Hayesomyia senata (Walley)

Namayandeh, Armin, Bilyj, Bohdan, Beresford, David V., Somers, Keith M. & Dillon, Peter J., 2012, 3324, Zootaxa 3324, pp. 1-65 : 7-9

Hayesomyia senata (Walley)

Figs 2A–F

Diagnosis. Head generally pale with a darkened posterior margin, gular sclerite pale; maxillary palp ( Fig. 2A) with 2-segmented sensillum b; antenna as in Fig. 2B, basal antennal segment 256–276 µm long, 1.9–2.1x as long as mandible, 2 nd segment 45–49 µm long, AR 4.3–4.6; mandible ( Fig. 2C) with small but distinct accessory tooth; pseudoradula slightly tapering to broader base with 8–10 rows (at midpoint) of fine to coarse granules, wavy lines near base; ligula (fig. 2D) with concave toothed margin, inner laterals distinctly out-turned; ventral cephalic setae and VP as in Fig. 2E; body with scattered setae about half as long as subtending segment. Posterior end of abdomen as in Fig. 2F.

Notes. The larva of H. senata is difficult to separate from larvae belonging to Thienemannimyia norena (Roback) and Thienemannimyia barberi (Coquillett) . All three have ARs below 5.0, a character that Epler (2001) used in part to separate the two genera. In T. barberi the length of antennal segment 2 is in the range of 50–54 µm, close to H. senata 43–50 µm. In T. norena the length is 37–41 µm. The only other Nearctic Thienemannimyia , Thienemannimyia fusciceps (Edwards) has an AR> 5.0. However, according to M. Bolton (pers. comm.) there is overlap in all characters used in the diagnosis of H. senata and T. norena , and possibly T. barberi and only the developing thoracic horn in pupating larvae will separate the species. If that is the case then species assignment above should be considered tentative. Only one species of Hayesomyia is known from the Nearctic region.

Ecology and habitat. In this study the larvae were mainly found in moss. It is noted by Hudson et al. (1990) that they generally occurs in large rivers and based on Roback (1981) species occur mainly in hard-water streams with pH 7.1–8.0 and water temperature of 19–28°C. All the study streams are soft-water with pH 5.5–6.92 and temperature never exceeds 16°C.

Sampling sites. We found the larvae inhabiting streams in all the provincial parks and districts located in our study area.

Nearctic distribution. Canada: Alberta, New Brunswick, Nova Scotia, Ontario, Québec, Saskatchewan. USA: California, Florida, Georgia, Illinois, Iowa, Kansas, Michigan, Minnesota, New Jersey, New York, Rode Island , South Dakota, Washington.