Proschizorhynchella shuttlecock Takeda & Kajihara 2018, sp. nov.

Proschizorhynchella shuttlecock sp. nov. (Figs 15, 16; Table 1)

Material examined. Holotype: ICHUM 4846, adult, whole mount, 44°03′03″N, 141°39′46″E, Obira, Hokkaido, Japan, intertidal sand, 25 May 2012. Paratypes: ICHUM 4845, adult, whole mount, 45°29′16″N, 141°58′05″E, Soya, Hokkaido, Japan, intertidal sand, 26 May 2012; ICHUM 4847, 4848, two adults, whole mounts, same data as holotype.

Description. Living animal body approximately 2.6 mm long, 0.6 mm wide. Proboscis 600 µm long, 100 µm wide; pair of proboscis glands 170 µm long, 110 µm wide (Fig. 15 A–C). Pair of black eyes situated behind proboscis (Fig. 15 A–C). Two testes, each 200–290 µm in diameter (Fig. 15A, B). Pharynx typical for genus, 300 µm long, 400 µm wide (Fig. 15A, B). No adhesive girdles (Fig. 15A, B). Pair of seminal vesicles, each 410–470 µm long, 30–40 µm wide, located posterior to pharynx (Fig. 15A). Stylet badminton shuttlecock shaped, 68 µm long, comprised of incomplete tube of thin sclerotic sheet with single, narrow (~ 2 µm), longitudinal gap; proximal three-quarters cone shaped, 22 µm in diameter at its base, narrowing toward its tip, with many longitudinal ridges inside; distal quarter bulbous, slightly elongated along stylet axis, 14 µm in maximum diameter, with single, transverse constriction slightly behind its widest portion; numerous, minute, wart-like projections present inside distal bulbous region (Fig. 16A, B); cirrus spine absent. Ovary 100 µm long, 70 µm wide, located posterior to pharynx (Fig. 15A). Common atrium 110 µm in diameter, leading to genital pore opening on ventral side of body located near caudal end (Fig. 15A).

Etymology. The specific name refers to the shape of the stylet in the new species.

Remarks. The stylet in Proschizorhynchella shuttlecock sp. nov. is badminton shuttlecock shaped, which is unique among the congeners, which mostly show a conical stylet (Table 1). Proschizorhynchella shuttlecock lacks adhesive girdles and thus resembles Proschizorhynchella faroeensis (Steinböck, 1931) and Proschizorhynchella spiracirro (Schilke, 1970). The latter two possess cirrus spines (Steinböck 1931; Schilke 1970) but P. shuttlecock does not.