Archigetes, Leuckart, 1878

Toma, Scholz, s, P, Gerardo & Leon, erez-Ponce de, 2021, Caryophyllidean tapeworms (Cestoda), Nearctic parasites of fish in Mexico, including description of a new species of Isoglaridacris and the first report of Khawia japonensis, an invasive parasite of common carp (Cyprinus carpio), International Journal for Parasitology: Parasites and Wildlife 15, pp. 70-78 : 72

2. Archigetes (?) sp. 2 Fig. 1B, E

Material studied: One specimen from Nazas shiner, Notropis nazas Meek ( Cypriniformes : Leuciscidae ), Río Nazas in Emilio Carranza, Durango, collected by Rogelio Rosas-Vald´ez in November 2008 ( CNHE 6797).

Host: Notropis nazas .

Distribution: Mexico (Durango).

Remarks

The tapeworm found in N. nazas is also tentatively placed in Archigetes based on the shape and small size of its body (2.5 mm; Fig. 1B ), shape of the scolex, which is bothrioloculodiscate ( Fig. 1E ), and dumbbell-shaped ovary (see Mackiewicz, 1994 for generic diagnosis of Archigetes ). The specimen from N. nazas is elongate and slender ( Fig. 1B ), with the maximum width of 430 μm, which represents only 17% of total length. The scolex is slightly separated from the neck region and is 260 μm long and 320 μm wide ( Fig. 1E ). Testes are not numerous (their precise number could not be counted), begin 106 μm posterior to anterior-most vitelline follicles ( Fig. 1E ); posterior extent of the testicular field could not be observe due to damage of the body, but testes apparently reach the anterior loops of the uterus ( Fig. 1 B ). Cirrus-sac is subspherical, thick-walled, 102 μm long and 88 μm wide. Presence of an external seminal vesicle could not be verified due to the presence of numerous eggs in broken part of the body. Anterior-most vitelline follicles, which are circum-medullary, i.e., in confluent lateral and median fields ( Fig. 1B ), begin 474 μm from the anterior extremity, i.e., 19% of total body length, anterior to the anterior-most testes ( Fig. 1E ). Preovarian follicles do not reach posteriorly as far as the ovary ( Fig. 1B ); postovarian follicles present, reach anteriorly the posterior end of the ovary. Eggs are very numerous and uterine region occupies a major part of the posterior half of the body ( Fig. 1B ); intrauterine eggs are 49–53 long and 31–34 μm wide (n = 5; only uncollapsed eggs measured).

Unfortunately, the specimen is in poor condition and its posterior part with the uterus is broken; lateral sides of the scolex are also slightly damaged ( Fig. 1E – dotted lines). Numerous eggs also prevent reliable observation of the presence of an external seminal vesicle (if present), which is a typical characteristic of species of Archigetes . Tentatively, the specimen from N. nazas is designated as Archigetes (?) sp. 2 to distinguish it from supposedly congeneric tapeworms from Notropis caliensis ( Archigetes sp. 1 – see above) and Chirostoma sp. ( Archigetes sp. 3 – see below).

Figures

Fig. 1. Archigetes sp. 1 from Notropis caliensis, Michoac´an (CNHE 6800) (A, C, F); Archigetes (?) sp. 2 from Notropis nazas, Durango (CNHE 6797) (B, E); Archigetes sp. 3 from Chirostoma sp., Michoac´an (CNHE 6801) (D). A, B – total view, dorsally; C, E – anterior part with scolex; note different position of anterior-most testes and vitelline follicles between C and E; D – total view, ventrally; F – ovarian and uterine region, dorsally. Abbreviations: cs – cirrus-sac; eb – excretory bladder; eg – eggs; esv – external seminal vesicle; lo – loculi; ov – ovary; sr – seminal receptacle; te – testes; vf – vitelline follicles.