Upogebia hexaceras ( Ortmann, 1894 )

Dworschak, Peter C. & Anker, Arthur, 2022, Axiidea (Crustacea: Callianassidae, Callichiridae and Ctenochelidae) and Gebiidea (Upogebiidae) collected during the Comprehensive Marine Biodiversity Survey of Singapore, Raffles Bulletin of Zoology 70, pp. 108-133 : 119-121

Upogebia hexaceras ( Ortmann, 1894)

( Figs. 2e, f , 9)

Gebia (Gebiopsis) hexaceras Ortmann, 1894: 23 , pl. 3 fig. 1.

Upogebia (Calliadne) hexaceras . — de Man, 1928: 24 (list), 81, pl. 8, fig. 11, 11a–f.

Upogebia (Upogebia) hexaceras . — Sakai, 1982: 23, pls. A4, C4.

Upogebia hexaceras . — Ngoc-Ho, 1990: 979, fig. 8; — Dworschak, 2019: 28 — Komai et al., 2020: 478 , figs. 1–4.

Upogebia darwinii . — Sakai, 2006: 101 (part), fig. 16 [not Upogebia darwinii ( Miers, 1884) ].

Not Upogebia (Calliadne) hexaceras . — Poore & Griffin, 1979: 299, fig. 50 [= Upogebia darwinii ( Miers, 1884) ].

