Morphology of the primary larva of Mantispa aphavexelte Aspöck & Aspöck, 1994 (Neuroptera: Mantispidae) and phylogenetic implications to the order of Neuroptera

Abstract

The external and internal morphology of the primary larva of Mantispa aphavexelte was studied and documented with a broad spectrum of techniques. The cephalic anatomy, which is very similar to conditions found in other neuropteran immatures, is mainly affected by the formation of specialized mandibulo-maxillary sucking tubes and associated internal features. The postcephalic anatomy largely follows a generalized holometabolan pattern, with well-developed muscles in the thorax and the abdominal segments, an elongate, uncondensed ganglionic chain, and well-developed Malpighian tubules. The phylogenetic analysis of 70 larval characters suggests a weakly supported clade comprising Dilaridae, Berothidae, Rhachiberothidae and Mantispidae. Mantispoidea comprising Rhachiberothidae, Berothidae and paraphyletic Mantispidae is suggested by overlapping scales on antennae and maxillae, thoracic “trichobothria”, and hypermetamorphosis with scarabaeiform 2nd instar larvae. The relationships of the mantispoid terminals are not resolved, and Mantispa (Mantispinae) and Plega (Symphrasinae) are not retrieved as sister taxa. Spider parasitism and feeding in spider egg sacs is characteristic for Mantispinae, whereas immatures of Berothidae and non-mantispine mantispid larvae prey on the offspring of social or non-social aculeatan Hymenoptera, on termites, or on immatures living in soil or under bark, for example scarab larvae. Specializations of the legs like a trumpet-shaped empodium and a fixed tarsal pseudoclaw, enable mantispine larvae to cope with functional challenges linked with their specialized form of parasitism, like entering a host or penetrating its egg sack. The largely immobilized and straight sucking stylets are suitable for piercing eggs of spiders, but not for grasping prey. The terminal eversible attachment structure probably provides anchorage of the abdominal apex and thus may facilitate the penetration of the egg sac or membranes of the body surface of a spider. It may also facilitate boarding a passing suitable host. Very small size of the 1st instars and hypermetamorphosis are likely linked with parasitism. Even though the primary larvae of M. aphavexelte belong to the smallest immatures in Neuroptera, the effects of miniaturization are very limited.