Uroptychus tracey, Ahyong & Schnabel & Baba, 2015

Ahyong, Shane T., Schnabel, Kareen E. & Baba, Keiji, 2015, Southern High Latitude Squat Lobsters: Galatheoidea and Chirostyloidea from Macquarie Ridge with Description of a New Species of Uroptychus, Records of the Australian Museum 67 (4), pp. 109-128 : 116-119

Uroptychus tracey n. sp.

Figs 5B , 6

Type material. NIWA 54266 , male holotype (cl 11.3, pcl 7.2 mm), Iceberg seamount, Andes seamount complex, Chatham Rise, 44°09.49–09.69'S, 174°33.30–33.14'W, 487–616 m, 28 June 2009 , TAN0905/119. Paratypes (all Chatham Rise ) : NMNZ CR.023843, 6 males (pcl 2.4, 2.7, 3.4, 3.8, 4.8, 5.2, 5.2 mm), 2 ov. females (pcl 3.4, 5.5 mm), 43°04.00'S, 178°39.00'W, 549 m, 13 September 1963 , NZOI stn. A910; NIWA 26452 , 1 ov. female (pcl 4.5 mm), Main Knoll, 43°31.84–31.67'S, 179°37.75–37.98'E, 378–390 m, 07 June 2006 , TAN0604/110; NIWA 60524 , 2 ov. females (pcl 3.8, 5.3 mm), Diamond Head seamount, Andes seamount complex, 44°08.38–08.54'S, 174°43.18–43.56'W, 641–758 m, 26 June 2009 , TAN0905/99; NIWA 60527 , 2 males (pcl 5.5, 6.7 mm), Diamond Head Peak C, Andes seamount complex, 44°08.85–09.00'S, 174°41.45–41.65'W, 458–648 m, 27 June 2009 , TAN0905/111; AM P97840, 2 males (pcl 6.2, 6.9 mm), 1 ov. female (pcl 4.8 mm), 1 female (damaged), Diamond Head seamount, Andes seamount complex, 44°08.97–09.02'S, 174°45.41–45.63'W, 519–609 m, 27 June 2009 , TAN0905/113.

Other material examined. Chatham Rise: NIWA 33673 , 1 male (pcl 5.3 mm), 1 female (pcl 6.0 mm), 43°47.31–47.74'S, 175°15.13–14.77'W, 520–532 m, 12 April 2007 , TAN0705/ 118; NMNZ CR.023844, 1 male (pcl 4.3 mm), 1 ov. female (pcl 5.9 mm), 43°51.00'S, 179°25.00'E, 309 m, 20 May 1970 , NZOI stn. J59; NMNZ CR.023845, 1 male (pcl 6.2 mm), 44°05.50'S, 176°12.00'E, 198 m, 17 May 1970 , stn. J55; NIWA 14575 , 1 female (pcl 3.4 mm), 44°07.00'S, 179°13.00'W, 402 m, 26 January 1968 , stn. G307A; NIWA 60525 , 1 ov. female (pcl 6.7 mm), Diamond Head seamount, Andes seamount complex, 44°08.84–08.87'S, 174°41.40– 41.68'W, 440–600 m, 26 June 2009 , TAN0905/97; NIWA 60520 , 4 males (pcl 5.2, 5.7, 6.0, 6.5 mm), 1 ov. female (6.0 mm), Diamond Head seamount, Andes seamount complex, 44°08.84–08.87'S, 174°41.4–41.68'W, 440–600 m, 26 June 2009 , TAN0905/97; NIWA 53847 , 1 ov. female (pcl 6.7 mm), Iceberg seamount, Andes seamount complex, 44°09.44–09.55'S, 174°33.25–33.41'W, 485–533 m, 26 June 2009 , TAN0905/105; NIWA 60521 , 1 ov. female (pcl 5.7 mm), Iceberg seamount, Andes seamount complex, 44°09.44–09.55'S, 174°33.25–33.41'W, 485–533 m, 26 June 2009 , TAN0905/105; NIWA 60522 , 1 male (pcl 5.9 mm), 2 ov. female (pcl 4.1, 5.2 mm), Iceberg seamount, Andes seamount complex, 44°09.49–09.69'S, 174°33.30–33.14'W, 487–616 m, 28 June 2009 , TAN0905/119; NIWA 60519 , 1 male (pcl 4.3 mm), Ritchie Hill Summit, Andes seamount complex, 44°10.50–10.39'S, 174°33.13–33.36'W, 716–745 m, 27 June 2009 , TAN0905/116.

