Tumidodromia dormia ( Linnaeus, 1763 ), 2009

Published, First, 2009, New records of crabs (Decapoda: Brachyura) from the New Zealand region, including a new species of Rochinia A. Milne-Edwards, 1875 (Majidae), and a revision of the genus Dromia Weber, 1795 (Dromiidae), Zootaxa 2111, pp. 1-66 : 19-23

Tumidodromia dormia ( Linnaeus, 1763)

( Figs 5a, b, 6a, b)

Cancer lanosus Rumphius, 1705: 19 , pl. 11, fig. 1. — Seba 1759: 42, pl. 18, fig. 1.

Cancer dormia Linnaeus, 1763: 413 : 1769: l043. — Fabricius 1775: 405.

Cancer dromia — Fabricius 1781: 501; 1787: 320: l793: 451 (erroneous spelling for dormia ).

Cancer dormitator Herbst , l790: 250, pl. 18, fig. 103.

Dromia rumphii Weber, 1795: 92 . — Fabricius 1798: 359. — Latreille 1803: 386; 1806: 27; 1818: 278, fig. 1. — Lamarck l818: 264. — Hilgendorf 1879: 812 (part, Mozambique). — Lenz 1901: 450. — de Man l902: 687. — Nobili 1906a: 144. — Edmondson 1922: 33, pl. l.

Dromia hirsutissima Dana, 1852: 403 (part).

Dromia dormia — Borradaile 1903: 298. — Macnae & Kalk 1958: 7 l, ll7, 125. — McLay 1993: 151, fig. 16c; 2001: 82.—Ng et al. 2000: 159, fig. 2a. —Ng et al. 2001: 5 (list). — Ng & Davie 2002: 370 (list). — Takeda & Manuel- Santos 2006: 84, fig. 1D.

Dromidiopsis dormia — Rathbun 1923b: 67. — Sakai 1936: 11, pl. 5, fig. 2. — Buitendjik 1939: 223. — Ward 1942: 70. — Tinker 1965: 66. — Holthuis 1968: 220. — Takeda 1973: 79. — Alcala 1974: 174, figs la, b. — Sakai 1976:9, pl. 3. — Dai, Yang, Song & Chen 1981: 131, figs l, 2, pl. 1 (1). — Lewinsohn 1984: 95, pl.2. — Dai & Yang 1991: 18, figs 4 (2, 3), pl. 1 (2).

[ Dromia ] dormia — Guinot & Quenette 2005: 287 , figs. 8 A, B, 9 A–C.

Not Dromia rumphii — H. Milne Edwards 1837: 174. — de Haan 1839: 107. — Stimpson 1858: 240; 1907: 177, pl.21, fig. 7. — Targioni-Tozzetti 1877: 207. — Ortmann 1892: 548. — Alcock 1900:137; l90l: 44, pl.2, fig. 4. — Borradaile 1903 b: 576, pl. 33, fig. 1 [= Dromidiopsis dehaani ( Rathbun, 1923b) ].

Not Dromia dormia – Rathbun 1902: 32. — Stebbing 1905: 61; l9l0: 342. — Ihle l9l3: 22. — Shen l93l: 96, figs 3a, b, 4 a, b. — Barnard 1950: 310, fig. 58c–e. [= Dromidiopsis dehaani ( Rathbun, 1923b) ].

Not Dromia dornica — Balss 1913: 109 (erroneous spelling for dormia ) (= Dromidia aegibotus Barnard, 1947 ).

Not Dromia dormia — Barnard 1947: 366 (= Dromidia aegibotus Barnard, 1947 ).

Material Examined. Taiwan, Ta-chi : ZRC2000.1819 , male, 130.2 mm x 103.3 mm, collected by P.K.L. Ng from local fishermen, Apr. 2000 .

Philippines, Pangalao, Balicasa I.: ZRC2002.0636 , female, 127.3 mm x 106.2 mm, collected in tangle nets by local shell fishermen, June 2002 .

Description (modified after McLay, 1993). Carapace wider than long (CW/CL = 1.1–1.2), strongly convex, rising steeply behind front and from anterolateral margins, covered by short velvety tomentum. Cardiac, branchial grooves shallow, as is frontal groove which extends back from median rostral tooth, separating two rounded protuberances. Frontal area narrowed, rostrum tridentate, median tooth large, blunt and extending further forward than lateral teeth, clearly visible dorsally. All 3 rostral teeth directed horizontally. Anterolateral carapace margin begins beneath suborbital level and bears 4 unequal teeth. The first tooth is by far the largest, second much smaller and more acute, third very small, close to the second and the fourth intermediate in size between the first and second narrow and more acute, directed slightly upward. Anterolateral teeth are arranged along an almost straight line connecting the rostrum and posterolateral tooth which is large, broad based, narrowing apically and directed anteriorly. Posterolateral carapace margin convergent and posterior margin almost straight. Supraorbital margin extends uninterrupted from lateral rostral tooth, concave to postorbital corner where there is a narrow fissure. Suborbital margin has small rounded lobe which is almost vertical rather than horizontal. Immediately beneath suborbital margin is large, prominent suborbital tooth which is clearly visible dorsally, and beneath this again is more acute tooth at corner of buccal frame, also visible dorsally. Sternal grooves in female gradually convergent, ending with divergent tips between bases of chelipeds, separated by prominent smooth ridge.

First article of antenna much wider than long, beaked medially, gaping narrowly, not twisted. Epistome triangular with smooth convex surface.

