Uroptychus tomentosus Baba, 1974: 384, figs 3, 4 [type locality: holotype, ♂, 45°14.3′S, 171°29.2′E, 116 m, ZLKU 15125].
Type material: 1 ♀ (11.3 mm), paratype, south Chatham Rise, 44° 50.3′S, 171° 51.8′E, 118–120 m, 19.vi.1968, FV Kaiyo Maru stn 4, coll. K. Baba (ZLKU 15126).
Other material examined: Northland Plateau: 1 ♀ (15.0 mm), north of New Zealand, 34° 7.50′S, 172° 47.00′E, 315 m, 13.x.1968, stn F924 (NIWA 23158). 1 ♀ (7.6 mm), 35° 49.00′S, 174° 30.00′E, 80 m (NIWA 9800). Bay of Plenty: 1 ♀ ovig. (8.3 mm), 2 ♀ (6.4, 8.1 mm), 1 ♂ (7.8 mm), from four stations. Chatham Rise: 2 ♂ (13.7, 14.3 mm), 43° 53.40′S, 173° 54.20′E, 400 m, 30.x.1979, stn S177 (NIWA 23143). 1 ♀ (4.3 mm), 44° 0.00′S, 172° 58.20′E, 81– 79 m, 6.x.1962, stn B554 (NIWA 10093). 2 ♀ (12.3, 16.8 mm), 44° 10.20′S, 176° 59.20′W, 278 m, 23.iii.1978, stn Q34 (NIWA 23149). 2 ♂ (9.0, 10.7 mm), 44° 12.30′S, 173° 29.90′E, 327 m, 28.x.1979, stn S156 (NIWA 23148). 1 ♂ (11.7 mm), 44° 57.00′S, 171° 46.00′E, 123 m, 19.i.1970, stn G668 (NIWA 10674). 1 ♀ ovig. (16 mm), 44° 9.00′S, 176° 6.50′E, 126 m, 23.x.1979, stn S134 (NIWA 10099). South-east New Zealand: 3 ♀ ovig. (10.4, 13.0, 16.8 mm), 5 ♀ (8.7–14.8 mm), 6 ♂ (6.7– 15.7 mm), from eight stations. Bounty Islands: 1 ♀ ovig. (14.3 mm), 48° 10.10′S, 179° 30.00′E, 228 m, 20.iii.1979, stn I700 (NIWA 23138). 1 ♂ (12.7 mm), 1 ♀ ovig. (14.3 mm), 1 ♀ (12.7 mm), 48° 12.60′S, 179° 29.10′E, 260 m, 25.ix.1978, stn S62 (NIWA 23144). 3 ♂ (8.5, 9.5, 17.7 mm), 4 ♀ ovig. (13.2–17.3 mm), 48° 9.50′S, 179° 47.00′E, 220 m, 15.iii.1979, stn I680 (NIWA 10900). 1 ♂ (6.4 mm), 48° 9.60′S, 179° 15.90′E, 250 m, 20.iii.1979, stn I701 (NIWA 23055).
Diagnosis: Carapace longer than wide, dorsal surface unarmed, covered with fine setae; lateral margins irregular but without spines, concavely divergent, distal portion with ridge. Rostrum 0.4 times as long as remainder of carapace, anteriorly rounded. Pterygostomian flap granulate, anterior portion covered with serrate ridges, with sharp anterior spine. Sternal plastron wider than long along midlength, sternite 3 with round anterior margin and semicircular median notch; sternite 4 entire. Abdomen unarmed, setose. Cornea small. Antenna stout; penultimate article with small distal spine; ultimate article unarmed; scale barely overreaching penultimate article to barely reaching midlength of ultimate article. Maxilliped 3 unarmed. Pereopod 1 (cheliped) slender, three times as long as carapace, setose and unarmed except small distodorsal spine on ischium. Pereopods 2–4 sparsely to strongly setose; meri smooth to irregular on proximal portion of dorsal crest, unarmed; carpi smooth along dorsal margin; propodi with pair of distal movable spines only; dactyli broad relative to length, less than half length of propodus, with three to six spines, loosely arranged, flexor margin with ultimate spine smaller than penultimate, subequal to antepenultimate.
Variation: Variations from the original account by Baba (1974) include the length and shape of the antennal scale. The length of the scale ranges from barely overreaching the penultimate to reaching to the middle of the ultimate article of the antennal peduncle, whereas the width of the scale remains 1.6–1.7 times that of the antennal peduncle (1.6 in the paratype) (Fig. 15 shows short scale of ovigerous female of NIWA 10900). More commonly, the scale terminates in a more round tip than illustrated in the holotype. One female (Mu 68–81, NMNZ Cr. 012092, south-east New Zealand) bears two small distal spines on the penultimate article.
The new records support Baba’s (1974) remarks on variation regarding the degree of setation of the body and appendages varying from densely setose to moderately setose with no clear pattern related to sex or size. With regards to the spination of the dactyli of the ambulatory legs, specimens most commonly (60%) bear five spines, larger specimens more often bear six spines, and smaller specimens bear three to four spines.
Further variation is exhibited in the length–width ratio of the carapace, 1.2 in paratype female, slightly more in smaller specimens (1.3 in 8.5 mm male, NIWA 10900) and slightly less in large specimens (1.1 in 14.3 mm female, NIWA 23138).
Females are generally larger than males (range of carapace length for ovigerous females: 10.4 to 17.3 mm, mean 14.6 mm, median 14.3 mm; females: 4.3 to 16.8 mm, mean 11.0 mm, median 11.8 mm; males: 6.4 to 17.7 mm, mean 10.6 mm, median 9.5 mm).
Large males show slightly gaping fingers of the cheliped.
The female paratype and the large female of the (NMNZ Cr. 012096, south-east New Zealand) are infected with akentrogonid rhizocephalans on the ambulatory legs, the antennae, and the third maxilliped. Additionally, two specimens are infected by kentrogonids beneath the abdomen (two kentrogonids on NIWA 23158; one large sacculinid rhizocephalan on NIWA 23160).
Remarks: Uroptychus tomentosus is recognizable by its setaceous body and appendages, round rostrum, small ocular peduncle, rounded frontal margin of the sternal plastron with a U-shaped median notch, short, rounded antennal scale, and the short dactyli of the ambulatory legs with three to six widely spaced spines.
The female paratype matches the description of the holotype. It represents the only female of the type series of seven specimens and was collected from close to the type locality and at a similar depth.
Uroptychus tomentosus is most similar to Uroptychus pilosus Baba, 1981, which shares the short antennal scale and short P2–4 dactyli. Uroptychus tomentosus differs from Uroptychus pilosus by having a distinct anterolateral and postorbital spine (vs. rounded), a small (sometimes minute) distal spine on the penultimate antennal article (vs. unarmed), and by having three to six spines on the dactyli of the walking legs (vs. only two terminal spines).
Distribution: Chatham Rise, east of New Zealand’s South Island (between 43° 09′S and 44° 50′S), at depths of 116– 382 m. This species is one of the more common New Zealand chirostylids and appears to be endemic to the continental shelf of the eastern coast of New Zealand (Fig. 16). Its range is extended to the northern tip of New Zealand (34°08′S) and to the Bounty Islands to the south (48°13′S) from a depth range of 64– 540 m.