Uroptychus scambus, BENEDICT, 1902

Schnabel, Kareen E., 2009, A review of the New Zealand Chirostylidae (Anomura: Galatheoidea) with description of six new species from the Kermadec Islands, Zoological Journal of the Linnean Society 155 (3), pp. 542-582 : 567-568

UROPTYCHUS SCAMBUS BENEDICT, 1902

Uroptychus scambus Benedict, 1902: 297 , fig. 41 [type locality: off Honshu, Japan, 337 fms (617 m); holotype, ♀ ovig., USNM 26165]. – Doflein & Balss, 1913: 134. – Van Dam, 1937: 100, fig. 1. – Baba, 1981: 120; 1988: 43; – Baba, 2005: 58, 217, 230 (list).

Uroptychus glyphodactylus MacGilchrist, 1905: 249 [type locality: east of the Andamans, ‘Investigator’ St. 331, 569 fm (1041 m); two syntypes, Zoological Survey of India, Calcutta]. – Alcock & MacGilchrist, 1905: pl. 70, fig. 4; pl. 71: fig. 1, 1a, 1b, 1c, 1d (no record).

Uroptychus edwardi Kensley, 1981: 69 , figs 6, 7 [type locality: between Durban and East London, South Africa; 900 m; holotype, ♀ ovig., South African Museum A16033].

Material examined: 2 ♂ (4.5, 7.3 mm), Makassar Strait , Indonesia, 03°56′S, 118°26′E, 2084 m, 24.viii.1951, Galathea stn 453 ( ZMUC CRU–11506) . 2 ♂ (5.4, 4.9 mm), 1 ♀ ovig. (5.0 mm), Norfolk Ridge , 26° 25.93–25.99′S, 167° 10.87–09.64′E, 750–774 m, 18.v.2003, TAN0308/43 ( NMNZ Cr. 012088) . 1 ♂ (5.4 mm), Kermadec Ridge , 31° 05.25–05.41′S, 179° 05.40–04.78′W, 1129– 944 m, 19.iv.2002, RV Tangaroa , stn TAN0205/48 ( NIWA 18590 ) . 1 ♀ (3.5 mm), Lord Howe Rise , 34° 12.43′S, 162° 39.49′E 760– 758 m, 26.v.2003, TAN0308/82 ( NMNZ Cr. 012089) . 1 ♀ (4.0 mm), Northland Plateau , 34° 12.79′S, 173° 01.30′E, 452–460 m, 23.xi.1977, stn I368 ( NIWA 10145 ) . 1 ♂ (4.9 mm), 1 ♀ ovig. (5.0 mm), Northland Plateau , 34° 42.30′S, 174° 17.59′E, 705– 684 m, 20.xi.1977, stn I366 ( NIWA 10136 ) . 1 ♀ ovig. (5.2 mm), Northland Plateau , 34° 43.49′S, 174° 31.49′E, 743 m, 11.x.1968, NZOI stn F913 ( NMNZ Cr. 012085) . 1 ♂ (4.1 mm), Northland Plateau , 35° 58.99′S, 173° 10.00′E, 701– 689 m, 23.iii.1968, NZOI stn E884 ( NMNZ Cr. 012086) . 1 ♀ ovig. (4.9 mm), Bay of Plenty , 37° 12.54–12.96′S, 177° 14.25–14.20′E, 910– 701 m, 11.xi.2004, RV Tangaroa , stn TAN0413/59 ( NIWA 10198 ) . 1 ♂ (5.4 mm), 1 ♀ ovig. (5.0 mm), 1 ♀ (5.5 mm), Bay of Plenty , 37° 32′S, 177° 20′E, 732 m, 30.ix.1962, VUW Haul 13 ( NMNZ Cr. 012087) . 1 ♂ (5.8 mm), Hikurangi Trough , 39° 26.80–27.40′S, 178° 19.99–18.40′E, 1000– 800 m, 16.vi.1990, stn R439 ( NIWA 16707 ) .

Diagnosis: Carapace broader than long, dorsal surface smooth; lateral margin strongly convex posteriorly, anterolateral spine well-developed, directed straight forward or slightly curved mesially. Sternal plastron at least three times wider than long; sternite 3 anterior margin widely and shallowly excavated, with small median notch. Rostrum short, barely reaching or slightly overreaching ocular peduncle. Antennal peduncle unarmed, ultimate and penultimate articles subequal length; antennal scale barely reaching end of antennal article 4. Maxilliped 3 unarmed; ischium with obsolete denticles on mesial ridge. Pereopod 1 (cheliped) slender, 4.8–5.7 times as long as carapace; ischium with stout distodorsal spine; merus and carpus with at least one terminal dorsal spine. Pereopods 2–4 slender; meri and carpi smooth along dorsal margins; carpi long, slightly shorter than propodi on P2–3, much shorter on P4; propodi unarmed; P4 propodus 0.4 times length of P2 propodus; propodus and dactylus subprehensile and subequal in length, gaping when folded, margins bearing plumose setae; flexor margin of dactylus with 9–16 spines nearly perpendicular to margin, all spines obscured by dense setae.

Variation and remarks: Uroptychus scambus Benedict, 1902 is a widespread Indo-West Pacific species and very distinct with its very wide carapace and sternum (wider than high for both characters), short rostrum (at most slightly overreaching the ocular peduncles) and subprehensile and setose propodus and dactylus of the walking legs. The New Zealand Uroptychus scambus closely agree with the description by Kensley (1981) for South African material.

Sexual dimorphism is not only significant with respect to the size of the cheliped palm but also in the height–width ratio of the sternal plastron. Male specimens have a more massive cheliped propodal palm than females (height–width ratio for males: 3.0–3.6; females: 3.7–4.0) and females have a significantly wider sternal plastron than males (height–width ratio for males: 3.2–3.8; females: 6.1–7.5) with the highest height–width ratio in ovigerous females where the sternum is both increased in width and simultaneously reduced in height in large females. This probably enlarges the cavity under the abdomen and may allow the females to support more eggs (female NIWA 10136 carried 14 eggs, each a diameter between 1.22 and 1.59 mm).

The cheliped spination increases with body size, with the cheliped carpus in the largest male ( ZMUC CRU–11506) bearing ten strong spines along its mesial margin. None of the New Zealand specimens had spines along the mesial margin but the largest specimens had a row of up to nine strong granules, progressively diminishing in number and size in smaller specimens. Additionally, large specimens also have two or three terminal spines on the carpus and merus in addition to the strong distodorsal spine.

The small female ( NMNZ Cr 012089) had a small kentrogonid rhizocephalan under its abdomen.

Distribution: East coast of South Africa, Andaman Sea, Nicobar Islands, Indonesia, Japan, New Zealand, and Tasman Sea, 296–2084 m. In New Zealand, U. scambus has been found between 452 and 1129 m ( Fig. 5 ).

Figures

Figure 5. Records of Uroptychodes spinimarginatus (Henderson, 1885), Uroptychus alcocki Ahyong & Poore, 2004, Uroptychus australis (Henderson, 1885), Uroptychus novaezelandiae Borradaile, 1916, Uroptychus maori Borradaile, 1916, Uroptychus politus (Henderson, 1885), Uroptychus scambus Benedict, 1902, and Uroptychus sp. around New Zealand. Solid symbols indicate type records. 250, 1000, and 2500 m bathymetric contours are shown.