Kirstenella Kuchta

Kuchta, Roman, Burianová, Alena, Jirkú, Miloslav, Chambrier, Alain, Oros, Mikuláš, Brabec, Jan & Scholz, Tomáš, 2012, Bothriocephalidean tapeworms (Cestoda) of freshwater fish in Africa, including erection of Kirstenella n. gen. and description of Tetracampos martinae n. sp., Zootaxa 3309, pp. 1-35 : 8-9

Kirstenella Kuchta n. gen.

Diagnosis: Bothriocephalidea , Bothriocephalidae . Medium-sized worms. Segmentation present. Segments trapeziform, craspedote. Scolex elongate. Bothria elongate, shallow. Apical disc present, as wide as, or slightly wider, than bothrial part of scolex, armed with large, simple hooks arranged in two lateral semicircles. Neck absent. Testes in two lateral fields, continuous between segments. Cirrus-sac thick-walled, spherical, large, representing as much as 1/6–2/5 of segment width; internal seminal vesicle present; cirrus unarmed. Genital pore dorsal, median. Ovary compact, bilobed, transversely elongate. Vagina posterior to cirrus-sac, enlarged distally. Vitelline follicles cortical, in two lateral fields continuous between segments. Uterine duct sinuous, S-shaped, enlarging in gravid segments. Uterus small, oval. Uterine pore median. Eggs operculate, unembryonated. In freshwater siluriforms. Africa.

Etymology: The new genus is named in honour of Kirsten Jensen, University of Kansas at Lawrence, USA, for her outstanding contribution to cestode systematics.

Type and only species: Kirstenella gordoni ( Woodland, 1937) Kuchta, n. comb.

Remarks: The new genus is placed in Bothriocephalidae Lönnberg, 1889 because it possesses the median genital pore, follicular vitellaria, and a ventral uterine pore ( Kuchta et al. 2008a, b). It is typified by combination of the following characteristics: (1) scolex is elongate with a small apical disc armed with two lateral semicircles of hooks; (2) cirrus-sac is large (its width represents as much as 1/6–2/5 of the width of segments) and it is situated perpendicularly; (3) a low number of testes (less than 75 per segment); (4) vagina is enlarged distally; (5) vitellaria are cortical.

Kirstenella differs from all but three bothriocephalid genera ( Polyonchobothrium Diesing, 1854 , Senga Dollfus, 1934 and Tetracampos Wedl, 1861 ) in the presence of an apical disc armed with two lateral semicircles of large hooks ( Kuchta et al. 2008b). The new genus can be distinguished from Tetracampos by the presence of cortical (instead of medullary) vitelline follicles and presence of operculate, thin-walled (vs. unoperculated, with hyaline membrane) eggs. The new genus can be distinguished from Polyonchobothrium and Senga mainly by the relative size of the cirrus-sac, which is markedly larger (ratio of its width to the width of segments 16–39%) than that of species of Senga (ratio 4–10%) and Polyonchobothrium (ratio 5–10%), and is situated more perpendicularly in Kirstenella , whereas longitudinally or obliquely in the two remaining genera ( Figs. 19, 22 , 38, 39 ). Moreover, Polyonchobothrium has a markedly wider apical disc (350–510 µm) and much larger hooks (up to 190 μm) mostly distributed in 4 quadrants, whereas Kirstenella has a slender apical disc (230–300 μm) with smaller apical hooks (shorter than 90 μm) distributed in 2 semicircles. Hooks of Senga have an indistinct blade and handle (data not shown), whereas those of Kirstenella have the blade well differentiated from the handle ( Figs. 16, 18 ).

Figures

FIGURES 15–22. Line drawings of Kirstenella gordoni (Woodland, 1937) ex Heterobranchus bidorsalis from Kenya (IPCAS C-609). 15, Complete worm. 16, Detail of hooks. 17, Scolex, dorsoventral view. 18, Complete circle of hooks. 19, Detail of genital complex of mature segment, dorsal view. 20, Egg. 21, Cross-section of gravid segment at level of cirrus-sac. 22, Mature segment, dorsal view. Abbreviations: cs, cirrus-sac; gp, genital pore; iv, internal seminal vesicle; lm, inner longitudinal muscles; ov, ovary; t, testes; up, uterine pore; ut, uterus; v, vagina; vd, vas deferens; vf, vitelline follicles; vr, viteline reservoir.

FIGURES 33–40. Line drawings of Polyonchobothrium polypteri (Leydig, 1853) ex Polypterus spp. from Kenya and the Sudan (IPCAS C-464). 33, Complete worm. 34, Scolex, dorsoventral view. 35, Complete circle of hooks. 36, Detail of hooks. 37, Egg. 38, Detail of genital complex of mature segment, dorsal view. 39, Mature segment, dorsal view, neotype. 40, Crosssection of the gravid segment at the level of cirrus-sac. Abbreviations: e, eggs; pg, prostatic glands; vd, vas deferens.