CMBS material. 2 females (17/5.1, 17/4.9) ( NHMW 26048 ), sta. DR001, Straits of Singapore near Raffles Lighthouse, 1°10.125′N 103°45.419′E, gravel, shells, rectangular dredge, 38.3–38.5 m, coll. B Richer de Forges et al., 21 May 2013 (SS-0313) ; 1 female (20/5.7), 1 male (15/5.3) ( ZRC 2018.0566 ), sta. DR013, between Pulau Hantu and Pulau Semakau, MPA grid 4513, rectangular dredge, in sponge (DR13_016), 21.1–21.9 m, coll . TMSI team, 3 July 2013 (DR13_027, DR13_028) ; 1 ov. female (22/6.1), 1 male (25/7.6) ( NHMW 26042 ), sta. DR111, Straits of Singapore outside Eastern Boarding Ground A, 1°12.989′N 103°53.062′E, mostly rock bottom, rectangular dredge, 125–136 m, coll. B Richer de Forges et al., 30 May 2013 (SS-3265) ; 1 ov. female (25/8.3), 1 male (22/6.8) ( NHMW 26041 ), sta. DR112, Straits of Singapore, Southern Fairway south of Sister Islands, 1°12.024′N 103°50.170′E, broken shells, rubble, rectangular dredge, 33.6–34.4 m, coll. B Richer de Forges et al., 30 May 2013 (SS-2943) ; 1 male (16/5.3) ( ZRC 2018.0567 ), sta. DR114, north of Pulau Tekong , MPA grid 0226, rectangular dredge, 6.4–8.7 m, coll . TMSI team, 7 October 2013 (SEA-1276) ; 1 female (21/6.3), 1 male (17/5.1) ( ZRC 2018.0541 ), 1 male (19/5.9) ( ZRC 2018.0542 ), sta. DR125, Straits of Singapore, near Sister Islands, 1°12.416′N 103°49.858′E, laterite gravel, sand, rectangular dredge, 25.3–30.8 m, coll. B Richer de Forges et al., 31 May 2013 (SS-4002) ; 1 ov. female (21/6.3), 1 male (20/5.9) ( ZRC 2018.0565 ), sta. DR222, east of Pulau Pawai , MPA grid 4411, rectangular dredge, 17.3–18.7 m, coll . TMSI team, 21 October 2013 (SEA-1613) ; 1 juvenile (7/2.3) ( ZRC 2018.0569 ), sta. DR239, south of Pulau Bukom , MPA grid 4613, rectangular dredge, 24.3–27.6 m, coll . TMSI team, 11 December 2013 (SEA-2058) ; 1 juvenile (8/2.3) ( ZRC 2018.0570 ), sta. DR241, north of Pulau Bukom , MPA grid 4614, rectangular dredge, 17.5–17.8 m, coll . TMSI team, 11 December 2013 (SEA-2089) ; 1 female (14/4.5) ( ZRC 2018.0571 ), sta. DR257, off southwestern tip of Jurong Island , MPA grid 4013, clay, mud, rocks, rectangular dredge, 19.4–22.5 m, coll . TMSI team, 19 December 2013 (SEA-3209) ; 1 male (24/7.0) ( ZRC 2018.0564 ), sta. RF 353, Pulau Senang , east of jetty, intertidal, rocks, rubble, hand collection, coll . TMSI team, 30 March 2014 (INT-0849) ; 1 ov. female (22/6.4), 2 males (17/5.0, 18/5.0) ( NHMW 26043 ), 1 ov. female (28/7.7) ( NHMW 26045 ), 1 ov. female (25/7.1) ( NHMW 26046 ), 1 male (23/7.0) ( ZRC 2018.0557 ), sta. SB067, Pulau Hantu , western patch reef, 1°13.6′N 103°44.8′E, coral rubble brushing 15.7 m, coll. HH Tan, S De Grave et al., 26 May 2013 (SS-1658, SS-1659, SS-1647) ; 1 female (27/7.6) ( NHMW 26044 ), 1 ov. female (27/8.0) ( ZRC 2018.0538 ), sta. SB146, west of Pulau Hantu , coral rubble brushing, 5–7 m, coll. HH Tan, S De Grave et al., 2 June 2013 (SS-2979) ; 1 ov. female (20/6.0), 1 male (168/5.9) ( NHMW 26047 ), sta. TB003, Straits of Singapore near Raffles Lighthouse, Gusong Boarding Ground, 1°10.653′N 103°46.772′E, 40.7–40.9 m, coll. B Richer de Forges et al., 21 May 2013 (SS-0310) ; 1 male (14/4.0) ( ZRC 2018.0559 ), sta. TB071, Straits of Singapore, south-west of Eastern Holding A, Singapore port limit, MPA grid 5414, beam trawl, 61.7–66.8 m, coll . TMSI team, 13 May 2013 (5414TB2-071) ; 1 male (18/5.7) ( ZRC 2018.0540 ), sta. TB073, Straits of Singapore south of Pulau Semakau, 1°11.282′N 103°46.6321′E, sandy bottom, beam trawl, 24.6–29.8 m, coll. B Richer de Forges et al., 26 May 2013 ; 1 ov. female (19/5.7), 1 male (16/4.7) ( ZRC 2018.0545 ), sta. TB091, Straits of Singapore, Southern Fairway near St. John’s Island, 1°12.926′N 103°51.647′E, beam trawl, 39.5–49.9 m, coll. B Richer de Forges et al., 28 May 2013 ; 1 male (19/6.0) ( ZRC 2018.0527 ), sta. TB113, Straits of Singapore, Southern Fairway south of Sister Islands, 1°12.001′N 103°50.261′E, silt with rocks, beam trawl, 29.3–30.5 m, coll. B Richer de Forges et al., 30 May 2013 ; 1 female (15/4.6), 1 male (12/4.0) ( ZRC 2018.0558 ), sta. TB128, Straits of Singapore beside Eastern Boarding Ground A, 1°12.889′N 103°52.460′E, mostly rock bottom, beam trawl, 75.2–83.7 m, coll. B Richer de Forges et al., 31 May 2013 (SS-3995) ; 1 ov. female (20/6.0) ( ZRC 2018.0544 ), sta. TB185, Straits of Singapore near Pulau Senang, 1°09.942′N 103°43.458′E, thick smelly mud, laterite rocks, gravel, beam trawl, 24.3–24.5 m, coll. B Richer de Forges et al., 6 June 2013 ; 1 male (16/5.1) ( ZRC 2018.0534 ), sta. TB186, Straits of Singapore off Raffles Lighthouse, 1°09.318′N 103°44.200′E, gravel, rocks, sponges, beam trawl, 35–38 m, coll. B Richer de Forges et al., 6 June 2013 ; 1 ov. female (17/5.1), 1 male (14/4.1) ( ZRC 2018.0552 ), sta. TB187, Straits of Singapore near Raffles Lighthouse, 1°09.239′N 103°44.674′E, sponges, rocks, gravel, beam trawl, 39.5–40.2 m, coll. B Richer de Forges et al., 6 June 2013 .

