Tribe Sogdini

Diagnosis. Tarsal formula 5-5-5 (rarely 4-4-4) in both sexes. First tarsomere as long as or longer than the second. Labrum usually deeply emarginate apically. Mandibles usually with reduced non-contiguous molar lobes. Galea narrow, its setose brush small and poorly developed. Lacinia with a large densely setose brush.

Key for the identification of the world genera of the tribe Sogdini

1 Labrum shallowly to deeply emarginate, the emargination at least one-fifth as deep as width of labrum. ....................................................................................................... 2

– Labrum very shallowly emarginate, the emargination less than one-sixth as deep as width of labrum. Head with microsculpture of fine, irregular lines; pronotum minutely punctured. Nearctic. ....................................... Kalohydnobius Peck & Cook, 2009

2(1) Antennal club 3-segmented. ..................................................................................... 3

– Antennal club interrupted 5-segmented. ................................................................... 5

3(2) Metafemur slender, metatibia not widened apically (Fig. 10); clypeus sexually dimorphic, deeply concave in males. Palaearctic, Nearctic. ........ Triarthron Märkel, 1840

– Metafemur robust, metatibia widened apically; clypeus weakly concave in both sexes. ......................................................................................................................... 4

4(3) Tarsal formula 5-5-5. Palaearctic, Nearctic. ........ Pseudotriarthron Normand, 1938

– Tarsal formula 4-4-4. Palaearctic. .............................. Deltocnemis J. Sahlberg, 1886

5(2) Pronotum almost as long as wide. Large species up to approximately 9 mm. Eastern Palaearctic. ......................................................................... Hinomoto Hoshina, 2002

– Pronotum distinctly broader than long. Smaller species (with exception of Macrohydnobius). ..................................................................................................................... 6

6(5) Pronotum margined at base. Mesoventrite flat or flatly depressed without longitudinal carina. ....................................................................................................................... 7

– Pronotum not margined. Mesoventrite flat or depressed, with or without carina. ..... 11

7(6) On average larger species usually more than 4 mm; pronotum with sub-basal transverse impression or row of punctures. Nearctic. ...... Macrohydnobius Peck & Cook, 2009

– On average smaller species, length at most up to 4 mm; pronotum without sub-basal transverse impression or row of punctures. .............................................................. 8

8(7) Right mandible with one tooth at middle of blade. Eyes protruding. ....................... 9

– Right mandible with two teeth, eyes not protruding. Nearctic, Palaearctic, Oriental. .......................................................................................... Hydnobius Schmidt, 1841

9(8) Parameres coalescent with median lobe far before base. Six visible abdominal ventrites. Male metafemur with tooth or series of distinct notches on posterior margin, mesofemur never with tooth. Nearctic, Palaearctic. ................. Sogda Lopatin, 1961

– Parameres free up to their base. Five visible abdominal ventrites. Male metafemur rarely toothed, in that case mesofemur also toothed. ............................................. 10

10(9) Parameres longer than median lobe, and with large setae on dorsal surface before apex. Nearctic and northern Neotropical Region. ........................................................ ........................................................................... Platyhydnobius Peck & Cook, 2009

– Parameres distinctly shorter than median lobe, without conspicuous setosity. Southern Afrotropical Region. ............................................................ Euliodes Portevin, 1937

11(6) Mesoventrite with high angulate (in lateral view) carina; mesoventrite excavate between transverse and longitudinal carina. Southern South America. ...................... ................................................................................... Metahydnobius Portevin, 1942

– Mesoventrite without high angulate longitudinal carina, at most with low short unobtrusive carina........................................................................................................12

12(11) Mesoventrite vertical between mesocoxae, with short very low wide unobtrusive longitudinal carina (Figs 3C–D), body highly convex and oval. Southern South America. ............................................................................................ Anaballetus gen. nov.

– Mesoventrite more or less horizontal, body dorso-ventrally compressed, oval and almost cylindrical. .................................................................................................. 13

13(12) Mesoventrite with distinct impression described by a rim; metaventrite with several foveae just behind mesocoxae. Southern South America. ........................................... ....................................................................................... Hydnodiaetus Jeannel, 1962

– Mesoventrite without distinct impression; metaventrite lacking distinct foveae. New Zealand. ................................................................................... Isocolon Broun, 1893