Meeting Abstract
The genera Dissodactylus and Clypeasterophilus (Family: Pinnotheridae, Phylum Arthropoda) are commensal or parasitic crabs that live in association with irregular sea urchins (Class Echinoidea, Phylum Echinodermata). The association of pinnotherid crabs on sand dollars was studied off of Steinhatchee, FL, in the eastern part of Gulf of Mexico during 2017 and 2018. A total of 18 sites were sampled by scuba, including repeated sampling of 2 sites. Each sand dollar along with its crabs was collected in a separate Ziploc bag while scuba diving. Sand dollars were identified to species level and body size was estimated in terms of maximum body length and body width. Morphological and molecular approaches were employed to identify species of crabs. The number of crabs found on each sand dollar, maximum carapace width, maximum carapace length and sex were also noted. A total of 606 echinoids hosting 1322 crabs were collected. The analytical results indicate that three molecularly distinct pinnotherid crab species (Clypeasterophilus stebbingi, Dissodactylus latus, Dissodactylus mellitae) were associated with five species of sand dollars. Distribution of crabs suggests host species preference. In contrast, pea crabs infested echinoid hosts across a wide range of size classes. Collectively, the mean burden (number of crabs per sand dollar) was 2.18 (including uninfested hosts), with individual burden varying from zero to sixteen crabs per host specimen. Male to female sex ratio was 1.16:1. Some sand dollars were heavily infested (59.74%-96.6%) and Mellita tenuis being the least infested host (37.3%).
