Figs 28A–E

Diagnosis. Head including posterior margin yellowish brown; distal end of premandible, mandible and mentum dark brown. Labrum as in Fig. 28A; SI seta plumose; premandible with two apical teeth plus one short inner tooth; antenna (Fig. 28B) 5-segmented, 3 rd segment shorter than 4 th, large LO enveloping 3 rd segment, AR 0.5; mandible (Fig. 28C) with 4 inner teeth, apical tooth as long as combined first two inner teeth; mentum (Fig. 28D) with divided broad median tooth and 5 lateral teeth, outer margin extended posterolaterally as a dorsal plate; VM plates with a convoluted posterior extension; setae submenti placed anteriorly between the VM plates; postmental distance 94 µm; posterior end of abdomen as in Fig. 28E; procercus with 3 short apical setae; anal tubules elongate, with three constrictions, about twice the length of posterior parapod.

Notes. The genus has been revised by Saether and Wang (1995) in which they list three subspecies under P. exagitans. The larva, collected in this study, probably belongs to the nominate species based on distribution that includes Ontario.

Ecology and habitat. Larvae occur mainly in semi-aquatic habitats, mainly in moss or moist soils of the stream banks and may also occur in springs, (Saether & Wang 1995).

Sampling sites. Algonquin Provincial Park.

Nearctic distribution. Canada: Ontario. USA: Arizona, California, Colorado, Florida, Georgia, Kansas, Illinois, New York, New Hampshire, New Mexico, Ohio, North Carolina, South Carolina, South Dakota, Tennessee, Wisconsin.