Uroptychus maori Borradaile, 1916

Baba, Keiji, 2018, Chirostylidae of the Western and Central Pacific: Uroptychus and a new genus (Crustacea: Decapoda: Anomura), Tropical Deep-Sea Benthos (Mémoires du Muséum national d'Histoire naturelle 212), pp. 1-612 : 297-300

Uroptychus maori Borradaile, 1916

Figures 139 , 140

Uroptychus maori Borradaile, 1916: 92 , fig. 6. — Schnabel 2009: 555 , figs 8, 9.

TYPE MATERIAL — Holotype: New Zealand, off Three Kings Islands , 34°15.60’S, 174° 6.00’E, 183 m, male ( BMNH 1917.1.29.116 ). [not examined].

MATERIAL EXAMINED — New Caledonia, Norfolk Ridge. BIOCAL Stn CP52, 23°06’S, 167°47’E, 540-600 m, 31.VIII.1985, 1 ov. ♀ 11.3 mm (MNHN-IU-2014-16720), 1 ♂ 8.2 mm (MNHN-IU-2014-16721) . New Caledonia, Loyalty Ridge. BERYX 2 Stn CH 16, 23°35.60’S, 169°36.52’E, 660- 675 m, 29.X.1991, 1 ov. ♀ 12.9 mm (MNHN-IU-2014-16722) . HALIPRO 1 Stn CH 872, 23°02’S, 166°52’E, 620-700 m, 30.III.1994, 1 ♂ 8.1 mm ( MNHN- IU-2014-16723) . New Caledonia, Hunter and Matthew Islands.VOLSMAR Stn DW05, 22°26’S, 171°46’E, 620-700 m, 01.VI.1989, 1 ♂ 7.6 mm, 1 ov. ♀ 11.2 mm (MNHN-IU-2014-16724) .

DISTRIBUTION„ New Zealand (Three Kings Islands, West Norfolk Ridge, and Bay of Plenty), 183-700 m; and now Loyalty Ridge, Hunter-Matthew and Norfolk Ridge; 540- 700 m.

SIZE„ Males 7.6-8.2 mm; females, 11.2-12.9 mm; ovigerous females from 11.2 mm.

DESCRIPTION„ Large species. Carapace: As long as broad; greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface granulose, somewhat convex from anterior to posterior, with distinct depression between gastric and cardiac regions. Lateral margins somewhat divergent posteriorly, slightly convex on both anterior and posterior branchial regions, with elevated ridge at anterior end of branchial region, ridged near posterior end; anterolateral spine well developed, overreaching much smaller lateral orbital spine, situated slightly posterior to and separated from that spine by basal breadth. Rostrum relatively broad triangular, with interior angle of 30-35°; about as long as broad; length 0.3- 0.4 × postorbital carapace length, breadth less than half carapace breadth at posterior carapace margin; dorsal surface concave. Pterygostomian flap granulose, anteriorly angular, acuminate at tip or ending in tiny spine.

Sternum: Excavated sternum anteriorly produced to small sharp spine, surface with weak ridge in midline. Sternal plastron as long as or slightly shorter than broad; lateral extremities gently divergent posteriorly. Sternite 3 well depressed; anterior margin of broad V-shape with 2 incurved submedian spines separated by narrow U-shaped sinus, laterally angular. Sternite 4 with anterolateral margin smooth, slightly convex, anteriorly subtriangular, 1.5 × longer than posterolateral margin. Anterolateral margin of sternite 5 1.2-1.3 × longer than posterolateral margin of sternite 4.

Abdomen: Somite 1 moderately convex from anterior to posterior. Somite 2 tergite 2.5-2.8 × broader than long; pleuron posterolaterally tapering, lateral margin concavely divergent. Pleuron of somite 3 tapering. Telson about half as long as broad; posterior plate 1.3-1.9 × longer than anterior plate, emarginate on posterior margin.

Eye: 2.0-2.2 × longer than broad, reaching or overreaching anterior quarter of rostrum; lateral and mesial margins subparallel or slightly concave. Cornea more than half as long as remaining eyestalk.

Antennule and antenna: Antennular ultimate article 2.4-3.0 × longer than high. Antennal peduncle slightly overreaching cornea, barely reaching rostral tip. Article 2 with distolateral spine usually small, occasionally tiny and discernible only under high magnification. Antennal scale 1.6-1.9 × broader than article 5, overreaching midlength of but barely reaching distal end of article 5. Article 4 with short blunt distomesial spine. Article 5 unarmed, length 1.9-2.1 × that of article 4, breadth 0.4-0.5 × height of antennular ultimate article. Flagellum of 22-24 segments varying from barely reaching to overreaching distal end of P1 merus.

Mxp: Mxp1 with bases close to each other. Mxp3 basis with a few denticles on mesial ridge. Ischium half as long as merus, crista dentata with 28-40 denticles, flexor margin not rounded distally. Merus 2.0 × longer than ischium, sharply ridged along flexor margin without distinct spines but a number of very small tubercles or granules; with no distolateral spine. Carpus unarmed.

