Tetralimonius, Etzler, 2019

Etzler, Frank E., 2019, Generic Reclassification of Limonius Eschscholtz, 1829 (Elateridae: Dendrometrinae) sensu Candèze 1860 of the World, Zootaxa 4683 (3), pp. 301-335 : 328

A key to the species of Tetralimonius

1. Anterior one-fourth of elytra, including humeral angle, orange-yellow, rarely with infuscate line along lateral edge of humeral angle; Nearctic....................................................................................... 2

- Anterior one-fourth of elytra unicolorous, remainder brown to black, rarely with indistinct light spot not reaching lateral edges of elytra; Holarctic.................................................................................... 3

2. Elytron pattern variable, never with striae 1 and 2 completely piceous (Figs. 60 and 61); size generally larger, 6.0–7.0 mm; parameres relatively wide and truncate basally, basal piece with membranous area short and triangular (Fig. 51)........................................................................................... Tetralimonius ornatulus

- Elytron with striae 1 and 2 completely piceous (Fig. 56); size generally smaller, 4.5–6.0 mm; parameres relatively narrower, basal piece with membranous area moderate and U-shaped (Fig. 52)......................... Tetralimonius humeralis

3. Palearctic region..................................................................................... 4

- Nearctic region...................................................................................... 5

4. Pronotal disc with sparse punctation, separated by diameter of a puncture or more; male antennae reaching posterior edge of pronotum, antennomeres 4–10 1.8× as long as wide; body piceous, with antennal base, part of legs, and sometimes the anterior and posterior edges of pronotum and posterior margin of hypomeron yellow-brown; 5.5–6.0 mm in length; Europe and Syria.................................................................................. Tetralimonius quercus

- Pronotal disc with dense punctation separated by less than diameter of puncture; male antennae not reaching posterior edge of pronotum, antennomeres 4–10 1.5× as long as wide; body piceous, with entire antenna, legs, anterior and posterior margin of pronotum, and medial and posterior edges of hypomeron pale yellow; 6.0 mm in length; Mongolia and China (Inner Mongolia)................................................................................ Tetralimonius reitteri

5. Hind angles and posterior edges of pronotum distinctly lighter colored dorsally; punctures on pronotum variable, eastern or western North America................................................................................. 6

- Posterior edge of pronotum only subtly lighter colored; punctures on pronotum very close, nearly touching throughout; aedeagus as in Fig. 54; eastern North America.............................................. Tetralimonius definitus *

6. Pronotal punctation very close, nearly touching on disc; size generally larger, 5–6mm; parameres elongate, basal piece with large membranous area (Fig. 53); western North America................... Tetralimonius maculicollis (Figs. 58 and 59)

- Pronotal punctation close, but not nearly touching on disc, with shining interspaces visible; size generally smaller, 3.5–5mm; aedeagus as in Fig. 55; eastern North America..................................... Tetralimonius nimbatus (Fig. 57)

* = some specimens of T. humeralis will key out here excepting the distribution and genitalia. They can be distinguished by small, indistinct spots on the base of each elytra (Fig. 59). Based on the few specimens I have examined it is unclear if this variation represents a cryptic species or is just variation.