Corynocera Zetterstedt, 1838

Namayandeh, Armin, Hudson, Patrick L., Bogan, Daniel L. & Hudson, John P., 2024, Chironomidae (Diptera: Insecta) of Alaska, USA, with descriptions of new species and a checklist, Zootaxa 5511 (1), pp. 1-95 : 77

Corynocera Zetterstedt, 1838

Epler et al. (2013) reported three species of Corynocera from the Holarctic: Corynocera ambigua Zetterstedt, 1838 , Corynocera oliveri Lindeberg, 1970 and at least one undescribed species. We collected adults of this undescribed species which we named Corynocera oliveri group from a small tundra lake east of King Salmon, in the Southwestern bioregion ( Fig. 9U–V ). Other Alaskan records include subfossil specimens identified as Dyadotanytarsus (junior synonym of Corynocera ) from Eight Lake located in the northern foothills of the Brooks Range collected by Livingstone et al. (1958). Kling et al. (1992) identified C. oliveri and C. ambigua in several lakes north of the Brooks Range. However, these records need to be confirmed, given C. oliveri is known to be a Palearctic species. Oliver & Dillon (1997) and Butler et al. (1980) commented on Corynocera having a widespread distribution in the Arctic.

The adults of Corynocera have a distinctive mating behavior, swarming in mass on the water surface. The swarming of C. ambigua begins in early spring when water and air temperatures are below 8 ℃ ( Brodersen & Lindegaard 1999). Adults have an atypical hypopygium, reduced mid and hind legs, wings, antennae, and palp, which make them adapted for swarming on the surface of the water. Lin et al. (2018) pointed out that these unusual morphologies make the phylogenetic comparison of this genus with other Tanytarsini genera difficult. Based on nuclear markers, Lin et al. (2018) found that Corynocera (i.e., C. oliveri group from King Salmon, Alaska) is closely related to Tanytarsus norvegicus group and cannot be separated from other Tanytarsus species. However, treating the genus as a synonym of Tanytarsus would create a nomenclature problem since the description of Corynocera predates that of Tanytarsus . Additionally, Tanytarsus has 355 known species compared to two known Corynocera . This issue is now before the ICZN whether or not to maintain the name Tanytarus for the group ( Lin et al. 2018). The status of unknown Corynocera species from Alaska is undecided until the ruling is confirmed (Torbjørn Ekrem, personal communication 4 March 2022).

Figures

FIGURE 9. Some of the study’s collection sites and habitats of Chironomidae in Alaska. A. Turner Lake, near Juneau. B. Bartlett River in Glacier Bay National Park and Preserve. C. Alaska, USA and Yukon Territory, Canada international boundary. D. Auke Lake outlet in Juneau. E. Rachael Lake near Bettles. F. Spike Creek on Revillagigedo Island. G. Auke Lake in Juneau. H. Hebert River near Juneau. I. Nugget Falls, in Juneau. J. Forested bog near Eagle crest Ski Area, Douglas Isand. K. Creek outlet at Margaret Bay on Revillagigedo Island. L. Mount Roberts (foreground) in Juneau. M. A snow-melt stream (arrows) on Thunder Mountain, Juneau. N. Tangle River near Paxon. O. Kanuti Lake outlet in Kanuti National Wildlife Refuge. P. Fish Creek on Douglas Island. Q. Antler River near Juneau. R. Harbor Mountain, Sitka. S. Observing Thalassosmittia marina (Saunders, 1928) larvae in intertidal rock pools near Lena Point, Juneau. T. Larvae of T. marina (arrows) inhabiting a rock pool in the upper tidal zone and feeding on periphytic algae near Lena Point, Juneau. U.A tundra lake east of King Salmon. V. Swarm of Corynocera oliveri group adults on a tundra lake east of King Salmon.