PRELIMINARY EXAMINATION OF CUTICULAR MICROSTRUCTURE WITHIN THE RANINOIDEA (DECAPODA, BRACHYURA)

Cuticular microstructure within the Raninoidea exhibits a wide range of variation. The utility of these microstructures as a taxonomic tool is currently under examination through high density sampling of cuticle. Study of thin section and SEM preparations of cuticle from specimens of extant and fossil species within Ranina, Lyreidus, and Raninoides has shown that cuticular structure is conserved within these genera through time. Additionally, examination of specimens within extinct genera such as Lophoranina, Cretacoranina, and Eumorphocorystes has added to the diversity of known raninoid cuticular microstructures. Preliminary results suggest a strong similarity in the cuticle of Raninoides and Lyreidus and similarity of cuticle of Ranina and Lophoranina. The relationship of extinct Cretaceous genera with other raninoids is more enigmatic. An additional observation stemming from the observation of raninoid cuticle structures is that the cuticle surface is extremely fragile and easily damaged. Although it is not clear whether the cuticle damage occurs during life, deposition and burial, or diagenesis, caution must be used when describing the exterior surface of decapod cuticle. Preparation of high resolution molds of specimen counterparts is a useful technique for obtaining external views of undamaged cuticle surface when the cuticle has suffered late diagenetic dissolution. An active program of continued collection and preparation of raninoid cuticle for microstructural examination will help refine the taxonomy of the Raninoidea and subsequently its phylogeny. This work was supported by NSF grant EF 0531670 to Feldmann and Schweitzer.