Branchiopod and Malacostracan Crustaceans 
11 
isopod genus are based solely on the collection of males, plus those 
females found at sites where males of only one species of Caecidotea 
were collected. Individuals of the two dominant amphipod species, 
Hyalella azteca and Crangonyx richmondensis richmondensis, were 
identified as male, female, or juvenile. Because immature members of 
these species resemble females, juveniles were defined as all individuals 
shorter than the smallest recognizable male collected for each species. All 
individuals of H. azteca were able to be sexed; however, many unsexed 
C. r. richmondensis juveniles were collected. Voucher specimens of all 
species have been deposited in the collections in the Division of 
Crustacea of the United States National Museum of Natural History, 
Washington, D.C. 
RESULTS AND DISCUSSION 
Branchiopods 
Results of the crustacean survey are shown in Table 1. Two species 
of non-cladoceran branchiopods were collected, the anostracan Strep- 
tocephalus seali and the conchostracan Eulimnadia ventricosa. Both 
species were found in one location only, two shallow pools adjoining a 
shaded borrow pit (depression formed by soil excavation) in a forest. 
They were absent in these pools in May 1982, present the following July 
and September, and absent in December 1982. In July and September 
S. seali was very abundant, with E. ventricosa less so. Also present were 
large numbers of the cladoceran Simocephalus exspinosus and the 
isopod Caecidotea forbesi. The pools, which contained water throughout 
1982, were approximately 3 x 4 m and 4 x 4.5 m and were separated by 
about 1 m; in July and September they were separated from the borrow 
pit by a ridge approximately 0.5 m wide and 15 cm in elevation above 
the water level. In July and September all four crustacean species were 
abundant in the two pools, but absent from the borrow pit. There were 
large numbers of small fish in the borrow pit, but none in the two pools. 
By December 1982, water levels had risen as a result of rainfall so that 
the pools and borrow pit were confluent. No anostracans or con- 
chostracans could be found at that time. Spring and summer were drier 
in 1983 than in 1982, and the pools were totally dry in May and August. 
They contained water in the early summer of 1983, but no branchiopods 
were found in this habitat during that year. Such sporadic occurrences 
of non-cladoceran branchiopods is not uncommon (Pennak 1978). 
Streptocephalus seali is the most widely distributed anostracan 
species in North America, being found in pools and ponds from the 
Canadian prairies south to Mexico and east to the Atlantic States 
(Moore 1966, Fitzpatrick 1983). There is only one previous record of its 
occurrence in South Carolina, and that is based on a single specimen 