Chelipeds (P1) massive. Merus trigonal, posterior margin with 7–8 small tubercles, inferior margin with 4–5 larger tubercles, anterior margin smooth. Outer surface of carpus sculptured, distal margin with two blunt extensions, superior margin with strong, acute distal tooth. Outer face of propodus inflated, inner superior margin with 4 tubercles, inner face covered with shaggy tomentum. Fixed finger armed with 7–8 large conical teeth. Dactylus with 8 teeth, the first large, blunt, second to fourth much smaller, fifth large, more acute, the last three much smaller. Fingers down curved, only last four teeth interlocking. Ratio of width to length of sternite 4 of approximately 1.9 (male) to 2.2 (female).

First two pairs of legs (P2 & P3) shorter than chelipeds, distal borders of carpi and propodi produced as rounded lobes. Dactyli much shorter than propodi, inner margins armed with 4–5 strong spines, set at an angle close to the dactylus and increasing in size distally.

Last 2 pairs of legs (P4 & P5) reduced, fourth pair slightly shorter and stouter. Dactylus of third leg (P4) opposed by strong propodal spine, no spine on outer propodal margin. Dactylus of fourth leg (P5) opposed by two similar spines with another small spine on outer propodal margin.

Telson about as wide as long, central longitudinal furrow present distally, central region distally convex which continues along adominal somites. Abdominal locking mechanism in male consists of large serrated boss on bases of first legs against convergent margin of penultimate somite with well developed uropods in front of bosses. All somites of abdomen freely movable in both sexes.

G1 a semi-rolled tube, bluntly tipped and setose, G2, needle-like, without exopod.

Remarks. Because of its large size and occurrence in shallow waters, T.dormia was one of the earliest dromiids collected. Because there are several large Indo-West Pacific dromiids, however, there has been much confusion about the identity of these species. The main problem was the separation of T. dormia ( Linnaeus, 1763) from “ Dromia rumphii ” Weber, 1795 . Rathbun (1923) pointed out that these two names had been used rather indiscriminately for two different species and provided a partial answer to the difficulties by erecting “ Dromidiopsis dehaani ” Rathbun, 1923 for some of the specimens that had been called “ Dromia rumphii ”. Lewinsohn (1984) also helped to clarify the situation, but placed T. dormia in “ Dromidiopsis dormia ”. The revision of the Dromiidae by McLay (1993) showed that the genus Dromidiopsis in fact contains only rather small-size dromiids and should not include either of the two above species. McLay (1993) used “ Dromia dormia” ( Linnaeus, 1763) and erected a new genus, Lauridromia McLay, 1993 . This allowed “ Dromia rumphii ” and “ Dromidiopsis dehaani ” to be placed in Lauridromia dehaani (Rathbun, 1923) . T. dormia and L. dehaani can be easily separated using some simple characters. In T. dormia , the anterolateral carapace margin is armed with 4 unequal teeth, first largest (anterolateral margin in L. dehaani armed with 3 teeth); the posterolateral carapace tooth is large, broad-based, blunt and directed anteriorly (posterolateral tooth similar to anterolateral teeth, pointed, directed laterally in L. dehaani ); the inner margins of the dactyli of the first two pairs of walking legs (P2 and P3) are armed with 4 or 5 strong spines (16–20 small spines in L. dehaani ); the female sternal grooves 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 in L. dehaani ); all the abdominal somites are freely moveable (joint between fifth and sixth somites partially fused in L. dehaani ). T. dormia is covered in an evenly short, dense, light brown tomentum whereas in L. dehaani the tomentum is longer and less dense. Lewinsohn (1984) also lists differences between these two species as well as L. intermedia Laurie, 1906 .

Specimens are often caught in shallow depths by fishermen and SCUBA divers.

Maximum recorded sizes are male 200 mm x 160 mm, female 172 mm x 136.5 mm. T. dormia is the largest known sponge crab and as such it is often collected, but the whereabouts of small specimens (CW<50 mm) remains a mystery. Perhaps they take shelter in coral reef crevices, but they should then be occasionally taken by divers.

Only two ovigerous T. dormia females have been collected: the first a female 112.2 mm x 95.6 mm, from New Caledonia, carrying approximately 24,000 eggs (0.5 mm diam.) ( McLay, 1993), and the second a female 137.3 mm x 104.0 mm from the Marquesas Is, carrying approximately 129, 600 new eggs, 0.5 mm diam.). T. dormia is a dromiid that produces large numbers of relatively small eggs, especially for a dromiid crab, and is similar to L. dehaani . T. dormia has a very wide geographic distribution, like G. wilsoni , but has much larger brood sizes. Larvae are not known for this species.

Tumidodromia dormia has been recorded carrying sponges ( Hyattella sp. ), sometimes clearly insufficient for the purpose of total concealment and covering only 40% of the body, the posterior third of the carapace (McLay, 2001). Edmondson (1946) provides several records and some interesting examples of the use of diverse varieties of camouflage carried by Hawaiian T. dormia : in one case a hollowed out piece of wood and in another an old shoe sole. Clearly, individual improvisation is possible in this species.

Distribution Tumidodromia dormia is found in the Indo-West Pacific region, from the Red Sea, East Africa, Madagascar, Seychelles, Mauritius, China, Japan, Ambon ( Indonesia), Philippines, New Caledonia, Hawaiian Is, and Marquesas Is ( French Polynesia). Depth range is 8– 112 m.