Uroptychus babai Ahyong & Poore 2004
Creators: name: Baba, Keiji
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chirostylidae
Uroptychus
Uroptychus babai

description: Uroptychus babai Ahyong & Poore, 2004
Figures 24-27, 305C
Uroptychus babai Ahyong & Poore, 2004: 22, fig. 4. — Poore et al. 2011: 328, pl. 6: fig. D.
Uroptychus granulatus — Baba 1990:923,fig. 9 (Not U. granulatus Benedict,1902).
Not Uroptychus babai: Baba et al. 2009: 38, figs 30-31 (= U.parilis Cabezas, Lin & Chan,2012).
TYPE MATERIAL — Holotype: Australia, E of Broken Bay, 33°31-34’S, 152°02-04’E, 905-914 m, male (AM P26782). [not examined].
MATERIAL EXAMINED — New Caledonia, Chesterfield Islands.MUSORSTOM 5 Stn CP324,21°15.01’S,157°51.33’E,970m,14.X.1986,1 ♀ 9.2 mm (MNHN-IU-2014-16300), 1 ov. ♀ 9.4 mm (MNHN-IU-2014-16301). Solomon Islands. SALOMON 2 Stn CP2181, 8°49.9’S, 159°39.8’E, 645-840 m, 22.X.2004, 1 ♂ 9.2 mm (MNHN-IU-2014-16302). – Stn CP2189, 8°19.6’S, 160°01.9’E, 660-854 m, 23.X. 2004, 5 ♂ 6.8-11.8 mm, 1 ov. ♀ 13.0 mm, 4 ♀ 7.5-12.5 mm (MNHN-IU-2014-16303). – Stn CP2193, 8°23.9’S, 159°26.6’E, 362-432 m, 24.XI.2004, 1 ♂ 7.8 mm, 1 ♀ 7.7 mm (MNHN-IU-2014-16304). – Stn CP2241, 6°55.3’S, 156°21.2’E, 815-1000 m, 30.X.2004, 1 ♀ 9.0 mm (MNHN-IU-2014-16305). – Stn CP2269, 7°45.1’S, 156°56.3’E, 768-890 m, 4.XI.2004,1 ♂ 5.2 mm (MNHN-IU-2014-16306). – Stn CP2272, 8°56.2’S,157°44.1’E,380-537 m, 5.XI.2004,1 ♀ 11.3 mm (MNHN-IU-2014-16307). – Stn CP2289,08°36’S, 157°28’E, 627-623 m, 07.XI.2004, 4 ♂ 3.1-5.2 mm (MNHN-IU-2014-16308). – No station number, XI.2004, 1 ♂ 7.8 mm, 1 ♀ 3.5 mm (MNHN-IU-2014-16309).
DISTRIBUTION„ Previously known from Madagascar, New South Wales, in 880-1152 m; and now from Chesterfield Islands and Solomon Islands, in 362-1000 m.
SIZE„ Males, 3.1-11.8 mm; females, 3.5-13.0 mm, ovigerous females from 9.4 m.
DESCRIPTION„ Large species. Body and appendages sparsely or thickly covered with fine setae (usually thick in large specimens). Carapace: Slightly broader than long (length 0.8-0.9 × breadth); greatest breadth 1.8 × distance between anterolateral spines. Dorsal surface granulose in large specimens, less so in small specimens, moderately convex from anterior to posterior, with very weak (in small specimens) or distinct (in large specimens) depression suggesting cervical groove, anteriorly smoothly continued on to rostrum. Lateral margins convex, with short, oblique granulate ridges: one at anterior end of branchial region well elevated, rarely representing tiny spine, another ridge behind posterior branchial region usually visible in dorsal view, and others discernible under high magnification; ridged along posterior half; anterolateral spine well developed, distinctly overreaching lateral orbital spine. Rostrum broad sharp triangular, with interior angle of 30-35°, somewhat upcurved distally; length 0.4-0.6 × that of remaining carapace (greater in small specimens than in large specimens), breadth less than half carapace breadth measured at posterior carapace margin; dorsal surface slightly concave. Lateral orbital spine small, occasionally reduced to acuminate angle, moderately remote from and slightly anterior to level of anterolateral spine. Pterygostomian flap with granulate short ridges or fine granules supporting setae on surface, anterior margin angular, produced to small sharp spine.