SW New Zealand: NMNZ CR.023846, 1 male (pcl 6.0 mm), 1 ov. female (pcl 3.8 mm), Caswell High , off Fiordland, 45°57.00'S, 166°9.00'E, 514–534 m, 21 October 1967, stn. E803 .

Macquarie Ridge: AM P97841, 1 male (pcl 5.2 mm), Seamount 6 (Australian EEZ), 52°29.24–29.03'S, 160°24.90– 24.55'E, 350–560 m, 09 April 2008, TAN0803/63 ; AM P97842, 1 male (pcl 5.7 mm), Seamount 6 (Australian EEZ), 52°23.85–23.91'S, 160°39.40–40.13'E, 451– 438 m, 09April 2008, TAN0803/69 .

Campbell Plateau: NMNZ CR.023847, 1 ov. female (pcl 6.0 mm), ESE of Campbell Island , 53°00.00'S, 172°45.00'E, 435 m, 01 February 1965, stn. F146 .

Diagnosis. Carapace lateral margin lined with distinct spines behind anterolateral spine; spines and short serrated ridges across entire dorsal surface. Antennal scale distinctly overreaching peduncle, slender (length about 5 × width). P1 palm with median pair of small spines close to proximal margin only, otherwise unarmed. P2–4 meri and carpi with spinose extensor margins; propodi each with row of movable spines along flexor margin. P2–4 dactyli tapering distally, more than half as long as propodi; entire flexor margin lined with spines, contiguous, prominent penultimate spine.

Description. Carapace: length [1.5]–1.8 × width (including rostrum) (0.8–[1.0] excluding rostrum); greatest width at midlength of branchial region. Dorsal surface slightly convex from anterior to posterior; cervical groove not deep but distinct. Entire dorsal surface covered with spines, short spinules and setose ridges; distinct row of epigastric spines, usually with large median spine. Orbit rounded; small outer orbital spine; frontal margin between outer orbital spine and anterolateral spine oblique, relatively straight; Anterolateral spine prominent. Lateral margin convex, divergent posteriorly, with 6 or 7 spines excluding anterolateral spine (1 or 2 small spines on hepatic margin, 1 prominent spine on anterior branchial margin, 4 (rarely 5) prominent spines on posterior branchial). Rostrum triangular, horizontal, [0.6]–0.8 × pcl; dorsal surface excavate, covered with small granules; lateral margins finely serrated posteriorly (nearly spinose sub-apically). Pterygostomian flap surface covered with small spines and granules, anterior margin narrowly triangular but not produced to spine.

Sternum: Sternites 1–3 with anterior margin strongly sinusoid between bases of maxilliped 1, not acute, surface with distinct ridge in midline. Sternal plastron width 1.1 × length, lateral extremities subparallel between sternites 5–7. Sternite 3 anterior margin deeply excavated with U-shaped median notch, produced anteriorly, lateral margins produced to tooth. Sternite 4 width 2.2 × sternite 3 width, anterior margin steeply convex, anterior midline grooved, anterolateral margin produced to tooth (not overreaching sternite 3), lateral midlength unarmed. Lines demarcating fifth to seventh sternites smooth, surfaces smooth. Widest at sternite 7.

Abdomen: Tergites smooth and unarmed; tergite 1 with transverse dorsal ridge; tergites 2–4 without transverse ridges or grooves. Pleural margins of somites 2–4 distally narrowing to triangular point. Telson length [0.4]–0.5 × width; posterior plate [1.3]–1.4 × longer than anterior plate, posterior margin emarginate.

