Cyproidea excavata, Myers, Alan A., 2012

Myers, Alan A., 2012, Amphipoda (Crustacea) from Palau, Micronesia: Families Ampeliscidae, Ampithoidae, Aoridae, Colomastigidae and Cyproideidae, ZooKeys 193, pp. 1-25 : 17-19

Cyproidea excavata sp. n. Figure 15

Type material.

Holotype unknown sex, 1.9 mm. OUMNH.ZC.2002 –24– 0095, Pkuklim Reef; Halimeda clumps on reef rubble, from Halimeda ( Chlorophyta ) washings, -6 m depth; 07°20.542'N, 134°34.023'E; leg. S. De Grave & C. Burras, 29 May 2002.

Other material.

1 specimen (unknown sex), dissected. Outside Risong channel, light trap sample,, 50 feet deep; 07°17.903'N, 134°28.544'E; leg. S. De Grave & C. Burras, night 25 th– 26th May 2002.

Etymology.

Named for the excavated palm of gnathopod 2.

Description.

Based on holotype 1.9 mm.

Head. Eye very large, round. Antenna 1 less than one third body length; peduncular articles 1 and 2 subequal in length, article 2 with strong anterodistal spine overreaching half of flagellar article 1; flagellum with 7 articles each bearing a pair of long posterodistal setae. Antenna 2 slender, longer than antenna 1; peduncular articles 4 and 5 subequal; flagellum shorter than peduncular article 5 with three articles. Mandible palp slender, rod-shaped, article 3 shorter than article 2, narrowing distally with one long and one short distal seta.

Pereon. Gnathopod 1 coxa vestigial; basis broad; ischium with posterodistal spine; carpus shorter than propodus with long posterodistal acute spine reaching tip of propodus; propodus subrectangular, palm with shallow excavation; dactylus overlapping palm. Gnathopod 2 basis slender, carpus posterodistal margin with blunt spine extending along one third length of posterior margin of propodus; propodus longer and wider then carpus, subovoid; palm oblique; dactylus elongate, strongly curved, greatly overlapping palm. Pereopod 3 coxa subtriangular. Pereopod 4 coxa subovoid. Pereopods 5-7 subequal in length.

Pleon. Urosomite 3 with dorsodistal hood extending over telson. Uropod 3 rami subequal a little longer than peduncle.

Habitat.

In Halimeda

Remarks.

Colomastix excavata sp. n. appears to be closest to Colomastix serratipalma Schellenberg (1938) from New Caledonia, but in that species, on gnathopod 2, the spine on the postero-distal margin of the carpus is very slender throughout its length (broad based in Colomastix excavata sp. n.) and the palm is evenly convex. Cyproidea excavata sp. n. differs from both Colomastix liodactyla Hirayama (1978) and Colomastix cobia Azman (2009) in gnathopod 1 which in those species has a serrated palm and spines on the posterior margin of the dactylus. It differs from Colomastix ornata Haswell (1880) in the more slender propodus of gnathopod 1, the excavate palm of gnathopod 2, and the subequal rami of uropod 3.

Distribution.

Known only from the type locality.