Oxypleurodon fultoni ( Grant, 1905 ) Yan & Lee & Forges & Ng, 2021

Yan, Bee, Lee, Forges, Bertrand Richer De & Ng, Peter K. L., 2021, The generic affinities of the Indo-West Pacific species assigned to Rochinia A. Milne-Edwards, 1875 (Crustacea: Brachyura: Majoidea: Epialtidae), Raffles Bulletin of Zoology 69, pp. 19-44 : 28-31

Oxypleurodon fultoni ( Grant, 1905) , new combination

( Figs. 6A–C , 8C, D )

Hyastenus Fultoni Grant, 1905: 313 , pl. 11 fig.1 (type locality: off Port Jackson ).

Scyramathia fultoni – Rathbun, 1918: 14, pl. 5.

Hyastenus fultoni – Griffin, 1966: 268.

Rochinia fultoni – Griffin, 1966: 280 (key) [new combination]. – Griffin, 1972: 71. – Serène & Lohavanijaya, 1973: 55 (key). – Griffin & Brown, 1976: 253, 254. – Griffin & Tranter, 1986a: 176 (key). – Davie, 2002: 329. – Poore, 2004: 387, fig. 118f. – Casadío et al., 2005: 159 (list). – Ng & Richer de Forges, 2007: 62 (list). – Ng et al., 2008: 105 (list). – Richer de Forges & Poore, 2008: 68, fig. 2a. – Ng & Richer de Forges, 2013: 363, fig. 5F. – Richer de Forges & Ng, 2013: 470, figs. 2A, 3A–C, 8A–D. – Tavares & Santana, 2018: 223 (list).

Material examined. Holotype: male (8.2 × 5.1 mm) (AM G.5427), East of Port Jackson, New South Wales, 457 m, coll. WF Pettard. Others: Australia: 1 male (with bopyrid; 10 × 7.4 mm), 2 females (with bopyrids; 8.0 × 6.1 mm, 7.2 × 8.21 mm) (NHM 1906.11.13.1–3), off Port Jackson, no other data. – 1 male (23.0 × 15.3 mm), 1 female (14.8 × 10.0 mm) (AM P.46505), east of Brush Island , New South Wales, 25 ° 32′S 150 ° 44′E, 264–282 m, coll. FRV “Kapala”, 21 October 1975. – 5 males (29.5 × 13.4 mm, 29.1 × 12.7 mm, 15.4 × 10.1 mm, 14.6 × 9.2 mm), 4 females (17.9 × 11.7 mm, 15.3 × 10.0 mm, 14.3 × 9.5 mm, 13.0 × 8.0 mm) (AM P.68743), east of Broken Bay , east of Sydney , New South Wales, 33 ° 35′S 151 ° 56′E, 70–80 m, coll. 29 October 1981. – 5 males (20.2 × 13.2 mm, 18.9 × 12.3 mm, 14.0 × 9.1 mm, 13.6 × 8.8 mm), 5 ovigerous females (16.9 × 11.0 mm, 16.8 × 10.7 mm, 16.5 × 11.0 mm, 13.5 × 8.7 mm), 1 female (17.1 × 11.2 mm) (AM P.25036), southeast of Broken Bay , New South Wales, 33 ° 26′43″S 151 ° 50′21″E, 329 m, coll. FRV “Kapala”, 5 October 1976. – 2 males (13.6 × 8.6 mm, 11.8 × 7.5 mm), 2 females (16.1 × 10.7 mm, 14.6 × 9.0 mm) (ZRC 1965.10.14.38–41), south of Cape Everard , Victoria, coll. 16 June 1929. Solomon Islands: 1 male (13.6 × 8.4 mm), 1 female (14.4 × 9.2 mm) (ZRC 2011.1057), stn CP2832, Coloman Island , 10 ° 44.54′S 162 ° 19.65′E, 410–430 m, coll. SALOMON BOA Cruise, 21 September 2007. – 1 male (15.2 × 9.4 mm) (ZRC 2011.1062), stn CP2812, Solomon Islands , 9 ° 42.71′S 161 ° 31.04′E, 280–326 m, coll. SALOMON BOA Cruise, 18 September 2007. Papua New Guinea: 1 ovigerous female (18.6 × 11.8 mm) (MNHN- IU-2013-2343) [photographed], stn CP4259, northeast New Ireland, Bismarck sea, 02°53′S 151°06′E, 370–429 m, coll. MADEEP Expedition, 25 April 2014. – 1 ovigerous female (17.6 × 10.9 mm) (MNHN-IU-2013-2398) [photographed], stn DW4280, north Bougainville Island, Solomon Sea, 05°40′S 154°02′E, 386 m, coll. MADEEP Expedition, 28 April 2014. – 1 male (16.5 × 10.7 mm) (ZRC 2018.1487, ex. MNHN-IU-2013-3034) [photographed], stn CP4337, Ainto Bay , southeast New Britain, Solomon Sea, 06°07′S 149°17′E, 287–447 m, coll. MADEEP Expedition, 7 May 2014. – 1 male (14.4 × 9.2 mm), 1 ovigerous female (15.9 × 10.1 mm) (ZRC 2018.1488, ex. MNHN-IU-2011-1286), stn DW3734, Papua New Guinea, 08°16′S 150°30′E, 389 m, coll. BIOPAPUA, 9 October 2010. – 1 ovigerous female (16.5 × 10.2 mm) (ZRC 2018.1489, ex. MNHN- IU-2015-585), stn CP4259, Gazelle Channel, northeast New Ireland, Bismarck Sea, 02°53′S 151°06′E, 370–429 m, coll. MADEEP Expedition, 25 April 2014. – 1 female (12.9 × 7.8 mm) (MNHN-IU-2011-3292), stn DW3733, off Lancasay Islands and reefs, 08°16′S 150°30′E, 353 m, coll. BIOPAPUA, 9 October 2010. – 1 female (12.1 × 7.4 mm) (MNHN-IU-2011-1272), stn DW3641, Tami Island , Gulf of Huon , 06°45′S 148°01′E, 380–476 m, coll. BIOPAPUA, 24 August 2010.

