This paper presents a synthesis of morphological information on larvae of the beetle suborder Archostemata. Larvae of the following families and species were studied: Ommatidae: Omma sp.; Micromalthidae: Micromalthus debilis LeConte, 1878; Cupedidae: Priacma serrata LeConte, 1861, Distocupes varians (Lea, 1902), Rhipsideigma raffrayi (Fairmaire, 1884), Tenomerga cinerea (Say, 1831) and Tenomerga mucida (Chevrolat, 1829). Morphological characters of the suborder and three families are described. Monophyly of the suborder is strongly supported by more than 10 larval autapomorphies. A close relationship between Micromalthidae and Cupedidae is confirmed. New larval characters are introduced, including chaetotaxy of first instar larvae of Micromalthus LeConte, 1878, Priacma LeConte, 1874 and Distocupes Neboiss, 1984. An identification key to families and subfamilies of Archostematan larvae is provided, along with a checklist of extant Archostemata taxa. The work is illustrated with 120 morphological drawings.
A review of all known descriptions of immature stages of the species of the genera Scaeva Fabricius, 1805, Ischiodon Sack, 1913 and Simosyrphus Bigot, 1882 is presented using SEM illustrations. The third instar larval and/or pupal morphology of Scaeva dignota (Rondani, 1857), Scaeva mecogramma (Bigot, 1860) and Simosyrphus grandicornis (Macquart, 1842) are newly described. All species of the genera studied in this paper are very similar for all the studied characters of their immature stages, including the chaetotaxy. Molecular characters of the mitochondrial cox1 gene (1128bp) were used for inferring relationships of the studied taxa. The nuclear internal transcribed spacer 2 (ITS2) was additionally applied for species delimitation of the closely related species Scaeva selenitica and S. dignota. The Palaearctic Scaeva species could be split into two groups based on the analysis of morphology of posterior respiratory process. These groups were previously diagnosed as S. selenitica-group [i.e., S. selenitica (Meigen, 1822), S. dignota (Rondani, 1857), S. mecogramma (Bigot, 1860)] and S. pyrastri-group [i.e., S. pyrastri (Linnaeus, 1758), S. albomaculata (Macquart, 1842), S. latimaculata (Brunetti, 1923)]. Semiscaeva Kuznetzov, 1985 and Scaeva Fabricius, 1805 are the available names for these two natural groups that should be classified as subgenera; the former name is proposed for S. selenitica-group and the latter for S. pyrastri-group. Mecoscaeva Kuznetzov, 1985 syn. n. is transferred as a junior synonym of the subgenus Semiscaeva Kuznetzov, 1985 according to the principle of the first reviser. Based on the analysis of immature stages, the generic name Ischiodon Sack, 1913 syn. n. is proposed as a junior synonym of the genus Simosyrphus Bigot, 1882. The similarity of immature stages between Scaeva s. str. and Simosyrphus grandicornis Macquart, 1842, Simosyrphus aegyptius (Wiedemann, 1830) comb. n. and Simosyrphus scutellaris (Fabricius, 1805) comb. n. is discussed. All the proposed subgeneric and generic taxa based on morphological studies received high support employing molecular characters.
The larval morphology of the western Palaearctic zygaenid species Aglaope infausta (Linnaeus, 1767) is described and figured in detail. Unlike other members of the zygaenid subfamily Chalcosiinae, the last instar larva of A. infausta has numerous secondary setae and a multitude of cuticular cavities that are devoid of openings. The other chalcosiine genera have primary setae and cuticular cavities with specialized openings through which a defensive secretion can be discharged. Imaginal characters, on the other hand, provide strong evidence for placing Aglaope in the Chalcosiinae.