Torrey Nyborg

Cretaceous and Eocene Decapod Crustaceans from Southern Vancouver Island, British Columbia, Canada

A large collection of fossil decapod crustaceans from Cretaceous and Eocene rocks of Vancouver Island, British Columbia, Canada, has yielded a remarkably diverse fauna. The Cretaceous decapod fauna, including previously described and new taxa, contains 17 genera in 14 families, represented by as many as 22 species. The Eocene fauna is less robust, with 7 species and 6 genera in 6 families. This publication includes one new family; three new genera; eight new species; and nine new combinations. The decapod fauna of the Nanaimo Group supports a position for Wrangellia well north of the current position of Baja California, Mexico. The decapod fauna of the Western Interior of North America is distinct from that of west coastal North America, suggesting limited faunal exchange between the two areas. Fewer than half of the decapod genera present in British Columbia during the Late Cretaceous Period became extinct by the end of the Cretaceous, most before the Maastrichtian. Two of the Cretaceous genera and none of the Eocene genera are extant; the extant genera are both members of the Callianassidae. Of the 14 families present in Cretaceous rocks of British Columbia, five are extinct. The North Atlantic and Central Americas appear to have been areas of rapid evolutionary expansion within the Decapoda during the Cretaceous, based upon the large number of decapod families that appear to have originated there during Cretaceous time.

NEW MIDDLE EOCENE DECAPODS (CRUSTACEA) FROM CHIAPAS, MEXICO

Abstract Decapod crustacean specimens from the middle Eocene San Juan Formation in central Chiapas represent the first record of Eocene decapods in southern México. New taxa include: Dardanus mexicanus new species (Diogenidae), Lophoranina cristaspina new species, Notopus minutus new species (Raninidae); Verrucoides stenohedra new genus and new species (Xanthidae); Stoaplax nandachare new genus and new species (Goneplacidae); and Viapinnixa alvarezi new species (Pinnotheridae). Verrucoides verrucoides new genus and new combination from the Paleocene of Greenland represents a new combination. In addition, the fauna includes Callianassa sensu lato sp., Laeviranina sp., Calappilia cf. C. hondoensis Rathbun, 1930, Eriosachila sp., and indeterminate calappid and xanthoid taxa. This assemblage bears close relationship with coeval faunas in the Tethyan region of southern Europe and southern North America and with Paleocene faunas of Greenland, strengthening the evidence for previously described patterns of dispersal within the Decapoda.

HOMOLIDAE DE HAAN, 1839 AND HOMOLODROMIIDAE ALCOCK, 1900 (CRUSTACEA: DECAPODA: BRACHYURA) FROM THE PACIFIC NORTHWEST OF NORTH AMERICA AND A REASSESSMENT OF THEIR FOSSIL RECORDS

Abstract New material collected from Cretaceous and Tertiary rocks of the Pacific Northwest of North America has prompted a reevaluation of the fossil record of the Homolidae de Haan, 1839 and the Homolodromiidae Alcock, 1900. The fossil records of the homolid genera Homola Leach, 1815; Homolopsis Bell, 1863; and Hoplitocarcinus Beurlen, 1928 are restricted, and Latheticocarcinus Bishop, 1988, which is synonymous with Eohomola Collins and Rasmussen, 1992 and Metahomola Collins and Rasmussen, 1992, is reinstated as a distinctive genus. Thirteen new combinations resulted from reinstatement of Latheticocarcinus: L. adelphinus (Collins and Rasmussen, 1992), L. affinis (Jakobsen and Collins, 1997), L. atlanticus (Roberts, 1962), L. brevis (Collins, Kanie, and Karasawa, 1992), L brightoni (Wright and Collins, 1972), L. centurialis (Bishop, 1992), L. declinata (Collins, Fraaye, and Jagt, 1995), L. dispar (Roberts, 1962), L. pikeae (Bishop and Brannen, 1992), L. punctatus (Rathbun, 1917), L. schlueteri (Beurlen, 1928), L. shapiroi Bishop, 1988, L. spiniga (Jakobsen and Collins, 1997), and L. transiens (Segerberg, 1900). A new species, Latheticocarcinus ludvigseni, is described from Cretaceous rocks of British Columbia. The first fossil occurrence of the extant homolid genus Paromolopsis, P. piersoni new species, is recorded from Miocene rocks of Oregon. Paromola pritchardi Jenkins, 1977 is formally transferred to Dagnaudus Guinot and Richer de Forges (1995) as suggested by Guinot and Richer de Forges (1995). The extinct family Prosopidae von Meyer, 1860 is referred to the Homolodromioidea Alcock, 1900, following previous work. Palehomola gorrelli Rathbun, 1926 is transferred from the Homolidae to the Homolodromiidae, and the new genus Rhinodromia is erected to contain Homolopsis richardsoni Woodward, 1896, from Cretaceous rocks of British Columbia. A new terminology is suggested for describing the rostral area in homolodromiids, in an attempt to alleviate considerable confusion over that issue. The morphologic similarity of fossil and extant members in both the Homolidae and the Homolodromiidae suggest that these two brachyuran families are evolutionarily conservative, much as the lobsters are. In addition, the similar paleobiogeographic and evolutionary patterns seen in the two families suggests that either they are closely related or that brachyuran families exhibited similar evolutionary and dispersal trends early in their history.

