Bathycalanus pustulosus n. sp.

(Figs 46, 74–76)

Bathycalanus sp.? Sewell, 1947, p. 34, fig. 5.

Type locality. 38.033o N, 124.183o W.

Material examined. MV 66-II, Stn 5, IKMT, 0–5500 mwo, 1♀ (9.7 mm) holotype.

Type specimens. Deposited in the collection of the Scripps Institution of Oceanography, California: Holotype female: PIC- 140409 -0014-HT.

Morphological description. Following description based on holotype specimen from MV 66-II, Stn 5. As for genus with following additional specific level features.

Female (Fig. 74 A–F). Total length 9.7 mm. Whole body covered in small pustules easily observed in profile. Anterior margin of head in dorsal view produced into distinct short rounded projection located dorsal to base of rostrum and bearing pair of stout small spine-like processes. In lateral view, posterolateral corners of pedigerous somite 5 produced into left rectangular and right rounded, asymmetrical lappets extending half way along genital double-somite in dorsal view. Genital double-somite symmetrical in dorsal view, about as wide as long, widest at midlength, with small genital operculum anteriorly situated, seminal receptacles not observed.

Antennules broken off.

Antenna (Fig. 75 A, B) exopod segment IV with short setae not extending as far as distal border of segment VII and bearing short setules.

Maxillule (Fig. 75 E, F) praecoxal arthrite with 13 setae including 2 on posterior surface and 2 setae on anterior surface, one of them very small; coxal endite with one seta, basal endites 1 and 2 with 2 subequal setae each; endopod segments with 2 (subequal), 2 (subequal), 5+1 anterior surface seta, respectively.

Maxilliped (Fig. 75 I) syncoxal endite 4 with longest toothed seta extending beyond distal border of endopod segment 2.

Leg 1 (Fig. 74 G) exopod with articulation between exopod segments 2 and 3 well developed.

Male. Unknown.

Remarks. It is possible that Sewell (1947) found a stage V individual (7.9 mm) in the Arabian Sea 0–1500 m. This possibility is based on the fact that the body of Sewell’s specimen was covered by ‘short ridges’, the right posterolateral corner of pedigerous somite 5 is drawn out into a rounded lappet, and there were two subequal setae on the basal endite 2 of the maxillule. Nevertheless, Sewell (1947) does not record a seta on the coxal endite of the maxillule as is present in Ba. pustulosus n. sp.

Distribution. Bathycalanus pustulosus n. sp. is probably an abyssopelagic species. The present specimen was taken at the type locality off California (Fig. 46, Table 1).

Species comparisons. This species is related to Ba. richardi in that it has a pair of small anterior spine-like processes on the anterior head. Nevertheless, Ba. pustulosus n. sp. can be distinguished from all other species by a combination of 1) having thickenings covering the whole body; 2) the distinctive left rectangular and right rounded posterolateral lappets of pedigerous somite 5, viewed laterally; and 3) having 1 seta on the coxal endite and 2 setae on the second basal endite of the maxillule (Table 10).

Etymology. The specific name is derived from the Latin adjective pustulosus meaning “full of blisters” referring to the nature of the surface of the body.