Sternum: Excavated sternum with convex anterior margin between Mxp1, with low ridge in midline. Sternal plastron slightly broader than long, lateral extremities gently divergent posteriorly. Sternite 3 strongly depressed from level of sternite 4; anterior margin deeply or moderately emarginate in broad V-shape, without submedian spines; lateral margin with small spine near lateral end. Sternite 4 with anterolateral margin somewhat or moderately convex anteriorly, anterior end rounded, angular or produced to anteriorly directed spine falling short of anterior end of sternite 3; posterolateral margin 0.6-0.8 × length of anterolateral margin.
Abdomen: Somite 1 with well-elevated, rounded transverse ridge. Somite 2 tergite 2.6-2.7 × broader than long, pleuron with concavely divergent lateral margin posteriorly ending in rounded corner. Pleuron of somite 3 tapering. Telson about half as long as broad; posterior plate emarginate on posterior margin, length 1.2-1.6 × that of anterior plate.
Eye: Relatively small, 1.5-1.8 × longer than broad, terminating in or slightly overreaching midlength of rostrum; lateral and mesial margins subparallel. Cornea not dilated, length much more than half that of remaining eyestalk.
Antennule and antenna: Ultimate article of antennular peduncle short relative to height in small specimens, long in large specimens (breadth-height ratio, 2.5-3.1 in specimens 3.2-7.6 mm, 4.5-4.9 in specimens 12.0- 12.8 mm). Antennal peduncle relatively slender. Article 2 with small lateral spine. Antennal scale 1.4-2.5 × broader than article 5, varying from slightly falling short of to terminating in distal end of article 5, rarely reaching proximal third segment of antennal flagellum. Distal 2 articles unarmed (in large specimens, each with very tiny tubercle-like ventral distomesial spine); article 5 1.6-2.1 × length of article 4; breadth 0.4-0.5 × height of ultimate antennular article. Flagellum consisting of 22-23 segments slightly falling short of or overreaching distal end of P1 merus (13 or 14 segments overreaching distal end of P1 merus in males 3.1-4.3 mm).
Mxp: Mxp1 with bases broadly separated. Mxp3 basis without distinct denticles on mesial ridge. Ischium with 26-47 tiny denticles on crista dentata, flexor margin not rounded distally. Merus 2.4 × longer than ischium, unarmed, flexor ridge not cristate, moderately rounded. Carpus unarmed.
P1: 3.2-6.6 × longer than carapace (usually shorter in small specimens than in large specimens), relatively slender; with simple fine setae more numerous in large specimens. Ischium with basally broad dorsal spine, ventromesially unarmed. Merus granulate dorsally and ventrally, with 2 distoventral spines and 1 or 2 small, often obsolescent distodorsal spines; length 0.9-1.3 × that of carapace (shorter in small specimens<4 mm). Carpus also granulate like merus, 1.2-1.6 × longer than merus (shorter in small specimens, longer in larger specimens), with distomesial and distolateral spines on ventral surface and 1 distodorsal spine (often obsolete). Palm more slender in females than in males, length-breadth ratio, 3.3-6.9 in males and 4.0-9.2 × in females, lateral and mesial margins subparallel, dorsal granulation more weak than on carpus; length subequal to that of carpus. Fingers slightly curving ventrally, distally incurved, crossing when closed (in small specimens, slightly incurved, not gaping, opposable margins nearly straight or with low eminence on movable finger); movable finger with obtuse proximal process fitting to narrow longitudinal groove on opposite fixed finger when closed, length 0.3-0.5 × that of palm (short in large specimens).
P2-4: Relatively slender, subcylindrical on meri, somewhat compressed mesio-laterally on propodi. Meri unarmed, successively shorter posteriorly (P3 merus 0.8-0.9 × length of P2 merus; P4 merus 0.8-0.9 × length of P3 merus), subequally broad on P2-4; length-breadth ratio, 4-5 on P2, 4 on P3, 3-4 on P4; P2 merus 0.7-1.0 × length of carapace (0.7-0.8 × in specimens<5.2 mm), 1.0-1.3 × length of P2 propodus (shorter in small specimens); P3 merus as long as P3 propodus; P4 merus 0.7-0.9 × length of P4 propodus; dorsal margin with obsolescent denticles on P2. Carpi subequal or slightly longer on P2 (P3 carpus 0.9 × length of P2 carpus), shorter than dactyli, 0.4 × length of propodi on P2, 0.3-0.4 × on 3 and P4. Propodi curving, shorter on P2 than on P3 and P4, subequal on P3 and P4 or slightly longer on P4 than on P3; flexor margin with pair of distal spines only. Dactyli relatively stout, slightly curved; length 0.4-0.6 × that of propodus on P2-4; flexor margin ending in slender spine preceded by much broader penultimate and 12-13 close (nearly contiguous), obliquely directed, proximally diminishing spines on P2, 12-14 on P3, 13-16 on P4, all spines obscured by dense setae; penultimate broadest, antepenultimate broader than ultimate, half as broad as penultimate.