PALEOCENE DECAPOD CRUSTACEA FROM THE RANCHO NUEVO FORMATION (PARRAS BASIN-DIFUNTA GROUP), NORTHEASTERN MEXICO

Abstract Nine species, including two new species of decapod crustaceans, are described from the Paleocene Rancho Nuevo Formation, collected from two localities of the Parras Basin, southeast Coahuila state, Mexico. The astacid Enoploclytia gardnerae (Rathbun, 1935) is represented by a pair of large chelae and one cephalothorax. An incomplete nephropid carapace is identified as Enoploclytia sp. Partial specimens of a callianassid and a pagurid are described. One partial carapace representing Linuparus wilcoxensis Rathbun, 1935 is described. A new raninid, Macroacaena venturai new species extends the genus into Mexico. Paraverrucoides alabamensis (Rathbun, 1935) is the most abundant species, followed by Tehuacana tehuacana Stenzel, 1944 and Viapinnixa perrilliatae new species. Taxonomic affinities of this assemblage confirm influence of the Mississippi Embayment, particularly from Paleocene stratigraphic units of Texas and Alabama.

Icriocarcinidae: a family of portunoid crabs from the Upper Cretaceous of North America

Icriocarcininae Števčić, 2005, an extinct North American subfamily of portunoid decapods, is elevated to family level to contain two Late Cretaceous genera—Icriocarcinus Bishop, 1988, from the Pacific Coast, and Branchiocarcinus Feldmann and Vega, 1995, from the Gulf of Mexico and Atlantic Coast Plain. The family is centered on Icriocarcinus xestos Bishop, 1988, described from the Late Campanian of Baja California. Closely allied with this species are: “Eryma” flecta Rathbun, 1926, originally described from the latest Campanian of Tennessee and now known to occur throughout the Maastrichtian of the adjoining Mississippi; Branchiocarcinus cornatus Feldmann and Vega, 1995, from the Maastrichtian of San Luis Potosí, Mexico; and undescribed material from the latest Maastrichtian of New Jersey. The Gulf and Atlantic populations compose a single new species—Branchiocarcinus flectus (Rathbun). Provisionally regarded as a lobster, on the basis of a single, eroded chela, B. flectus is now known from complete bodies found at several locations in the eastern US. The additional material also clarifies the identity of B. cornatus, which is based on a distorted external mold of a lone dorsal carapace. Members of the family lack the typical portunoid flattened fifth pereiopod but share other characters that enable placement within the Portunoidea.KurzfassungIcriocarcininae Števčić, 2005, eine ausgestorbene nordamerikanische Unterfamilie von portunoiden Dekapoden, wird auf Familienniveau gehoben und beinhaltet die zwei oberkretazischen Gattungen Icriocarcinus Bishop, 1988, von der pazifischen Küste und Branchiocarcinus Feldmann und Vega, 1995, vom Golf von Mexiko und der atlantischen Küstenebene. Die Familie zentriert sich um Icriocarcinus xestos Bishop, 1988, beschrieben aus dem Obercampanium von Baja California. Nahe verwandte Arten sind: “Eryma” flecta Rathbun, 1926, ursprünglich beschrieben aus dem obersten Campanium von Tenessee, heute bekannt aus dem gesamten Maastrichtium des angrenzenden Mississipi; Branchiocarcinus cornatus Feldmann und Vega, 1995, aus dem Maastrichtium von San Luis Potosi, Mexiko; sowie unbeschriebenes Material aus dem obersten Maastrichtium von New Jersey. Die Populationen vom Golf und Atlantik stellen eine einzige neue Art dar: Branchiocarcinus flectus (Rathbun). Aufgrund von ungenügenden Merkmalen ursprünglich als Hummer angesehen, ist B. flectus heute in Form von vollständigen Körpern aus verschiedenen Lokalitäten der östlichen Vereinigten Staaten bekannt. Das zusätzliche Material klärt auch die Identität von B. cornatus, welcher auf einem deformierten Häutungshemd eines dorsalen Karapax basiert. Mitgliedern dieser Familie fehlt das charakteristische portunoide flache fünfte Pereiopod, aber sie besitzen andere Merkmale, die eine Platzierung in die Portunoidea rechtfertigen.