Diagnosis. Lateral ridges of gastric region projecting forward. Linea thalassinica not reaching posterior end of carapace. Rostrum rounded, as long or slightly longer than eyestalks, with 6 or more frontal teeth. Postocular spine absent. Antennal peduncle longer than antennular peduncle. First pereopod chelate; ischium smooth or with few spinules; merus with small lower spines proximally, without proximal upper spine; carpus with small upper and several small median spines, without lower spine mesially; propodus smooth on lower mesial face and upper border; dactylus with row of tubercles on mesial face and prominent rounded tooth proximally; fixed finger with serrated cutting edge proximally. Second pereopod merus without proximal upper spine; propodus 2.5–3.1 times as long as high. Third pereopod merus with smooth lower border, without proximal upper spine. Pleomere 6 with prominent lateral spines; posterior border denticulated. Uropodal endopod squarish. Telson 0.8–1.1 times as long as maximal width; inverted U-shaped carina with tubercles. First and third maxillipeds without epipods. Third maxilliped exopod flagellate. Arthrobranchs of type B. Embryos 550–750 µm in diameter.

Distribution. Known with certainty from Thursday I., Torres Strait, northern Australia (type locality), Philippines ( Dworschak, 2019), Singapore (this study), Indonesia, India ( Komai et al., 2020), Red Sea and Persian Gulf ( Ngoc-Ho, 1990). Exact distribution (especially in Australia) uncertain due to confusion with U. darwinii (see below).

Habitat. Sand, silt, mud, gravel and rubble bottoms from the intertidal zone to 84 m; often associated with sponges ( Komai et al., 2020; this study).

Remarks. Upogebia hexaceras was described based on two specimens (sex not given) from Thursday Island (Torres Strait) ( Ortmann, 1894). De Man (1928: 83) studied the “single type specimen, a male” (24/8.3) deposited in what is now the Phyletisches Museum in Jena, Germany (PMJ), and provided a complementary description of the species. One specimen is still extant in the PMJ collections; however, it is a female with cl 9 mm, with the pleomere 6 bearing lateral projections and its posterior border denticulated (R. Beutel, pers. comm., 25 March 2014).

Upogebia hexaceras was treated as a valid species by Sakai (1982), although he concluded that it showed no differences from U. darwinii . Ngoc-Ho (1990) considered it as valid and outlined the differences between the three similar species, viz. U. darwinii , U. hexaceras , and U. octoceras ( Nobili, 1904) . Sakai (1993, 2006) considered U. hexaceras again as a synonym of U. darwinii , which was later rebutted by Ngoc-Ho (2008). Most recently, Dworschak (2019) and Komai et al. (2020) considered U. hexaceras a valid species.

The material of U. hexaceras from CMBS is very consistent in its morphological characters. All specimens display strong, sharp, lateral projections on the sixth pleomere and its posterior border is strongly denticulate. The rostrum is short, rounded, with 6–12 spines (see below), whereas the lateral projections of the carapace are prominent. It differs clearly from the CMBS material herein identified as U. darwinii (see above).

The number of the rostral spines is quite variable in the present material of U. hexaceras , with 2 specimens armed with 6 spines, 12 with 8, 1 with 9, 13 with 10, 1 with 11, and 7 with 12. These numbers exceed the range of the rostral spines (6–9) in the diagnosis of U. hexaceras provided by Ngoc-Ho (1990: table 1) and also that of U. octoceras (6–10, idem). None of the CMBS specimens, however, has a distomesial spine on the first pereopod propodus near the articulation with the dactylus, a feature typical of U. octoceras ( Ngoc-Ho, 1990: fig. 9g, f).

Figures

Fig. 2. Specimens, habitus (dorsal and ventral views), showing colouration in life: a, Upogebia carinicauda (Stimpson, 1860), male (21/6.1) (NHMW 26035); b, same, male (23/6.6) (NHMW 26034); c, d, U. darwinii (Miers, 1884), ovigerous female (44/12.6) (NHMW 26038); e, U. hexaceras (Ortmann, 1894), male (23/7.0) (ZRC 2018.0557); f, same, ovigerous female (22/6.1) (NHMW 26042); g, U. ancylodactyla de Man, 1905, female (40/11.3) (ZRC 2018.0551); h, same, male (29/8.4) (ZRC 2018.0549). Not to scale. [Photographs by AA].