Uroptychus yaldwyni, 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 : 575-578

UROPTYCHUS YALDWYNI SP. NOV. ( FIG. 18 )

Type material: HOLOTYPE: ♀ ovig. (4.2 mm), Macaulay Island , Kermadec Ridge, 30° 17.59′S, 178° 25.30′W, 398–412 m, 28.vii.1974, stn NZOI K840 ( NMNZ Cr. 012098).

Diagnosis: Carapace slightly longer than broad; strong anterolateral spine; lateral margin widening posteriorly, with seven or eight spines, one spine in branchial region, six or seven spines in posterior branchial region, unarmed in lateral hepatic region; dorsal surface unarmed, anterior cardiac region inflated, smooth. Sternal plastron slightly wider than long along midlength, sternite 3 medially produced to acute angular point at anterior margin, U-shaped median notch with pair of submedian spines. Maxilliped 3 unarmed. Pereopod 1 (cheliped) more than four times as long as carapace, ischium with distodorsal spine; with palm 4.5 times as long as broad. Pereopods 2–4 meri and carpi smooth along dorsal margin; propodi with pair of distal spines only; dactyli with six spines (excluding ultimate), perpendicular and loosely arranged along flexor margin, penultimate spine approximately twice as wide as ultimate, penultimate spine subequal to antepenultimate.

Description of holotype: Carapace: 1.2 times as long as broad (0.8 without rostrum), moderately convex from side to side. Dorsal surface sparsely setose and unarmed; cervical groove medially deep and distinct; postcervical region slightly inflated towards the anterior portion. Frontal margin deeply excavate. Outer orbital angle produced to a sharp tooth, falling short of anterolateral spine. Anterolateral margin with well-developed spine, directed slightly dorsad; lateral margin subparallel, slightly wider posteriorly (widest in posterior three-quarters), with seven or eight small and inclined spines (excluding anterolateral spine). One spine in anterior branchial region, six or seven lateral spines in posterior branchial region. Posterior margin unarmed. Rostrum triangular, horizontal, 0.4 times length of remaining carapace; dorsal surface slightly excavate; lateral margins smooth. Pterygostomian flap lateral surface covered with small spines and with a row of spines along dorsal margin, anterior margin produced into a sharp spine, directed slightly dorsad.

Sternum: sternal plastron 1.3 times as wide as long, lateral extremities subparallel between sternites 5–7, surface smooth. Anterior margin of sternite 3 acutely produced medially, with median U-shaped notch flanked with pair of submedian spines. Lateral margins rounded. Sternite 4 2.1 times as wide as sternite 3, anteriorly shallowly concave; anterolateral margin narrow triangular, reaching midlength of sternite 3.

Abdomen: tergites covered with short, fine, scattered setae, tergites without transverse ridges or grooves. Pleural margins of segments 2–4 rounded (margin of segment 2 slightly concave). Telson and tergite 6 2.2 times as broad as long; posterior portions 1.3 times length of anterior portion, posterior margin moderately emarginate.

Eyes: cornea subglobular, slightly tapering distally; 0.3 times length of ocular peduncle, nearly reaching end of rostrum.

Antennal peduncle: article 2 with blunt but distinct outer spine. Penultimate article with distal spine. Ultimate article unarmed, 1.2 times as long as penultimate. Antennal scale slightly overreaching penultimate article, 3.5 times as long as wide.

Maxilliped 3: surface smooth, ischium without distal spines, very small teeth on mesial ridge, no teeth on basis. Maxilliped otherwise unarmed.

Pereopod 1: very slender, 4.2 times as long as carapace, surface moderately setose. Ischium with dorsal distal spine. Merus and carpus surfaces smooth and unarmed; carpus 1.1 times as long as palm. Propodus with palm 4.6–5.1 times as long as high, unarmed. Dactylus 0.4 times as long as palm, occlusal margins not gaping, denticulate.

Pereopods 2–4: similar (slightly decreasing in length posteriorly); surfaces setose. Merus unarmed, 1.1–0.9 times as long as propodus (meri subequal, propodi increasing in length posteriorly). Carpus unarmed. Propodus about two times as long as dactylus, extensor margin smooth; flexor margin with only distal pair of spines. Dactylus straight; flexor margin with six spines along distal two-thirds of flexor margin; ultimate small, penultimate largest, preceded by successively diminishing, loosely arranged spines perpendicular to margin.

Ovum : 0.6–0.7 mm.

Remarks: Uroptychus yaldwyni sp. nov. belongs to the group of small-bodied species with spines or granules on lateral carapace margin, unarmed dorsal carapace surface, sternite 3 with median notch, P2–4 dactylar spines loosely arranged, and penultimate spine not extremely broad. Uroptychus yaldwyni is most closely related to Uroptychus altus Baba, 2005 , Uroptychus paenultimus Baba, 2005 , and Uroptychus wolffi Baba, 2005 . It can be distinguished from these three species by the presence of six or seven small, slender spines on the lateral branchial margin of the carapace with an additional small spine on the anterior border of the anterior branchial region, a very strong anterolateral spine, nearly level with the dorsal margin of the ocular peduncle, a distinct cervical groove, distinct ridge along proximal third of lateral carapace margin, unarmed maxilliped 3, and dactylar spination of the walking legs: Uroptychus yaldwyni has four large triangular spines proximal to two distal spines, directed perpendicular to the flexor margin, whereas U. altus , U. paenultimus , and U. wolffi have three, eight to nine, and six slender and inclined spines proximal to two distal spines, respectively. Additionally, the cheliped is more slender and elongate in Uroptychus yaldwyni (4.2 times as long as carapace, palm greater than 4.5 times as long as broad; in Uroptychus altus the cheliped is 2.7 times as long as carapace, palm 1.9 times as long as broad; in Uroptychus paenultimus , the cheliped is three times as long as carapace, the palm is three times as broad as long; in Uroptychus wolffi the cheliped is 3.3 times as long as the carapace, the palm is three times as broad as long).

Uroptychus yaldwyni is also very similar to Uroptychus amabilis Baba, 1979 in carapace shape and size. Uroptychus amabilis , however, does not bear spines along the lateral carapace margin, has spines on the mesial ridge of the maxilliped 3, a distal spine on the distal antennal article, the antennal scale nearly reaching the end of the antennal peduncle, and the dactyli of the walking legs shorter than half length of the propodi.

All legs of the holotype are detached.

The record for Uroptychus yaldwyni is closest to the known distribution of Uroptychus amabilis from New Caledonia. All others, Uroptychus altus , Uroptychus wolffi , and Uroptychus paenultimus have only been recorded from the Kei Islands, Indonesia.

Distribution: Macauley Island, Kermadec Islands, 398–412 m ( Fig. 7 ).

Etymology: Named in honour of the late Dr John C. Yaldwyn (1929–2006), recognizing his contributions to the knowledge of New Zealand decapod crustacean research.

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 18. Uroptychus yaldwyni sp. nov., holotype, ♀ ovig., NMNZ Cr. 012098: A, carapace and abdomen dorsal, setae omitted; B, carapace and abdomen, lateral, setae omitted; C, sternal plastron; D, telson, setae omitted; E, antenna, left, ventral; F, endopod of third maxilliped, right, lateral, setae omitted. G, mesial ridge, right; H, right cheliped, dorsal; I–K, right pereopods 2–4. Scale bars = 2 mm.