Diamesa Meigen, 1835

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 : 48

Diamesa Meigen, 1835

The majority of Diamesa species, 11 out of 12, recorded and described in Alaska by Hanson and Cook (1976) were collected by K.M. Sommerman and R.P. Simmet using a car-top trap mainly along the Seward Highway (Highway 1) up to Palmer, with some trips along Highways 3 and 9 ( Sommerman & Simmet 1965).These species include Diamesa aberata Lundbeck, 1898 , Diamesa ancysta Roback, 1959 , Diamesa arctica (Boheman, 1865) , Diamesa chorea Lundbeck, 1898 , Diamesa colenae Hanson, 1976 , Diamesa davisi Edwards, 1933 , Diamesa heteropus (Coquillett, 1905) , Diamesa incallida (Walker, 1856) , Diamesa nivicavernicola Hanson, 1976 , Diamesa simplex Kieffer, 1926 , Diamesa sommermani Hanson 1976 , and Diamesa spinacies Saether, 1969 . Milner (1994) and Willassen (1985) collected and identified Diamesa alpina Tokunaga, 1936 , and Diamesa lupus Willassen, 1985 from Glacier Bay National Park and Preserve, respectively. We also collected these two species from the Herbert River near Juneau ( Fig. 9H ). We also added Diamesa leoniella Hansen, 1976 , a new state faunistic record, from the Nugget Falls ( Fig. 9I ) adjacent to Mendenhall Lake (see Makarchenko 2021). Tilley (1978) collected Diamesa nivoriunda (Fitch, 1847) from the headwaters of two arctic-alpine streams, the Dietrich and Atigun Rivers, in northern Alaska. Makarchenko & Semenchenko (2023) added Diamesa parancysta Serra-Tosio, 1983 to the Alaskan list based on the barcoded specimens of Webb et al. 2022 labeled as Diamesa sp. X JC. Webb et al. (2022) collected the larvae of this species from Jack Creek, Wrangell-St. Elias National Park and Preserve. The Alaskan records of larval specimens identified and described by Tilley (1978) and Doughman (1983) are unclear. The records of Diamesa haydaki Hanson & Cook, 1976 by Oliver et al. (1990) at best is doubtful, as no location is given, and we could not find any records.

Some of the Diamesa species found in Alaska belong to the Diamesa davisi group which have elongated legs and reduced antennae and resemble Tipulidae adults. These structural modifications are associated with mating on the ground or under ice shelves associated with winter conditions in streams, terminal ends, or surfaces of glaciers. Hansen & Cook (1976) found adults running around on the exposed rocks, for which they suggested just turning over the rocks in streams to find adults. Only one species collected by Sommerman belongs to this group, D. davisi , which suggests collecting by using a car-top trap or sweep net, Sommerman & Simmet (1965) could have missed some of the species in this group. Our collection in this group includes D. alpina Tokunaga, 1936 from the Hebert River, collected in February, D. leoniella Hansen, 1976 from Nugget Falls in March and July, D. lupus from the Herbert River in February and October, D. davisi from Nugget Creek in January. These widely separated emergence dates suggest multiple generations per year. Sommerman & Simmet (1965) ’s collection included adults collected in June/July and late August and September. Willassen (1985) has also suggested this emergence pattern for other species in the davisi group. More targeted sampling throughout the state will certainly find this genus widely distributed in all of the Alaskan bioregions. Larvae of most of the Diamesa species live in cold, small bodies of flowing waters including steams originating from glaciers ( Oliver & Dillon 1997).

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.