Diagnosis of the genus Acolastus
Body cylindrical. Eyes oval, with feeble emargination on inner rim, antennae filiform, clypeus broad and short. Pronotum highly transverse, with rounded angles, median lobe truncate at apex. Scutellum large, not elevated, triangular, with rounded apex. Prosternum narrow and elevated between coxae, elytra with base turned upward to form a ridge with a distinct denticle, punctation iregular, epipleurae indistinct. Kotpresse composed by five sclerites, ventrally two apodemes, dorsally three sclerites, the two lateral ones adjusted in a dorso-ventral direction, without broadened terminations, dorsal central plate almost quadratic. Spermatheca simply hook-shaped. Tegmen Y-shaped, tegminal manubrium is present, tergalapodem Y-shaped and simple. Four subgenera of Acolastus were described, Anodontelytrus, Anopsilus, Thelyterotarsus (Jacobson 1916) and Thelylankus (Lopatin, 1987).
Etymology of Acolastus
In his description, Gerstäcker did not comment on the etymology of Acolastus. Presumably, he was inspired by a bible drama play on the popular prodigal son theme, Acolastus (1529) by Gulielmus Gnapheus, a Dutchman, educated at Louvain and Cologne, and twice imprisoned by the inquisition. The prodigal son, named Acolastus (acolastox´= the naughty), was leaving home to live in the distance (Rädle, 1992). A genus of Lepidoptera (Hesperidae, Pyrginae) was also named Acolastus Scudder, 1872. In this description the etymology was also not explained. Acolastus Scudder, 1872 was found to be a junior synonym of Polygonus Hübner, 1825.
Distribution of Acolastus
117 species of Acolastus were described (see catalogue), mostly as Thelyterotarsus and Pachybrachis. After the preliminary study of unrevised specimen, the estimated total species number of Acolastus is 151. The geographical distribution comprises the old world subtropics and tropics. In the Afrotropical Region from the cape, all over Southern Africa except the Kalahari desert, in Eastern and Central Africa, except for the humid tropics around the equator, to the horn of Africa in the east and Mauretania in the west. Within the Sahara desert, there is a record from the Tibesti-mountains. In the Palaearctic Subregion, the distribution ranges from the mediterranean-saharian transition zone via the Near East, the Arabian peninsula, the upper course of the Euphrat, the Kaspi-Sea and Kazakhstan to Mongolia in the north. In the south, disjunctive groups of species inhabit Southern India and Sri Lanka, and Yunnan and Sichuan. Obviously, Acolastus is lacking in the humid old world tropics around the equator. The genus seems to be restricted to habitats in arid, semi-arid and Mediterranean climates. Centres of diversity are Southern Africa and Kazakhstan. However, the relatively few species known in north-eastern Africa and the Arabian Peninsula may also be due to a lower collecting intensity. All species south of the Sahara desert were described as Acolastus.
Ecology of Acolastus
The available ecological information suggest that Acolastus inhabits mainly semi-deserts and steppe biotops, they were found both in dry forests and savannah vegetation in mountains and plains. Being polyphagous on the generic level, amongst the plants the beetles were collected from are Gymnospermae: Ephedra distachya (Ephedraceae) and Angiospermae, Dicotyledoneae: Artemisia monosperma, Haloxylon persicum and Sympegma sp. (Chenopodiaceae), Atraphaxis spinosissima, Calligonum mongolicum, Polygonum sp. (Polygonaceae), Tamarix and Reaumuria sp. (Tamaricaceae), Spireanthus (Rosaceae), Acacia sp. (Fabaceae), Combretum sp. (Combretaceae), Hymenocrater bituminosus, Ziziphus sp. (Rhamnaceae), Pappea capensis (Sapindaceae), Rhus oxyacantha, Pistacia sp. (Anacardiaceae) (Kulenova 1968; Lopatin 1984), Zygophyllum dumosum (Zygophyllaceae), Prangos pabularia (Apiaceae), Chondrilla (Asteraceae), Elytropappus rhinocerotis and Angiospermae, Monocotyledoneae: Pennisetum sp. (Selman 1963) and Aristida pungeus (Poaceae) (Berti & Doguet 1994).