Eggs. About 40 eggs carried by largest female (12.8 mm); size, 1.11 mm × 1.33 mm - 1.28 mm × 1.55 mm.
Color. The coloration of the female (MNHN-IU-2014-16300) from MUSORSTOM 5 Stn CP324 is exactly the same as that of the figure of the holotype from eastern Australia provided by Poore et al. (2011): pinkish red on anterior part of carapace, paler on rostrum, whitish on remaining carapace and abdomen; P1 pale pinkish red, other pereopods much paler.
REMARKS — Specimens> 10 mm are usually very setose on the body and appendages. Small specimens <5.2 mm are very sparsely setose, as also are some of large specimens (male 9.2 mm, MNHN-IU-2014-16302; females 9.2 mm, MNHN- IU-2014-16300; ovigerous female 9.4 mm, MNHN-IU-2014-16301). The specimens as illustrated in Figures 25-26 look very much like U. parilis Cabezas, Lin & Chan, 2012. The holotype of U. parilis from Taiwan was first referred to U. babai by Baba et al. (2009) but subsequently described as new. Cabezas et al. (2012) noted that the major differences between the two species are found on the carapace lateral margin (almost smooth in U. parilis, crenulated in U. babai), thoracic sternite 4 (anterolaterally produced to a distinct spine in U. parilis, lacking spine in U. babai), and the antennal scale (falling short of to slightly overreaching the distal end of antennal article 5 in U. parilis, distinctly overreaching article 5 in U. babai).
The present specimens seem to cover all these differences. Two distinct ridges visible in dorsal view on the lateral margin of the carapace are usually small in large specimens so as to be seen as smooth but discernible in all the specimens examined (Figure 24 A-E), as well as in the holotype of U. parilis illustrated in Baba et al. (2009: fig. 31a). Sternite 4 is also variable, even in several specimens from one sampling station (Figure 27F, G, H); the anterolateral spine as diagnosed for U. parilis is also present in some of the specimens examined as well as in one of the specimens of U. babai from Madagascar (MNHN-Ga 2234), although not so strong to reach the anterior end of sternite 3 as in the holotype of U. parilis (see Figure 27). The antennal scale varies from falling short of to overreaching the distal end of the antennal article 5 (Figure 24G, H).
P1 appears longer relative to the carapace in U. parilis, measuring 6 times longer than the carapace (Cabezas et al. 2012), whereas about 4 times as long in U. babai (Ahyong & Poore, 2004, fig. 4a). However, the present specimens (poc 3.1-13.0 mm) show a wide, age related variation in P1-carapace length ratios: 3.3-4.8 in small specimens (3.2-5.2 mm), 5.0- 6.8 in large specimens (6.8-13.0 mm). An exceptional case is two large females (9.2, 9.4 mm) from the Chesterfield Islands (MNHN-IU-2014-16300 & MNHN-IU-2014-16301), which have ratios 4.5 and 4.7. P 1 in U. parilis looks much more slender than in U. babai, as illustrated by Cabezas et al. (2012: fig. 1A) and Ahyong & Poore (2004: fig. 4A). This difference appears to be sex-related, as usual in other species of Uroptychus. In the present material, the P1 palm is 3.3- 6.9 (males), 4.0-9.2 (females) times longer than broad, the length-breadth ratio being greater in large specimens. However, the females from the Chesterfield Island the ratios are 4.0 and 4.3, whereas three females from SALOMON 2 Station CP2189 (MNHN-IU-2014-16303) of nearly the same size as the Chesterfield specimens show the ratios 8.7-9.2 and the largest female 5.6. The ratio is thus widely variable.
In conclusion, the morphological differences noted by Cabezas et al. (2012) do not seem to be applicable especially to small specimens. The only definite difference resides on coloration: orange red overall including appendages in U. parilis versus reddish on the anterior part of the carapace, whitish on remaining carapace and abdomen in U. babai. Molecular data would clarify their systematic status.
description: Published as part of Baba, Keiji, 2018, Chirostylidae of the Western and Central Pacific: Uroptychus and a new genus (Crustacea: Decapoda: Anomura), pp. 1-612 in Mémoires du Muséum national d'Histoire naturelle 212 on pages 81-87, DOI: 10.5281/zenodo.3760976