“Pallenopsis (Pallenopsis) lateralia, new species Fig. 7
Material examined. Eltanin: 27-1867 (two males, two females (paratypes, USNM 234706)), 32-2129 (one male (holotype, USNM 234707), four males, six females (paratypes, USNM 234708)).
Distribution. The Ross Sea, off Cape Adare, marks the very restricted distribution of this new species, in the narrow depth range of 2273-2421 m. These depths are deeper than usual for this subgenus and more in keeping with its closely related subgenus, P. (Bathypallenopsis). These depths are not unknown for P. (Pallenopsis) and several species range to even deeper localities, including P. (P.) pilosa reported on herein.
Description. Size only slightly larger than average for the genus, leg span about 105 mm. Trunk robust, segmentation ridges with several short spines on tiny tubercles or tubercles only (spines broken off?). Lateral processes crowded, almost touching, about 1.5 times longer than diameters, with 4-5 short dorsodistal spines on tiny tubercles or tubercles only, spines often missing.
Neck constricted proximally, expanded and widest distally at insertion of chelifores, with pair of low lateral tubercles on each side. Ocular tubercle at extreme anterior of segment, with small apical tubercle, eyes prominent, with slight pigment or without. Proboscis moderately short, inflated medially, and slightly inflated distally, with encircling distal fringe of long setae, ventral setae longer, just proximal to abruptly tapered oral surface. Abdomen moderately long, base articulated, with few small setae on low dorsal tubercles or tubercles only, setae missing, length extending to distal rim of first coxae of fourth leg pair.
Chelifores large, first scape segment about 1.5 times length of second, with rows of setae, distal setae longer than segment diameter. Chela palm cylindrical, curved proximally, with lateral and distal setae, some longer than palm diameter. Fingers well curved, immovable finger placed perpendicular at half lateral palm length, movable finger at distal tip, anaxial to palm, longer than immovable finger, without proximal setose pad. Lateral palp buds long.
Oviger typical, with moderate lateral setae on most segments, mostly in patches. Strigilis feeble, very setose with most setae longer than segment diameters. Tenth segment short, conical.
Leg tibiae with many dorsal and lateral setae slightly longer than segment diameters, second tibiae the longest segments. Femur with few proximoventral setae and 4-5 dorsodistal setae, one longer than segment diameter. Cement gland causing a very low ventral bulge with central dimple holding tube about 0.5 to 0.6 as long as segment diameter. Tarsus very short, with long ventral spine, several shorter setae. Propodus short, hardly curved, sole with about 10 spines of varying lengths, single heel spine slightly longer than others. Main claw little longer than half propodal length, auxiliary claws slightly longer than half main claw length.
Female slightly larger except for 10-segmented oviger which is unusually small with few short lateral setae rows.
Measurements (of holotype in millimeters). Trunk length (chelifore insertion to tip of 4th lateral processes), 9.5; trunk width (across 2nd lateral processes), 6.9; proboscis length, 5.1; abdomen length, 3.5; third leg, coxa 1, 2.6; coxa 2, 4.7; coxa 3, 2.9; femur, 10.6; tibia 1, 10.5; tibia 2, 12.4; tarsus, 0.8; propodus, 2.8; claw, 1.6.
Etymology. The species name (Latin: lateral is, pertaining to or of the side) refers to the unusual placement of the immovable finger on the near proximal side of the palm rather than in its usual distal location.
Remarks. There are several species of this genus in Antarctic waters with similar characters such as setose legs, crowded lateral processes, cement gland tubes as long as those of this species, and similar propodi. But, there are none known with the unusually remote lateral placement of the immovable finger in relation to the distal placement of the movable finger. Closure of its fingers is complete only at their tips and a wide proximal gap remains between the two fingers even when closed. The immovable finger placement separates this new species from all others known in the Antarctic.
There are also very few species of subgenus P. (Pallenopsis) known to live at depths below 2000 m. The greatest exception is P. (P.) pilosa, which has been taken as deep as 3566 m. This subgenus is usually known as the shallower water congener of the group of deeper water species in the subgenus P. (Bathypallenopsis).
This species, in lateral view, brings to mind the subgeneric synonym P. (Rigona) with its compact nature of closely crowded lateral processes.” (Child 1995, p. 145-147)
