Uroptychus insignis ( Henderson, 1885 )

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 : 111-116

Uroptychus insignis ( Henderson, 1885)

Figs 1–4 , 5A

Diptychus insignis Henderson, 1885: 419 (type locality: off Marion Island , Prince Edward Islands, 46°41'S, 38°10'E, 567 m).

Uroptychus insignis .—Henderson, 1888: 175, pl. 21, figs 1, 1a, 1c [not 1b].— Baba, 2005: 227 (key, synonymies).— Baba et al., 2008: 34 (synonymies).

Type material. BMNH 1902.10.2.9–14, ov. female lectotype (cl 17.1, pcl 10.6 mm), 6 male paralectotypes (cl 7.6, pcl 4.5 to cl 16.7, pcl 10.7 mm), 7 female paralectotypes (pcl 3.1–11.0 mm), off Marion Island , Prince Edward Islands, southern Indian Ocean, 46°41'S, 38°10'E, 567 m, “Challenger” Stn. 145A .

Other material examined. Macquarie Ridge: NIWA 40904 , 1 ov. female (cl 15.9, pcl 10.5 mm), 1 female (cl 8.7, pcl 5.5 mm), 2 males (cl 12.0, pcl 7.4; cl 18.1, pcl 11.8 mm), Hjort Seamount, 56°14.78–14.49'S, 158°30.34–30.9'E, 676–750 m, 16 April 2008, TAN0803/98 ; NIWA 40664 , 1 male (pcl 13.1 mm), 1 unknown (pcl 11.6 mm), Seamount 8 (Australian EEZ), 55°13.75–13.75'S 158°15.49–15.89'E, 501–775 m, 15 April 2008, TAN0803/88 (specimens lost at sea; studied from images) .

Crozet Islands: MNHN IU-2010-5427 , 1 male (cl 18.0, pcl 11.5 mm), 1 female (pcl 5.6 mm), 46°36.56'S, 49°39.28'E, 902–1217 m, on black coral , R / V “Croix du Sud” Palangre No. 36, 25 December 2002 ; MNHN IU-2010- 5433 , 1 male (pcl 9.3 mm), no specific locality , R / V “ Anyo Maru 22”, coll. Jérôme Maison, January–April 1997 ; MNHN IU-2010 - 5431,1 ov.female (cl. 17.0,pcl 10.2 mm), 46°29.06'S, 50°0.15'E, 830–930 m , R / V “Anyo-Maru 22” Palangre 164, coll. Jérôme Maison, 15 March 1997 ; MNHN IU-2010-5434 , 1 female (pcl 7.2 mm), 46°54.12'S, 51°09.12'E, 544 m , R / V “Anyo-Maru 22” Palangre 183, coll. Jérôme Maison, 30 March 1997 ; MNHN IU-2014- 12002 , 9 males (pcl 4.9–9.0 mm), 1 ov. female (pcl 10.9 mm), 7 females (pcl 6.0–10.0 mm), 46°21'S, 50°07'E, 490–495 m , MD30 /BIOMASS , R / V “ Marion Dufresne ” stn. 25-CP59, 10 February 1982 .

Kerguelen Islands: MNHN IU-2010-5429 , 3 females (pcl 8.8–10.0 mm), 49° 5 9.40'S, 67° 5 0.70'E, 760 m, Kerguelen 472 , R / V “Esperance-Anyo” Ligne 77, coll. David Beaufils, 11 May 2008 ; MNHN IU-2010-5432 , 1 male (cl 4.8, pcl 2.9 mm), 1 female (cl 7.3 mm, pcl 4.4 mm), 49°31.69'S, 67°18.22'E, 980–1031 m , R / V “ Albius ” Palangre No. 111, 18 May 2002 ; AM P97998, 1 female (cl 14.3, pcl 9.0 mm), 50°06'S, 64°48'E, 489 m, Poker II st. 180, 22 September 2010 ; AM P97999, 1 male (cl 11.8, pcl 7.2 mm), 50°11'S, 64°55'E, 483 m, Poker II stn. 179, 22 September 2010 ; MNHN IU-2007-4986 , 1 female (cl 9.2, pcl 5.7 mm), 50°11'S, 64°55'E, 483 m, Poker II stn. 179, 22 September 2010 ; MNHN IU-2007-4996 , 1 female (cl 4.6, pcl 2.7 mm), 50°11'S, 64°55'E, 483 m, Poker II stn. 179, 22 September 2010 ; AM P98003, 1 male (cl 4.3, pcl 2.7 mm), 50°11'S, 64°55'E, 483 m, Poker II stn. 179, 22 September 2010 .

