Cenozoic Crustaceans of the East and West Indies

Abstract

This is an issue of Scripta Geologica from the Nationaal Naturhistorisch Museum, Leiden around a single theme concerning Cenozoic crustaceans edited by Stephen Donovan. The lead-off paper by Schweitzer, Feldmann, and Bonadio (2009) erects a new family of heterotreme Brachyura, Martinocarcinidae, for that old problematic species Martinocarcinus ikeae Bohm, 1922 from the Late Eocene of Java. The authors do a reasonable job of redescribing the species, comparing it to contemporaneous and modern families, and concluding the uniqueness of this form is yet another example of the blast of experimental morphologies at a time in the Eocene of maximal diversity in the Brachyura. This paper highlights anew the fact that understanding family level diversity (Ng et al., 2008) is rather incomplete without inclusion of fossil forms. Collins, Mitchell, and Donovan (2009) have a short paper describing a new species of Pleistocene grapsid from Jamaica, Sesarma primigenium. The material consists of assorted claw parts, and demonstrates the limits of what can be done with these kinds of fossils. Collins, Donovan, and Stemann (2009) review the crustacean fauna from a new Late Pleistocene locality in the Port Morant Formation. The bulk of the fauna consists of claws of thalassinidean and brachyuran decapods. A few barnacles are included. Not much is done with the material except to list and illustrate the species. The final paper by Collins, Portell, and Donovan (2009) presents a more synthetic treatment of Neogene decapods of the Caribbean. The authors offer a useful country-bycountry catalog of what is currently known, but this section is loaded with statements such as this one from page 75 concerning Venezuela: ‘‘Falconoplax kugleri Van Straelen, 1933, has characters in common with Falconoplax bicarinella Collins & Morris, 1976, an Eocene species from Barbados ... .’’ One is left wondering what are those characters, and why is it important to know this: is a phylogenetic connection hinted at, or a possible synonymy? It is all the more intriguing because the discussion lays out in tabular form a great deal of the catalog, except only a single Falconoplax is recorded from the Castilla Formation, Lower Miocene (the F. kugleri I suppose). This was a bit disconcerting until one realizes the F. bicarinella mentioned above is Eocene, and only Neogene material is the subject of the paper. We are getting only half of the picture. An Appendix by Collins formally describes several new taxa. There is a lot of information in this paper, and someday someone will make an interesting story of the evolution of Cenozoic crustaceans of the Caribbean, but that is only hinted at here, e.g., the similarity indexes of Table 5. I wish the authors had gone further. For those interested in the taxonomy and evolution of Cenozoic crustaceans, it will be useful to know this little packet of papers exists.