Scaptognathus ventridiscus Abé, 1990

Scaptognathus ventridiscus Abé, 1990

Diagnosis. Glp-1 not found. Ds-2 on membranous cuticle. PE with 1 dorsal seta. GA bipartite in female, fully sclerotized plate and separated membranous disc in male. Female with 6 Pgs and 6 Sgs. Male with 29–39 Pgs and 6 Sgs. Tr I–IV with 1-1-1-1 setae; Bf I–IV with 2-2-1-1 setae; Tf I–IV with 4-4-3-3 setae, 2-1-0-0 Bp setae; Gn I–IV with 4-5-3-3 setae, 2-1-0-0 Bp setae; Tb I–IV with 9-7-7-7 setae, 6-4-4-4 Bp setae; Ta I–IV with 3-3-3-3 dorsal setae, 1-0-0-0 Bp setae. Lc I with unidentate accessory process. Idiosoma length 350–384 in male ( holotype 358), 375 in female, 258 in DN, 133 in LV. Idiosoma width 200–236 in male ( holotype 200), 200 in female, 142 in DN, 100 in LV. Gnathosoma length 192–217 in male ( holotype 196). Gnathosoma width 100–108 in male ( holotype 100). Ratio of gnathosoma to idiosoma 0.55 in male holotype, 0.57 in female, 0.58 in DN, 0.69 in LV. Ratio of P-2 to P-1 4.00 in male holotype.

Remarks. This species is distinguished from other species by the ventral membranosum disc in male. Female, male, DN, LV are known.

Habitat. Intertidal zone: Coarse sands at tidal line.

Distribution. North Pacific Ocean: Oshoro Bay ( Hokkaido) [ Japan].

References. Abé (1990a, e), Abé & Green (1994), Bartsch (1994b).

Depository. NSMT, USNMNHW.