Medaeops edwardsi Guinot, 1967

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 : 467-469

Medaeops edwardsi Guinot, 1967

( Fig. 4 )

Medaeops edwardsi Guinot, 1967: 369 , figs. 33, 42; 1971: 1073 (type locality: Malabar Coast, SW India). — Serène, 1984: 92, fig. 53, pl. 12 fig. E. — Ghani & Tirmizi, 1992: 54, fig. 20. — Ng et al., 2008: 199 (list). — Naderloo, 2017: 260, figs. 21.34, 21.35.

Material examined. 1 female, 24.5 × 15.7 mm ( ZRC 1996.2637 ), Singapore, Pasir Ris, coll. P. K. L. Ng, April 1982 .

in the present specimen ( Fig. 2A ), similar to that seen in a smaller specimen from Okinawa (cf. Maenosono, 2021: figs. 1E, 3A), whereas in other specimens, the dorsal border either curves laterally ( Davie & Turner, 1994: fig. 1A; Naderloo, 2017: fig. 21.25) or, as in large individuals, recurves anteriorly Remarks. Guinot (1967) described Medaeops edwardsi based on a male specimen from the Malabar Coast, southwestern India, and a female specimen purportedly from Madagascar (see also Serène, 1984). Ghani & Tirmizi (1992) subsequently reported several specimens from the coast of Pakistan on the Arabian Sea. Mendoza et al. (2009) reported a specimen of M. edwardsi included among the type material of M. granulosus ( Haswell, 1882) , which had been collected from Queensland, Australia. The present specimen from Pasir Ris, Singapore, was found in the ZRC misidentified as “ Macromedaeus distinguendus ”. It agrees well with the figures and description of M. edwardsi , particularly in having the transversely subovate, fan-shaped carapace, where the anterolateral margin is divided into four denticulate lobes (not teeth) separated by thin fissures ( Fig. 4A ), the relatively sharp (not spoon-tipped) fingers of the chelae ( Fig. 4G ; seen in the minor chela only as the fingertips have been broken off in the major chela) and the presence of a short tomentum on the dorsal carapace and pereopods ( Fig. 4F–H ), although much of this tomentum has been abraded off in the process of brushing the specimen clean of debris (cf. Guinot, 1967: fig. 33; Serène, 1984: pl. 12 fig. E; Ghani & Tirmizi, 1992: fig. 4; Naderloo, 2017: fig. 21.34). The present specimen differs, however, in having the frontal median cleft gaping wider (it is a narrow cleft in the holotype), and having larger and more prominent denticles on the carapace anterolateral margin (much smaller in the holotype) ( Fig. 4A ). However, these morphological differences seen in a single specimen are not sufficient to make taxonomic distinctions, not unless more material is collected and these differences are seen to be consistent. The vulvae ( Fig. 4E ) are also shown here for the first time: they are oval in outline, and open mesially and upward. The sixth sternite on which they are placed has the mesial portion being angular and projecting and abruptly intercepting the fifth sternite, arresting its progress toward the midline of the thoracic sternum.

Medaeops edwardsi is currently known from the Malabar Coast of India (type locality) and possibly Madagascar ( Guinot, 1967; Serène, 1984), Pakistan ( Ghani & Tirmizi, 1992), eastern Australia ( Mendoza et al., 2009), the Gulf of Oman ( Naderloo, 2017), and now also from Singapore.

Figures

Fig. 4. Medaeops edwardsi Guinot, 1967, female, 24.5 × 15.7 mm (ZRC 1996.2637), Pasir Ris, Singapore. A, habitus, dorsal view; B, eyes, antennae, and third maxillipeds, anteroventral view; C, cephalothorax, anterior view; D, female thoracic sternum and pleon, ventral view; E, female thoracic sternum and vulvae, ventral view; F, left P4 and P5, dorsal view; G, left (minor) chela, external view; H, right (major) chela, external view. Scale bars: A = 10.0 mm; C, D, F–H = 5.0 mm; B, E, 3.0 mm.

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.