Uroptychus annae, 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 : 61-65

Uroptychus annae n. sp.

Figures 14 , 15

Uroptychus tridentatus — Baba 2005, 61 (part), fig. 21 (not U. tridentatus ( Henderson, 1885)) .

TYPE MATERIAL — Holotype: Vanuatu. MUSORSTOM 8 Stn DW 1100, 15°04.72’S, 167°09.99’E, 258-265 m, 10.X.1994, 1♀ 4.2 mm ( MNHN-IU-2014-17285 ) . Paratypes. Vanuatu. MUSORSTOM 8 Stn CP1099, 15°05.39’S, 167°10.51’E, 275- 284 m, 7.X.1994, 1 ♂ 4.0 mm (MNHN-IU-2014-17286) . – Stn CP1018, 17°52.88’S, 168°25.08’E, 300-301 m, 27.IX.1994, 1 ♂ 4.1 mm (MNHN-IU-2014-17287). – Stn CP 1017, 17°52.80’S, 168°26.20’E, 294-295 m, 27.IX.1994, 1 ♂ 3.8 mm (MNHN-IU-2014-17288). New Caledonia. Loyalty Islands. CALSUB PL03, 20°36’S, 167°13’E, 2465-2885 m, 22.II.1989, 1 ♀ 1.8 mm (MNHN-IU-2014-17289). MUSORSTOM 6 Stn DW 482, 21°21.50’S, 167°46.80’E, 375 m, 23.II.1989, 1 ♀ 3.7 mm (MNHN-IU-2014-17290). New Caledonia. EBISCO Stn DW 2530, 22°48.8’S, 159°23.0’E, 338-343 m, 9.X.2005, 1 ov. ♀ 3.5 mm (MNHN-IU-2014-17291). LAGON. Stn DW 393, 22°46’S, 167°04’E, 265 m, 22.I.1985, 1 ov. ♀ 3.2 mm (MNHN-IU-2014-17299). New Caledonia. Norfolk Ridge. AZTÈQUE Stn CH 01, 23°16.7’S, 168°04.7’E, 290-460 m, 12.II.1990, 1 ♂ 4.1 mm (MNHN-IU-2014-17292 [= Ga 4612]) (incorporated in Baba 2005). CHALCAL 2 Stn CP 27, 23°15.29’S, 168°04.55’E, 289 m, 3.X.1986, 2 ov. ♀ 3.7, 3.9 mm (MNHN-IU-2014-17293). SMIB 5 Stn DW 101, 23°21.2’S, 168°04.9’E, 270 m, 14.IX.1989, 1 ov. ♀ 3.5 mm (MNHN-IU-2014-17294). SMIB 8 DW182, 23°19.28’S, 168°04.82’E, 314- 340 m, 31.I.1993, 1 ♂ 3.1 mm (MNHN-IU-2014-17295). BATHUS 3 Stn CP 804, 23°41.40’N, 168°00.42’E, 244-278 m, 27.XI.1993, 1 ov. ♀ 4.3 mm (MNHN-IU-2014-17296) . – Stn CP 806, 23°42,31’S, 168°00,52’E, 27.XII.1993, 308- 312 m, 1 ♂ 3.7 mm, 1 ov. ♀ 3.8 mm, 1 ♀ 4.6 mm (MNHN-IU-2014-17297). Norfolk 1 Stn DWCP1671, 23°41’S, 168°00’E, 320-397 m ,

21.VI.2001, 1 ov. ♀ 3.8 mm (MNHN-IU-2014-17298[= Ga 4613]) (incorporated in Baba 2005). New Caledonia, Hunter and Matthew Islands. VOLSMAR Stn DW39, 22°20.5’S, 168°43.5’E, 305 m, 8.VI.1989, 1 ♂ 2.3 mm, 2 ov. ♀ 3.0, 3.2 mm, 2 ♀ 3.1, 4.0 mm (MNHN-IU-2014-17300).

