Uroptychus poupini, Baba, 2018

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 : 422-429

Uroptychus poupini n. sp.

Figures 210 , 211 , 214E-H

TYPE MATERIAL — Holotype: Fiji Islands. BORDAU 1 Stn CP1444, 17°11’S, 178°41’W, 398-409 m, 3.III.1999, 1 ♂ 6.7 mm ( MNHN-IU-2014-16867 ) . Paratypes: Fiji Islands. MUSORSTOM 10 Stn CP1317, 17°11.99’S, 178°14.14’E, 471-475 m, 5.VIII.1998, 1 ♂ 9.2 mm (MNHN-IU-2014-16868) . – Stn CP1327, 17°13,26’S, 177°51,62’E, 370-389 m, 7.VIII.1998, 2 ♂ 8.5, 8.7 mm, 7 ov. ♀ 6.5-8.8 mm (MNHN-IU-2014-10145, MNHN-IU-2014-10146, MNHN-IU-2014-16869) . – Stn CP1360, 17°59,57’S, 178°48,20’E, 402-444 m, 13.VIII.1998, 1 ♂ 7.1 mm, 1 ♀ 5.0 mm (MNHN-IU-2014-16870) . BORDAU 1 Stn CP1411, 16°05’S, 179°28’W, 390-403 m, 26.II.1999, 3 ♂ 4.8-7.3 mm, 3 ov. ♀ 5.8-6.9 mm (MNHN-IU-2014-16871) . – Stn CP1412, 16°06’S, 179°28’W, 400-407 m, 26.II.1999, 1 ♂ 5.2 mm, 1 ov. ♀ 7.7 mm, 1 ♀ 6.1 mm (MNHN-IU-2014-16872) . – Stn CP1434, 17°11’S, 178°41’W, 400-401 m, 2.III.1999, 1 ♂ 6.9 mm (MNHN-IU-2014-16873) . – Stn CP1467, 18°12’S, 178°36’W, 417-427 m, 6.III.1999, 1 ♂ 7.1 mm, 1 ov. ♀ 7.3 mm (MNHN-IU-2014-16874) . – Stn CP1468, 18°16’S, 178°41’W, 478-500 m, 7.III.1999, 2 ♂ 4.9, 6.0 mm, 1 ov. ♀ 6.8 mm, 2 ♀ 5.8, 7.0 mm (MNHN-IU-2014-16875) . – Stn DW1421, 17°08’S, 178°59’W, 403-406 m, 28.II.1999, 1 ♂ 3.8 mm, 1 ov. ♀ 6.0 mm, 1 ♀ 4.9 mm (MNHN-IU-2014-16876) . – Stn DW1469, 19°40’S, 178°10’W, 314-377 m, 8.III.1999, 1 ♂ 6.7 mm (MNHN-IU-2014-16877) . – Stn CP1493, 18°43’S, 178°24’W, 429-440 m, 11.III.1999, 1 ♂ 8.7 mm, 1 ♀ 5.0 mm (MNHN-IU-2014-16878) . Tonga. BORDAU 2 Stn CP1592, 19°08’S, 174°17’W, 391-426 m, 14.VI.2000, 1 ov. ♀ 6.8 mm (MNHN-IU-2014-16879) . – Stn CH 1596, 19°06’S, 174°18’N, 371-437 m, 14.VI.2000, 1 ♂ 7.9 mm, 2 ov. ♀ 7.4, 8.7 mm (MNHN-IU-2014-16880) . – Stn DW1633, 22°59’S, 175°35’W, 442-453 m, 20.VI.2000, 1 ♂ 6.3 mm, 1 ♀ 6.7 mm (MNHN-IU-2014-16881) . New Caledonia. BATHUS 1 CP658, 21°13’S, 165°55’E, 515-580 m, 12.III.1993, 1 ♂ 4.3 mm, 1 ov. ♀ 5.8 mm, 1 ♀ 6.3 mm (MNHN-IU-2014-16882) . MUSORSTOM 4 Stn CP236, 22°11.3’S, 167°15.0’E, 495-550 m, 2.X.1985, 1 ♀ 6.5 mm (MNHN-IU-2014-16883) .

ETYMOLOGY„ Named for Joseph Poupin for his friendship and for the inspiration he provided to me with specimens he collected.

DISTRIBUTION„ Fiji Islands, Tonga, and New Caledonia, in 314- 580 m.

SIZE„ Males 3.8-9.2 mm; females, 4.9-8.8 mm; ovigerous females from 5.8 mm.

