Proschizorhynchella magnoliae, 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 : 6-8

Proschizorhynchella magnoliae sp. nov.

( Figs 8 , 9 ; Table 1 )

Material examined. Holotype: ICHUM 4859 , adult, whole mount for fluorescent staining, 43°01′16″N, 144°50′13″E, Akkeshi Bay , Hokkaido, Japan, intertidal sand, 24 June 2013 . Paratypes: ICHUM 4849, 4850, two adults, whole mounts, type locality, 1 July 2011; ICHUM 4851, 4852, two adults, whole mounts, type locality, 7 July 2011; ICHUM 4853–4857, five adults, whole mounts, type locality, 15 June 2012; ICHUM 4858, 4860, two adults, same data as holotype.

Description. Living animal body approximately 1.5 mm long and 160 µm wide ( Fig. 8 ). Proboscis 240–290 µm long, 30 µm wide; pair of proboscis glands 90 µm long, 50 µm wide ( Fig. 8 ). Pair of black eyes situated anterior to brain ( Fig. 8A, B, D ). Two testes, each 90–150 µm in diameter ( Fig. 8A ). Pharynx 120 µm long, 170 µm wide ( Fig. 8 A–C). Three adhesive girdles present; anterior one located at the level of posterior end of pharynx, middle one at level of seminal vesicles, posterior one near caudal end; each girdle composed of six adhesive papillae arranged in regular intervals ( Fig. 8A ). Pair of yolk glands 400–440 µm long, 120– 170 µm wide ( Fig. 8A ). Pair of seminal vesicles, each 220– 230 µm long, 20 µm wide, located posterior to pharynx ( Figs 8A , 9A, B ). Male copulatory organ tubular in shape, 120 µm long, 50 µm wide ( Figs 8C , 9A ), tapering toward its tip, equipped with stylet. Stylet cone shaped, 31 µm long, 13 µm wide, comprised of thin sclerotic sheets (exact number of sheets not clear but appears to be more than one), equipped with ridges and processes inside ( Fig. 9C, D ). Common genital pore opening on ventral side of posterior region of body, posteriorly leading to saccate common atrium, middle part of which is dorsally connected to male copulatory organ and pair of yolk glands ( Fig. 9A, B ). Ovary 80 µm long, 60 µm wide, connected to the end of common atrium ( Fig. 9A, B ).

Etymology. The specific name is a noun in the genitive case, referring to the stylet of the new species, which resembles a flower of lily magnolia.

Remarks. Proschizorhynchella magnoliae sp. nov. most closely resembles Proschizorhynchella helgolandica ( L’Hardy, 1965) , which they has (i) a pair of eyes, (ii) two testes, (iii) three adhesive girdles, (iv) a single genital pore, and (v) no cirrus spine ( Table 1 ). In P. helgolandica , the copulatory stylet comprises a pair of elongated cuticular sheets that face each other, with a concave confronting surface; the tip of each sheet is sharply pointed. On the other hand, in P.magnoliae , the copulatory stylet takes the form of spiral sheets that are complicatedly coiled with each other, with an elaborate inner surface with numerous ridges and short spines.

Figures

Fig. 8. Proschizorhynchella magnoliae sp. nov. A. Illustration of fixed specimen showing arrangement of various internal organs, ICHUM 4859 (holotype); B. Photograph of fluorescent-staining specimen of the entire animal taken under a bright field, ICHUM 4859 (holotype); C. Confocal laser scanning micrograph, ICHUM 4859 (holotype); D. Composite photomicrograph taken in life, ICHUM 4849 (paratype). Abbreviations: ap, adhesive papilla; c, male copulatory organ; cp, common genital pore; e, eye; m, mouth; o, ovary; p, proboscis; pg, proboscis gland sac; ph, pharynx; st, stylet; sv, seminal vesicle; t, testis; y, yolk gland.

Fig. 9. Proschizorhynchella magnoliae sp. nov. A. Illustration showing the structure of reproductive system, ICHUM 4859 (holotype); B. Confocal laser scanning microscopy image of the reproductive system, ICHUM 4859 (holotype); C, Illustration of stylet, ICHUM 4859 (holotype); D, Photomicrograph of stylet, ICHUM 4859 (holotype). Abbreviations: c, male copulatory organ; ca, common atrium; cp, common genital pore; o, ovary; st, stylet; sv, seminal vesicle; y, yolk gland.