ETYMOLOGY„ Named for Anna W. McCallum for her contributions to the knowledge of western Australian Chirostylidae .

DISTRIBUTION„ Vanuatu, Loyalty Islands, New Caledonia, Norfolk Ridge, Grand Récif du Sud, and Hunter-Matthew Islands; 248-460 m (the depth record of CALSUB Dive 03 from the Loyalty Islands, 60-600 m, is not cited here).

SIZE„ Male, 2.3-4.1 mm; females, 1.8-4.6 mm; ovigerous females from 3.0 mm.

DESCRIPTION„ Small species. Body and appendages sparingly with long fine setae. Carapace: Slightly shorter than (0.90-0.95) broad; greatest breadth 1.5-1.7 × distance between anterolateral spines. Dorsal surface unarmed, slightly convex from anterior to posterior. Lateral margins convex or convexly somewhat divergent posteriorly, usually with 7 spines: first anterolateral, overreaching lateral orbital spine; second and third much smaller, situated ventral to level of other spines; fourth to seventh usually acute, placed on branchial region, seventh situated at point one-third from posterior end, occasionally followed by obsolescent spine. Rostrum triangular, with interior angle of 20-30°, bearing subterminal small spine on each side; dorsal surface concave; length slightly less than half that of remaining carapace, breadth about half carapace breadth measured at posterior carapace margin. Lateral orbital spine small, located directly mesial to anterolateral spine. Pterygostomian flap anteriorly sharp angular, produced to sharp spine, surface with small spines on anterior half, anterior half distinctly higher than posterior half.

Sternum: Excavated sternum with distinct ridge in midline arising from center, leading anteriorly to bluntly produced anterior margin between bases of Mxp1. Sternal plastron slightly longer than broad, lateral extremities subparallel. Sternite 3 depressed well, anterior margin shallowly concave, with relatively narrow, deep median notch without flanking spine; posterolateral margin much more than half length of anterolateral margin. Anterolateral margins of sternite 5 subparallel or slightly convergent posteriorly, about as long as posterolateral margin of sternite 4.

Abdomen: Somite 2 tergite 2.4-2.7 × broader than long; pleuron posterolaterally blunt. Pleuron of somite 3 posterolaterally bunt. Telson half as long as broad; posterior plate 1.1-1.3 × longer than anterior plate, posterior margin feebly convex or feebly concave.

Eyes: Elongate, 1.6 × longer than broad, distally narrowed, overreaching midlength of rostrum; cornea more than half length of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.5-3.0 × longer than high. Antennal peduncle overreaching cornea. Article 2 with acute lateral spine. Antennal scale fully reaching or overreaching opposite peduncle. Distal 2 articles each with strong distomesial spine; article 5 1.5 × longer than article 4, breadth 0.7-0.9 × height of ultimate article of antennule. Flagellum of 9-12 segments not reaching distal end of P1 merus.

Mxps: Mxp1 with bases broadly separated. Mxp3 basis without denticles on mesial ridge. Ischium with small spine lateral to rounded distal end of flexor margin, crista dentata with about 12 denticles. Merus 1.8-2.2 × longer than ischium, flattish, with distolateral spine and 2 (rarely 1) small spines on distal third of flexor margin. Carpus with distolateral spine and 1-3 spines on extensor surface.

