ABSTRACT

Herpetocypris amychos n. sp. occurs both living and dead in 9 of 43 quantitative (100 cc.) bottom samples in the Bay. Although its distribution appears patchy, 529 total (live + dead) individuals out of the 1845 making up the rest of the ostracods in the 43 samples are this species. Thus it accounts for 29% of the sampled ostracod fauna, and is an important endemic of the Holocene brackish-water bay regime. The species is almost cosmopolitan in the Bay, occurring in estuarine, marsh, and inner bay environments in both thanatocoenosis and biocoenosis, but is not present in Mississippi Sound. It is adapted to the following ranges of environmental characteristics: depth 0.33-3.00 m. (r=2.67 m.), salinity 0.0-15.0 (r=15.0 ), pH 3.9-7.4 (r=3.5 pH units), temperature 27.2-31.0° C. (r=3.8° C.), Eh -30 - +85 mv. (r=115 mv.), dissolved oxygen 2.4-7.0 p.p.m. (r=4.60 p.p.m.). Sampling stations in the Bay where grain size control is available indicate it occurs in sand-mud mixtures. Relative abundances of this species (16 occur) are variable. Total (live + dead) abundances range from 11.5% to 100%; relative abundance of living specimens is from 0% to 100%. Scanning electron micrographs are utilized in taxonomic analysis of the carapace; these are complimented by transmitted light micrographs of appendage morphology in order to establish a "natural" taxonomy.