Exaesiopus Reichardt, 1926

Lackner, Tomáš, 2010, Review of the Palaearctic genera of Saprininae (Coleoptera: Histeridae), Acta Entomologica Musei Nationalis Pragae (suppl.) 50, pp. 1-254 : 111-112

Exaesiopus Reichardt, 1926

Exaesiopus Reichardt, 1926: 14 . Exaesiopus: REICHARDT (1941) : 156, 329; PEYERIMHOFF (1936): 226; KRYZHANOVSKIJ & REICHARDT (1976): 112, 232; MAZUR & KASZAB (1980): 7, 61; VIENNA (1980): 117, 195; MAZUR (1984): 101; MAZUR (1997): 263; YÉLAMOS (2002): 245, 338; MAZUR (2004): 92.

Type species: Saprinus grossipes Marseul, 1855 , original designation.

Diagnosis. Frontal stria carinate; frontal disc impunctate, with irregular deeply impressed longitudinal rugae (as in several species of Hypocaccus ); pronotum rounded laterally; pronotal hypomeron setose; elytral epipleuron glabrous; metepisternum, lateral disc of metaventrite and lateral parts of all visible abdominal sternites setose, setae on abdominal sternites very short; protibia on outer margin with several low teeth, topped by rounded denticle, followed by three to four short denticles; meso- and metatibiae thickened and dilated, metafemora conspicuously thickened.

When composing the diagnosis of this genus the morphological characters of the species Exaesiopus grosclaudei Normand, 1935 have not been taken into account since this species belongs to genus Hypocacculus (Nessus) (see also the diagnosis of this subgenus).

Differential diagnosis. Exaesiopus is superficially strikingly similar to the genus Hypocaccus , differing from it chiefly by the setose lateral disc of metaventrite, lateral parts of all visible abdominal sternites (as well as setose pronotal hypomeron) and dilated and thickened meso- and metatibiae. Several species of Hypocaccus have also underside of their bodies with short setae (e.g. Hypocaccus (Hypocaccus) crassipes ( Erichson, 1834)) , but their pronotal hypomeron is always asetose, whereas it is setose in Exaesiopus .

Biology. Although the species of the genus Exaesiopus are mostly collected on beaches, they are, unlike most members of the similar genus Hypocaccus , found also further inland. Their biology is generally poorly understood. Species Exaesiopus atrovirens Reichardt, 1926 and E. torvus Reichardt, 1926 from Central Asia are occasionally found under Tamarix spp.

Distribution. Exaesiopus is predominantly a Palaearctic genus, occurring on the sandy soils from the Canary Islands throughout northern Africa, southern Europe and southern parts of Central Europe (reaching the northernmost point of its distribution in southern Slovakia) eastwards through Turkey and Caucasus as far as Central Asia (up to Afghanistan). One species, Exaesiopus laevis Thérond, 1964 has been described from Somalia.

Species examined. Exaesiopus atrovirens Reichardt, 1926 , E. grossipes berberus Peyerimhoff, 1936 , E. grossipes grossipes ( Marseul, 1855) , E. henoni ( Schmidt, 1896) , E. torvus Reichardt, 1926 .

Discussion. This taxon is most likely not monophyletic and its relationship with the genus Hypocaccus should be the focus of the future studies. It is supported by only a few weak synapomorphies, e.g. shape of the protibia, thickened meso- and metatibiae or vestiture of the underside of body, but these may be simply results of the convergent evolution and do not present valuable taxonomic characters. Revision of the species of Exaesiopus is in progress.