Meeting Abstract

P2.56  Jan. 5  Ontogeny and homology of succineid reproductive structures (Gastropoda, Pulmonata, Succineidae) DEMAINTENON, Marta J; University of Hawaii at Hilo demainte@hawaii.edu

In pulmonate land snails, the anatomy of the reproductive system is commonly relied on to provide characters for systematic research. Because pulmonates are simultaneous hermaphrodites with internal fertilization, the reproductive system in these taxa can be quite complex, and homologies of different reproductive structures are generally not well understood. The systematic classification of Succineidae, a diverse family of stylommatophoran pulmonates, is based almost entirely on reproductive anatomy. The two recognized subfamilies of Succineidae, Succineinae and Catinellinae, differ primarily in the overall structure of the male genital complex. Reproductive structures in pulmonate taxa are often considered homologous, based on structural and positional similarity; however the relationships of anatomically dissimilar structures within complexes are unknown. One additional criterion that may be used to suggest homology between dissimilar anatomical structures is similarity in development. The objective of this study is to investigate the organogenesis of the reproductive system comparatively in representatives of both subfamilies of the Succineidae, to identify ontogenetic homologies in the reproductive tract overall, and more specifically in the male genitalia. Preliminary research on juveniles of a catinelline species indicates that early in development, the male reproductive structure has a pair of longitudinal internal ridges with a furrow between that may be homologous to the tube-within-a-tube structure seen in succineines. If this is the case, then knowledge of these homologies will enable better character state definition, as well as allowing a better understanding of the evolutionary transitions between taxa.