Notes on Identification and Ecology of Tumbling Flower Beetles (Mordellidae) from Ossabaw Island, Georgia

Abstract

A unique opportunity on April 25, 1995, to intensively search for mordellid beetles resulted in finding four species on Ossabaw Island, Chatham County, Georgia. This is the first report of their host plant associations and the sympatry of Mordellistena trifasciata and M. minuta. Historically, there has been confusion between these two species (Liljeblad 1945, Khalaf 1971) because their elytral color patterns are practically identical. I provide some overlooked distinctions between them. Mordellistena pubescens (Fabricius) (Fig. 1): 6 specimens on black cherry Prunus serotina (Rosaceae), sparkleberry Vaccinium arboreum (Ericaceae), and wax myrtle Myrica cerifera (Myricaceae). According to Liljeblad (1945), the color patterns of this species are quite variable. The dermal color of the Ossabaw specimens varies from reddish brown to black. There are three (sometimes four) dark spots surrounded by cinereous pubescence on the basal half (posterior) of the pronotum. Cinereous pubescence totally covers the anterior portion of the pronotum. The elytral markings of golden pubescence in the Ossabaw specimens are inconsistent with those illustrated by Liljeblad (1945). Because both base and apex are covered with golden pubescence, there appear four golden crossbands on the elytron. The lateral margins are heavily covered with golden pubescence that encloses three dark spots on the elytron. The middle dark spot is usually more or less a crossband. In one specimen, the apical dark spot is so heavily encroached by the apical and penultimate golden crossbands that it is almost obliterated. The short oblique ridges on the posterior tibia vary from 2-6 with the apical two obvious and the basal remainder rudimentary; the basitarsus has 2-4 ridges, again only the apical two are obvious; the second tarsal segment has only one ridge with a rudimentary second barely visible. These counts by Liljeblad (1945) are 3-4, 3, and 2, respectively. Determination of the number of ridges on the posterior leg is therefore highly subjective. Mordellistena andreae andreae Leconte (Fig. 2): 10 specimens on black cherry Prunus serotina (Rosaceae), sparkleberry Vaccinium arboreum (Ericaceae), wax myrtle Myrica cerifera (Myricaceae). Liljeblad (1945) named three varieties of this species. The form M. ancilla, regarded as a variety of M. andreae (Liljeblad 1945, Bright 1986), was said by Khalaf (1971) to have the penultimate segments of the anterior and middle tarsi truncated at apex. These segments on all Ossabaw specimens are slightly emarginate or notched at apex. This may be why Khalaf called ancilla a full species. Head and thorax are yellow in the male and black in the of M. andreae andreae. However, one from Ossabaw has a totally ferruginous head. Liljeblad (1945) also reported female with black head except a space in front of antennae which is yellowish. Apparently head color is variable in this form. Mordellistena trifasciata (Say) (Fig. 3 & Table 1): 2 specimens on red buckeye Aesculus pavia (Hippocastanaceae) and sparkleberry Vaccinium arboreum (Ericaceae).