Uroptychus maori, BORRADAILE, 1916

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 : 555-559

UROPTYCHUS MAORI BORRADAILE, 1916 ( FIGS 8 , 9 )

Uroptychus maori Borradaile, 1916: 92 , fig. 6 [type locality: off Three Kings Islands , New Zealand, 34° 15.60′S, 174° 6.00′E, 183 m, 25.vii.1911, Terra Nova stn 90].

Type material: HOLOTYPE: ♂ (12.9 mm), off Three Kings Islands , New Zealand, 34° 15.60′S, 174° 6.00′E, 183 m, 25.vii.1911, Terra Nova stn 90 ( BMNH 1917 . 1.29.116).

Other material examined: 2 ♂ (12.0 mm, carapace of second specimen mostly missing), West Norfolk Ridge , 34° 37.20′–37.68′S, 168° 57.03′–58.09′E, 521– 539, 3.vi.2003, RV Tangaroa , stn TAN0308/154 ( NMNZ Cr. 012082) . 1 ♀ ovig. (20.5 mm), 1 ♂ (15.3 mm), Three Kings Ridge , 31° 58.82′S, 174° 15.87′E, 700 m ( NIWA 23133 ) . 1 ♀ ovig. (17.5 mm), 1 ♂ (13.3 mm), Bay of Plenty, 37° 25.39′–25.99′S, 176° 52.99′–54.10′E, 464–631 m, 6.viii.1997 ( NIWA 23134 ) .

Diagnosis: Carapace longer than wide, finely granulated on dorsal surface, unarmed, cervical groove distinct; lateral margin convexly divergent, without spines but finely serrate, distal portion with ridge. Rostrum narrow, triangular, 0.4 times remainder of carapace length. Pterygostomian flap with distinct spine on anterior margin; granulate on surface. Sternal plastron wider than long along midlength, sternum 3 deeply excavate, anteriorly produced to blunt angular point. Abdomen unarmed. Corneal breadth more than half length of ocular peduncle. Antennal peduncle unarmed; article 2 with small distolateral spine; antennal scale reaching midlength or nearly reaching end of ultimate article, width more than 1.5 times that of peduncle. Pereopod 1 (cheliped) with very large curved spine on ventral margin of ischium; merus with row of spines and eminences along ventral margin, covered with small ridges along dorsal surface. Pereopods 2–4 meri and carpi smooth along dorsal margins; propodi without convex flexor margin; with row of spines along less than distal three-quarters, distally paired; dactyli with 11–12 stout triangular spines along entire length; almost perpendicular to flexor margin, slightly decreasing in size proximally, with fringe of plumose setae on extensor margin.

Description of holotype: Carapace: 1.4 times as long as broad (as long as broad excluding rostrum), moderately convex from side to side. Dorsal surface unarmed, finely granulated. Frontal margin deeply excavate, relatively straight; outer orbital angle produced into small spine. Anterolateral margin with well-developed spine, lateral margin convexly divergent posteriorly, unarmed but irregular, with pair of granules on anterior border of branchial lateral margin, posterior margin unarmed. Rostrum narrow, triangular, slightly deflected ventrally, 0.4 times length of remaining carapace; dorsal surface smooth, glabrous, slightly excavate dorsally; lateral margins with fine lateral serration along posterior two-thirds, unarmed. Pterygostomian flap lateral surface slightly granulate, anterior margin produced into a small spine.

Sternum: Sternal plastron 1.2 times as wide as long, lateral extremities subparallel between sternites 5–7. Anterior margin with median notch flanked by pair of submedian spines and deeply excavated, produced anteriorly to blunt, angular point; lateral margins square; surface smooth. Sternite 4 2.5 times as wide as sternite 3, anteriorly deeply V–shaped, anterior midline grooved. Anterolateral margin produced to blunt tooth (not overreaching sternite 3); surface smooth, unarmed.

Abdomen: Tergites smooth and unarmed. Abdominal tergite 1 with ridge at posterior margin. Pleural margins of segments 2–4 distally narrowing to broad triangular point. Telson and tergite 6 1.2 times as broad as long, posterior margin emarginate; two times length of proximal portion.

Eyes: Smooth. Cornea subcylindrical, 0.4 times length of ocular peduncle, reaching distal third of rostrum.

Antennal peduncle: Article 2 with small distolateral spine. Penultimate article unarmed distally. Ultimate article unarmed, 2.3 times as long as penultimate. Antennal scale nearly reaching end of ultimate article; 2.2–2.6 times as long as wide, more than 1.5 times as wide as the peduncle.

Maxilliped 3: surface smooth, unarmed except for two small granules on median portion of merus flexor margin; ischium with 27–30 small denticles; basis with row of larger spines than on ischium.

Pereopod 1: relatively stout, 2.3 (right) and 3.1 (left) times as long as carapace (including rostrum), surface glabrous on carpus and propodus. Ischium with disto-dorsal and disto-ventral spines (dorsal spine very large and curved). Merus surface with rows of granules, ventral row of eminences and round spines, with two small ventral spines distally. Carpus surface smooth, with two ventral spines distally (small and blunt), carpus 0.6–0.7 times as long as palm. Propodus with palm 2.1–2.2 times as long as high, unarmed. Dactylus 0.3–0.4 times as long as propodus, occlusal margins slightly or not gaping, denticulate.

