Key to known Nearctic larvae of Procladius

1. Two small claws with broad bases and short distal ends, with or without teeth on inner margin, longest claws with pointed apices (Fig. 14 I, J); hypopharyngeal pecten (Fig. 13 K) with 6–9, usually 6 or 7, teeth; blade (Fig.13 A) as long as segments 2 and 3 combined; lamellae of galea and chaetulae of palpifer (Fig.14 A) broad and undivided; head capsule length 0.47–0.72 mm .................................................................................................... 2

- All claws with narrow bases, without teeth although small spines may be present on inner margins, long claws with attenuated whip-like apices (Fig.14 K, L); hypopharyngeal pecten (Fig. 13 L, M) with 10–14, usually 11–13, teeth; usually at least as long as segments 2–4 combined; at least some lamellae of galea and chaetulae of palpifer (Fig.14 B, C) divided at apical half to third; head length more than 0.58 mm ..................................................................... 3

2. Two of the smaller posterior parapod claws sharply hooked, no claws with strong points on inner side.............................................................................................. P. (Psilotanypus) nietus Roback

- The smaller posterior parapod claws not sharply hooked, 0, 1, or 2 claws with strong points on inner side............................................................................................. P. (Psilotanypus) bellus Loew

3. Blade shorter than segments 2–4 combined (Fig.13 B); two-segmented sensilla basiconica (SBP in Fig. 14 E) of maxillary palp shorter than bisensillum (Bs in Fig.14 E), its basal segment shorter than its apical segment; head capsule length 0.62–0.78.................................................................................... P. (H.) freemani Sublette

- Blade at least as long as segments 2–4 combined or usually longer (Fig. 13 C–E); SBP (Fig. 14 F–H) of maxillary palp longer than Bs, its basal segment longer than its apical segment; head capsule length 0.65–1.05 mm .......................... 4

4. Blade at least as long as segments 2–4 combined, accessory blade usually nearly as long as blade (Fig. 13 C); head capsule length 0.58–0.81 mm ................................................................................... 5

- Blade as long as segments 2–4 combined or, if as long as segments 2–5 combined, head capsule length over 0.92 mm; accessory blade distinctly shorter than blade (Fig. 13 D, E)........................................................................................................ 6

5. Sclerotized part of basal segment of maxillary palp (Fig. 14 F) 1.9–2.6 times as long as wide....... P. (H.) culiciformis (L.)

- Sclerotized part of basal segment of maxillary palp about 3.2 times as long as wide................ P. (H.) wilhmi Roback

6. Procercus with 18–19 setae; both mandible and basal antennal segment longer than 210 µm............ P. (H.) ruris Roback

- Procercus with 9–14 setae; mandible and basal antennal segment often shorter than 210 µm.......................... 7

7. Sclerotized part of basal segment of maxillary palp (Fig. 14 E) 45–58 µm long and 2.4–2.9, mean 2.5, times as long as wide; basal antennal segment 4.5–5.6, 5.0 times as long as wide and 3.4–4.5, mean 4.0, times as long as basal palpal segment; head capsule length 0.72–0.91 mm ......................................................... P. (H.) sublettei Roback

- Sclerotized part of basal segment of maxillary palp (Fig. 14 G) 55–74 µm long and 2.7–3.5, mean 3.0, times as long as wide; basal antennal segment 5.1–6.4, mean 5.5 times as long as wide and 2.9–3.9, mean 3.4, times as long as basal palpal segment; head capsule length 0.79–1.05 mm long.............................................. P. (H.) denticulatus Sublette