Acalcarella sp.

  • photomicrograph of the head capsule of a chironomid midge larva showing the mentum and ventromental plates

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    Figure 1. Acalcarella sp. mentum and ventromental plates, note the overall pale coloration.

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  • photomicrograph of the head capsule of a chironomid midge larva showing the pectin epiharyngis

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    Figure 2. Acalcarella sp. pecten epipharyngis is an elongate-triangular scale that is deeply divided.

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Acalcarella sp.

Taxa description

Acalcarella sp. (Shilova, 1955) is a medium-sized freshwater Chironomidae in the subfamily Chironominae. This genus can be distinguished from all other Chironominae by the large, triangular median tooth, relatively large and triangular lateral teeth, and the triangular, deeply divided medially pecten epipharyngis. Overall, the head capsule is a pale yellow, with an equally pale mentum, large median tooth, and mandibular teeth. The mentum is not strongly arched, rather straight in overall shape except for the peak of the large concave-triangular median tooth. The distinct mentum has 6 to 7 pairs of pointed lateral teeth that face toward the median tooth, almost saw-like, decreasing in size away from the median tooth. The ventromental plates are relatively long, and only about as deep as the height of the mentum itself. The ventromental plates are heavily striated, with the striations visible along the entire length and nearly the entire width. The mandible has three inner teeth and no dorsal tooth. The antenna lacks lauterborn organs and is five segmented, although the segments can be difficult to discern as they are very pale and not sclerotized well. The pecten epipharyngis is a very distinct, large, elongate-triangular single scale that is deeply divided distally. The premandible has four teeth, with the two apical teeth much larger and longer than the other two, as well as having a visible brush.

Lake occurrence

Lake Superior

Relative size

Acalcarella sp. is a medium-sized chironomid.

Does it have a barcode reference from the Great Lakes?

No, this genus does not yet have a barcode reference from the Great Lakes.

References

Andersen, T., Cranston, P.S., Epler, J.H., 2013. The larvae of the Chironomidae (Diptera) of the Holarctic Region. Insect Systematics & Evolution, Supplement No 66. pp. 452, 548.

Stroom, K. T., Schmude, K. L., Snitgen, J., Lozano, S. J., Corry, T. D. & Scharold, J. V. 2010 New records and range extensions for several chironomid genera in Lake Superior. In: Proceedings of the XV International Symposium on Chironomidae (Ed. L.C. Ferrignton Jr.), Chironomidae Research Group, Saint Paul, Minnesota, pp. 140-155.