Uroptychus paku, Schnabel, 2009

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 : 562-564

UROPTYCHUS PAKU SP. NOV. ( FIG. 12 )

Type material: HOLOTYPE: ♀ (3.1 mm), Esperance Rock, Kermadec Ridge, 32° 11.10′S, 179° 05.20′W, 122–307 m, 6.iv.1998 ( NIWA 9805 ).

Diagnosis: Carapace more than 1.5 times longer than broad; lateral carapace margins subparallel, with five spines (excluding anterolateral spine); dorsal surface with three small epigastric spines, two submedian spines on anterior cardiac margin, and one pair of posterior branchial spines. Sternal plastron slightly longer than broad. Antennal peduncle with distal spines on ultimate and penultimate articles; antennal scale reaching end of peduncle. Sternite 3 with median notch flanked by submedian spines; sternite 4 produced to spines on anterolateral corner. Pereopod 1 (cheliped) with one small distodorsal and ventral spine; rows of spines on merus and carpus, palm smooth. Pereopods 2–4 with spines on dorsal crest of merus and carpus; propodus with terminal pair of spines only; dactyli slender and elongate, with rows of slender inclined spines, loosely arranged, penultimate spine more than twice as broad as antepenultimate spine.

Description of holotype: Carapace: 1.7 times as long as broad (0.9 excluding rostrum) shallowly convex from side to side. Dorsal surface smooth; cervical groove indistinct (faintly indicated); gastric region with three small spines; cardiac region with pair of small spines on anterior margin; posterior branchial region with pair of large spines (right spine with additional small lateral spine). Frontal margin deeply excavate. Outer orbital angle produced into small spine. Anterolateral margin with well-developed spine; lateral margins subparallel, with five spines excluding anterolateral spine: one hepatic, one anterior branchial region, three posterior branchial spines on lateral margin, posterior-most spine largest (excluding anterolateral spine). Posterior margin unarmed. Rostrum narrow triangular, slightly deflected ventrally, 0.9 times length of remaining carapace; dorsal surface slightly excavate; lateral margins with two or three spines and with fine lateral serration along posterior portion. Pterygostomian flap lateral surface smooth, anterior margin narrow triangular and produced to spine.

Sternum: sternal plastron 0.9 times as wide as long, lateral extremities subparallel between sternites 5–7; surface smooth, unarmed. Anterior margin of sternite 3 acutely produced anteriorly, with median notch flanked by pair of submedian spines; lateral margin produced to acute tooth. Sternite 4 2.2 times as wide as sternite 3, anterior margin shallowly concave, anterior midline grooved; anterolateral margin produced to tooth (not overreaching sternite 3).

Abdomen: tergites smooth and unarmed. First abdominal tergite with transverse ridge; tergite 2 with anterior ridge. Second pleural margin anteriorly produced to narrow angle. Telson and tergite 6 two times as broad as long; posterior portion 1.3 times length of anterior portion.

Eyes: cornea subglobular, 0.2 times length of ocular peduncle, nearly reaching distal quarter of rostrum.

Antennal peduncle: article 2 with acute outer spine. Penultimate and ultimate article with distal spine. Ultimate article 2.5–2.6 times as long as penultimate. Antennal scale slightly overreaching peduncle; 4.7– 5.0 times as long as wide.

Maxilliped 3: surface smooth, ischium unarmed. Merus extensor margin with well-developed distal spine with accompanying small spine proximal to it; flexor margin with one median spine and with distal spine. Carpus with proximal spine on extensor margin and long distal spine.

Pereopod 1: slender, 2.8 times as long as carapace, surface with scattered long setae. Ischium with dorsal and ventral spines distally. Merus surface with three rows of spines, with five or six distal spines. Carpus with three rows of spines and with three distal spines, length 1.3–1.4 times that of palm. Propodus with palm 3.3–3.7 times as long as high, unarmed. Dactylus 0.6 times as long as propodus; occlusal margins not gaping, denticulate.

Pereopods 2–4: similar (meri slightly shortening and reduction in spination from P2–4). Merus dorsal margin with five to seven spines on dorsal crest (including one to two distal spines); ventral margin with distal spine only; length 0.7–0.9 times that of propodus. Carpus, dorsal margin with three to five spines (including distal spine); ventral margin without spines. Propodus 1.3–1.4 times as long as dactylus, extensor margin smooth; flexor margin with only distal pair of spines. Dactylus straight and slender; flexor margin with ultimate spine slender, penultimate spine broad triangular and prominent, preceded by six to seven slender inclined spines along entire length.

Variation and remarks: Uroptychus paku sp. nov. belongs to the group of species in the genus with spines along the lateral carapace margin and on the dorsal surface (not restricted to the epigastric region) and P2–4 dactyli with pronouncedly broad penultimate spine preceded by slender inclined spines on the flexor margin. Uroptychus paku is closely allied to Uroptychus sexspinosus Balss, 1913 and Uroptychus fusimanus Alcock & Anderson, 1899 but differs from both in dorsal carapace ornamentation and rostrum. Uroptychus sexspinosus has six lateral carapace spines and a number of equally sized spines on the epigastric, hepatic, cardiac, and branchial regions. In contrast, Uroptychus paku has five spines on the lateral carapace margin and only eight dorsal spines (the paired branchial spines being much larger than the remaining spines). Furthermore, the rostrum in Uroptychus sexspinosus is half the length of the remaining carapace, whereas the rostrum of Uroptychus paku is nearly as long as the remaining carapace. Uroptychus fusimanus differs from Uroptychus paku in having the dorsal carapace surface with many spines in more or less distinct rows, seven spines along the convex lateral carapace margin (see above for Uroptychus paku ), rostrum simple (distally serrated in Uroptychus paku ) and shorter than half length of remaining carapace (nearly as long as carapace in Uroptychus paku ), P2–4 meri and carpi unarmed (dorsally furnished with strong spines in Uroptychus paku ).

Neither of these species have a distribution that is close to Uroptychus paku ; Uroptychus sexspinosus is known from Japan and Uroptychus fusimanus is known from India.

Distribution: North of L’Esperance Island, Kermadec Islands, 122–307 m ( Fig. 7 ).

Etymology: Paku is the Māori word for small or tiny, a reference to the small size of the specimen.

Figures

Figure 7. Records of Uroptychus kaitara sp. nov., Uroptychus paku sp. nov., Uroptychus rutua sp. nov., Uroptychus toka sp. nov., Uroptychus webberi sp. nov., and Uroptychus yaldwyni sp. nov. around the Kermadec Islands, New Zealand. 250, 1000, and 2500 m bathymetric contours are shown.

Figure 12. Uroptychus paku sp. nov., holotype, ♀, NIWA 9805: A, carapace and abdomen, dorsal, setae omitted; B, carapace and abdomen, lateral, setae omitted; C, sternal plastron; D, telson, setae omitted; E, antenna, right, ventral; F, endopod of third maxilliped, left, lateral, setae omitted; G, right cheliped, dorsal, setae omitted; H–J, right pereopods 2–4; K, dactylus and distal portion of propodus of right pereopod 3, lateral. Scale bars = 1 mm.