Eyes: movable, sparsely setose. Cornea subglobular, 0.3 × length of remaining eyestalk.

Antennule: Distal article of antennular peduncle relatively slender, length 3.8–[5.6] × width (most slender in largest specimen, holotype).

Antenna: Antennal peduncle overreaching cornea (cornea slightly overreaching midlength of antennal article 5). Article 2 with distinct outer spine. Antennal scale [1.5]–1.7 × wider than article 5, length 4.2–[5.6] × width, overreaching tip of article 5. Article 4 with distal spine. Article 5 length [2.0]–2.5 × article 4 length, armed with distomedian spine (small to large spine). Flagellum of 12–18 segments, not reaching end of P1 merus.

Maxillipeds: Maxilliped 1 with bases broadly separated. Maxilliped 3 surfaces smooth; ischium with small spine lateral to rounded distal end of flexor margin, crista dentata with obsolescent or very small denticles; merus longer than wide, extensor margin with curved distal spine, flexor margin with 2 median spines; carpus with distal extensor spine.

Pereopod 1 (cheliped): Moderately setose. Elongate, length [2.5]–2.9 × cl (in both sexes) ([4.0]–4.9 × pcl, longest in large male holotype). Ischium with dorsal and ventral spines distally. Merus and carpus surface with longitudinal rows of spines; 6 distal spines. Merus [1.0]–1.4 × pcl. Carpus subequal in length to both merus and palm. Propodus with palm 2.1–2.7[2.5] (males), 2.3–3.4 (females) × as long as high (subequal right and left); surface covered with small granules and setal pits; two small spines proximally adjacent to carpal articulation. Dactylus length about 0.5 × palm length; occlusal margin finely denticulate.

Pereopods 2–4 (walking legs): Similar, surfaces spinose. Meri successively shorter posteriorly (P3 merus length 0.8–[0.9] × P2 merus length, P4 merus length [0.8]–0.9 × P3 merus length); extensor margin with row of 5 or 6 spines (excluding distal spine); flexor margin irregular or with small spines or serrations; length-breadth ratio 3.0–3.5. Carpi equal in length from P2–4, 0.4 × length of propodi; extensor margin with row of 2–4 spines (excluding 2 distal spines) paralleling row of smaller spines on lateral surface; flexor margin smooth. Propodi subequal in length; length-width ratio ranging from 4.4 (P2) to 5.3 (P4); extensor margin smooth (slightly irregular in proximal portion of P2 and P4); flexor margin straight (not inflated), with pair of terminal spines preceded by 3–6 spines along, on P4 distributed along entire length; distal pair of flexor spines not remote from penultimate spine. Dactyli length 0.6–0.7 × propodi length; flexor margin straight, with 20 obliquely directed, contiguous spines along entire length (excluding distal spine); distal spine slender, penultimate spines prominent, more than twice width of ultimate and antepenultimate; remaining spines gradually more slender and elongate towards proximal end.

Eggs: 1.0– 1.7 mm in diameter.

Colour in life ( Fig. 5B ). Carapace, cheliped and legs base colour pale orange, abdomen clear. Dark orange on tips of spines, cheliped fingers and in central patches of abdominal tergites 1–3.

Remarks. The specimens of U. tracey n. sp. agree well in proportions and spination in most parts. Some variability is present in the size of the distal spine on the ultimate antennal article, ranging from a minute granule to a small spine in most specimens, to distinct and large in two specimens (male, NIWA 40304; ovigerous female, NMNZCR.023847). The posterior branchial margin of the carapace bears four prominent spines, or rarely five through bifurcation of one of the spines, as in the holotype ( Fig. 6A ). The expression of the dorsal carapace ornamentation also varies slightly, with the holotype having mostly finely serrated ridges (other than the distinct spines in the epigastric region). In some specimens, however, the median portion may be produced to a spine in some areas and in the most spinose specimen (ovigerous female, NZOI stn. F146, NMNZ CR.023847), all of these ridges are produced into spines. Slight differences were also observed in two females (NIWA 60520 and 26452), which lacked the median epigastric spine that is present in all other specimens. One parasitized female (NIWA 33673) has the externa of a sacculinid rhizocephalan under its abdomen.

