Key to Nearctic Phthinia

(based on males though external characters and distributional data will also distinguish some females)

1 Wing with microtrichia easily observable between more widely-spaced macrotrichia (Fig. 3); laterotergite with at least a few

seta (Fig. 2); A1 weakly divergent from stem of cubital fork (Fig. 3); gonostylus articulating with gonocoxites apically (ventroapically in P. cascadica n. sp.) (Figs. 7, 13, 19, 29, 48); minute dorsal and posterior setae of hind tibia present.......... 4 - Wing with microtrichia present, but difficult to distinguish between dense macrotrichia (microtrichia in these species most easily observable along posterior edge of petiole of cubital fork) (Fig. 32); laterotergite bare (Fig. 31); A1 strongly divergent from stem of cubital fork (Fig. 32); gonostylus articulating with gonocoxites dorsally (Fig. 23, 36, 42); hind tibia with minute dorsal setae present, but posterior setae absent.................................................................... 2

2 Gonostylus trilobate (Figs. 36, 40, 42–43)..................................................................3

- Male gonostylus bilobate (Figs. 22–23); Nova Scotia .............................................. mikmaqi n. sp.

3 Male terminalia as Figs. 39–43; Nearctic boreal distribution...................................... ramificans Zaitzev

- Male terminalia as Figs. 33–37; western Nearctic................................................. neptunei n. sp.

4 Posterodorsal corners of male gonocoxite developed into a pair of elongate dorsally directed rods (Figs. 4–6); western Nearctic........................................................................................ cascadica n. sp.

- Posterodorsal corners of male gonocoxite without such developments; eastern Nearctic.............................. 5

5 Outer surface of gonostylus developed into a single long, apical, spine-like lobe (Figs. 12, 19)........................ 6

- Outer surface of gonostylus with two spine-like lobes (Figs. 28, 48); one long apical spine and a second more basal spine that may be either shorter (Fig.48) or subequal in length (Fig. 28) to apical spine....................................... 7

6 Inner surface of gonostylus with a semi-transparent, curved, apically spatulate lobe (Figs. 12–13); male terminalia as Figs. 9–13; eastern Nearctic....................................................................... lobata Zaitzev

- Inner surface without such a lobe (Figs. 15–19); male terminalia as Figs. 15–19; Michigan.............. meicigama n. sp.

7 Dorsobasal spine of gonostylus shorter than apical spine (Fig. 48); median aedeagal complex rectangular and apically truncate (Figs. 47–48); inner, setose, lobe, of gonostylus with a very short semi-transparent, curved, apically spatulate lobe; male terminalia as Figs. 44–48; eastern Nearctic........................................................... tanypus Loew

- Dorsobasal spine of gonostylus subequal in length to apical spine (Fig. 28); median aedeagal complex long slender, apically acute (Fig. 28); inner, setose, lobe, of gonostylus with a thin elongate semi-transparent, curved, apically spatulate lobe (Figs. 26, 28); male terminalia as Figs. 25–29; northeastern Nearctic...................................... miranda Zaitzev