Description of First Instar Larvae of the Subgenus Praocis (Praocis) Eschscholtz, 1829 (Coleoptera: Tenebrionidae: Praociini)

Abstract

The subgenus Praocis Eschscholtz, 1829 (Pimeliinae: Praociini) is an endemic group of north-central Chile consisting of 18 flightless species distributed mostly across the Chilean desert and coastal steppe. In this work we describe the morphology and structure of first instar larvae of Praocis (Praocis) spinolai Gay and Solier, 1841, Praocis (Praocis) subaenea Erichson, 1834, and Praocis (Praocis) curta Solier, 1841 (Coleoptera: Tenebrionidae). Larvae were obtained by rearing wild-caught male and female individuals under laboratory conditions. The structure and external morphological characters of the larvae were analyzed by scanning electron microscopy (SEM). Results show that first instar larvae have morphological adaptations to edaphic environments, such as prothoracic legs for digging, a strongly sclerotized cephalic capsule, and well-developed IX and X abdominal segments (pygidium and pygopods). The interspecific differences in head morphology (cephalic capsule and epicranium), mouthparts (labrum, clypeus and mandibles), and IX and X abdominal segments (pygidium, pygopods, and apical spines) are highlighted.