First record of a skating crane fly: The unusual ecology, behavior, and morphology of Phantolabis lacustris (Alexander, 1938) (Diptera:Limoniidae) with descriptions of the immature stages

Abstract

In 2003, large numbers of pupal exuviae and adults of an unusual skating crane fly (Tipuloidea: Limoniidae) were collected from a trout stream in southern Minnesota, USA. The species was identified as Phantolabis lacustris (Alexander, 1938), a crane fly with undescribed immature stages and biology. In this paper, we describe the immature stages and adult female along with the ecology and behavior of this unusual crane fly. Phantolabis lacustris is the first record of a skating crane fly and has a number of morphological characteristics related to this behavior. These characteristics include expansion of the 3 rd tarsus of the meso-and meta-thoracic legs, subapical insertion of the tarsal claws, and enlargement of the male hypopygium. Supercooling points for this fly ranged from 221.3 to 25.27C, indicating that it is moderately cold tolerant. The skating behavior and cold tolerance of this crane fly is probably related to its emergence in late winter and early spring. A review of P. lacustris specimens collected as part of biomonitoring or ecological studies or deposited in museum collections indicates that the species has a broad distribution in the upper Midwest and eastern portions of North America. Phantolabis lacustris has probably been overlooked because of its early emergence in March, April, and May and the morphological similarity of its larvae with those of the genus Hesperoconopa. The larvae of P. lacustris cannot be morphologically separated from Hesperoconopa at this time, but their discrete geographic distributions permit the identification of P. lacustris and Hesperoconopa larvae.

The genus Phantolabis (Diptera: Limoniidae) new to the Palearctic: description of a new species and re-definition of the genus

“…In a generic key (Alexander & Byers 1981) it was listed as the genus Phantolabis. In its adult and especially larval (Bouchard & Gelhaus 2019) characters this genus is close to Hesperoconopa Alexander, 1948(Alexander 1948, 1952, 1962, 1967, 1976Savchenko 1980). The Nearctic species of Hesperoconopa have well-developed merons (Bouchard & Gelhaus 2019), while H. acutistyla Savchenko, 1980 from South Kurils has a reduced meron and tuberculate pits indistinct (Savchenko 1980).…”

“…In its adult and especially larval (Bouchard & Gelhaus 2019) characters this genus is close to Hesperoconopa Alexander, 1948(Alexander 1948, 1952, 1962, 1967, 1976Savchenko 1980). The Nearctic species of Hesperoconopa have well-developed merons (Bouchard & Gelhaus 2019), while H. acutistyla Savchenko, 1980 from South Kurils has a reduced meron and tuberculate pits indistinct (Savchenko 1980). In Phantolabis the meron is not separated by a suture from the katepimeron and fuses with the lower portion of the katepimeron to form a composite region referred to by Crampton (1943) as meropleurite or meropleuron.…”

“…The wings of both sexes of P. glacialis sp. nov. are entirely brownish, while the wings of females of P. lacustris have lighter areas (Bouchard & Gelhaus 2019). The new species also differs in some venation characters, such as vein r-m connecting to Rs some distance before its fork, apex of R 3 bent to the costal margin, and CuP strongly curving toward the wing margin.…”

“…It also has well-developed interbases and lateral processes of the aedeagal sheath (or parameres), aedeagus not divided apically. A characteristic biological feature of Phantolabis is the appearance of adults at low temperatures at river banks during the early spring (Bouchard & Gelhaus 2019).…”

“…A recent publication by Bouchard & Gelhaus (2019) provided a redescription and biological data for the little-known Nearctic genus Phantolabis Alexander, 1956 with a single species, Phantolabis lacustris Alexander, 1938, and made it clear that the Russian specimens represented a new species of the same genus.…”