New Miocene Decapoda (Thalassinidea; Brachyura) from Tierra Del Fuego, Argentina: Paleobiogeographic Implications
ABSTRACT A decapod crustacean fauna of Tierra del Fuego, Argentina, is documented from the middle Miocene Carmen Silva Formation and the early? Miocene Cerro Águila Conglomerate of the Cabo Domingo Group. Three new genera and five new species are named: Asthenognathus australensis, new species; Miotymolus quadratus, new genus and species; Mursia fuegiana, new species; Pharkidodes agele, new genus and species; and Tierrapilumnus edseli, new genus and species. Compilation of all described species of decapods from late Oligocene to early Pliocene exposures in 18 general localities in Patagonia, southern Argentina, and Chile documents two paleobiogeographic provinces, Argentine and Chilean. Coupled with evidence from the biogeographic patterns of associated mollusks, the faunas from Tierra del Fuego have been assigned to the Argentine Paleobiogeographic Province. Comparison of the distribution of Miocene decapods with that of extant decapods (Boschi 2000) leads to the conclusion that the thermal separation of South Atlantic and South Pacific water in the Miocene was more pronounced than today, so that there is no evidence of a discrete Magellanic Biogeographic Province characterizing the high southern latitude region during the Miocene.
NEW DECAPODS FROM THE NAVIDAD FORMATION (MIOCENE) OF CHILE
Abstract A new Miocene decapod fauna is described from the Navidad Formation of coastal Chile. The fauna includes five callianassoid taxa, none of which is preserved sufficiently to identify to species level. New species include Calappilia? chilensis, Hepatus spinimarginatus, Proterocarcinus navidad, Pilumnus cucaoensis, and Pinnixa navidadensis. A possible rhizopine member of the Pilumnidae Samouelle, 1819, is described. Trichopeltarion levis Casadío et al., 2004, previously known from the late Oligocene of western Argentina, was also recovered from these rocks. Calappa circularis Beurlen, from the lower Miocene Pirabas Formation in Brazil, is herein referred to Calappilia. This report greatly increases the known number of fossil decapods from Chile and sets the stage for paleobiogeographic comparison of the decapod faunas of Chile and Argentina.
The family Goneplacidae MacLeay, 1838 (Crustacea: Decapoda: Brachyura): systematics, phylogeny, and fossil records
Abstract A phylogenetic analysis of 14 genera of the family Goneplacidae MacLeay (Decapoda: Brachyura: Xanthoidea) is presented based upon 45 adult morphological characters. Two most-parsimonious trees were obtained (length = 87, CI = 0.6667, RI = 0.8242, RC = 0.5495). The present analysis suggests that the Goneplacidae is divided into six subfamilies: Carinocarcinoidinae subfam. nov., Chasmocarcininae Serène, Euryplacinae Stimpson, Goneplacinae MacLeay, Mathildellinae subfam. nov., and Trogloplacinae Guinot. The Carcinoplacinae H. Milne Edwards is synonymised with the Goneplacinae. The family and six subfamilies are defined or redefined based upon the phylogenetic analysis. Within the Goneplacidae, the Trogloplacinae and Chasmocarcininae are sister groups nested as the most derived clade, followed by the Carinocarcinoidinae, Goneplacinae, Euryplacinae, and the most basal Mathildellinae. Our analysis supports recognition of the family Pseudoziidae Alcock by Ng and Liao and suggests that it is the sister to the Eriphiidae MacLeay. A reexamination of fossil records of the Goneplacidae shows that 62 species, 20 genera, and five subfamilies are recognized as fossils. A new monotypic genus Viaplax (Euryplacinae) is erected for Pilumnoplax urpiniana Via. Chlinocephalus Ristori and Gillcarcinus Collins and Morris are moved to the Goneplacidae. Paleopsopheticus Hu and Tao is synonymised with Psopheticus Wood-Mason. Glaessneria Takeda and Miyake is here the junior synonym of Goneplax. Eleven extinct genera previously assigned to the Goneplacidae are not referred to any subfamilies and are transferred out of the Goneplacidae. New combinations include: Carcinoplax proavita (Glaessner), Goneplax arenicola (Glaessner), Euphylax zariquieri (Via) (Portunidae Rafinesque), and Psopheticus shujienae (Hu and Tao).