dcsimg

Description

provided by NMNH Antarctic Invertebrates

Nymphon pagophilum, new species Fig. 14

Material examined. Yelcho: sta. Y-2-6 (one male (holotype, USNM 234687), four females (paratypes, USNM 234688)).

Other Material. Vema: sta. V-17-43 (11 males, six females, three juveniles).

Eltanin: sta. 6-413 (one female, damaged), 6-432 (one male, without legs), 12-1002 (one male).

Hero: sta. 702-511 (one female).

Distribution. The types were taken just south of Anvers Island, Palmer Archipelago, in 326 m. The other material is from the South Shetland Islands, in 655-670 m (Vema), Gerlache Strait, off Anvers Island, in 283-311 m (Hero), a more distant station west of the South Orkney Islands, in 1112-1170 m (Eltanin 6-413), in Bransfield Strait, in 265 m (Eltanin 12-1002), and another locality nearby in 884-935 m. This distinctive species thus has the rather wide depth range of 265­1170 in, but a relatively restricted distribution only from the Palmer Archipelago, through the South Shetlands, to the South Orkney Islands.

Description. Size moderate for Antarctic Nymphon: leg span about 44 mm. Trunk slender, completely segmented, lateral processes about 3 times longer than their diameters, each separated by about 3 diameter widths, glabrous. Neck long, slender, oviger bases separated from first lateral processes by very small open space, ocular tubercle at anterior of first lateral process­es, eyes unpigmented. Chelifore insertion lobes bulging, much broader than neck. Proboscis moderately short, cylindrical, with 3 slight distal bulges around lips. Abdomen swollen distally, upcurved, slightly longer than fourth lateral processes, glabrous.

Chelifore scapes moderately short, not as long as proboscis, with few lateral and distal setae. Chelae with short palms, long fingers, few setae on immovable finger. Fingers only curved distally, armed with 17 (immovable) and 15 (movable) curved teeth.

Palps moderately short, second segment length subequal to third, fourth little shorter, fifth very short, half length of fourth, both distal segments with many short setae.

Ovigers long, slender, fourth segment about 0.75 length of fifth. Fifth and sixth with row of short lateral setae. Strigilis with small segments bearing short denticulate spines having 3 lateral lobes per side, in formula, 8: 5: 4: 7, with short terminal claw bearing 9 small teeth.

Legs very slender, with few short setae, first tibiae the longest segments, second tibiae notably shorter, femora slightly shorter than second tibiae. Slender tarsus about 0.9 length of propodus, both with row of tiny sole spines, row of short dorsal setae, claw long, about 0.6 length of propodus, auxiliary claws lacking.

Female character: oviger bases placed closer to first lateral processes with only very little space between. Propodal claws vary, sometimes shorter in length.

Measurements (in millimeters). Trunk length from chelifore insertion to tip fourth lateral processes, 5.62; trunk width across second lateral processes, 2.68; proboscis length, 1.25; abdomen length, 0.98; third leg, coxa 1, 0.76; coxa 2, 2.21; coxa 3, 0.86; femur, 3.65; tibia 1, 5.22; tibia 2, 3.96; tarsus, 1.45; propodus, 1.61; claw, 0.95.

Etymology. The species name is composed of two words (Greek: pago, referring to ice, and philios, meaning lover) emphasizing its preferred cold water habitats.

Remarks. This species shares several characters with N. lomani and N. longicollum, including a long slender trunk with moderately long and well separated lateral processes. Neither of these known species have the same form of chelifores with large teeth, but they do have long necks with the oviger bases separated to a greater or lesser degree from the anterior pair of lateral processes. The ocular tubercle of N. pagophilum is similar to that of N. lomani, but that of N. longicollum is a tall conical tubercle without eyes. This new species has a long propodal claw without auxiliaries while the others have auxiliaries and the main claw is much shorter. There are many other smaller differences in diagnostic characters.” (Child, p.46-48)