Rhamphochela carinata (Heron & Damkaer 1978)

Lubbockia carinata

MATERIAL STUDIED (Tables 1, 2).—NE PACIFIC: 4 females, 1.40–1.53 mm, NP 4 et al. (including: holotype, 1.44 mm, NP 4, USNM 168487; 1 paratype, 1.41 mm, NP 12, USNM 168489); 1 male, allotype, 1.41 mm, NP 7, USNM 168488; 1 juvenile, stage IV, 1.16 mm, NP 32. ANTARCTIC OCEAN: 2 males, 1.30–1.33 mm, AA 41, 42.

FEMALE.—Average length 1.47 mm. Prosome (Figure 3a) about 1.6 times length of urosome, with rounded posterior corners.

Pediger 5 (Figure 3b) with faint transverse ridge dorsoposteriorly. Genital segment with areas of external genital apparatus on anteriolateral third of segment, each area with 3 setules; genital segment and each postgenital segment with delicate spinules on posteroventral margin. Uropod approximately half the length of genital segment, with short spinules on ventral surface; dorsal, innermost, and outer long terminal setae nearly as long as inner long terminal seta; rounded laminal flap (Figure 3c) extending over base of dorsal seta.

Rostrum (Figure 3d) with thickened posteroventral margin, truncate as shown in ventral view.

Antenna 1 (Figure 3d) 7-segmented, with rudimentary articulation between segments 3–4 and 5–6. Armature formula: 4, 13 + 1 spinule, 1 + 2 spines, 4, 4 + 1 esthete, 2 + 1 esthete, 7 + 1 esthete.

Antenna 2 (Figure 3d) 3-segmented, with incomplete suture at distal third of terminal segment. Second segment with 1 seta. Third segment with inner setules and 3 subapical setae; armed terminally with 3 setae and 4 claws, all short.

Labrum (Figure 4a) with free margin divided into 2 deltoid posteroventral lobes; a number of conspicuous gland vents on outer surface and rows of setules inserted on under surface.

Mandible (Figure 4b) with 2 outer elements ornamented with rows of setules; mandible blade with row of graduated, scalelike denticles on the median edge; apical lash slender and long; concave edge of base with a hirsute element and rows of long setules supported by 2 riblike processes.

Maxilla 1 (Figure 4c) flat, bilobed; 3 barbed elements on outer lobe and 1 barbed and 1 setose element on inner lobe.

Maxilla 2 (Figure 4d) 2-segmented. First segment with expanded base and outer row of setules. Second segment outer margin with a hyaline setule and setose, stout seta; terminally bearing 2 setulose elements; a constriction and sclerotization suggesting segmentation near the anterior base but posterior base fused; curved setulose element on inner margin.

Maxilliped (Figure 4e) apparently 4-segmented; complicated sclerotized pattern in area of segment 3. Second segment with a remarkable anterior keel-like process, curving posteriorly beside an inner pocket which serves as a sheath for the terminal claw; segment 2 with short outer spinules.

Leg 1 (Figure 4f) without inner spine on basis, third exopod segment with 2 short outer spines. Leg 2 (Figure 5a) third exopod segment with 2 short outer spines. Leg 3 (Figure 5b) inner edge of third endopod segment with 2 setae and 1 spine. Leg 4 (Figure 5c) inner edge of third endopod segment with 1 seta and 1 spine. Legs 2–4 endopods terminate with a small vented conical projection between spines.

Leg 5 (Figure 3b) with short free segment; 2 terminal elements, the longer tapering in a way which suggests there is a fine serrate, hyaline flange; length less than twice that of the outer. Seta on body near leg.

Leg 6 probably represented by 3 short, hyaline setules in area of external genital apparatus.

MALE.—Average length 1.35 mm. Prosome (Figure 6a) about 1.7 times the length of urosome.

Urosome (Figure 6b) with the 4 postgenital segments bearing spinules on posteroventral margins. Uropodal setae with relative lengths as in female.

Rostral area and mouthparts, except antenna 1 and maxilliped, as in female.

Antenna 1 with segments corresponding to terminal 3 of female, fused in male; armature similar to corresponding segments of female.

Maxilliped (Figure 6c) with segment 2 and claw elongate compared to female; 2 short segments proximal to claw.

Swimming legs and leg 5 resemble those of female.

Leg 6 (Figure 6b) probably represented by posteroventral pointed flap on genital segment.

STAGE IV.—Length 1.16 mm, with 4 segments and uropod in urosome; leg 5 small and segmented (Figure 6d). Maxilliped with keel-like process well developed.

ETYMOLOGY.—The specific name carinata, from the Latin carinatus (keeled) refers to the keel-like process on the maxilliped of the female.

DISTRIBUTION.—Northeast Pacific and Antarctic Ocean (Tables 1, 2).