Uca (Austruca) mjoebergi Rathbun, 1924

Naderloo, Reza, Türkay, Michael & Chen, Hui-Lian, 2010, Taxonomic revision of the wide-front fiddler crabs of the Uca lactea group (Crustacea: Decapoda: Brachyura: Ocypodidae) in the Indo-West Pacific, Zootaxa 2500, pp. 1-38 : 22

Uca (Austruca) mjoebergi Rathbun, 1924

( Figs. 12 d–f, 13a–j, 14b, 15b)

Uca mjobergi Rathbun 1924: 9 .

Uca lactea mjoebergi — Crane 1975: 299, figs. 17A–C, 19O–P, 54H, 69B.

Uca mjoebergi — George & Jones 1982: 10 (in key), 80–83, figs. 4b, 7a, 53a–f, 58d. — von Hagen & Jones 1986: 57 (in key), 66. — Morgan 1990: 62, 69 (in list). — Davie 2002: 362. — Shih et al. 2009: 377. — Barnes 2010: 250, fig. 1.

Material examined. Indonesia: 1 male ( NNM 32589), Indonesia, Irian Jaya (= Western New Guinea), mangroves near Kampong Madong, between Mokmer and Bosnek, SE Biak, 20.02.1955, leg. L.B. Holthuis; 34 males, 14 females (UZM), 1 male ( SMF 17163), Banda-Isles, Lontor, Coast near Lavvande, 0 6.06.1922, "Dan. Expedition to the Kei Islands, 1922"; 2 males, 1 female (UZM), same locality and expedition, 0 7.06.1922.

Australia: Northern Territory: 2 males ( NHMB 574C), Port Darwin, 1eg. E. Handschin. —Western Australia: 10 males, 13 females ( ZMH), 2 males, 2 females ( SMF 17155), Broome, mangroves, 24.11.1975, leg. G. Hartmann & G. Hartmann-Schröder; 10 males, 2 females ( ZMH); 2 males ( SMF 17156), Harbour, 1 km E. of Onslow, about 500 m. from mouth of Beadon Creek, 0 7.06.1975, leg. G. Hartmannn & G. Hartmann- Schröder; 12 males, 4 females ( ZMH), Exmouth, external side of peninsula, Reef near Tantabiddy Creek, 11.10.1975 or Carnavon, Pelican Point, inner beach with mangroves, 13.10.1975, leg. G. Hartmann & G. Hartmann-Schröder.

Western Samoa: 1 male (SMF 5676), Upolu, vend. Mus. Goddefroy [this locality is probably wrong].

Diagnosis. Front broad. Anterolateral borders of carapace slightly convergent. Palm of major male chela ( Figs. 13 c, d) without supramarginal groove adjacent to lower margin; oblique ridge at inner surface low. G1 generally as in U. annulipes , but horny endpiece comparatively broader, directed remarkably in a dorsolateral direction ( Fig. 13 e), mesial border of stem between palp and endpiece bulging outward.

Distribution. Australia: Northern Territory and Western Australia, New Guinea (where it probably is sympatric with U. annulipes ), central Indonesia (Sulawesi Tenggara, Pulau Kaledupa) sympatric with U. perplexa ( Barnes 2010) .

Remarks. The most reliable characters to recognise this species is the shape of the G1, especially the curb in the distal part of stem adjacent to the horny endpiece as well as its convexity, of course with a certain amount of variability (see Figs. 11 f–i). It is easily distinguished from U. perplexa by the lack of the supramarginal groove at the outer surface of the palm of the large male chela. From U. annulipes it can be also easily distinguished by this last character. All Australian specimens examined are typical both in the shape of the G1 and the palm of the male chela. In the examined specimens also the oblique ridge on the inner surface of large male chela palm is typically low as described by Crane (1975) and George & Jones (1982). In U. annulipes this crest is typically high, but there is a certain amount of variability in this character, so that it cannot be used as good discrimination character. In the specimens from the Banda Archipelago different forms of G1 were found, exhibiting some variations from typical U. annulipes to typical U. mjoebergi (see Fig. 11 f–i). The specimen from New Guinea identified by Crane (1975) as U. mjoebergi is quite typical in the major chela. Regarding the features of median and lateral teeth of the gastric mill, this species is readily separated from all other members of this group. The median tooth plate ( Fig. 14 b) has four teeth, the two first ones being variable in size, the third and fourth ones nearly equal, one very small tooth attached dorsally to the basal plate. The lateral tooth plate ( Fig. 15 b) is typical in having a shoe-shaped form, with 17 combshaped teeth. U. mjoebergi has a local distribution in northern and Western Australia (Davie 2002). There are also specimens from western New Guinea, where it is likely sympatric with U. annulipes . More recently, Barnes (2010) recorded this species from Sulawesi Tenggara in central Indonesia in sympatry with four different species of fiddler crabs, including U. perplexa from the present group. These records from outside Australia extend its distiribution north to South East Asia, but still within Wallacea.

Figures

FIGURE 11. Uca lactea (De Haan, 1835): a, female (SMF 17159) Taiwan; b, c, paralectotype male (ZMG 105), Japan; a, genital opening; b, apical part of G 1, lateral surface; c, apical part of G 1, mesial surface.

FIGURE 12. Uca annulipes (H. Milne Edwards, 1837): a, b, Mozambique, Inhaca Island; c, Thailand, Phuket, Ao Tang Kheng. d – f, Uca mjoebergi Rathbun, 1924: d, Indonesia, Sulawesi Tenggara; e, f, Australia, Darwin Island;. Photos credits: a, b, e, f by T. Detto (The Australian National University); c by S. Komai (Natural History Museum and Institute, Chiba, Japan); d by R. S. K. Barnes (Cambridge University).

FIGURE 13. Uca mjoebergi Rathbun, 1924. a – e, male (SMF 17156), Western Australia, 1 km E. Onslow; f – i, males (ZUM), Banda Islands; j, female (SMF 17155), Western Australia, Broome. a, merus of major chela, outer surface; b, merus of major chela, inner surface; c, major chela, outer surface; d, major chela, inner surface; e, G 1, lateral surface. f, g, h, i, apical part of G 1, lateral surface; j, genital opening of female.

FIGURE 14. Median tooth of the gastric mill, ventral face. a, Uca lactea (De Haan, 1835), male (SMF 17161); b, Uca mjoebergi Rathbun, 1924, male (SMF 17163).

FIGURE 15. Lateral tooth of the gastric mill, mesial face. a, Uca lactea (De Haan, 1835), male (SMF 17161); b, Uca mjoebergi Rathbun, 1924, male (SMF 17163).