Melita pahuwai J. L. Barnard 1970

Melita pahuwai

DIAGNOSIS OF MALE.—Head with deep lateral slit below subnasiform lateral lobes; eyes narrowly ovatopyriform, retaining brownish-purple pigment in alcohol; flagellum of second antenna 1.3 times as long as article 5; coxa 1 not anteroventrally produced; article 6 of gnathopod 1 distally expanded, anterior margin swollen, palm short and oblique, bearing 3 stout medial spines and 5–6 thin lateral spines, then distally excavate for reception of large dactylar bulge, beyond that produced again, dactyl thick, bulging basally, fitting palm, distally unguiform and bearing accessory setal spine; gnathopod 2 with unlobed articles 2–3, article 4 with posterodistal cusp, article 5 with narrow, setose posterior lobe, article 6 elongate, expanding distally like young male M. palmata, dactyl longer than palm and overriding medial face, palm short and scarcely oblique, but rounding onto posterior margin of article 6 and minutely spinose, medial face of hand with axial channel toward posterior side, channel defined anteriorly by sharp ridge bearing distal spines and by shorter sharp ridge proximally; channel filled with pectinoplumose setae; all pereopodal dactyls with distal double constriction and nail, with stout marginal seta and small facial setule, locking spines simple; pereopods 3–5 of regular form but relatively short and thick, dactyls also thick; outer ramus of uropod 3 with 1 article only; telson with sharp apices, lobes gaping, each lobe with 2 medial spines, one long subterminal medial spine guarded by sharp cusp, small apicolateral spine, and 3 basolateral spines, plus setules subapically; pleonal epimera 1–3 each with small posteroventral tooth, no other serrations; only urosomite 2 with small lateral cusp guarding 2 spines, cusp obtusely angular. Mouthparts like M. palmata as figured by Sars (1895, pl. 179).

FEMALE.—Gnathopod 1 with simple bulging palm, unbulging article 6, basally unthickened dactyl; gnathopod 2 small, palm evenly oblique and defined by 2 spines on medial face and bearing several slender marginal spines; posteroventral teeth of epimera blunter than in male; cusp on urosomite 2 sharply attenuate, bearing 2 spines (or 1 in juvenile); telson with few spines in slightly different arrangement (see figures); coxa 6 with anterior hook bearing gland.

HOLOTYPE.—Bishop Museum collections, catalog number 7277, male, 4.5 mm.

TYPE-LOCALITY.—JLB Hawaii 17, Kawela Bay, Oahu, intertidal, Sargassum, algae, rocks, corals, 24 May 1967.

MATERIAL.—JLB Hawaii 17(3), 18(2).

RELATIONSHIP.—Closely related to Melita koreana Stephensen (1944), a species with similar male gnathopod 2 palm lacking a distinct channel on medial face of hand but strongly setose thereon. Melita koreana has 3 spines but no cusp on each dorsolateral side of pleonite 4, and male gnathopod 1 dactyl is a stout, short coniform piece not reaching the end of the palm, the latter simply convex. The telson lacks mediobasal spines and articles 3–6 of pereopods 3–5 are more slender than in M. pahuwai.

Melita laevidorsum Stephensen (1944), from Japan, also has 3 spines and no cusp on each side of pleonite 4, no basomedial spines on the telsonic lobes, slender pereopods 3–5, and a longer flagellum on antenna 2 than does M. pahuwai, but gnathopod 1 is more like that of the Hawaiian species than is gnathopod 1 of M. koreana. Gnathopod 2 of the male, possibly not fully developed, has a simple, sloping, spinose palm with many medial setae and a spinose medial defining ridge.

Melita pahuwai has its closest affinities with M. zeylanica Stebbing (1904) from Ceylon. The latter has a similar gnathopod 2, apparently similar ornaments on pleonite 4, has medial spines on the telsonic lobes but has larger coxae than does M. pahuwai, and male gnathopod 1 article 6 is evenly rectangular, not distally expanded and has a simple palm like the female of M. pahuwai. Article 4 of pereopods 3–5, especially pereopod 5 of M. zeylanica, is much stouter than in M. pahuwai and article 6 is very short on pereopod 5 but not on pereopods 3–4.

The west American representatives of M. nitida Smith (Shoemaker, 1935b) have long coxae, a simple palm on male gnathopod 1 and a weak, poorly setose gnathopod 2, palm very oblique, but with dactyl overriding the surface to close against a spinose locking ridge. Pleonite 4 has only 3 dorsolateral spines on each side.

DISTRIBUTION.—Hawaiian Islands.

Nuuanu, new genus

DIAGNOSIS.—Eyes weakly developed; lateral cephalic lobe with deep notch; antenna 1 geniculate between articles 1 and 2, accessory flagellum 3-articulate; mandibular palp article 3 subfalcate, strongly setose and longer than article 1, molar triturative; lower lip apparently lacking inner lobes, inner plates of maxillae 1–2 densely setose medially, palp of maxilla 1 with 2 articles; maxillipeds basic; gnathopod 1 small and slender but subchelate, palm nearly transverse; gnathopod 2 of male large (female unknown); coxa 4 strongly excavate posteriorly; second articles of pereopods 3–5 with strong castelloserrations; metasome with weak dorsal teeth, urosome with a few dorsal spines not in bundles, urosomites separate; uropod 3 short, scarcely extending beyond uropods 1–2, inner ramus short and scalelike, outer with 2 articles, article 2 short; telson short, deeply cleft.

TYPE-SPECIES.—Nuuanu amikai, new species.

RELATIONSHIP.—This genus belongs in the Eriopisa-Melita group with shortened and scalelike inner ramus of uropod 2. It differs from Eriopisella Chevreux and Netamelita J. L. Barnard in the medially setose inner plates of the maxillae, from Melita Leach in the short uropod 3, from Melitoides Gurjanova and Netamelita in the absence of inner lobes on the lower lip, the 2-articulate outer ramus of uropod 3, and from Eriopisa Stebbing in the short uropod 3 and presence of weak dorsal sculpture. The geniculate antenna 1, with article 2 bending strongly past the lateral extension of article 1, is also a character distinguishing Nuuanu from other Gammaridae mentioned above, the telson apparently is unusually short for this group, and the conspicuous castelloserrations of pereopods 3–5 are signficant. The 3-articulate accessory flagellum exceeds that of the other genera except Melita by at least 1 article.

The dorsal sculpture, though weak, and the long coxae suggest closest affinities with Melita more than with Eriopisa and mandibular palp article 3 is scarcely more swollen than in M. palmata (Montagu) (Sars, 1895, pl. 179).