Dromia dormia ( Linnaeus, 1763 )

Mclay, Colin L. & Ng, Peter K. L., 2005, On a collection of Dromiidae and Dynomenidae from the Philippines, with description of a new species of Hirsutodynomene McLay, 1999 (Crustacea: Decapoda: Brachyura), Zootaxa 1029 (1), pp. 1-30 : 12-13

Dromia dormia ( Linnaeus, 1763)

Cancer dormia Linnaeus, 1763: 413

Cancer dormitator Herbst, 1790: 250 , pl. 18, fig. 103.

Dromia rumphii Weber, 1795: 92 .De Man 1902: 687.

Dromia hirsutissima Dana, 1852: 403 (part).

Dromia dormia . Borradaile 1903 a: 298.— McLay 1993: 151, fig. 16c.— Ng et al. 2000: 159, fig. 2a.— Ng et al. 2001: 5.

Dromidiopsis dormia .— Rathbun 1923: 67.— Buitendijk 1939: 223.— Alcala 1974: 174, figs. 1a–b. — Sakai 1976: 9, pl. 3.— Lewinsohn 1984: 95, pl. 2.

Not Dromia dormia .— Ihle 1913: 22 [= Lauridromia dehaani ( Rathbun, 1923) ].

Material. 1 male, 96.3 x 78.6 mm, 1 female, 126.9 x 106.8 mm, reefs, Balicasag Island , Philippines, ca. 10 m water, coll. local fisherman, Jun 2002, ZRC 2002.636 .

Remarks. In the past, Dromia dormia has often been confused with Lauridromia dehaani ( Rathbun, 1923) because both are large dromiids with a carapace much wider than long, but there are some simple characters that can be used to separate them. In D. dormia , the anterolateral carapace margin is armed with four unequal teeth, first largest (anterolateral margin in L. dehaani armed with three teeth); the posterolateral carapace tooth is large, broad­based, blunt and directed anteriorly (posterolateral tooth similar to anterolateral teeth, pointed, directed laterally); the inner margins of the dactyli of the first two pairs of walking leg are armed with 4 or 5 strong spines (16–20 small spines in L. dehaani ); the female sutures 7/8 are convergent, ending between the cheliped bases with the spermathecal openings separated by a ridge (7/8 sutures end apart with spermathecal openings at base of well developed tubes behind chelipeds); and all the abdominal segments are freely moveable (joint between fifth and sixth segments partially fused). Dromia dormia is covered in a short, dense, light brown tomentum whereas in L. dehaani the tomentum is longer and less dense. The cheliped fingers in D. dormia are usually white while in L. dehaani , they are usually pink. Lewinsohn (1984) lists differences between these two species as well as L. intermedia Laurie, 1906 .

Dromia dormia is one of the largest dromiid crabs, reaching carapace widths of 200 mm in males and 172mm in females. The female (123.9 x 104.4 mm) had plugged spermathecal apertures, indicating that it had mated recently.

A mystery regarding D. dormia is where do they live when they are small? Almost all the reported specimens exceed 50 mm in carapace width.

Distribution. Includes the Indian Ocean, Amboina, New Caledonia, Philippines, China, Japan, Hawaii and Marquesas Islands, French Polynesia.