Description of the Egg and First-Instar Larva of Scotobius pilularius Germar, 1823 (Coleoptera: Tenebrionidae: Scotobiini), and Analysis of Larval Primary Chaetotaxy

Abstract

Larval morphology of the New World tenebrionid genus Scotobius Germar is studied based on a description of the first instar of S. Pilularius Germar, with emphasis on chaetotaxic analysis of the cephalic capsule, head appendages, legs, and thoracic and abdominal segments. This represents the first description of a larva of Scotobius, and the first detailed treatment of the larval primary chaetotaxy pattern of a tenebrionid. A short description and photographs of the eggs are also provided, which are deposited individually and agglutinate small substrate particles. As remarkable characteristics of the studied larvae, the sclerome is a simple oval structure, the tergum IX is acuminate posteriorly, the segment X is extremely small and almost completely concealed by the sternum IX, and prothoracic legs are somewhat more robust than the meso- and metathoracic pairs, which is generally the case in soil-dwelling larvae. Some discussion is provided on a long-standing controversy regarding homology and terminology of the last leg segments in coleopteran larvae.