Pereopods 2–4: decreasing in length posteriorly, surface slightly setose and unarmed. Merus dorsal margin unarmed; 1.2–0.9 times as long as propodus (merus shortening from P2 to P4). Carpus, dorsal margin unarmed, 0.6 (P2) to 0.5 (P4) times propodal length. Propodus 2.2 times as long as dactylus, extensor margin smooth; flexor margin with spines along 0.7–0.4 length of margin (from P2 to P4); with 7 to 10 spines. Dactylus gently curved; flexor margin with 11–12 spines along entire length; stout triangular, subequal, slightly decreasing in size proximally; fringe of plumose setae along the extensor margin.

Ovum : 1.4–2.7 mm.

Variation: The additional material examined can unequivocally be identified as Uroptychus maori . Examination of many specimens reveals that the bilateral asymmetry of the chelipeds and the antennal scale as illustrated by Borradaile (1916) is unusual. The left cheliped is considerably larger than the right in the male holotype but subequal in all other specimens except for the male from NIWA 23134 where the left cheliped is smaller than the right. The left antennal scale is shorter and narrow triangular in the holotype but examination of the material shows that the more common form is the larger scale of the right scale of the holotype: nearly reaching the end of the peduncle, rounded and at least 1.5 times as wide as the peduncle. The asymmetries can probably be attributed to regrowth of a lost appendage.

Notes on variation from the holotype are as follows: the granulation and spination of the ischium and merus of the cheliped are more pronounced in large specimens with two large spines along the ventral margin of the merus. The rostrum of the male from NIWA 23134 is stunted, shorter than the ocular peduncle. Females appear larger than males (females’ carapace length range: 17.5–20.5 mm, mean: 19.0 mm; males from 12.0– 15.3 mm, mean: 13.4). The propodal palm is more massive in females with a height–width ratio of 2.2–2.6 for males and 3.3–3.5 for females (holotype male is 2.1–2.2). Large specimens have up to 14 inclined spines along the flexor margin of the propodus of the walking legs.

Remarks: Uroptychus maori Borradaile, 1916 most closely resembles the species with denticulate lateral carapace margins and massive chelipeds: Uroptychus brucei Baba, 1986 , Uroptychus litosus Ahyong & Poore, 2004 , and Uroptychus nitidus occidentalis Faxon, 1893 . Uroptychus maori differs from Uroptychus brucei in having the rostrum not deeply excavate, the absence of spines on antennal article 4 where Uroptychus brucei bears a distal spine, Uroptychus maori has spines on P2 propodus along less than three-quarters of length of flexor margin, Uroptychus brucei has spines along the entire flexor margin of the propodus, the anterior margin of sternite 3 is angular in Uroptychus maori whereas produced to spines in Uroptychus brucei . Uroptychus maori differs from Uroptychus litosus in the shape of the carapace, with Uroptychus litosus lateral margins distinctly convex posteriorly whereas Uroptychus maori has more subparallel lateral margins; Uroptychus maori has a finely granulated dorsal carapace surface where the carapace is smooth in Uroptychus litosus ; very strong anterolateral spines, distinctly overreaching the outer orbital spine (the anterolateral spine only slightly overreaches the outer orbital spine in Uroptychus litosus ); the anterior margin of sternite 4 is rounded and entire (laterally serrated and with strong anterior spine in Uroptychus litosus ) and Uroptychus maori has a more elongate cheliped (ratio of cheliped length to carapace length for Uroptychus maori 2.8–3.5 for the longer cheliped and Uroptychus litosus approximately 2). Uroptychus maori differs from Uroptychus nitidus occidentalis in the fine granulation of the carapace surface (the latter having a smooth surface), in the shape of anterior margin of sternite 3 (medially produced angular margin and overreaching lateral angle in Uroptychus maori and laterally produced to spine, overreaching medial angle in Uroptychus nitidus occidentalis ); in the relative length of the articles of the antennal peduncle (in Uroptychus maori , the ultimate article is 2.3 times as long as the penultimate, whereas in Uroptychus nitidus occidentalis , the two are subequal).

Uroptychus maori also differs from all the above species by the extremely large and curved spine on the distodorsal margin of the ischium of the cheliped and the presence of plumose setae on the extensor margin of the dactyli of the walking legs.

Of all closely allied species, the distribution range of Uroptychus maori is most proximate to Uroptychus litosus (known from Tasmania). Uroptychus brucei has only been recorded from north-western Australia and Uroptychus nitidus has a known Atlantic and north-western Pacific distribution range.

Distribution: Three Kings Islands north of the North Island of New Zealand from a depth of 183 m (type locality) and now from the West Norfolk Ridge, the Three Kings Ridge, and the Bay of Plenty ( Fig. 5 ); 183– 700 m.

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.

Figure 8. Uroptychus maori Borradaile, 1916, holotype, ♂, BMNH 1917.1.29.116: A, carapace and abdomen, dorsal, setae omitted; B, carapace and abdomen, lateral, setae omitted; C, sternal plastron; D, telson, setae omitted; E, left cheliped, dorsal; F, right cheliped, dorsal; G, left cheliped, ischium and merus, lateral; H–J, right pereopods 2–4; K, dactylus and distal portion of propodus of right pereopod 3, lateral. Scale bars = 2 mm.

Figure 9. Uroptychus maori Borradaile, 1916, holotype, ♂, BMNH 1917.1.29.116. A, antenna, right, ventral; B, antenna, left, ventral; C, endopod of third maxilliped, right, lateral, setae omitted; D, mesial ridge, right. Scale bars = 2 mm.