DESCRIPTION„ Medium-sized species. Carapace: 1.0-1.1 × longer than broad; greatest breadth 1.3-1.4 × distance between anterolateral spines. Dorsal surface somewhat depressed between indistinct gastric and cardiac regions; epigastric region with small median spine directly behind rostrum and 2 small spines behind each eye (lateral of these occasionally obsolescent). Lateral margins with row of spines: anterolateral spine well-developed, slightly overreaching smaller lateral orbital spine, occasionally followed by small spine on hepatic margin; spine at anterior end of anterior branchial region largest, with accompanying small spine mesial to it; spine at anterior end of posterior branchial region usually smaller than preceding pronounced spine, rarely about as large as anterolateral spine or reduced to small size, occasionally preceded by 1 or 2 small spines, followed by 3 or 4 posteriorly diminishing spines. Rostrum sharp triangular, with interior angle of 32-35°; dorsal surface concave; lateral margin with a few very tiny denticle-like spines; length half or slightly less than half that of remaining carapace; breadth about half carapace breadth at posterior carapace margin. Pterygostomian flap anteriorly roundish with tiny spine.

Sternum: Excavated sternum anteriorly produced to sharp spine, surface with small central process. Sternal plastron as long as or slightly shorter than broad, lateral extremities divergent posteriorly. Sternite 3 strongly depressed, anterior margin deeply excavated, with 2 well-developed submedian spines separated usually by deep narrow notch, occasionally by shallow notch; laterally angular or rounded. Sternite 4 with left and right anterolateral ends each produced to acute spine directed somewhat laterally or straight forward, anterolateral margin relatively long, about twice length of posterolateral margin, 0.63-0.74 × distance between anteriorly produced left and right spines. Anterolateral margin of sternite 5 1.4- 1.5 × longer than posterolateral margin of sternite 4.

Abdomen: Somite 1 without transverse ridge; somite 2 tergite 2.1-2.5 × broader than long; pleuron tapering to sharp or bluntly angular tip, lateral margin strongly concave and strongly divergent posteriorly. Pleuron of somite 3 posterolaterally moderately angular. Telson 0.6-0.7 × as long as broad; posterior plate slightly or distinctly emarginate on posterior margin, length 1.3-2.0 × that of anterior plate (greater in small specimens).

Eye elongate, 2 × longer than broad, barely or fully reaching apex of rostrum, mesial margin concave, cornea moderately dilated, half as long as remaining eyestalk. Antennule and antenna: Ultimate article of antennular peduncle 1.9-2.3 × longer than high. Antennal peduncle slender, not reaching distal end of cornea; article 2 with very small lateral spine; antennal scale barely or fully reaching distal end of article 5, breadth 1.9-2.0 × that of article 5; article 4 without spine; article 5 with ventral distomesial spine of very small to good size, about 3 × longer than article 4, breadth 0.4 × height of ultimate article of antennule; flagellum consisting of 14-22 segments (fewer in small specimens), barely reaching distal end of P1 merus.

Mxps: Mxp1 with bases nearly contiguous. Mxp3 basis with 1 or 2 denticles on mesial ridge. Ischium with flexor margin not rounded distally, crista dentata with 19-28 denticles. Merus 2.0-2.2 × longer than ischium, well ridged along flexor margin; merus and carpus each with very small distolateral spine.

P1: Moderately massive in large males, slender in females and small males, length 5.2-5.5 × that of carapace length in both sexes; granulate on ventral surface of merus and carpus in large males, less so in large females. Ischium with strong, curved dorsal spine, ventromesially with no submedian spine. Merus and carpus with small lateral and mesial distoventral spines; merus 1.2-1.4 × longer than carapace. Carpus 1.2-1.3 × longer than merus. Palm 2.3-3.3 × (males), 2.6-4.3 × (females) longer than broad; usually smooth on ventrolateral margin but a row of tubercles or very small spines continued on to fixed finger in large males and occasionally in large females; length 0.8-0.9 × that of carpus. Fingers gaping somewhat in proximal half, moderately in proximal third or strongly in proximal two-thirds, distally incurved, crossing when closed; movable finger about half or slightly more than half as long as palm, opposable margin with pronounced proximal process.

