Metacrangon laevis ( Yokoya, 1933 )

Komai, Tomoyuki, 2012, 3468, Zootaxa 3468, pp. 1-77 : 41-42

Metacrangon laevis ( Yokoya, 1933)

( Fig. 40)

Crangon laevis Yokoya, 1933: 36 , fig. 16 [type-locality: west of Tubaki-zaki , Aomori Prefecture, Sea of Japan, 73 m].

Sclerocrangon laevis .— Derjugin and Kobjakova 1935: 142 (list); Kobjakova 1936: 201 (list), 212 (list), 224 (key), pl. 2, fig. 20; 1937: 137, fig. 15; Vinogradov 1950: 219 (key), fig. 81; Kobjakova, 1958: 244 (list); Adrianov & Kussakin 1998: 265 (list).

Metacrangon laevis .— Zarenkov 1965: 1764 (list); Miyake 1982: 189 (list); Komai 1994: 83 (list); 1995: 893, figs 1–4; De Grave & Fransen 2011: 457 (list).

Material examined. Off Ohmu , Hokkaido, Sea of Okhotsk , 44°33.844’N, 143°08.151’E, 47 m, 22 August 1996, sledge, coll. J. Sasaki, 1 female (cl 9.5 mm), CBM-ZC 2995; similar locality, 43°38.579’N, 143°14.268’E, 57 m, sand, 22 August 1996, sledge, coll. J. Sasaki, 1 male (cl 4.2 mm), CBM-ZC 3828; off Onishika , Obira, western Hokkaido, Sea of Japan, 45 m, 21 August 1991, small beam trawl, coll. S. Maruyama, 1 female (cl 7.0 mm), CBM- ZC 506 ; off Usujiri, Oshima Peninsula, southern Hokkaido, 15–25 m, coarse sand and volcanic pebbles, 13 November 1992, coll. T. Komai, 3 ovigerous females (cl 6.5–6.6 mm), CBM-ZC 171; same locality, 30–40 m, 11 May 1993, dredge, coll. T. Komai, 5 females (cl 5.7–6.0 mm), CBM-ZC 3021; same locality, 15–25 m, 11 June 1993, dredge, coll. F. Muto, 2 females (cl 6.5, 6.6 mm), CBM-ZC 87 .

Type material. Holotype: RV Soyo-maru , stn 638, west of Tsubaki-zaki, Aomori Prefecture, Sea of Japan, 40°31.15’N, 139°30.45’E, 73 m, 18 August 1930, Kamiya’s dredge, 1 female (size not specifically indicated). Presumed to be no longer extant.

Diagnosis. Rostrum triangular, directed forward, tip subacute to rounded; dorsal surface shallowly concave; ventral carina high. Carapace with anterior middorsal tooth arising slightly anterior to 0.2 of carapace length; posterior middorsal tooth arising at about 0.6 of carapace length; submedian teeth present; postorbital angle gently rounded; antennal tooth directed forward in dorsal view, somewhat ascending in lateral view, acuminate; branchiostegal tooth moderately strong, directed forward in both dorsal and lateral views. First to fifth abdominal somites rounded dorsally. First to third abdominal pleura rounded. Sixth abdominal somite rounded dorsally. Eye 1.4–1.5 times as long as wide. Antennular peduncle reaching midlength of antennal scale; first segment with prominent, blunt distolateral process; stylocerite falling short of distolateral process of first segment; second segment approximately as long as wide, having prominent, blunt distolateral process. Antennal scale about 0.5 times as long as carapace, 2.2–2.4 times longer than wide; lateral margin nearly straight or faintly sinuous; distolateral tooth falling short of distal margin of broadly rounded distal lamella. Third maxilliped with ultimate segment about 4.0 times longer than wide. First pereopod with palm about 2.5 times longer than wide, slightly narrowed distally.

Description. See Komai (1995).

Distribution. Sea of Japan and Sea of Okhotsk ( Fig. 41); 15– 73 m.

Remarks. This species was redescribed in detail by Komai (1995) based on specimens from Hokkaido, northern Japan. As discussed by Komai (1995), it is morphologically similar to Metacrangon munita and M. richardsoni , but is unique within the genus in the lack of submedian carinae on the sixth abdominal somite.