P1: Relatively massive in males, 4.9-5.5 × (males), 5.0-5.4 × (females) longer than carapace. Ischium with strong dorsal spine and distinct subterminal spine on ventromesial margin. Merus with a few small ventral spines proximally, short ventromesial and ventrolateral spines distally, length 1.1-1.3 × that of carapace. Carpus 1.0-1.2 × length of merus, dorsal surface with 3 proximal tubercles. Palm 2.7-3.3 × (males), 2.7-4.0 × (females) longer than broad, length 1.1-1.3 × longer than carpus. Fingers distally narrowed and slightly incurved, slightly gaping in males; movable finger 0.4-0.5 × length of palm, opposable margin with subtriangular blunt proximal process fitting to opposite groove proximal to low eminence of fixed finger when closed; opposable margin of fixed finger sinuous. P2-4: Meri compressed mesio-laterally and relatively broad, mesial face flattish, successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8-0.9 × length of P3 merus), subequally broad on P2-4; length-breadth ratio, 3.1-3.6 on P2, 3.0-3.6 on P3, 2.6-3.5 on P4; dorsal margin with a few small proximal spines distinct on P2, occasionally obsolescent on P3, obsolete on P4, ventrolateral margin distally lobe-like, not produced to spine; P2 merus 0.8-0.9 × length of carapace, slightly longer (1.1 x) than P2 propodus; P3 merus as long as or very slightly shorter than P3 propodus; P4 merus 0.8- 0.9 × length of P4 propodus. Carpi relatively short, subequal (slightly longer on P2 than on P3 and P4 or successively slighter shorter posteriorly), unarmed, length less than half that of propodus. Propodi successively shorter posteriorly, successively longer posteriorly or subequal on P3 and P4 and slightly shorter on P2; flexor margin slightly concave, with pair of terminal spines preceded by 1-3 single spines (often distal pair only on P4). Dactyli subequal in length on P2-4 or slightly shorter on P2 than on P3 and P4, slightly longer than carpi (dactylus-carpus length ratio, 1.1 on P2, 1.2 on P3, 1.1-1.3 on P4); flexor margin nearly straight, bearing slender terminal spine preceded by 3 triangular spines proximally diminishing and perpendicular to margin, and additional 1 or 2 (rarely 3) slender, somewhat inclined proximal spines; penultimate slightly larger than antepenultimate.

Eggs. Up to 18 eggs carried; size, 0.83 mm × 0.88 mm - 0.81 mm × 0.92 mm.

REMARKS — Uroptychus tridentatus ( Henderson, 1885) has been discussed in my earlier paper ( Baba, 2005), in which some of the present material was included. The occurrence of another specimen from the Philippines (MNHN- IU-2014-16995; see Uroptychus tridentatus ) that is more like the non-intact type material of U. tridentatus , suggests that the New Caledonian material discussed earlier and listed above from the collection of the Paris Museum would better be placed in a different species. This is now named U. annae n. sp.

Uroptychus annae is distinguished from U. tridentatus ( Henderson, 1885) by the following differences: the carapace lateral margin has the posteriormost spine more remote from the posterior end (situated at point one-third instead of quarter from the end); the P2-4 propodi have fewer flexor spines other than the distal pair (1-3 instead of 5 or 6); the P2-4 dactyli have fewer flexor spines (6 instead of 8 other than the slender terminal spine); and the P2-4 meri have the ventrolateral margin distally ending in a lobe-like instead of acuminate process. Uroptychus annae resembles U. oxymerus Ahyong & Baba, 2004 from northwestern Australia, from which it is distinguished by the following details: the carapace lateral margin bears 7 instead of 6 spines (4 instead of 3 on the branchial margin), the second and third much smaller, and the last located at the posterior third instead of slightly posterior to the midlength; the antennal article 5 bears a distomesial spine only instead of additional small spines on the mesial margin; and the P1 merus is spineless on the ventral mesial margin, instead of beraring a row of five spines. In addition, the small spine mesial to the fourth lateral spine of the carapace is distinct in U. oxymerus , absent in U. annae .

Figures

FIGURE 14 Uroptychus annae n. sp., holotype,♀ 4.2 mm (MNHN-IU-2014-17285).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, left Mxp3,ventral. G, same, lateral. Scale bars: 1 mm.

FIGURE 15 Uroptychus annae n. sp., holotype, ♀ 4.2 mm (MNHN-IU-2014-17285). A, left P1, dorsal.B, same, proximal part, setae omitted, ventral. C, right P2,lateral.D, same,distal part,lateral.E, right P3,lateral.F, same,distal part,lateral.G, right P4,lateral.H, same,distal part,lateral. Scale bars:1 mm.