Preliminary key to eastern Nearctic species of Polistes (Fuscopolistes) based on male genitalia

1. Anteroventral lobe of digitus with a vertical groove (Figs 35, 36), bordered on each side by a carina; inner surface of digitus sparsely haired (Figs 35, 36). Aedeagus with very regular dentition (Fig. 49), teeth of equal size (except at the ends of each row), regularly spaced and perfectly aligned; teeth strongly inclined anteriorly. [Aedeagus slender, with small teeth; Fig. 57].................................................................................... P. dorsalis (Fabricius)

- Anteroventral lobe of digitus simple (e.g., Figs 37, 38), lacking groove or clearly defined carinae; inner surface of digitus with hairs more numerous (Figs 37, 38). Aedeagus with dentition more or less irregular (Figs 47, 48, 50–54), usually large teeth alternating with smaller ones (except in some P. fuscatus) and sometimes teeth variably spaced or not perfectly aligned in one row (ventral view: Fig. 58); teeth usually less inclined....................................................... 2

2. Median expansion of aedeagus with row of teeth extending almost to apex of lateral process (Figs 50, 58, 63); teeth large (length of largest teeth ca. 60–90 μm along central axis). [Aedeagus stout AL/MEW = 1.56–1.82, AL/MPW = 4.4–6.3; Fig. 58]................................................................................... P. fuscatus (Fabricius)

- Median expansion of aedeagus with row of teeth extending about halfway to apex of lateral process (e.g., Figs 51, 55, 66), teeth smaller (length of largest teeth ≤ 50 μm)............................................................... 3

3. Aedeagus stout, AL/MPW ≤ 6.0, AL/MEW <2.0 (e.g., Fig. 59)..........................................................................................." P. carolina " cluster A*, P. bellicosus Cresson (part.), and P. metricus Say

- Aedeagus slender, AL/MPW> 6.0, AL/MEW usually ≥ 2.0 (except sometimes in P. bellicosus) (Figs 55, 56, 60–62)..... 4 * See molecular study (below).

4. Anteroventral lobe of digitus with slender, rounded to slightly pointed apex (Figs 30–31). [Aedeagal teeth small, length of largest teeth 30–43 μm; Fig. 53]........................................................... P. hirsuticornis sp. nov.

- Anteroventral lobe of digitus with apex usually distinctly pointed (e.g., Figs 32, 34) and often stouter than in P. hirsuticornis (only slightly pointed in some P. bellicosus, Fig. 33, which has largest aedeagal teeth 42–48 μm)....................... 5

5. Aedeagal teeth small, length of largest teeth 30–40 μm (Fig. 52)............................ P. rubiginosus Lepeletier

- Aedeagal teeth usually larger, length of largest teeth ≥ 40 μm (Figs 47, 48, 54)..................................................................... " P. carolina " cluster X/TX*, P. bellicosus Cresson (part.), and P. parametricus sp. nov. * See molecular study (below).