Compteromesa Sæther

Description

Introduction

Large larvae, up to 10 mm long.

Antenna

With 4 segments, AR 1.7–2.3. Basal antennal segment with ring organ situated near base. Blade much longer than flagellum, accessory blade short.

Labrum

SI palmate, with 5–6 branches; SII–IV simple. Labral lamella broad and pectinate. Pecten epipharyngis of 3 subequal scales. Premandible with one apical tooth, without brush.

Mandible

With apical tooth at most as long as combined width of 4 inner teeth. Seta subdentalis lanceolate. Seta interna with 6 weakly serrate branches.

Mentum

With 2 median teeth and 9 pairs of lateral teeth. Ventromental plates long and broad, with about 7 weak and short setae. Setae submenti situated about at widest point of ventromental plates.

Maxilla

Maxillary palp about twice as long as wide, with basal ring organ. Galea without pecten galearis, with 6 lacinial chaetae. Cardinal beard absent.

Body

Posterior parapods with simple and stout claws. Procercus slightly higher than wide, with 2 lateral and 7 anal setae. Body without conspicuous setae.

Notes

Taxonomic Notes

Compteromesa resembles Prodiamesa but differs in having a premandible with a single apical tooth and the ventromental beard with fewer, weaker setae.

Ecological Notes

Compteromesa contains two species, the Nearctic C. oconeensis Sæther and C. haradensis from Japan (Niitsuma and Makarchenko, 1997). The larva of C. haradensis was collected from a benthic sample of decomposed emergent plants, mainly Sparganium, in a stream flowing slowly through a rice paddy area. Imagines of C. oconeensis were collected near seeps and small streams in the upper Piedmont of South Carolina.

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