P1: Length 4.2-5.0 × that of carapace; ventrally granulated on merus and carpus, tuberculate on merus in large specimens, setose on fingers. Ischium with strong dorsal spine, ventromesially with well-developed subterminal spine proximally followed by tubercles. Merus varying from slightly shorter to slightly longer than carapace, mesially with tubercles or small spines, ventrally with a few spines in line with subterminal spine of ischium, median one usually larger. Carpus 1.2-1.3 × length of merus. Palm 2.4-3.5 × longer than broad, as long as or slightly shorter than carpus; lateral and mesial margins not carinated but rounded. Fingers not gaping, distally incurved, crossing when closed; movable finger with 2-toothed broad process on proximal half of opposable margin, proximal one smaller; length 0.4-0.5 × that of palm; opposable margin of fixed finger with low prominence at distal third and low processes at midlength.

P2-4: Relatively thick mesio-laterally, very sparsely setose except for distal 2 articles. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8 × length of P3 merus), subequally broad on P2-4; length-breadth ratio, 5.0-5.7 on P2, 4.1-5.3 on P3, 3.4-4.3 on P4; dorsal margin with row of denticle-like very small spines distinct at most on proximal half on P2, obsolescent on P3, absent on P4; P2 merus 0.8-0.9 × length of carapace, 1.3-1.4 × length of P2 propodus; P3 merus 1.1 × length of P3 propodus; P4 merus 0.9 × length of P4 propodus. Carpi successively slightly shorter posteriorly or P3 and P4 carpi subequal; carpus-propodus length ratio, 0.5-0.6 on P2, 0.4-0.5 on P3 and P4. Propodi subequal on P3 and P4, shortest on 2; flexor margin straight, ending in pair of spines preceded by 9-12 spines on P2, 6-10 on P3, 6-8 on P4. Dactyli slightly longer on P3 and P4 than on P2, slightly shorter than carpi (dactylus-carpus length ratio, 0.7-0.8 on P2, 0.8-0.9 on P3, 0.9-1.0 on P4), dactylus-propodus length ratio, 0.4 on P2 and P3, 0.4-0.5 on P4; flexor margin curving at proximal third, with 11 or 12 sharp triangular, loosely arranged, slightly obliquely directed, proximally diminishing spines on P2 and P3, 10-13 spines on P4, distal 3 subequal; extensor margin with plumose setae at least on median third.

Eggs. Number of eggs carried, 12-20; size, 1.16 mm × 1.26 mm - 2.05 mm × 1.84 mm.

REMARKS — The present specimens agree well with the species account of Schnabel (2009), except that the rostrum is short relative to breadth (length-breadth ratio, 1.1 versus 1.4), and the pterygostomian flap is anteriorly acuminate or ends in a tiny spine rather than being produced to a distinct spine.

This species resembles U. brachydactylus Tirmizi, 1964 , U. brucei Baba, 1986a and U. granulipes n. sp. in the carapace shape and the spination of P2-4. Uroptychus maori is readily distinguished from U. brachydactylus by the P1 ischium that bears a strong subterminal spine instead of being unarmed; the P1 palm is not carinated along the mesial margin; the P2-4 dactyli are longer relative to the propodi, the dactylus-propodus length ratio being 0.40-0.44 on P2, 0.43-0.45 on P3, 0.40-0.47 on P4, instead of 0.27-0.30 on P2-4. Uroptychus maori looks much closer to U. brucei and U. granulipes than to U. brachydactylus . Their differences are very slight but this new species may be differentiated from U. brucei by the following: the anterolateral spine of the carapace is closer to the lateral orbital spine than in U. brucei in which it is separated by twice its basal breadth when viewed from dorsal side; the P1 merus and carpus are granulose instead of smooth on the dorsal surface in large specimens; the palm has the mesial margin rounded instead of sharply ridged; the antennal article 4 bears a small blunt distoventral process rather than a distinct spine, and article 5 is unarmed instead of bearing a distinct distomesial spine; the antennal article 2 bears a tiny instead of a distinct lateral spine; and the P2-4 dactyli are relatively long, the dactylus-carpus length ratio being 0.7-0.8 on P2, 0.8-0.9 on P3, 0.9-1.0 on P4, instead of 0.6 on P2 and P3, 0.7 on P4. Differences between U. maori and U. granulipes are discussed under the latter species (see above).

Figures

FIGURE 139 Uroptychus maori Borradaile, 1916, ovigerous female 11.3 mm (MNHN-IU-2014-16720). A, carapace and anterior part of abdomen, proximal part of left P1 included, dorsal. B, same, lateral. C sternal plastron, with excavated sternum and basal parts of Mxp1.D, telson. E, left antenna,ventral.F, left Mxp3, ventral.G, same,lateral.H, left P1, proximal part,ventral.I, same, proximal part omitted, dorsal.Scale bars: A,B,H, I, 5 mm; C-G,1 mm.

FIGURE 140 Uroptychus maori Borradaile,1916,ovigerous female 11.3 mm (MNHN-IU-2014-16720).A, right P2,lateral.B,same,distal part,setae omitted, lateral.C, left P3,setae omitted,lateral. D, left P4,setae omitted, lateral. Scale bars: 1 mm.