Premnobius

Atkinson, Thomas H., Rabaglia, Robert J. & Cognato, Anthony I., 2010, Two newly detected bark and ambrosia beetles from southern Florida (Coleoptera: Curculionidae, Scolytinae), Zootaxa 2338, pp. 63-68 : 65-66

Key to Genera of Female American Xyleborina North of Mexico

1. Antennal club strongly flattened, basal corneous area small, its margin procurved; pregula expanded and flush with ventral surface of head .................................................................................................................... Premnobius

- Antennal club obliquely truncate, not strongly flattened, basal corneous portion larger, margin recurved; pregula impressed.................................................................................................................................................................. 2

2 (1). Scutellum conical, base of elytra at suture notched, with abundant setae ............................................... Xyleborinus

- Scutellum moderately large, its surface flush with adjacent elytra, glabrous ......................................................... 3

3 (2). Procoxae moderately to widely separated, intercoxal piece continuous, not longitudinally emarginate.................... ............................................................................................................................................................... Xylosandrus

- Procoxae contiguous, intercoxal piece longitudinally emarginate ........................................................................... 4

4 (3). Posterior face of antennal club marked by two sutures on apical third; anterior face with segment two compara- tively large, sclerotized, slightly recurved sutures. ................................................................................................... 5

- Posterior face of antennal club with no sutures visible at or near apex, anterior face with segment 2, if visible, not sclerotized, strongly recurved.................................................................................................................................... 7

5 (4) Posterior 1/3 of elytra narrowed or acuminate, narrowly curved behind, suture weakly to strongly emarginated .... .................................................................................................................................................................. Coptoborus

- Posterior of elytra parallel sided, broadly rounded behind; suture not emarginated. ............................................... 6

6(5) Posterior face of protibiae smooth. ............................................................................................................ Theoborus

- Posterior face of protibiae rugose. ....................................................................................................... Dryocoetoides

7 (4). Antennal club distinctly obliquely truncate, with segment 1 corneous, its distal margin forming a complete circle extending from anterior face to apex, suture on apical area of posterior face not visible, segment 2 on anterior face not visible ................................................................................................................................................................ 8

- Antennal club with segment 1 on both faces rounded, extending to subapical area of posterior face, segment 2 on anterior face conspicuous ......................................................................................................................................... 9

8 Anterior margin of pronotum distinctly armed by several coarse serrations; body stout, <2.2 times as long as wide ................................................................................................................................................................... Anisandrus

- Anterior margin of pronotum unarmed by large serrations, if serrations present, smaller than asperities on anterior slope of pronotum; body more slender>2.3 times as long as wide ........................................ Xyleborus (major part)

9 (7). Third segment of antennal club visible on anterior face but not on posterior face; elytral vestiture uniseriate or confused................................................................................................................................................................... 10

- Third segment of antennal club (i.e., 2 sutures) clearly visible on both anterior and posterior face; elytral vesiture uniseriate on disc..................................................................................................................................................... 11

10(9) Elytral punctures confused, vestiture abundant and confused on disc and declivity.................... Xyleborus (in part)

- Strial and interstrial punctures clearly in rows, vestiture less abundant, uniseriate. ......................... Ambrosiophilus

11 (9).Pronotal asperities extending from anterior to base, asperities on disc and posterior half almost as coarse as those on anterior half; posterolateral margin of declivity rounded; elytral vestiture abundant.................... Ambrosiodmus

- Pronotal asperities confined to anterior half, posterior half of pronotum often punctate; posterolateral margin of declivity subacutely elevated from sutural apex to interstriae 7; strial and interstrial punctures in rows, elytral vestiture sparse, confined to strial and interstrial rows ................................................................................. Euwallacea