Macrophthalmus (Mareotis) pacificus Dana, 1851

(Figs. 1 E, F)

Macrophthalmus pacificus Dana, 1851: 248. — 1952: 314, pl. 19, fig. 4. — Tesch 1915: 190, pl. 8, fig. 11.

Macrophthalmus (Mareotis) pacificus — Barnes 1967: 218, pl. 2 (b), fig. 6; 2010: 37 (key). — Komai et al. 1995: 128, fig. 11.

Material examined. 1 male (9.45 x 12.36 mm), 1 ovig. (15.09 x 19.82 mm) (MZB Cru 3276), Kamora, 09.05.2003; 1 female (8.5 x 11.4 mm) (MZB Cru 3277), Otakwa, 09.07. July 2008; 1 male (13.10 x 18.20 mm), 1 female (8.60 x 12.20 mm) (ZRC 2011.1003), Kamora, 24 05.2007; 1 male (8.36 x 10.54 mm) (ZRC 2011.1004), Ajkwa I., Papua, 19.03.2008; 2 males (8.18 x 10.36 mm, 9.27 x 11.27 mm) (ZRC 2011.1005), Ajkwa, Papua, 02.04.2008; 1 male (8.6 x 11.7 mm) (RCLA-C.B.0268), Ajkwa, 13.04.2006; 7 males (6.54 x 7.45 – 8.36 x 10.36 mm), 6 females (5.64 x 7.09 mm – 8.72 x 10.73 mm) (RCLA-C.B.0269-0270), Ajkwa I., 26.03.2007, 22.06.2008; 2 males (10.54 x 13.27 mm, 11.11 x 15.21 mm) (RCLA-C.B.0271), Otakwa, 9 July 2008 ..

Remarks. This species is easily recognized by its smooth and shiny carapace, the light blue color of the chelipeds and the absence of mat of setae on the inner surface of the cheliped dactylus. The male cheliped figured by Komai et al. (1995) has a longitudinal ridge on the outer surface of the fixed finger, whereas Barnes (1967) did not mention it in his description or the figure. Most of the specimens studied had a faint longitudinal ridge on the outer surface of the cheliped dactyli.

Habitat. Muddy substrate of seaward fringe of mangrove forests and river mouths.

Geographical distribution. Widely distributed in the Indo-West Pacific from India across Malaysia to New Guinea, Solomon Islands, Ishigaki and Irimote islands in Japan, and Australia (Komai et al. 1995; Davie 2002). It was recorded from Pontianak, Indonesia (De Man 1895) and now Papua.