Comparative Parasitology 68(2) 2001 - Peru State College
Comparative Parasitology 68(2) 2001 - Peru State College
Comparative Parasitology 68(2) 2001 - Peru State College
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224 COMPARATIVE PARASITOLOGY, <strong>68</strong>(2), JULY <strong>2001</strong><br />
Remarks<br />
Fischthal and Kuntz (1975) described Mesostephanoid.es<br />
taiwanensis from the small intestine<br />
of E. chinensis from Taipei Prefecture in<br />
Taiwan on the basis of a single specimen. We<br />
examined that specimen, USNPC No. 73148,<br />
and, even though it was not from the gallbladder,<br />
we considered our specimens from Vietnam<br />
conspecific with it. Data for the holotype fit<br />
those for our specimens. We, however, interpret<br />
differently the terminal genitalia described and<br />
illustrated by Fischthal and Kuntz (1975) in their<br />
Figure 15. Perhaps they misinterpreted the nonillustrated<br />
muscular looping of the metraterm as<br />
spines. In any event, the cirrus sac of the holotype<br />
contained a club-shaped seminal vesicle<br />
measuring about 260 u,m long, a straight pars<br />
prostatica 113 u,m long, and a short ejaculatory<br />
duct 45 fjim long. The metraterm coiled once<br />
prior to descending to the genital atrium. We observed<br />
spines in none of these features. Because<br />
of the lack of a spined cirrus and lack of anterior<br />
confluence of the bands of vitelline follicles, we<br />
consider that the species belongs to Szidatia Dubois,<br />
1938, as Szidatia taiwanensis (Fischthal and<br />
Kuntz, 1975) comb. n.<br />
Dubois (1951) differentiated the monotypic<br />
genus Mesostephanoides Dubois, 1951, from<br />
other cyathocotylid genera on the basis of Mesostephanoides<br />
burmanicus (Chatterji, 1940),<br />
having a forebody to total body length ratio that<br />
we estimate as 1:1.14-1.18, a spined cirrus 300<br />
(Jim long, and vitelline follicles confluent anteriorly.<br />
We consider the first 2 features of questionable<br />
generic significance, and an examination<br />
of M. burmanicus and related species may<br />
show that Mesostephanoides is a synonym of<br />
Gogatea Lutz, 1935, a genus with species having<br />
anteriorly confluent vitelline follicles.<br />
Szidatia taiwanensis resembles its 2 congeners<br />
in that the vitelline follicles are in separate<br />
lateral fields, as opposed to being in a single<br />
confluent field underlying the tribocytic organ as<br />
reported for species of Gogatea, the only other<br />
genus in Szidatiinae. Szidatia taiwanensis most<br />
closely resembles Szidatia nemethi Dollfus,<br />
1953, from the water snake TV. maura (as N. viperina)<br />
from Charrat, Morocco, but differs from<br />
this species by having a much smaller tribocytic<br />
organ (283—447 jjim long by 246-423 |xm wide<br />
vs. 885 (Jim long by 765 u,m wide), larger eggs<br />
(140-169 jxm long by 80-99 (Jim wide vs. 105<br />
Copyright © 2011, The Helminthological Society of Washington<br />
(xm long by 55 (Jim wide), and a club-shaped<br />
rather than a coiled seminal vesicle. Szidatia taiwanensis<br />
differs from S. joyeuxi, the type and<br />
remaining species in the genus, by having a<br />
longer esophagus (67-149 |JLm compared with<br />
40 |xm), ceca that reach only to the level of the<br />
anterior testis rather than beyond the posterior<br />
testis, an acetabulum that lies between the middle<br />
and anterior % of the forebody rather than<br />
exactly in the middle, and oblique rather than<br />
tandem testes; the anterior testis is almost entirely<br />
within the forebody rather than in the<br />
hindbody, the seminal vesicle is club-shaped<br />
rather than coiled, and the eggs are larger (140-<br />
169 (xm long by 80-99 (Jim wide vs. 100 (Jim<br />
long by 70 (xm wide). The minute papillae on<br />
the tegument at the posterior end, too small to<br />
illustrate to scale, probably serve a sensory<br />
function during mating or egg deposition. The<br />
intestine, the infection site of the specimen reported<br />
by Fischthal and Kuntz (1975), may have<br />
resulted from postmortem migration from the<br />
gallbladder. A few specimens of other species<br />
normally found in the gallbladder occasionally<br />
occur in the intestine normally. We do not think<br />
the difference in sites based on 1 specimen is<br />
significant.<br />
As with the echinostomate specimens of S.<br />
vietnamensis, the initial specimens of S. taiwanensis<br />
had been placed in fresh water prior to<br />
fixation in unheated formalin (see Fig. 6). Unlike<br />
those of S. vietnamensis, these specimens<br />
were not fixed under any pressure; nevertheless,<br />
their measurements and features varied dramatically<br />
from those obtained from specimens fixed<br />
with heat and used for the above description.<br />
Hindbody length was generally shorter (146-<br />
506 (Jim vs. 326—762 (Jim), and both the anterior<br />
and posterior testes occurred entirely in the forebody<br />
of specimens exposed to water, whereas<br />
the posterior testis was always in the hindbody<br />
of heat-killed specimens. The cirrus sac was<br />
generally straighter in osmotically stressed specimens<br />
and more bent or curled in the region of<br />
the pars prostatica in heat-killed specimens. In<br />
addition, the tribocytic organ was greatly enlarged<br />
(492-650 (Jim long by 520-<strong>68</strong>5 |xm wide<br />
vs. 283-447 fxm long by 245-423 ujn wide) in<br />
the stressed specimens. The most important difference<br />
due to fixation techniques pertained to<br />
the configuration of the vitellarium. In the<br />
stressed specimens, vitelline follicles appeared<br />
confluent anteriorly (horseshoe-shaped distribu-