Mursia Leach, 1823

Schweitzer, Carrie E. & Feldmann, Rodney M., 2010, New fossil decapod crustaceans from the Remy Collection, Muséum national d’Histoire naturelle, Paris, Geodiversitas 32 (3), pp. 399-415 : 404

Genus Mursia Leach, 1823

TYPE SPECIES. — Mursia cristiata H. Milne Edwards, 1837 , by subsequent monotypy (see Ng et al. 2008).

FOSSIL SPECIES INCLUDED. — Mursia armata De Haan, 1837 (also extant); M. aspina Schweitzer & Feldmann, 2000 ; M. australiensis Campbell, 1971 (also extant); M. bekenuensis Collins, Lee & Noad, 2003 ; M. circularis (Karasawa, 1989) ; M. creutzbergi Collins & Donovan, 2004 ; M. granulosa Collins & Donovan, 2002 ; M. lienharti (Bachmayer, 1962) ; M. marcusana Rathbun, 1926 ; M. macdonaldi Rathbun, 1918 ; M. minuta Karasawa, 1993 ; M. obscura Rathbun, 1918 ; M. simplex ( Remy, 1960) n. comb.; M. takahashii Imaizumi, 1952 ; M. yaquinensis Rathbun, 1926 .

DIAGNOSIS. — Carapace about as wide as long or wider than long, ovate; orbits circular, directed forward, front narrow; anterolateral margins with small spines and long lateral spine or entire; carapace ornamented with five or seven ridges, one axial and two or three on each side; ridges can be granular; carapace may be granular between ridges; merus of cheliped may have long distal spine; manus with spines on upper margin; sternum ovate, narrow.

DISCUSSION

Mursia is easily diagnosed by the presence of welldeveloped carapace ridges and generally granular ornamentation. It has been a widespread genus from Eocene to recent time, recorded from tropical to temperate regions ( Schweitzer & Feldmann 2000).

Remy (1960) referred a small, ovate specimen to Cenomanocarcinus simplex . Th is species cannot be referred to Cenomanocarcinus for several reasons (see illustrations in Schweitzer et al. 2003 and Guinot et al. 2008).Species of Cenomanocarcinus are characterized by ridges on the carapace, but they are arrayed both transversely and longitudinally. Cenomanocarcinus simplex has carapace ridges that are axially and obliquely arrayed on the lateral regions of the carapace.Species of Cenomanocarcinus have well-defined axial,protogastric, and hepatic regions, whereas C. simplex has axial regions that are defined only by a deep lateral groove along the entire axial region. Cenomanocarcinus spp. have a transverse ridge on the cardiac and branchial regions which C. simplex lacks. Cenomanocarcinus spp. have an arcuate epibranchial ridge extending from the last anterolateral spine and terminating along the axis, which C. simplex lacks.

Cenomanocarcinus simplex is better accommodated within the Calappidae and Mursia . Cenomanocarcinus simplex possesses large, circular, rimmed orbits; a granular anterolateral margin with a small lateral spine; and five dorsal carapace ridges with large transverse granules. Th ese features are typical of Mursia spp.; thus, we refer the species to Mursia , resulting in Mursia simplex n. comb. Mursia simplex n. comb. differs from other species of the genus in having less granular ornamentation overall.