Sergentia sp.

  • photomicrograph of the head capsule of a chironomid midge larva showing the mentum (4 median teeth and 6 lateral teeth on either side) and broad ventromental plates in line with the edge of the outer median teeth

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    Figure 1. Sergentia spp. has a mentum with 4 large widely separated, equally broad and slightly elevated inner median teeth, with 6 pairs of scarcely differing lateral teeth. A distinct line connects the posterior margin of the outer median teeth with the ventromental plate.

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  • photomicrograph of the head capsule of a chironomid midge larva showing the mandibles with 4 inner teeth in addition to the long one on the end and a small tooth on top of the longest tooth. The antenna has 5 segments and the antennal blade is as long as the last 4 segments.

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    Figure 2. Sergentia spp. has antennae with 5 segments and 4 mandibular teeth.

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  • photomicrograph of the head capsule of a chironomid midge larva showing the pecten epipharyngis, which is made of three plates that each have a few very long serrations that look like fused teeth. Arrows point to the three plates.

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    Figure 3. Sergentia spp. has a pecten epipharyngis consisting of 3 separate, distally serrated platelets.

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Sergentia sp.

Taxa description

Large larvae, up to 18mm, color red, with 2 pairs of eyes. Antenna with 5 segments, ring organ situated about 1/3 of basal segment. Pecten epipharyngis consisting of 3 separate, distally serrated platelets. Mentum with 4 large widely separated, equally broad and slightly elevated inner median teeth, with 6 pairs of scarcely differing lateral teeth. A distinct line running from the posterior margin of the outer median teeth of the anteromedial margin of the ventromental plate.

Distinguishing features

Habitat

Sergentia spp. occur in the sublittoral and profundal of oligotrophic to mesotrophic lakes. Sergentia coracina was found in splash in splash zone of freshwater coastal rock pools in Lake Superior at Isle Royale, Michigan (Egan and Ferrington, 2015).

Lake occurrence

Sergentia spp. have been found in all Great Lakes, however, was more often documented in Lake Michigan compared to other Great Lakes (Mozley & Howmiller, 1977).

Similar species

Sergentia spp. can be easily confused with the closely related Phaenopsectra spp. and has been used as a synonym of Phaenopsectra spp. by many North American authors. However, Sergentia spp. has 4 rather than 3 mandibular teeth.

Relative size

Sergentia spp. are relatively large chironomid larvae, up to 18mm.

Does it have a barcode reference from the Great Lakes?

References

Anderson, T., P.S. Cranston, and J.H. Epler. 2013. The larvae Chironomidae (Diptera) of the Holoarctic Region: Key and diagnosis. Insect Systematics & Evolution. Supplement No 66.

Occurrence in scientific literature

Egan, A.T., and L.C. Ferrington Jr. 2015. Chironomidae (Diptera) in freshwater coastal rock pools at Isle Royale, Michigan. Transactions of the American Entomological Society 141:1-25.
Mozely, S. C., and R.P. Howmiller. 1977. Environmental status of the Lake Michigan region. Volume 6. Zoobenthos of Lake Michigan. Environmental Control Technology and Earth Sciences. 148pp.