Amsterdam Island: MNHN IU-2010-5428 , 1 ov. female (pcl 4.5 mm), 1 female (pcl 4.6 mm), 37°47.20'S, 77°38.98'E, 940–1680 m , R / V “Marion- Dufresne”, CP7, 9 July 1986 .

Prince Edward Islands: MNHN IU-2014-12003 , 1 male (pcl 8.4 mm), 1 ov. female (pcl 10.8 mm), 1 female (pcl 6.0 mm), Marion Island , 46°41'S, 38°07'E, 315–570 m , MD08 /BENTHOS, R / V “Marion Dufresne” stn. 36, CP173, 29 March 1976 .

Diagnosis. Carapace excluding rostrum wider than long; dorsum smooth, with transverse row of epigastric spines; lateral margins divergent, spinose; anterolateral spine overreaching outer orbital spine; anterior branchial spine separated from remaining branchial spines by wide unarmed margin (occasionally with 1 or 2 small spines). Rostrum sharply triangular, margins unarmed or with few minute denticles. Sternite 3 anterior margin with deep, V-shaped median emargination. Basal antennal article with small outer spine; ultimate and penultimate articles each with distomesial spine. Antennal scale extending almost to apex of ultimate peduncle article. Crista dentata uniformly and minutely dentate. P2–4 similar; merus with small spines on extensor margin; propodus flexor margin broadened distally and lined with movable spines; dactylus flexor margin lined with strong, obliquely directed, corneous teeth.

Description of type material. Carapace: Wider than long (length 0.8–[0.9] × width); greatest width 1.7–[2.1] × distance between anterolateral spines. Dorsal surface moderately convex from anterior to posterior, large specimens with feeble depression between gastric and anterior branchial regions; with sparse short setae; bearing transverse field of 6–9[7] small spines in addition to few acute granules across epigastric region. Lateral margins broadly convex, divergent posteriorly, with row of distinct spines: first (anterolateral spine) well developed, directed straight forward, overreaching lateral orbital spine, followed by 2 (rarely 1) small spines on hepatic margin; fourth spine situated on anterior end of anterior branchial margin, smaller than anterolateral spine; fifth strong, distantly posterior to preceding spine, situated on anterior end of posterior branchial margin (rarely 1 or 2 extra small spines between fourth and fifth), followed by 3–6[4] posteriorly diminishing spines; last spine followed by low ridge along lateral margin. Rostrum elongate triangular, with interior angle of 22–27°[23°], horizontal and directed straight forward; dorsal surface flattish basally, becoming rounded in cross-section distally; lateral margin straight, with up to 3 minute spines distally; length 1.6–[2.0] × width, 0.6 (rarely 0.7) × pcl, width about half (small specimens) or less than half (large specimens) carapace width at posterior carapace margin. Outer orbital spine very small, moderately remote from and slightly anterior to base of anterolateral spine of carapace. Pterygostomian flap anteriorly angular, produced to small spine, surface somewhat granular or with several small spines on anterior portion.

Sternum: Sternites 1–3 with anterior margin convex between bases of maxilliped 1, surface without distinct ridge in midline. Sternal plastron length 0.7–0.8 × width, lateral extremities divergent posteriorly. Sternite 3 distinctly depressed, anterolateral angle blunt or rarely sharply produced; anterior margin with deep V-shaped median emargination, without median spines. Sternite 4 with bluntly or obsolescently denticulate anterolateral margin, anteriorly blunt angular or rounded, posterolateral margin 0.5–0.6 length of anterolateral margin. Sternite 5 slightly broader than sternite 4, anterolateral margins strongly convex anteriorly, 1.3–1.4 × length of posterolateral margin of sternite 4. Widest at sternite 7.

Abdomen: Tergite 1 gently convex from anterior to posterior. Tergite 2 2.7–[3.3] × wider than long; pleural lateral margins weakly concave and weakly divergent posteriorly, posterolaterally angular. Pleuron 3 with angular lateral margin. Telson about half as long as wide; posterior plate 1.1–1.5[1.4] × longer than anterior plate (longer in small specimens), posterior margin distinctly emarginate.

Eye: Relatively short (length 1.4–[1.5] × width), somewhat narrowed distally, reaching anteriorly at most to proximal one-third of rostrum. Cornea not dilated, more than half length of remaining eyestalk.

Antennule: Distal article of antennular peduncle relatively slender, 3.0–[4.0] × longer than high (proportionally longer in large specimens).

