintained a
larger population of nematodes than light soils,
and Sayre and Mountain (1962) reported a
high mortality of D. dipsaci in wet soils at
70 F.
The present investigation was initiated to
study seasonal populations of D. dipsaci relative to temperature and soil moisture conditions in an alfalfa field.
A field of 6-year-old Ranger alfalfa (Medicago sativa L.) on Millville silt loam located
near Smithfield, Utah, was selected for this
study. The alfalfa was infected with the alfalfa
stem nematode, Ditylenchus dipsaci (Kiihn)
Filipjev. The experimental design consisted of
dividing the field into 16 sections in a randomized square block, and marking off a
square plot 5 by 5 meters in each section. The
distance between the centers of any two adjacent plots was 12 meters.
Soil samples were collected from each plot
at 2-week intervals, from 6 August 1965 to
26 June 1966. Sampling depths were 0-10,
10-20, 20-30, and 30-40 centimeters. Three
subsamples were taken from each plot at each
sampling date using a soil auger of 10 cm in
diameter. These were thoroughly mixed, a 400
cc composite collected in a plastic container.
Soil remaining from the subsamples was immediately replaced into the hole. During the
winter, a pick was used for breaking through
the frozen soil to facilitate the use of the soil
auger.
Soil moisture was determined on each sampling date at the various sampling depths for
four of the 16 plots. Soil moisture was determined by the gravimetric method, and expressed as a per cent of field capacity. The
field capacity of the soil was as follows:
1 Cooperative investigations of the Utah Agricultural Experiment Station, Logan, Utah and the Crops Research
Division, Agricultural Research Service, USDA. Journal
Paper No. 614 of the Utah State Agricultural Experiment
Station. Part of a thesis submitted by the senior author in
partial fulfillment of the requirements of the M.S. degree.
- Respectively former Graduate Assistant, Professor of
Plant Science, Utah State University, and Research Nematologist, Crops Research Division, Agricultural Research
Service, Crops Research Laboratory, Utah State University,
Logan, Utah.
Copyright © 2011, The Helminthological Society of Washington