A review of the biology of Symphrasinae (Neuroptera: Rhachiberothidae), with the description of the egg and primary larva of Plega Navás, 1928

Abstract

The mantispoid subfamily Symphrasinae is a highly specialized taxon traditionally included within Mantispidae, but recent morphological and molecular studies suggested this group belongs to the family Rhachiberothidae. Knowledge about the biology of the Symphrasinae is summarized, and all biological interactions are tabulated. Larvae of all species whose biology has been documented are ectoparasitoids of larvae and pupae of holometabolous insects. Species of Plega Navás, 1928, and apparently of Anchieta Navás, 1909 probably have a generalist feeding ecology with primary larvae actively seeking for hosts, likely with some degree of “host-searching” ability of the females. Meanwhile, species of Trichoscelia Westwood, 1852 appear to have a specialized feeding on larvae and pupae of the vespid wasps Polybia Lepeletier, 1836, as well as a complex mechanism to invade wasp nests. The egg and first larval instar of Plega are described and illustrated. The main characteristics of the genus are discussed in a comparative context of the known primary larva and egg of Mantispoidea. The genus is distinguished among other Mantispoidea by the presence of a elongate head capsule, with two anterolateral stemmata, inwardly curved mandibulo-maxillary stylets, where the mandibles are robust with serrate apex; in the labium, the postmentum is enlarged and subquadrate and the palpus is 2-segmented, although a first palpomere was probably fused to the prementum; the legs have all the podomeres differentiated as separate subunits, with setal characters providing a landmark to understand the leg morphology of Mantispa Illiger, 1798, in which a partial fusion of the tibia and tarsus has taken place.