Chivaenius Olexa, 1980

Lackner, Tomáš, 2010, Review of the Palaearctic genera of Saprininae (Coleoptera: Histeridae), Acta Entomologica Musei Nationalis Pragae (suppl.) 50, pp. 1-254 : 85

Chivaenius Olexa, 1980

Chivaenius Olexa, 1980: 252 . Chivaenius: MAZUR (1984) : 91; MAZUR (1997): 256; MAZUR (2004): 91.

Type species: Chivaenius kryzhanovskii Olexa, 1980 , original designation.

Diagnosis. Terminal labial and maxillary palpomeres thickened, truncate, sensory region of maxillary and labial palpi wide; labral pits absent; head comparatively small; frontal disc with vague shallow punctures and vaguely marked longitudinal rugae; frontal stria straight, carinate, continued as carinate supraorbital stria; eyes inconspicuous from above. Pronotal disc laterally shallowly areolate-rugulose, hypomeron glabrous; marginal pronotal stria carinate, visible along its entire length from dorsal view. Pre-apical foveae very small (in some specimens even absent); carinal prosternal striae absent (at most vaguely marked on prosternal apophysis); lateral prosternal striae strongly convergent anteriorly; prosternal process compressed, almost knife-like; lateral parts of pleura and sterna setose. Protibia strongly dilated, outer margin with three low teeth topped with large triangular denticle, followed by four minuscule denticles; meso- and metatibiae slender, not dilated or thickened.

Differential diagnosis. Chivaenius is somewhat superficially similar to the species of the genera Hypocaccus and Hypocacculus differing from them by the shape of protibia, compressed, almost knife-like prosternal process, absent lateral prosternal striae and tiny (occasionally even absent) pre-apical foveae. Species of the genus Hypocaccus are also devoid of ventral vestiture, whereas this taxon is densely setose on pleura and sterna. By the shape of protibia and setose pleura and sterna this genus is, on the other hand, similar to species of the genus Exaesiopus differing by the absence of prominent rugae on frontal disc, absent lateral prosternal striae as well as tiny (and at times even absent) pre-apical foveae (large and well developed in Exaesiopus ). The lateral prosternal striae are (except for this taxon) absent in several Palaearctic genera of Saprininae : Eremosaprinus , Philothis , Ctenophilothis and Ammostyphrus . Chivaenius differs from Ammostyphrus by the shape of protibia as well as absent lateral pronotal stria (present in Ammostyphrus ); from Philothis and Ctenophilothis it differs also by the shape of protibia and the shape of prosternal process, as well as the shape of meso- and metatibiae; from Eremosaprinus by the present ventral body vestiture and present frontal and supraorbital striae (both absent in Eremosaprinus ).

Biology. Monotypic genus with Chivaenius kryzhanovskii as its only representative collected in the sand dunes. The beetles were found under Tamarix , together with other psammophilous species of Saprininae and Tenebrionidae ( OLEXA 1980) .

Distribution. Chivaenius kryzhanovskii has been found near the city of Khiva, western Uzbekistan.

Species examined. Chivaenius kryzhanovskii Olexa, 1980 .

Discussion. Chivaenius is most likely a well-defined monophyletic genus characterised by a few putative synapomorphies, the ‘strongest’ of which is probably the absence of labral pits and setae. Very small (and in some specimens even absent) pre-apical foveae as well as absent carinal prosternal striae can likewise be accounted among synapomorphies of this taxon; most of these are also present with the presumably most derived psammophilous Saprininae like Philothis .