Thalassosmittia Strenzke & Remmert, 1957

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 : 73

Thalassosmittia Strenzke & Remmert, 1957

Seven out of eight known species of Thalassosmittia have larvae that are marine littoral dwellers (Andersen et al. 2013). Three out of those seven species occur in Alaska. Thalassosmittia clavicornis ( Saunders, 1928) adults were reported from Attu Island in mid-June by Thompson & Epler (2009). We collected adults of this species in mid-August at the Jensen-Olsen Arboretum near Juneau. O’Clair (1977) reported adult specimens of Thalassosmittia marina ( Saunders, 1928) from Amchitka Island. We collected adults of this species from Lena Point and Jensen-Olsen Arboretum in the Juneau area from mid-June to mid-August. We observed and collected T. marina larvae feeding on periphytic algae in rock pools in the upper tidal zone ( Fig. 9S–T ). One of these pools received freshwater from a nearby seep. Thompson & Epler (2009) reported adults of Thalassosmittia pacifica ( Saunders, 1928) from Attu Island in mid-June. We collected adults of this species from Unalaska Island and several locations in the Juneau area in mid-July and August. We also observed and collected adults of this species swarming over a pile of marine algae, Fucus sp. in early June near Lena Point during low tide. Carlson (1997) reported an unknown Thalassosmittia from the karst ecosystems on Prince of Wales Island. Morley & Ring (1972a, b) discuss life history and population dynamics of the above species along the coast of British Columbia. They found the species inhabiting a variety of rocky shore types but not on sandy shores. They found adult emergence occurs year-round but is most common in fall and least common in late spring and summer. Lab-reared material from eggs to adult emergence took 110 days for T. clavicornis and 150 days T. marina . Based on our Alaska data, one might conclude emergence from June to August involving several generations. Saunders (1928) adds the following observations on the three species of Thalassosmittia from the Pacific coast of Alaska. The larvae of all three species live among filamentous algae freely at first, and later they make loose open-ended tubes. The larvae of T. marina are confined to high tide levels and the other two to lower depths. Adults of T. clavicornis never swarm and rarely fly, with males seeking females by running over the rocks and algae. The other two species swarm, but mating takes place on the ground.

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.