Lamoha longirostris ( Chen, 1986 )

Ng, Peter K. L. & Forges, Bertrand Richer de, 2017, On a collection of Homolidae from the South China Sea, with descriptions of two new species of Homologenus A. Milne-Edwards, in Henderson, 1888, and the identities of Homologenus malayensis Ihle, 1912, and Lamoha superciliosa (Wood-Mason, in Wood-Mason & Alcock, 1891), Raffles Bulletin of Zoology 65, pp. 243-268 : 245-246

Lamoha longirostris ( Chen, 1986)

( Figs. 3, 4, 5A–D, 6A–G, 7A–F, 23, 24A)

Hypsophrus longirostris Chen, 1986: 227 .

Hypsophrys futuna Guinot & Richer de Forges, 1995: 456 , figs. 61l, 66 a, g. – Cleva et al., 2007: 251, fig. 20A.

Lamoha superciliosa – Serène & Lohavanijaya, 1973: 30, pl. 4 fig. A. – Ahyong et al., 2009: 98, figs. 66–68. – Richer de Forges & Ng, 2008: 23, figs. 19A–C, 20A–E, 21A–D, 22E, F (not Hypsophrys superciliosa Wood-Mason , in Wood-Mason & Alcock, 1891)

Lamoha longirostris – Ng & Chen, 1999: 760. – Ng et al., 2001: 54. – Takeda et al., 2005: 106, fig. 1B. – Ng et al., 2008: 40. – Richer de Forges & Ng, 2008: 20, figs. 17A–D, 18A–G, 22B–D. – Ahyong et al., 2009: 94, figs. 61–63.

Material examined. Paralectotype: male (22.9 × 18.6 mm) ( ZRC 1999.0007 ), East China Sea, St. 2V-9, 28°10′N 127°30′E, 900 m, coll. 3 January 1981 . Others: 1 male (29.2 × 24.2 mm) ( ZRC 2008.0990 ), station CP 2753, eastern Luzon , 15°37.23′N 121°58.24′E, Philippines, 1252–1350 m, trawl, coll. AURORA 2007 Expedition, 3 June 2007 . – 1 male (25.2 × 20.2 mm) ( ZRC 1999.0410 ) , off Tungsha Island, Taiwan, South China Sea , trawl coll. P.-H. Ho, 23 mm) ( USNM 1150828 ) , station 98, Pagan Island , Northern Mariana Islands, 18°05′48′′N 145°41′48′′E, 896 m, coll. Townsend Cromwell, 6 May 1982 . – 1 male (22.0 × 18.3 mm) ( USNM 1150825 ), station 231, Agrihan Island , Mariana Islands, 18°47.4′N 145°35′E, 1280 m, coll. Townsend Cromwell, 11 July 1982 . – 1 ovigerous female (18.5 × 16.6 mm) (MNHN-IU-2011-2732), station CP 3686, Papua New Guinea, 03°16′S 147°18′E, 964–1025 m, coll. BIOPAPUA, 26 September 2010 .

Remarks. The specimen from the East China Sea is a paralectotype (see Ng & Chen, 1999). Lamoha futuna ( Guinot & Richer de Forges, 1995) was synonymised with L. longirostris by Ng & Chen (1999) after examining the types of both species. The distribution of this deep-sea species is therefore very wide, from the South China Sea and China to the central Pacific.

The prominent black spot on each side of the propodus of their chelipeds (see Richer de Forges & Ng, 2008: fig. 18C, D) is distinct in all specimens, but varies in size. This spot was “interpreted” by Williams (1976) as being a luminescent organ. Nobody, however, has observed this phenomenon on a live animal.