Antenna: Antennal peduncle extending far beyond cornea, overreaching midlength of rostrum. Article 2 with small distolateral spine.Antennal scale tapering, [1.8]–2.1 × wider than article 5, slightly falling short of, fully reaching or slightly overreaching tip of article 5. Articles 4 and 5 each with small distomesial spine. Article 5 about twice as long as article 4, width 0.6 × height of distal article of antennule. Flagellum of 9–17 segments, overreaching distal end of P1 merus.

Maxillipeds: Maxilliped 1 with bases broadly separated. Maxilliped 3 basis with mesial ridge proximally lobe-like, with a few obsolescent denticles; ischium distally not rounded on flexor margin, crista dentata with numerous tiny denticles; merus wide relative to length, about twice length of ischium, flattish on mesial face, distolateral spine distinct, flexor margin ridged along distal half, with 4–6 small spines distal to midlength; distolateral spine of carpus distinct.

Pereopod 1 (cheliped): Sparsely to moderately setose, length 3.0–4.1 pcl (males), 3.0–[3.8] pcl (females), (greater in larger specimens). Ischium with well-developed dorsal spine, ventromesial margin with strong subterminal spine proximally followed by small spines. Merus, carpus and palm with sparse denticles on dorsal surface (fewer on palm). Merus 0.6–[0.9] pcl (longer in large specimens), distally and mesially spinose, a few mesial spines strong, ventrally with small spines along mesial margin. Carpus [1.0]–1.1 × length of merus, distally spinose. Palm length 2.1–2.4 (males), 2.3–2.7[2.6] (females) × width, [1.2]–1.4 × carpus length. Fingers (dactylus and pollex) inclined somewhat laterally in large specimens, straight in small specimens, not gaping, distally crossing. Dactylus length 0.6–[0.7] × palm length (shorter in large specimens), occlusal margin with low median process proximal to position of opposite eminence on pollex.

Pereopods 2–4 (walking legs): Sparsely setose. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8 × length of P3 merus), P2–3 meri subequally broad, P4 merus slightly narrower than P3 merus; length-breadth ratio, 3.1–[4.2] on P2, 3.0–[3.8] on P3, 2.5–[3.3] on P4 (relatively narrow in large specimens); dorsal margin with several small spines including terminal spine, ventrolateral margin with terminal spine only. P2 merus length 0.7–[0.9] × pcl, subequally long as (in large specimens) or slightly shorter than (in small specimens) P2 propodus; P3 merus length 0.8–[1.0] × length of P3 propodus; P4 merus length 0.7–[0.8] × length of P4 propodus. Carpi successively slightly shorter posteriorly; carpus-propodus length ratio, 0.5–[0.6] on P2–3, 0.4–[0.6] on P4; extensor margin with small proximal spine. Propodi subequal on P2–4 or shorter on P2 than on P3–4; flexor margin distally convex strongly in large specimens, feebly so in small specimens, ending in pair of spines preceded by 5–8, 4–7, 3–7 spines (fewer in small specimens) on P2, 3 and 4 respectively. Dactyli 0.3–[0.4] × as long as propodi on P2, 0.4 on P3, 0.4–[0.5] on P4; dactylus-carpus length ratio, 0.5–0.9[0.6] on P2, 0.6–0.9[0.8] on P3, 0.8–1.1[0.9] on P4 (smaller in large specimens); flexor margin slightly curving, with 6–10 [9 or 10] acute, proximally diminishing, somewhat inclined spines (fewer in small specimens).

Eggs: Number of eggs carried, about 50; size, 1.3 × 1.2 mm to 1.3 × 1.3 mm.

Colour in life ( Fig. 5A ). Bright red.

Remarks. Uroptychus insignis ( Henderson, 1885) , originally described from the south-west Indian Ocean off Marion Island, Prince Edward Islands, has not been recorded elsewhere until now. The Macquarie Ridge specimens ( Figs 1 , 2 ) are tentatively assigned to U. insignis based on their strong similarity to the type material and other specimens from the south-west Indian Ocean (Amsterdam Island, Kerguelen Islands, Crozet Islands) reported here ( Figs. 3 , 4 ). The type material is re-described and figured herein along with comparative material from the Crozet and Kerguelen islands for comparison with the Macquarie Ridge specimens. Among the Indian Ocean specimens, no morphological differences worthy of note were observed. Size related variation is evident, however. In the smallest specimen from the Kerguelen Islands (pcl 2.9 mm, male, MNHN IU-2010-5432), P1 is much shorter (2.3 × pcl) and the P2–4 propodi have fewer spines on the flexor margin and are not distally inflated as in large specimens ( Fig. 4J–L ). The branchial and epigastric spines are more pronounced in the largest specimens. The ovigerous female (pcl 10.2 mm, MNHN IU-2010-5431) has the rostrum somewhat curving dorsally. Number of eggs carried and size for three specimens: 6, 1.4 × 1.7 to 1.6 × 1.6 mm (pcl 4.5 mm, MNHN IU-2010-5428); 30, 1.6 × 1.7 to 1.7 × 1.9 mm (pcl 10.2 mm, MNHN IU-2010-5431); ca 50, 1.3 × 1.3 mm to 1.2 × 1.4 mm (pcl 10.9 mm, MNHN IU-2014-12002).

