Cichlidocestus, Alain de Chambrier & Carlos Daniel Pinacho-Pinacho & Jesus Servando Hernández-Orts & Tomáš Scholz, 2017

Alain de Chambrier, Carlos Daniel Pinacho-Pinacho, Jesus Servando Hernández-Orts & Tomáš Scholz, 2017, A New Genus And Two New Species Of Proteocephalidean Tapeworms (Cestoda) From Cichlid Fish (Perciformes: Cichlidae) In The Neotropics, J. Parasitol. 103 (1), pp. 83-94 : 84-87

Cichlidocestus n. gen.

(Figs. 1–21)

Diagnosis: Proteocephalidae, Proteocephalinae. Testes , ovary, vitellarium, and uterus medullary. Small-sized worms. Strobila acraspedote, with immature and mature proglottids wider than long, pregravid proglottids wider than long to longer than wide, and gravid proglottids longer than wide. Scolex without metascolex, rosette-like, with 4 prominent lobes posteriorly, separated from one another by longitudinal grooves, each lobe bearing central, small uniloculate sucker. Apex of scolex with muscular sucker. Inner longitudinal musculature well-developed, formed by small bundles of muscle fibers. Ventral osmoregulatory canals numerous (8–10), in medulla just beneath fibers of inner longitudinal musculature; 2–4 dorsal canals in medulla. Testes medullary, in 3 to 4 layers and 2 separate lateral fields, with some testes reaching posterior margin of proglottids, thus being posterior to ovary or even vitelline follicles. Vas deferens (internal sperm duct) enlarged in cirrus-sac to form voluminous, spherical internal seminal vesicle filling almost entirely proximal half of cirrus-sac. Vaginal canal short, opening posterior to cirrus-sac, with circular vaginal sphincter in its terminal (distal) part. Genital atrium deep and narrow, irregularly alternating, near anterior margin of proglottids. Ovary large, medullary, bilobed, with narrow ovarian isthmus almost in center of proglottid and folliculate (grape-like) lateral wings that may reach to vitelline follicles; ovary occupies middle and posterior thirds of median portion of mature proglottids. Vitelline follicles forming 2 lateral bands, not reaching anterior margin of proglottids. Uterus ventral, with lateral diverticula, with Type 2 of uterine development of de Chambrier et al. (2004a). Parasites of Neotropical cichlids ( Perciformes : Cichlidae ). Type species: Cichlidocestus gillesi n. sp. (Figs. 1–7, 20, 21). Another species: Cichlidocestus janikae n. sp. (Figs. 8–19).

Taxonomic summary

Etymology: The new genus is named according to the family of fish hosts ( Cichlidae ) and suffix ‘‘- cestus ’’, which means a tapeworm. The name is treated as masculinum.

Remarks

The new genus is placed in the subfamily Proteocephalinae as defined by Rego (1994) because of the medullary position of the testes, ovary, vitelline follicles, and uterus, and the absence of a metascolex (which is, however, present in a recently erected Frezella Alves, de Chambrier, Scholz and Luque, 2015 ; see Alves et al., 2015).

Cichlidocestus n. gen. differs from the genera of the Proteocephalinae and also from all but one remaining proteocephalidean genera by the unique appearance and position of the ovary, which occupies the middle and posterior thirds of the median region of proglottids with the ovarian isthmus situated almost equatorially, i.e., at the half-length of mature proglottids. All other proteocephalideans have the ovary in the posterior third or fourth of proglottids, usually near their posterior margin ( Rego, 1994), except for S. megalodiscus Diesing, 1850 . This species differs from both species of Cichlidocestus most conspicuously by a different morphology of the scolex, which possesses an umbrella-like metascolex which is markedly wider than the strobila (see Rego et al., 1999b), development of the uterus which forms capsule-like formations filled with eggs in gravid proglottids (vs. simple lateral diverticula in species of Cichlidocestus ), and number of ventral osmoregulatory canals (only 2 vs. 8–10) (A. de Chambrier and T. Scholz, unpubl. data).

Cichlidocestus can also be distinguished from all proteocephalidean genera including Sciadocephalus Diesing, 1850 by the presence of a spherical internal seminal vesicle that occupies the proximal half of the cirrus-sac. The new genus is also characterized by morphology of its scolex, which is tetralobed and possesses a muscular apical sucker with a deep cavity, and the presence of several (8–10) ventral osmoregulatory canals in the medulla just beneath fibers of the inner longitudinal musculature.