Key to the Aploderus species of the Western Palaearctic region (exclusive of Middle Asia)

1. Eyes minute, approximately 1/3 the length of postocular region in dorsal view or even smaller, composed of approximately 10 ommatidia (Figs. 12, 22). Elytra extremely short, at suture about half the length of pronotum, combined width narrower than pronotum, humeral angles completely obsolete. Hind wings completely reduced. Northern Anatolia ....................................................................................................... 2

- Eyes much larger, at least about as long as postocular region and composed of>40 ommatidia. Elytra at suture at least as long as pronotum and with pronounced humeral angles. Hind wings fully developed or of reduced length. ........................................................................................................................................ 4

2. Head with pronounced sexual dimorphism, in males very large, larger than pronotum and approximately as broad as abdomen (Figs. 7–8); dorsally with distinct clear–cut median furrow of at least half the length of distance between fronto-clypeal suture and posterior margin, on either side of this furrow with elevations (Figs. 8–11). Antennomere I longer, approximately 3.5 times as long as wide (Fig. 13). Male sternite VII modified, middle extensively impressed, with dense pubescence, and with pronounced microsculpture; male sternite VIII posteriorly broadly and deeply concave, with 3 submarginal setae on either side of middle, and with conspicuously long dark setae in posterior angles (Fig. 15). Aedeagus larger, approximately 0.7 mm from base of median lobe to apex of paramere; apices of median lobe longer and more slender (Figs. 16–18); paramere shaped as in Fig. 28. Sinop (Fig. 19) .......................... A. magniceps sp. n.

- Head without or with less pronounced sexual dimorphism, in males at most only slightly larger than in females and distinctly narrower than abdomen (Figs. 1, 20); dorsally without or with much more weakly pronounced and shorter median furrow, without distinct elevations on either side of this furrow (if present) (Figs. 2, 3, 21). Antennomere I shorter, approximately 3 times as long as wide (Fig. 23). Male sternite VII unmodified; male sternite VIII posteriorly more shallowly concave and with shorter dark setae in posterior angles. Aedeagus shorter, at most approximately 0.6 mm from base of median lobe to apex of paramere; apices of median lobe shorter. Distribution different..................................................... 3

3. Head without appreciable size dimorphism. Head dorsally without median furrow (Fig. 21), at most shortly and finely striate. Pronotum and elytra with shorter dark lateral setae. Male sternite VIII strongly transverse, almost 3 times as wide as median length, and with moderately concave posterior margin (Fig. 25). Aedeagus larger, approximately 0.6 mm from base of median lobe to apex of paramere; apices of median lobe distinctly bent in lateral view; apex of paramere obliquely truncate (Figs. 26, 29). Northeastern Anatolia: Trabzon (Fig. 19) ..................................................................................... A. capitulatus sp. n.

- Head with weakly pronounced size dimorphism, in males on average somewhat larger than in females. Head dorsally usually with weakly pronounced median furrow (Fig. 2). Pronotum and elytra with longer dark lateral setae. Male sternite VIII less strongly transverse, approximately twice as wide as median length, and with weakly concave posterior margin (Figs. 4–5). Aedeagus smaller, approximately 0.5 mm from base of median lobe to apex of paramere; apices of median lobe not distinctly bent in lateral view; apex of paramere of different shape (Figs. 6, 27). Northwestern Anatolia: Bolu, Zonguldak (Fig. 19) ....... ................................................................................................................................ A. schweigeri (Smetana)

4. Dorsal surface of head posteriorly with distinct median furrow. Forebody with coarse, well-defined, and dense puncturation. Western, central, and eastern Europe. .......................................... A. caesus (Erichson)

- Dorsal surface of head posteriorly without distinct median furrow ............................................................ 5

5. Forebody with distinct microsculpture and reduced shine. Head and pronotum with rather large, but shallow, ill-defined, and irregularly spaced puncturation. Widespread in the Palaearctic region. ...................... .............................................................................................................................. A. caelatus (Gravenhorst)

- Forebody with or without very shallow microsculpture, interstices glossy. Head and pronotum with welldefined and rather coarse puncturation. Distribution confined to Turkey ................................................... 6

6. Pronotum and elytra dark brown to blackish brown; abdomen blackish. Pronotum 1.35–1.45 times as wide as long. Elytra larger and longer, at suture 1.15–1.20 times as long as pronotum. Aedeagus as illustrated in Figs. 10–12 in Assing (in press). Western Anatolia (Aydın, Izmir) .................................. A. lydicus Assing

- Pronotum and elytra yellowish brown to rufous; abdomen brown. Pronotum 1.30–1.35 times as wide as long. Elytra narrower and shorter, at suture approximately 1.05 times as long as pronotum. Aedeagus as in Figs. 30–34. Southwestern Anatolia (Muġla, Antalya) ................................................ A. endogaeus Assing