Liocarcinus Stimpson, 1871

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 : 409-410

Genus Liocarcinus Stimpson, 1871

TYPE SPECIES. — Portunus holsatus Fabricius, 1798 , by original designation.

INCLUDED FOSSIL SPECIES. — Liocarcinus atropatanus (Aslanova & Dschafarova, 1975) ; L. corrugatus (Pen-

nant, 1777), also Recent; L. depurator (Linnaeus, 1758) , also Recent; L. holsatus (Fabricius, 1798) , also Recent; L. kuehni ( Bachmayer, 1953) ; L. lancetidactylus ( Smirnov, 1929) (see Garassino & Novati 2001); L. marmoreus (Leach, 1814) , also Recent; L. oroszyi ( Bachmayer, 1953) ; L. praearcuatus Müller, 1996 ; L. pusillus (Leach, 1815) , also Recent; L. rakosensis ( Lőrenthey, 1929) .

DIAGNOSIS. — Carapace wider than long, length about 80% maximum width measured about half the distance posteriorly on carapace; front variably ornamented; orbits with two fissures on upper orbital margin; anterolateral margins with five flattened spines including outer-orbital spine, first four spines directed forward, last spine may be directed laterally or anterolaterally; regions generally well defined, epibranchial region markedly arcuate and inflated; regions may be ornamented with transverse ridges or granules; posterolateral reentrant large; posterior margin nearly straight; merus of cheliped without distal spine on inner margin, carpus with large spine on inner angle, dactylus with three ridges; dactyl of pereiopod 5 lanceolate (after Poore 2004).

DISCUSSION

Species of the genus are quite variable in their dorsal carapace ornamentation, both fossil and extant. The extant Liocarcinus corrugatus is characterized by transverse ridges on the dorsal carapace, and such ornamentation is seen on the fossil species L. kuehni and possibly on L. rakosensis . The illustration of L. rakosensis in Lőrenthey & Beurlen (1929: pl. 13, fig. 1a) shows six anterolateral spines; however, it has been reported that some of the illustrations in that volume are inaccurate (P. Müller pers. comm. 2004). Liocarcinus oroszyi is less well preserved than some other species and appears to have had some granular ornamentation on the dorsal carapace ( Bachmayer 1953). Th e other fossil specimens are compression specimens, making details of the carapace and ornamentation difficult to interpret.

The new species is referred to Liocarcinus based upon its possession of a wider than long carapace; five anterolateral spines, the first four of which are directed forward; marked posterolateral reentrants; granular ornamentation; and well-defined carapace regions. Th ese are typical of Liocarcinus . The referral of the new material to Liocarcinus marks the second Oligocene occurrence of the genus. Liocarcinus lancetidactylus had already been noted from the Oligocene of the Caucasus ( Smirnov 1929; Karasawa et al. 2008). Species of this genus are known

from the fossil record in Europe and what is now southern Russia, and extant species are Atlantic and Indo-Pacific in distribution ( Ingle 1980; Poore 2004). Thus, the genus may have had a Tethyan distribution and dispersal route in the past.