Metadromia, Published, 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 : 15-17

Metadromia gen. nov.

Dromia McLay, 1993: 149 (part).

Definition Carapace oval, wider than long (CW/CL> 1.2), surface smooth or sculptured, covered by fine, rippled tomentum. Rostrum tridentate. Female sternal grooves end apart between or behind cheliped bases. Prominent subhepatic tooth at or below level of suborbital margin, 3 well developed anterolateral teeth. Branchial groove well marked with small tubercle near base of posterolateral tooth. Cheliped with epipod, well developed, blunt teeth, fingers not gaping. Anterior extension of sternite 4 short, margins parallel, truncated anteriorly, ratio of width of sternite 4 to length approximately 1.0, episternites extending laterally between coxae of cheliped (P1), first walking leg (P2). Walking legs (P2–P5) knobbed, length of propodi, dactyli usually equal, inner margins of dactyli with 5–7 small spines. P4 dactylus opposed by propodal spine, no spine on the outer propodal margin (there may be some small spines on margin of inner dactylus). Fourth leg (P5) shorter than second leg (P3), dactylus opposed by a single spine, with sometimes another spine on the outer propodal margin. External surface of abdomen sculptured, margin of telson rounded. Uropod plates well developed, visible externally, used in male abdominal locking mechanism by fitting in front of serrated flange on bases of first legs (P2). All somites of abdomen freely movable in both sexes. Vestigial pleopods may be present on third-fifth somites in males.

Type Species: Cryptodromia wilsoni Fulton & Grant, 1902 .

Included Species: Metadromia wilsoni ( Fulton & Grant, 1902) .

Etymology. The generic name Metadromia is a combination of meta, meaning “after” or “beyond” and the genus Dromia . Gender is feminine.

Distribution Metadromia is the most widespread genus of all the dromiids as its distribution includes the Indo-West Pacific and South Atlantic. The only species, M. wilsoni , occurs in cooler waters: in tropical areas it is found in greater depths whereas in temperate areas it can be found in much shallower depths, even in the intertidal.

Discussion. Fulton & Grant (1902) placed their new species in Cryptodromia Stimpson, 1858 , before the generic definition was revised. Borradaile (1903) made an important addition to generic characters in the Dromiidae when he stated that a cheliped epipod is absent in Cryptodromia but present in Petalomera Stimpson, 1858 . Applying this new definition Rathbun (1923) changed the Australian species to Petalomera , but this was never correct because it lacked the essential defining feature of this genus, having petaloid meri on the first two pairs of pereopods. Finally in his revision of Petalomera, McLay (1993) transferred it to Dromia , but not without some misgivings. The comparison of larval characters by Lim and Ng (2001), which was based on groupings of species on the basis of adult characters by McLay (1993), showed that it was apparent that Cryptodromia wilsoni did not belong in Dromia and thus deserved a new genus.