Hepatoporus guinotae ( Zarenkov, 1971 ), 1984

Mendoza, Jose Christopher E., 2021, Marine crabs new to Singapore, with a description of a new species of intertidal xanthid crab of the genus Macromedaeus Ward, 1942 (Crustacea: Decapoda: Brachyura), Raffles Bulletin of Zoology 69, pp. 463-480 : 465-467

Hepatoporus guinotae ( Zarenkov, 1971)

( Figs. 2 , 3 )

Carpoporus guinotae Zarenkov, 1971: 191 , fig. 86 (type locality: Red Sea).

Hepatoporus guinotae Serène, 1984: 75 , fig. 40, pl. 10 figs. D–F. — Davie & Turner, 1994: 83, fig. 1A, B. — Ng et al., 2008: 199 (list). — Naderloo, 2017: 252, figs. 21.20d, 21.25. — Takeda & Komatsu, 2018: 161, figs. 1D, 2B. — Maenosono, 2021: 25, figs. 1E, 3.

Carpoporoides distinctus Takeda & Nagai, 1986: 549 , fig. 1a, b.

Material examined. 1 male, 8.5 × 6.6 mm ( ZRC 2019.0663 ), Singapore, Pulau Hantu , seabed, rubble, night dive, 10 m, coll. C. H. Toh, 16 March 2019 .

Remarks. Zarenkov (1971) described Carpoporus guinotae from the Red Sea. Serène (1984) erected the genus Hepatoporus to separate the Indo-West Pacific species ( C. orientalis Sakai, 1935 , and C. guinotae ) from the Atlantic, and type, species, C. papulosus Stimpson, 1871 ; and with C. orientalis designated as type species for Hepatoporus . Subsequently, other species were described from Japan ( H. distinctus ( Takeda & Nagai, 1986)) , Australia ( H. asper Davie & Turner, 1994 ), and the Philippines ( H. pumex Mendoza & Ng, 2008 ). Davie & Turner (1994) also reported H. guinotae from northwestern Australia, and further suggested that H. distinctus is possibly synonymous with H. guinotae due to the lack of morphological distinctions beyond the shape of their subhepatic cavities. Subsequent reports of H. guinotae from Japan (i.e., Ogasawara Islands and Okinawa Island) supported this synonymisation ( Takeda & Komatsu, 2018; Maenosono, 2021), suggesting that the shape of the subhepatic cavity of H. guinotae undergoes size-related variation to some degree. The validity of this synonymisation will have to be evaluated rigorously when all material reported thus far, especially the types of C. guinotae Zarenkov and C. distinctus Takeda & Nagai , as well as additional material from the entire range of H. guinotae , can be examined side by side.

The present specimen from Singapore ( Figs. 2 , 3 ) agrees well with the description and illustrations of H. guinotae (cf. Zarenkov, 1971: fig. 86; Serène, 1984: pl. 10 figs. D–F; Naderloo, 2017: figs. 21.20d, 21.25; Takeda & Komatsu, 2018: figs. 1D, 2B; Maenosono, 2021: figs. 1E, 3). The reticulate pattern of connected granules and small cavities on the dorsal surface of the carapace is prominent and widespread in the present specimen ( Fig. 2A ), similar to that seen in a much larger (CW 17.0 mm) specimen from Kenya (cf. Serène, 1984: pl. 10 fig. D), whereas similarly sized or smaller specimens tend to have less prominent pits, giving the dorsal carapace a smoother appearance ( Naderloo, 2017: fig. 21.25; Takeda & Komatsu, 2018: fig. 2B). Similarly, this reticulate pattern can also be seen in the external surfaces of the chelae ( Fig. 2E ) and on the thoracic sternum and pleon ( Fig. 2G, H ). The dorsal border of the subhepatic cavity slopes continuously towards the posterior ( Serène, 1984: pl. 10 fig. D). The subhepatic cavity itself ( Fig. 2C, D ) has a well-developed dorsal roof, which is seen in most specimens of H. guinotae except for the holotype of H. distinctus , where the dorsal roof is mostly effaced (cf. Takeda & Nagai, 1986: fig. 1a). The presence of capped, mushroom-like (fungiform) spines on the ventral floor of the subhepatic cavities appears to be a consistent feature for this species; in the Singapore specimen, there are two such spines in each cavity (cf. Serène, 1984: 75). The G1 of the present specimen ( Fig. 3B–D ) closely resembles the illustration by Serène (1984: fig. 40) for a slightly larger male from Madagascar in the lobulation of the distal tip, although the former is relatively more slender and has fewer subdistal setae.

The live colouration of the Singapore specimen ( Fig. 3A ) is orange, with scattered and small patches of white on the carapace and pereopods. In life, the specimen was lightly covered with silt.

Hepatoporus guinotae is currently known from the Red Sea, the type locality ( Zarenkov, 1971); Madagascar and the coast of Kenya ( Serène, 1984); the Gulf of Oman ( Naderloo, 2017); the Northwest Shelf, Australia ( Davie & Turner, 1994); Kii Peninsula, central Japan ( Takeda & Nagai, 1986), the Ogasawara Islands ( Takeda & Komatsu, 2018), Okinawa, southern Japan ( Maenosono, 2021); and now also from Singapore.

Figures

Fig. 2. Hepatoporus guinotae (Zarenkov, 1971), male, 8.5 × 6.6 mm (ZRC 2019.0663), Pulau Hantu, Singapore. A, habitus, dorsal view; B, eyes, antennae, and third maxillipeds, anteroventral view; C, cephalothorax, anterior view; D, left subhepatic cavity, anterolateral view; E, right chela, external view; F, right P4 and P5, dorsal view; G, male thoracic sternum and pleon, ventral view; H, male thoracic sternum and pleon, posteroventral view. Scale bars: A = 2.0 mm; B–H = 1.0 mm.

Fig. 3. Hepatoporus guinotae (Zarenkov, 1971), male, 8.5 × 6.6 mm (ZRC 2019.0663), Pulau Hantu, Singapore. A, in situ photograph showing live colouration (photographed by Toh Chay Hoon); B, left G1, pleonal view; C, distal tip of left G1, pleonal view; D, distal tip of left G1, sternal view. Scale bars: B = 0.5 mm; C, D = 0.25 mm.