Mesozoic and Tertiary Decapod Crustacea from Mexico

In recent years, the number of described species of fossil crustaceans from Mexico has increased noticeably. Numerous new occurrences and new taxa were described from lithostratigraphic units that range in age from Early Cretaceous to Miocene. These reports included not only the systematic description of the specimens, but also information on paleoenvironment, paleoecology and evolution. The present work is a review of the fossil record of fossil crustaceans from Mexico, including comments on new localities and fauna that are under study. Based on the ongoing research in this field, it is possible that the number of fossil species of brachyurans will reach twice as much as the ones reported nowadays in a few years.

A NEW CRAB FROM THE LATE EOCENE HOKO RIVER FORMATION, OLYMPIC PENINSULA, WASHINGTON: THE EARLIEST RECORD OF EUPHYLAX (DECAPODA: PORTUNIDAE)

Abstract Euphylax feldmanni new species from the late Eocene Hoko River Formation, northwestern Olympic Peninsula, Washington, represents the first occurrence of Euphylax in pre-Oligocene strata, the earliest fossil record for the subfamily Podophthalminae, and the first record of the genus from the eastern North Pacific. This small, aberrant crab is one of 26 described species of decapod crustaceans from an unusual allochthonous invertebrate assemblage of the upper Eocene Hoko River Formation conglomerates at Kydikabbit Point, on the Makah Indian Nation, northwestern Olympic Peninsula, Washington, U.S.A. Species of Euphylax live today in the Pacific Ocean from Baja California south to Peru and Chile, and have been found as fossils from the Pleistocene of Jamaica, the Miocene of Costa Rica, Brazil, and Haiti, and questionably from Malaysia and Japan. The discovery of a fossil species of Euphylax from the Pacific Northwest, U.S.A. greatly expands the paleobiogeography of the genus.

Bicornisranina bocki, n. gen., n. sp. (Decapoda: raninidae) from the Cretaceous of Vancouver Island, British Columbia, Canada

Abstract A new genus and species of raninid crab, Bicornisranina bocki, is described from the Upper Cretaceous Haslam and Pender formations of Vancouver Island, British Columbia, Canada. Bicornisranina bocki (Raninidae: Raninoidinae) shares similar characteristics with other genera within Raninidae, including a bifid anterolateral spine, as seen in Rogueus, and a similar frontal spine conformation as seen in Raninoides. Although B. bocki shares morphological characteristics with other genera within Raninidae, B. bocki possesses a distinct sternum that sets it apart and warrants establishment of a new genus. With the occurrence of Bicornisranina from lower Campanian rocks of Vancouver Island, the range of Raninoidinae is confidently extended into the Cretaceous.

A new genus and species of raninoid crab from the Upper Cretaceous of Mississippi

A new genus and species of raninoid crab, Carinatus galebishopi, is described from the upper Maastrichtian Prairie Bluff and Owl Creek formations of Mississippi. Carinatus galebishopi gen. et sp. nov. fits best within the Raninidae, Subfamily Symethinae, based upon similar dorsal carapace characteristics of member genera. The new crab possesses distinctive dorsal carapace ornamentation setting it apart from described symethines and warrants establishment of a new genus. Carinatus galebishopi represents the first Cretaceous symethine crab and suggests the subfamily may have migrated eastward across the North Atlantic—Maastrichtian of Mississippi, Danian of New Jersey, and Ypresian of Spain—before dispersing to the Indo-Pacific.KurzfassungEine neue Gattung und Art raninoider Krabben (Carinatus galebishopi gen. et sp. nov.) wird aus den Prairie Bluff- und Owl Creek-Formationen (Ober-Maastrichtium) des Bundesstaates Mississippi beschrieben. Carinatus galebishopi wird, basierend auf ähnlichen dorsalen Carapaxmerkmalen vergleichbarer Gattungen, der Familie Raninidae (Unterfamilie Symethinae) zugeordnet. Die neue Krabbe besitzt eine unverwechselbare (dorsale) Carapaxornamentierung, die von anderen beschriebenen Symethinae nicht bekannt ist und somit die Aufstellung einer neuen Gattung rechtfertigt. Carinatus galebishopi stellt den ersten kretazischen Vertreter der Symethinae dar und zeigt an, dass Vertreter dieser Unterfamilie möglicherweise zuerst ostwärts über den Nordatlantik gewandert sind: Mississippi (Maastrichtium), New Jersey (Danium), Spanien (Ypresium) – bevor sich diese im Indo-Pazifik ausgebreitet haben.