Trichorhina donaldsoni, New Species, A Terrestrial Isopod Crustacean from Florida

Abstract

Trichorhina donaldsoni, new species, was collected in two localities in south Florida. The species, a small (about 3.0 mm long), pigmentless isopod, is described. Individuals were cultured and the spe- cies was found to reproduce parthenogenetically. The average number of young per brood in broods of 44 females which were raised was 5.9 per female. Females laying two broods molted twice between each brood. A second generation of young were raised and they produced young. No males were ever found. Trichorhina donaldsoni, n. sp., has been found in two locations in south Florida: West Hollywood and Frostproof. All of the specimens so far collected are females and the species apparently reproduces parthenogenetically as do some other members of the genus (Legrand, 1953). The animals were found in leaf litter under trees and shrubs and were not abundant. Trichorhina donaldsoni, new species Small, unpigmented, flat, ovoid and covered with small spatulate, pointed and paddle-shaped setae. From 2.5 to 3.0 mm long, with occasional specimens to 3.5 mm; about half as wide as long. First antennae triarticulate and prominent even though the animal itself is small. Second antennae about one-third length of body and cov- ered with pointed setae. First peduncular segment very short; second much larger, third and fourth each about as large as the second. Fifth peduncular segment longest, about half again as long as fourth. Fla- gellum shorter than last peduncular segment, composed of two articles. (From anterior view flagellum appears to have three articles, but it has only two.) Distal article of flagellum with stout, short, apical, sensory setae. Head (dorsal view) large, rectangular, and not well set into first thoracic segment. Well-developed lateral lobes not abruptly separated from head, but rather extensions of head. Spatulate and paddle- shaped setae thick and mask any abrupt break between lateral lobes and head. Head covered with scale-like spatulate setae generally bent posteriorly, especially distinct on the posterior border of head and thoracic tergites. Prominent eyes (one ocellus each) present and very distinctly pigmented brownish or yellowish. Prominent group of setae on clypeus. Thoracic tergite I large, with no posterior curves on lateral borders. Tergites II to IV with posteriolateral borders slightly curved back- ward. Tergites V to VII with acutely curved posterior borders, each