Proschizorhynchella caudociliata, Takeda & Kajihara, 2018

Takeda, Naoya & Kajihara, Hiroshi, 2018, A New Genus and Five New Species of Kalyptorhynchia (Platyhelminthes: Rhabdocoela) Discovered in Northern Japan, Species Diversity 23 (1), pp. 1-11 : 4-5

Proschizorhynchella caudociliata sp. nov.

( Figs 6 , 7 ; Table 1 )

Material examined. Holotype: ICHUM 4863 , adult, whole mount, 42°33′25″N, 141°55′42″E, Mukawa , Hokkaido, Japan, intertidal sand, 20 May 2012 . Paratypes: ICHUM 4262, 4264, 4265, three adults, whole mounts, same data as holotype.

Description. Living animal body approximately 3.0 mm long and 0.3 mm wide ( Fig. 6 ). Proboscis 230–270 µm long, 70–80 µm wide ( Fig. 6 ). Pair of black eyes situated behind proboscis ( Fig. 6 ). Two testes, each 150–280 µm in diameter ( Fig. 6 ). Yolk gland 750 µm long, 110 µm wide ( Fig. 6A ). Two adhesive girdles present; anterior one located at level of posterior end of pharynx, posterior one near caudal end; each girdle composed of six adhesive papillae arranged in regular intervals ( Fig. 6A ). Pharynx 220 µm long, 150 µm wide ( Fig. 6 ). Pair of seminal vesicles, each 150–310 µm long, 10–30 µm wide, located posterior to pharynx ( Fig. 6A ). Male copulatory organ 160 µm long, 50 µm wide ( Fig. 6A ). Stylet cone shaped, 45 µm long, 12 µm wide, comprised of thin sclerotic sheet rolled up four times ( Figs 6A , 7 ). Ovary 120 µm long, 60 µm wide, located posterior to pharynx ( Fig. 6A, B ). Uterus, 90 µm long, 40 µm wide, located around ovary ( Fig. 6A ). Common genital pore opening on ventral side of body between two adhesive girdles ( Fig. 6A ). Bursa 190 µm long, 80 µm wide, located around common genital pore ( Fig. 6A ). Large oval structure (adhesive gland?) 120 µm long, 100 µm wide, located at the caudal end ( Fig. 6A ). Caudal end covered with long tactile cilia ( Fig. 6A ).

Etymology. The specific name refers to the long tactile cilia on the caudal region, which look like a brush.

Remarks. Proschizorhynchella caudociliata can be distinguished from all congeners, except Proschizorhynchella papillata ( Doe, 1974) and P. shibazakii sp. nov., based on the characteristics listed in Table 1 . These three species, however, can be distinguished on the basis of two characteristics: (i) four coils of the copulatory stylet in P. caudociliata and three in P. papillata and P. shibazakii and (ii) a vacuolated region and long tactile hair present near the caudal end in P. caudociliata but absent in P. papillata and P. shibazakii .

Figures

Fig. 6. Proschizorhynchella caudociliata sp. nov. A. Illustration showing the arrangement of various internal organs, ICHUM 4863 (holotype); B. Photomicrograph of fixed specimen, ICHUM 4863 (holotype); C. Photomicrograph taken in life, ICHUM 4862 (paratype). Abbreviations: ag, adhesive gland; ap, adhesive papilla; b, bursa; c, male copulatory organ; e, eye; gp, genital pore; m, mouth; o, ovary; p, proboscis; ph, pharynx; st, stylet; sv, seminal vesicle; t, testis; u, uterus; y, yolk gland.

Fig. 7. Proschizorhynchella caudociliata sp. nov., stylet, ICHUM 4863 (holotype). A. Illustration; B. Schematic diagram of transverse section through the region indicated by the arrowheads in A; C. Photomicrograph.