Comparative material examined. See Appendix 1.

Remarks. As discussed earlier, of the five groups of “ Rochinia ” recognised by Ng & Richer de Forges (2013: 363, fig. 5F), R. fultoni was in its own group because of its carapace and male thoracic sternal features. Oxypleurodon fultoni was described from two males and four females from the east coast of Australia, with one measured male designated as the holotype by Grant (1905). This species lacks the typical carapace plates that are distinct in most Oxypleurodon species (see Richer de Forges & Ng, 2009b). It is, however, morphologically close to O. sphenocarcinoides ( Rathbun, 1916) , which has long been regarded as an atypical member of the genus in that it also lacks large and distinctive carapace plates (see Richer de Forges, 1995: pl. 3 fig. A, B; Richer de Forges & Ng, 2009b: fig. 3f). Rochinia fultoni , however, does possess other characters of Oxypleurodon , such as the lobe-like supraorbital eave with sharp preorbital angle ( Fig. 6C ), and the male thoracic sternum is concave anteriorly with sternites 3 and 4 narrow and the lateral margins constricted medially ( Fig. 6B ). The posterior region of the carapace for R. fultoni actually forms a slightly raised ridge, which is similar to the plate-like structure seen in the carapace posterior regions of more typical species of Oxypleurodon . The pterygostomial region is also similar between O. sphenocarcinoides and R. fultoni , with both species possessing distinct granules on the outer margin ( Fig. 6B ) instead of a single raised plate-like granule like on congeners ( Fig. 6A ). As such, the present morphological data indicates that Rochinia fultoni should be transferred to Oxypleurodon . In an unpublished molecular phylogeny of the genus using three mitochondrial (COI, 12S, 16S) and two nuclear (18S, H3) genes (Lee BY, in prep), O. fultoni , new combination, also clusters with other Oxypleurodon species , far from Samadinia as defined here.

It is possible that O. fultoni and O. sphenocarcinoides form a distinct species-group in Oxypleurodon with the shared character of lacking carapace plates. There are also other species-group in Oxypleurodon that were discussed by Richer de Forges & Ng (2009b), some of which are morphologically close to Stegopleurodon Richer de Forges & Ng, 2009 . It is likely that Oxypleurodon is polyphyletic and more work will need to be done to revise the genus.

Distribution. This species is known from southeastern Australia (Port Jackson, New South Wales, and Victoria) to Tasmania (Cape Pillar) ( Grant, 1905; Richer de Forges & Poore, 2008; Richer de Forges & Ng, 2013), and PNG ( Lee et al., 2019). The depth range observed is 314– 456 m.

Figures

Fig. 6. A–C, Oxypleurodon fultoni (Grant, 1905) new combination, holotype male (8.2 × 5.1 mm) (AM G.5427), Australia; D–F, Pugettia vesicularis (Rathbun, 1907) new combination, holotype male (14.6 × 10.6 mm) (USNM32860), Galapagos. A, D, overall dorsal view; B, E, overall ventral view; C, F, lateral view of carapace.

Fig. 8. A–C, Siderochinia kagoshimensis (Rathbun, 1932) new combination, holotype male (11.2 × 6.8 mm) (USNM 48253), Japan; D–F, S. aglaos, new species, holotype male (10.7 × 6.9 mm) (ZRC 2016.0549), South China Sea. A, D, side view of cardiac spine; B, E, dorsal view of intestinal spine along lateral carapace margin; C, F, dorsal view of P5.