April 1995. – 2 ovigerous females (20.8 × 18.2 mm, 26.3 × 20.8 mm) (ZRC 2008.0991), Taiwan, South China Sea, 1400 m, coll. Taiwan University, 2000s. – 1 male (15.0 × 12.8 mm), 1 ovigerous female (23.2 × 18.9 mm), 1 female (24.9 × 20.3 mm) (ZRC 2016.0555), station CP 4167, off Tungsha Island, 22°06.12′N 119°07.77′E – 22°02.69′N 119°03.64′E, Taiwan, South China Sea, 1306–1756 m, mud substrate, trawl, coll. ZHONGSHA 2015 Cruise, 1 August 2015. – 2 males (24.9 × 20.5 mm, 15.3 × 12.6 mm), 1 ovigerous female (24.2 × 20.4 mm), 1 female (23.4 × 19.4 mm) (ZRC 2016.0556), station CTS 2, cold seep, 22°5.19′N 119°48.03′E – 22°2.22′N 119°48.02′E, off southern Taiwan, South China Sea, 1360–1669 m, mud sediment with many dead bivalves and vent tubes, trawl, coll. 30 May 2015. – 1 female (17.9 × 15.0 mm) (ZRC 2008.0993), Taiwan, station OCP 280, 24°23.71′N 122°14.22′E, 1213–1261 m, eastern Taiwan, South China Sea, trawl, coll. TAIWAN 2005 Cruise, 14 June 2005. – 1 male (18.0 × 14.8 mm), 2 females (13.1 × 10.0 mm, 10.8 × 8.5 mm) (ZRC 2008.0992), station CP 277, 24°23.57′N 122°14.12′E, 1222–1261 m, southern Taiwan, South China Sea, trawl, coll. TAIWAN 2005 Cruise, 14 June 2005. – 1 male (13.8 × 11.2 mm), 2 juvenile females (11.8 × 9.1 mm, 10.0 × 7.2 mm) (ZRC 2016.0557), station CST 17, muddy sediment, Pointer Ridge, Taiwan, 22°3.79′N 118°58.80′E – 22°3.78′N 119°4.11′E, 1482 m coll. 1 May 2016. – 2 ovigerous females (28.6 × 25.3 mm, 27.1 × 23.9 In L. longirostris , the supraorbital margin varies from almost entire, without trace of any tooth or spine ( Fig. 6G), possessing a low tooth ( Fig. 6A, B, E, F) or distinct spine or tooth ( Fig. 6C, D). Both specimens of L. superciliosa have a small tooth on the supraorbital margin ( Fig. 6H). The subhepatic region of L. longirostris always has one distinct spine and there is sometimes also a sharp granule or a small spine present on the outer part as well, but always distinctly smaller than the inner one ( Figs. 5A, 7A, C, E, F). Many of the specimens of L. longirostris , however, have only one spine, with the remainder of the surface smooth ( Fig. 5B–D, 7B, D). In L. superciliosa , however, this second tooth is either small ( Fig. 7G) or can be as large as the inner one ( Figs. 1A, C, 7H).

Colour. In life, the carapace, chelipeds and ambulatory legs are red to pink, with the fingers dark-brown to almost black ( Figs. 23, 24A) (see also Richer de Forges & Ng, 2008: fig. 18; Ahyong et al., 2009: figs. 61, 62, 66, 67).

Ecology. A specimen of L. longirostris was observed by a submersible at a depth of 1212 m in the Mariana Island group (18.323°N 165.979°E) on 13 August 2016 carrying an unidentified sea anemone ( Fig. 23). Another Lamoha species , L. inflata ( Guinot & Richer de Forges, 1981) has also been observed to use the P5 to cling to and manipulate sea anemones. Chintiroglou et al. (1996) first reported that specimens of L. inflata caught in deep-water traps often carried a species of Isanthus ( Anthozoa, Actiniaria , Isanthidae ). They noted the crabs were caught from hard bottoms and suggested that because the “special chelate structure of the last pair of legs which is raised over the carapace, that the crab must be the active partner, probably manipulating the anemone with the P5 to take it off the substratum and to establish the association.” ( Chintiroglou et al., 1996: 22) (see also Guinot et al., 1995). The present photographs of a L. longirostris photographed in situ ( Fig. 23) in his natural hard bottom habitat carrying an unidentified anemone confirms their hypothesis. Another homolid, Paramola japonica ( Parisi, 1915) is also reported to carry sea anemones (see Wicksten, 1985; Guinot & Wicksten, 2015).