The Macquarie Ridge specimens agree closely with the Indian Ocean material in almost all respects, but differ subtly in being less setose, especially on the chelipeds and carapace, and, more significantly, in having more pronounced epigastric spines on the carapace. The development of the epigastric spines varies allometrically in both Macquarie Ridge and Indian Ocean material but in size-matched specimens, the spines of the Macquarie Ridge specimens are comparatively larger, except in the smallest specimens in which the epigastric armature is yet to appear. The difference in epigastric armature is most noticeable in the largest specimens in which the largest epigastric spines in Macquarie Ridge specimens are as large as, instead of smaller than, the adjacent branchial marginal spines. The Macquarie Ridge specimens might prove to be specifically distinct from the Indian Ocean populations, but are here regarded as U. insignis pending further studies currently underway.

Uroptychus insignis most closely resembles U. zeidleri Ahyong & Poore, 2004a , from Tasmania. The two species are readily separated by the branchial marginal carapace spination (arranged in a single, even, unbroken row in U. zeidleri ; anterior branchial spine separated from the remainder by an unarmed interval, or at most with 1 or 2 small, well-spaced spines in U. insignis ) and dentition of the crista dentata (teeth evenly decreasing in size distally in U. zeidleri ; teeth uniformly minute in U. insignis ).

Six specimens of U. insignis were collected from Macquarie Ridge during TAN0803, but the two specimens from stn. 88 were unfortunately lost at sea under adverse weather conditions.

Distribution. Southern Indian Ocean off Prince Edward Island, Amsterdam Island, the Crozet and Kerguelen Islands, and now from the southwestern Pacific from seamounts on the Macquarie Ridge; 315–1680 m (501–775 m on the Macquarie Ridge).

Figures

Figure 1. Uroptychus insignis (Henderson, 1885), ov. female pcl 10.5 mm, Hjort Seamount, Macquarie Ridge (NIWA 40904). (A) dorsal habitus. (B) carapace, right lateral. (C) right antenna, ventral view. (D) right maxilliped 3, lateral. (E) right crista dentata. F, right P1 ischium and merus, ventral.(G) sternal plastron. (H) telson. Scales: A, B, F = 2.5 mm; C, D, G, H = 1.25 mm; E = 0.5 mm.

Figure 2. Uroptychus insignis (Henderson, 1885), carapace, Hjort Seamount, Macquarie Ridge (NIWA 40904). (A) female pcl 5.5 mm. (B) male pcl 7.4 mm. (C) male pcl 11.8 mm. Scale = 2.5 mm.

Figure 3.Uroptychus insignis (Henderson, 1885), lectotype, ov.female, pcl 10.6 mm, (BMNH 1902.10.2.9–14).(A) carapace and anterior part of abdomen, proximal part of left cheliped, dorsal. (B) carapace and abdomen, right lateral. (C) sternal plastron. (D) telson. (E) left antenna, ventral. F, left maxilliped 3, ventral. (G) same, setae omitted, lateral. (H) left P1, setae omitted. (I) left P1 fingers, ventral view. (J) left P1 ischium and merus, ventral. (K) same, proximal part, lateral. (L–N) right P2–4. (O–Q) same, distal articles. Scales: A, B, H–N = 5 mm; C = 2.0 mm; D–G, O–Q = 2.5 mm.

Figure 4.Uroptychus insignis (Henderson, 1885).(A) female pcl 4.4 mm, Kerguelen Islands (MNHN IU-2010-5432).(B–E) paralectotype, male pcl 4.5 mm (BMNH 1902.10.2.9–14). (F) female pcl 7.2 mm, Kerguelen Islands (AM P97999). (G) paralectotype, male pcl 10.7 mm, (BMNH 1902.10.2.9–14). (H–I) male pcl 11.5 mm, Crozet Islands (MNHN IU-2010-5427). (J–L) female pcl 2.9 mm, Kerguelen Islands (MNHN IU-2010-5432). (A, B, G, H) carapace and proximal articles of P1; (C–E) right P2–4; (F) carapace; (I) right P1; (J–L) left pereopods 2–4; Scale: A–E = 2.5 mm; F–I = 5.0 mm; J–L = 1.0 mm.

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.