The genus Schistocerca, famously known for the desert locust, S. gregaria, includes 22 species and numerous subspecies and deserves a major revision. A preliminary morphological study was conducted to resolve the current subspecific status of North American alutacea species group. A detailed study on male genitalia determined that the subspecies of Schistocerca alutacea in Dirsh's (1974) revision are valid species. This study also revealed that it is important to recognize the genitalic form of sexually matured males for the taxonomic studies. Freshly molted adults are not sexually mature because their internal genitalia are not fully developed. These undeveloped genitalia are morphologically very different from the fully developed genitalia, and can be incorrectly considered as ones from different species.
To test phylogenetic relationships of the genus, a cladistic analysis of North American Schistocerca including 5 species in alutacea group was performed. Ten Schistocerca species were included in the analysis, and Austracris guttulosa, Acanthacris ruficornis, and Cyrtacanthacris aeruginosa were used as outgroups. Thirty-one characters from male genitalia and external morphology were used in the analysis. The resulting cladogram indicated the monophyly of all the North American Schistocerca. Although Dirsh (1974) treated S. obscura separately from the alutacea group due to the subgenital plate morphology, it is more closely related to S. albolineata. Hubbell (1960) treated S. lineata, S. alutacea, and S. rubiginosa as sibling species, but the present analysis showed that only the latter two are sisters, and S. lineata is more related to S. shoshone. This preliminary study highlights problems with current taxonomy and calls for more studies on North American Schistocerca.
Species 1: Orthoptera Acrididae Schistocerca alutacea (bird locust)
Species 2: Orthoptera Acrididae Schistocerca albolineata
Keywords: genitalia, cryptic species
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