Extracted from: Snelling R.R., (1983). The North American Species of the Bee Genus Lithurge (Hymenoptera: Megachilidae). Contributioun in Science, number 343, pp. 1-11. The Natural History of Los Angeles County, 1983|
The female of L. gibbosa is easily recognized by the high, bowed supraclypeal process, similar to that of members of the Palaearctic species allied to L. cornuta (Fabricius).
Males are recognizable by the combination of densely punctate supraclypeal area, the presence of a single labral tubercle, and the long ocelloccipital distance. The labral tubercle is a curved, transverse, subapical ridge; in the center, this ridge is elevated. Males from Florida and Georgia have this median elevation abrupt and quite prominent (Fig. 12). The median elevation in males from Texas is less pronounced (Fig. 13). This difference between specimens from the two areas is consistent but does not correlate with other features.