Metacrangon cornuta Komai & Komatsu, 2009

Komai, Tomoyuki, 2012, 3468, Zootaxa 3468, pp. 1-77 : 46-47

Metacrangon cornuta Komai & Komatsu, 2009

( Fig. 41)

Metacrangon cornuta Komai & Komatsu, 2009: 515 , figs 2–4, 19G [type locality: off Kushiro, Hokkaido, 1535–1543 m]; De Grave & Fransen 2011: 457 (list).

? Metacrangon spinirostris .— Birshtein & Zarenkov 1970: 441.

Material examined. Holotype: male (cl 5.4 mm), RV Tansei-maru, KT 07-29 cruise, stn K2, off Kushiro , Hokkaido, 42°30.3’N, 144°50.5’E to 42°30.6’E, 144°52.2’E, 1535–1543 m, 7 November 2007, beam trawl, NSMT-Cr 19425.

Diagnosis. Male. Rostrum triangular with acute tip in dorsal view, strongly ascending (angle about 50° against horizontal plane of carapace), overreaching antennal teeth (0.3 times as long as carapace). Carapace with anterior middorsal tooth obliquely erect, much longer than posterior tooth, arising at 0.2 of carapace length; posterior tooth arising at 0.6 of carapace length; submedian teeth present; antennal tooth ascending in similar degree to rostrum, acuminate; branchiostegal tooth strong, directed slightly laterally in dorsal view, ascending in lesser degree to rostrum in lateral view. Second somite with trace of middorsal carina, third to fifth somites with low, but distinct middorsal carina. First to third abdominal pleura rounded. Sixth abdominal somite with distinct submedian carinae; posterodorsal margin slightly bilobed. Eye about 1.2 times longer than wide. Antennular peduncle overreaching midlength of antennal scale; first segment with prominent, acute distolateral process directed dorsolaterally; stylocerite terminating in acute spine, far falling short of distolateral process of first segment; second segment with prominent, acute distolateral process directed laterally and reaching distal margin of third segment. Antennal scale 0.6 times as long as carapace, 2.9 times longer than wide; lateral margin concave; distolateral tooth distinctly overreaching distal margin of relatively narrow, rounded lamella. Third maxilliped with ultimate segment 6.0 times longer than wide. First pereopod with palm 3.5 times longer than wide.

Females unknown.

Description. See Komai & Komatsu (2009).

Coloration. Generally light reddish brown; cornea black ( Komai & Komatsu, 2009).

Size. The only known specimen is a male, measuring cl 5.4 mm.

Distribution. Known only from the type locality, off Kushiro, Hokkaido, Japan ( Fig. 42); 1535–1543 m deep.

Remarks. As discussed by Komai & Komatsu (2009), Metacrangon cornuta is morphologically similar to M. spinirostris ; differences between the two species are indicated in Komai & Komatsu (2009).

Birshtein & Zarenkov (1970) reported Metacrangon spinirostris from the Kuril Islands area at depths of 1440– 1540 m (RV Vitjazi, stn 5594) and 780 m (RV Vitjazi, stn 5640). Considering the distributional proximity and the morphological similarity, it is likely that their material represents M. cornuta instead of M. spinirostris .