Alloreferent and Apparent Seasonal Polyphenism of Dielis tejensis with an Updated Key to Nearctic Dielis Species (Hymenoptera: Scoliidae)

Scoliidae are fossorial aculeate wasps (Hymenoptera: Apocrita) whose larvae develop as parasitoids of beetle grubs, mainly from the family Scarabaeidae. Despite their distinctive appearance and economic importance, the taxonomy and biology of Scoliidae are less well understood compared to other Hymenoptera. Recently, a new species of Scoliidae, <i>Dielis tejensis</i> Szafr., was described based on about a dozen male specimens from Texas (Nearctic realm). This article reports on mtDNA-verified discovery of the female <i>D. tejensis</i>. As in the case of other members of the tribe Campsomerini, <i>D. tejensis</i> exhibits strong sexual dimorphism in body structure and color pattern. Females of <i>D. tejensis</i> most closely resemble <i>Dielis plumipes</i> (Drury) and were previously confused with <i>D. plumipes fossulana</i> (Fabr.), with which <i>D. tejensis</i> is partially sympatric. <i>D. tejensis</i> has more than one generation per year, characterized by a male-biased sex ratio, perhaps resulting from the female immature stages entering a state of aestivation. The multi-generational developmental cycle of <i>D. tejensis</i> correlates with the existence of a partial seasonal polyphenism in this species. The data presented also shows a similarity in the distribution ranges of <i>D. tejensis</i> and one of its main nectaring plants, <i>Hymenopappus artemisiifolius</i> DC (Asteraceae), that may suggest similarity in the environmental requirements of both organisms or specialized trophic relationship between the still-unknown beetle host of the wasp larvae and <i>H. artemisiifolius</i> or another plant with a similar range. <i>D. tejensis</i> has been included in the accordingly modified key to the Nearctic species of <i>Dielis</i> Sauss. & Sichel, which is also presented here.