The morphological diversity of long-necked lacewing larvae (Neuroptera: Myrmeleontiformia)

Abstract

Threadwinged lacewings (Crocinae) nowadays occur in Africa, South America, Australia and the southern part of Eurasia. They have very distinct larvae, roughly resembling antlion larvae, yet, in many larvae the neck region is extremely elongated, earning them the name long-necked antlions. Fossil lacewing larvae with recognisably long necks, but other characters differing from those of extant longnecked lacewing larvae, are known from Myanmar amber (100 mya, "Burmese amber"). We here summarise all already known larvae of extant threadwinged lacewings (53 specimens) and fossils of lacewing larvae with long necks (8 specimens). Moreover, we add further extant larvae of thread-winged lacewings (4 specimens) and fossil lacewing larvae with long necks (5 specimens), providing us a dataset of 70 specimens representing two distinct time slices. We compared these larvae concerning their shape by using outline analysis (based on elliptic Fourier transformation), including shape of the mandibles, the head, the neck, the trunk and the overall body shape. Fossil longnecked lacewing larvae differ from modern longnecked lacewing larvae especially in mandible and trunk shape. Their preservation in amber indicates that these larvae had a different ecology from their modern counterparts, which occur in sandy, arid environments. It remains unclear whether the fossil longnecked larvae are closely related to Crocinae. In any case these fossils represent a now extinct type of morphology, and most likely ecology.