P2.19 Thursday, Jan. 5 A zoogeographic analysis of galatheoid and chirostyloid crabs in the Gulf of Mexico KILGOUR, M.J.*; SHIRLEY, T.C.; Texas A&M University-Corpus Christi; Texas A&M University-Corpus Christi email@example.com
Galatheoid and chirostyloid crabs include squat lobsters or pinch bugs, and are prominent and abundant crustacean macrofauna in the deep Gulf of Mexico; we examined 3 galatheoid families and 2 chirostyloid families. We found 76 of the 84 species known from the Gulf from 1185 personal collections and museum lots. A typical inverse J curve was present; a few species were abundant, but most were rare. Munida valida and Munida pusilla were the most common species and represent one of the most common genera. Regional analysis of beta diversity and species richness of squat lobsters was completed by subdividing the Gulf into 48 polygons based on region and depth. Squat lobsters occurred in 39 of the 48 polygons in depths of 0 to >3000 m; 36 species occurred in one polygon in the Florida Strait. Diversity of galatheoids among the polygons and their distributional patterns were analyzed using similarity metrics, cluster and ordination techniques. Depth and region explained many distributional patterns; some species were depth restricted, while others were spatially restricted. The northern and eastern Gulf had higher species richness and diversity and were more similar to each other than to the southern and western Gulf. Sampling effort bias may offer partial explanations for this pattern. Each family of the Galatheoidea displayed bathymetric zonation. Although the Gulf of Mexico is approximately 2% of the area of either the Atlantic or Indian Oceans and is considerably shallower than either, the species richness of galatheoids and chirostyloids in the Gulf is about 50% of the species richness of these oceans. The Gulf of Mexico appears to be a galatheoid biodiversity hotspot; we expect more species to be discovered with continued exploration of deep habitats.