Occurrence and distribution of an outbreak of infection of Loxothylacus texanus (Rhizocephala) in blue crabs in Galveston Bay, Texas, with special reference to size and coloration of the parasite's external reproductive structures.
Externae (reproductive structures) of Loxothylacus texanus were found on 10.3% of 1,521 blue crabs (Callinectes sapidus) examined in Galveston Bay, May through July 1989. Infections were found in areas of the bay where annual salinities average between 15 and 30 ppt. No externae were found on 577 crabs in intertidal areas. Of 944 crabs collected in subtidal habitats, 156 (16.5%) bore the parasite's externae. In a separate analysis of 284 externae collected from 237 host crabs, the number of externae per crab ranged from 1-4 (mean = 1.2). The volume of externae (in cm cubed) ranged from 0.5-5.8 (mean = 3.3). The carapace width (in mm) of host crabs ranged from 49-100 mm (mean = 68.9). The developmental sequence of externae as indicated by external coloration is: white, tan, yellow, brown, salmon, and purple.