This species belongs to the group of spiny species having distinct spines along the lateral carapace margin, across the entire dorsal carapace surface and on P1–4. The unarmed abdomen and cheliped palm align this new species with Uroptychus sexspinosus Balss, 1913 ( Japan, 500 m) and U. fusimanus Alcock & Anderson, 1899a (Travancore coast, southern India, 787 m). Balss (1913: fig. 21) illustrates U. sexspinosus with only scattered small spines on the dorsal carapace surface, although the description records the carapace dorsum as unarmed. It differs from U. tracey n. sp. in having P2–4 much more slender, with smooth instead of spinose flexor margins of the propodi. Uroptychus fusimanus differs from U. tracey n. sp. in having the antennal scale not over-reaching the peduncle (distinctly over-reaching in the new species), the length of the P2–4 dactyli being less than one-third propodi length instead of more than half that of the propodi in the new species. In addition, the penultimate spine of the P2–4 dactyli is most prominent in U. tracey ; in U. fusimanus , however, the ultimate spine appears to be larger than the remaining spines (see Alcock & Anderson, 1899b: pl. 44, fig. 4). This could prove to be a distinctive difference between the two species given that Alcock & McArdle (1902: pl. 57, figs. 1, 1a) clearly depicted this pronounced spine for U. nanophyes . Both U. sexspinosus and U. fusimanus , known only from their respective type material, require detailed redescription.

Among southwestern Pacific species, U. tracey n. sp. most closely resembles U. cardus Ahyong & Poore, 2004 , but the dorsal carapace spination of U. cardus is restricted to the epigastric region (compared to the entire dorsal surface in the new species), the extensor margins of the P2–4 meri and carpi are unarmed (with a row of spines in the new species) and the antennal scale is broader in U. cardus than in U. tracey n. sp. (about 3 times longer than wide versus about 5 times longer than wide).

Etymology. Named in honour of our colleague Di Tracey for her contributions to New Zealand deepwater marine science and her instrumental role in collecting the Macquarie Ridge specimens; used as a noun in apposition.

Distribution. This is a cold temperate species, endemic to New Zealand continental shelf and seamount localities south of the subtropical convergence. Currently known from the Chatham Rise, off Fiordland, Macquarie Ridge, Campbell Rise; 198–758 m ( Fig. 9 ).

Figures

Figure 5. Colour in life. (A) Uroptychus insignis (Henderson, 1885), male pcl 13.1 mm, Hjort Seamount, Macquarie Ridge, TAN0803/98 (NIWA 40664).(B) Uroptychustracey n. sp., holotype, malepcl 7.2 mm, Iceberg Seamount,Andes seamount complex,TAN0905/119 (NIWA 54266). (C) Munidopsis pyrochela Ahyong, 2014, male pcl 13.6 mm, Clementsville Seamount, Macquarie Ridge, station TAN0803/33 (NIWA 39722). Scale = 10 mm.

Figure 6. Uroptychus tracey n. sp., holotype, male pcl 7.2 mm, NIWA 54266: (A) carapace, dorsal; (B) carapace, lateral; (C) sternal plastron; (D) telson; (E) left antenna, ventral; (F) endopod of left maxilliped 3, lateral; (G) right crista dentata; (H) right P1, dorsal; (I) right P1 ischium and merus, ventral; (J–L) right P2–4, lateral, setae omitted; (M) left P4 dactylus and propodus, lateral. Scale:A–C, H–J = 2 mm; D–G, M = 1 mm.

Figure 9. New Zealand region showing the Macquarie Ridge (¡) and Christable (¡ c) seamounts, and sampling