Abstract

AbstractPissodes approximatus Hopkins (1911) is a junior subjective synonym of P. nemorensis Germar (1824). The conspecificity of these entities, traditionally considered distinct based only on distribution and slight morphological differences, is corroborated here with comparative studies of ecology, behavior, and morphology. When pheromone-baited traps were deployed during the spring (May–June) and fall (November–December) in several localities to examine seasonal activity, southern populations (P. nemorensis sensu Hopkins) responded only in the fall and northern populations only in the spring, but a population in Virginia responded during both seasons. Laboratory studies found that individuals from five southern populations became reproductively mature under 16:8, 12:12, and 8:16 (L:D) photoperiods but weevils in a New York population did not mature under the 8:16 photoperiod. A two-species model based on strict seasonal isolation between northern and southern populations is rejected. Morphometrics revealed significant differences in six body dimensions and three morphometric ratios among 13 populations, but there was no geographic pattern of differences to suggest the existence of two species. Sexual dimorphism in rostrum length was most pronounced in southern populations but occurred in all five populations in which it was investigated. Examination of male and female genitalia revealed similar variation in northern and southern populations and conflicted with previously reported diagnostic differences. Our study and the results of earlier work lead us to conclude that the populations previously represented by the names P. nemorensis and P. approximatus comprise one widely distributed species and display intraspecific variation in life history and morphological characters.

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