Review of the last instar larvae and pupae of Hexatoma (Eriocera) and Hexatoma (Hexatoma) (Diptera, Limoniidae, Limnophilinae)

Abstract

Description, illustrations and habitat characteristics are given for the previously unknown larvae and pupae of Nearctic species Hexatoma (Eriocera) californica, H. (E.) fuliginosa and East Palaearctic species H. (E.) sachalinensis, H. (E.) stackelbergi, H. (E.) ussuriensis and H. (s.str.) nubeculosa. Hexatoma (E.) sachalinensis, H. (E.) stackelbergi, and H. (s.str.) nubeculosa are reported new for Mongolia based on larval and reared adult collections. There are no distinguishing morphological characters to separate last instar larvae of the subgenera H. (Eriocera) and H. (Hexatoma), while pupae of these subgenera can be separated by the size and shape of the spines on the terminal segments. This study indicates that microscopic setae on the last abdominal segment, length of maxillary palpi, sclerotization of the spiracular field, length of spiracular lobes, length of setae on the apical part of the ventral lobes, the shape of the labrum and the arrangement of sensory structures on the labrum are the main larval characters to distinguish among species in this genus. The shape and length of the respiratory horns, size and number of the horns of the cephalic crest, length of the antennal sheaths, the lengths of the sheaths of the legs, size and shape of tubercles on the antennal scape are the main distinguishing pupal characters for the species of this genus. Nearly all known species of Hexatoma develop in sand or gravel in bottom of large and medium size rivers, smaller streams and creeks while last instar larvae and pupae can be found in the riparian zone, usually in gravel, sand or under stones.

Facilitation of benthic assemblages by Bluehead Chubs: Testing the stress‐gradient hypothesis in streams

“…The cranefly genus Limoniidae: Hexatoma burrows in sand or gravel, or under cobble in riffles and riparian edges, while its confamilial Antocha clings to the top of larger rocks in fast‐flowing water (Alexander et al, 1920). Hexatoma is a predator that burrows among smaller substrate particles; its exploitation of the interstitial spaces between gravel in mesohabitat where chub nests occur, as well as the potential food sources within chub nests, are potential driving factors for Hexatoma 's close association with chub nests (Nakagawa, 2021; Podeniene & Gelhaus, 2015). Some eastern species of Antocha lack spiracles and must, therefore, rely on unobstructed access to the water column for oxygen; unlike Hexatoma , Antocha is likely prevented from burrowing under substrate by its respiration requirements and is typically associated with the dorsal surfaces of substrate of larger diameter than chub nest gravel (Alexander et al, 1920).…”

Distribution of Aquatic Diptera larvae of Yeşilırmak River (Turkey) and ecological characteristics

“…Despite that, Hexatoma sp. is one of the largest and also most widely distributed genus of this family, the information about preimaginal stages is inadequate (Podeniene and Gelhaus, 2015). Hexatoma sp.…”

Twenty years of Dipterology through the pages of Zootaxa

“…Two papers in particular provided me with great joy as editor in charge of the group. The first is a paper about the last instar larvae and pupae of Hexatoma (Eriocera) and Hexatoma (Hexatoma), by Podeniene & Gelhaus (2015). The second is a paper describing new Dicranoptycha craneflies (Diptera: Limoniidae) from North and South Korea, by Podenas et al (2015).…”