Platycuma marginalis Zimmer 1943

Platycuma marginalis Zimmer

Platycuma marginalis Zimmer, 1943:162–164.

DESCRIPTION OF YOUNG MALE.—Viewed from above (Figure 59), general form resembles that of the female which Fage (1929) regarded as the female of P. holti, but greatest width of the carapace not as far posterior, and sides therefore more evenly curved. Anterior lateral angles also less acute. Ocellar lobe present, although very minute, but is, however, distinctly set off as small point against frontal lobe (as figured but not described by Calman and Fage). Characteristic for this genus is the somewhat dorsoventrally flattened carapace with a sharp lateral margin. Lateral margin with very thin and brittle lamella, incompletely preserved. Lamella with irregular and not very distinctly developed serration on anterior margin of the “lateral horns” of carapace. Similar lamella found also on lateral parts of last thoracic segment and appears to have been present also on the abdominal segments; at least the remains of one are present on one side of fifth abdominal segment (Figure 61). The 2 longitudinal ridges on last thoracic segments and first 5 abdominal segments are present. They also have appearance of thin, brittle, more or less distinctly serrated lamellas that are splintered in places. Last abdominal segment truncated transversally as figured by Calman and not drawn upward triangularly as shown by Fage.

Dactylus of first pereopod (Figure 60) about half as long as propodus; latter somewhat shorter than carpus. Second pereopod with dactylus about as long as 2 preceding articles combined; propodus considerably shorter than carpus.

Uropod peduncle (Figure 61) shorter than last 2 abdominal segments combined; lateral margin with thin lamella with irregular serration. Inner ramus of uropod about ¾ as long as peduncle; margins with indistinctly serrated lamella. Exopodite much more slender, about ¾ as long as endopodite. Uropod without spines or setae or perhaps these were broken off.

Length about 3.5 mm.

LOCATION OF SINGLE EXISTING SPECIMEN.—39°03′15″N, 70°50′45″W, 2795 m (1537 fms), 6 Sep 1884, Albatross Sta 2222.