P2-4: Very slender, compressed mesio-laterally, with long setae especially on carpi and propodi. P3 merus subequally long as and slightly broader than P3 merus, P4 merus 0.7-0.8 × length of P3 merus, slightly narrower than P3 merus; P2 merus 1.0-1.2 × length of carapace, 1.6-1.7 × length of P2 propodus; P3 merus 1.4 × length of P3 propodus; P4 merus 1.0-1.1 × length of P4 propodus; length-breadth ratio, 7.3-9.7 on P2, 6.8-8.9 on P3, 5.7-6.3 on P4. Carpi much longer than dactyli (carpus-dactylus length ratios successively smaller posteriorly, 1.9-2.3 on P2, 1.7-2.0 on P3, 1.4-1.7 on P4); P3 carpus slightly longer than or subequal to P2 carpus, P4 carpus shortest. Propodi with flexor margin ending in pair of terminal spines preceded by row of 10-15 spines. Dactyli about one-third length of propodi on P2-4; dactylus-carpus length ratio, 0.4-0.5 on P2, 0.5-0.6 on P3, 0.6-0.7 on P4, flexor margin strongly curving at proximal third, with 9-10 spines diminishing toward base of article, ultimate spine larger than others, penultimate closer to ultimate than to antepenultimate on P2, somewhat closer to antepenultimate on P3 and P4.

Eggs. Number of eggs carried, 4-30; size, 1.08 mm × 1.20 mm - 1.30 mm × 1.60 mm.

REMARKS — All morphological features displayed by this species from the Western Pacific are very similar to those of U. longioculus Baba, 1990 from Madagascar (see Figures 212 , 213 , 214 A-D) but the sizes are clearly different. The largest in the present material measures cl 12.8 mm (poc 9.2 mm) in males and 12.7 mm (poc 8.8 mm) in females, whereas in U. longioculus it is cl 8.9 mm in both sexes; the smallest ovigerous female is also larger in the present material (cl 8.5 mm [poc 5.8 mm] versus cl 5.8 mm).

DNA analyses employed at my request showed a high genetic divergence between them (Corbari et al. personal comm.), so that a closer examination has been made to detect possible morphological differences. The only difference I have found resides on sternite 4, which has a longer anterolateral margin relative to the breadth measured at the anterior end in U. poupini : the length ratio of the anterolateral margin to the distance between left and right anteriorly produced anterolateral spines is 0.63-0.73 in U. poupini , 0.53-0.56 in U. longioculus . Also, the ratio of the breadth at the anterior end (between anterolateral spines) to the greatest breadth measured between the left and right posterolateral lobes is 0.45-0.49 in U. poupini , whereas it is 0.55 in U. longioculus ( Figure 214 ).

Figures

FIGURE 210 Uroptychus poupini n. sp.,holotype, male 6.7 mm (MNHN-IU-2014-16867).A, carapace and anterior part of abdomen,dorsal.B, same, lateral.C, sternal plastron, with excavated sternum and basal parts of Mxp1. D, telson. E, right antenna,ventral.F, right Mxp3, ventral. G, same, lateral.Scale bars: 1 mm.

FIGURE 211 Uroptychus poupini n. sp., holotype, male 6.7 mm (MNHN-IU-2014-16867). A, left P1, dorsal. B, same, proximal part, ventral. C, right P2, lateral. D, same, distal part, setae omitted, lateral. E, right P3, setae omitted, lateral. F, same, distal part, lateral.G, right P4, lateral.H, same, distal part, lateral.Scale bars: A,B,5 mm; C-H,1 mm.

FIGURE 212 Uroptychus longioculus Baba,1990,paratype,ovigerous female 4.9 mm (MNHN-IU-2014-12822 [=Ga1536]).A, carapace and anterior part of abdomen,dorsal.B, same,anterior part,lateral.C, sternal plastron,with excavated sternum and basal parts of Mxp1.D, telson. E, left Mxp3, ventral.F, same,merus and carpus, ventrolateral. Scale bars:1 mm.

FIGURE 213 Uroptychuslongioculus Baba,1990,paratype,ovigerous female 4.9 mm (MNHN-IU-2014-12822 [=Ga1536]).A, right P1,dorsal.B, same, proximal part, ventral.C, right P2, lateral. D, same, distal part, setae omitted, lateral. E, left P3, setae omitted, lateral.F, same, distal part, lateral.G, left P4, lateral.H, same,distal part,lateral. Scale bars:1 mm.

FIGURE 214 Anterior part of sternal plastron. A-D, Uroptychus longioculus Baba, 1990, paratypes; E-H, U. poupini n. sp., paratypes. A, ovigerous female 4.0 mm (MNHN-IU-2014-12822[=Ga1536]).B,ovigerous female 4.2 mm (MNHN-IU-2014-12823 [=Ga1457]).C,ovigerous female 4.9 mm (MNHN-IU-2014-12822 [=Ga1536]).D, female 5.2 mm (MNHN-IU-2014-12824 [=Ga1465]).E,male 4.1 mm (MNHN-IU-2014-16872).F,female 7.4 mm (MNHN-IU-2014-16880). G, male 7.5 mm (MNHN-IU-2014-16880).H, female 8.7 mm (MNHN-IU-2014-16880).