Autalia Leach in Samouelle, 1819
This very widespread genus includes about 35 species; 10 are known from the Palaearctic region, of which 5 occur in Europe and 4 extend to the UK, 5 are known from North America, 7 from the Neotropical region, 2 from the Oriental region and 10 occur in tropical Africa. So far as is known most of the tropical species are endemic to particular areas e.g. A. Ruwenzori Klimaszewski, 1992 from Uganda, A. tetracarinata Cameron, 1950 from Zaire and Rwanda, A. yoopaa Hoebeke & Ashe, 1994 from Mexico, and A. minuta Cameron, 1936 from Sumatra. The Palaearctic fauna also includes localized species e.g. A. smetanai Pace, 1991 from Nepal, and several are endemic to China e.g. A. schuelkei Assing, 1998 and the quaintly-named A. imbecilla Assing, 1985, while some are more widespread e.g. A. rufula Sharp, 1888 from China and Japan. While most have limited distributions the European species are generally much more widespread and with the exception of A. kabyliana Fagel, 1959, which occurs in North Africa and Spain, all extend into northern regions. Another localized species, A. inopinata Assing, 2003, which is endemic to Turkey, has yet to be recorded from Europe.
A. impressa (Olivier, 1795), the type species of the genus, is common throughout Europe and North Africa and is also known from Nepal, to the north it extends into southern provinces of Fennoscandia and the UK where it is widespread and generally common across England and Wales and is known from a few records in Southern Scotland and Northern Ireland. This is the most frequently recorded species in Central and Northern Europe.
A. longicornis Scheerpeltz, 1947 is widely distributed though sporadic in Europe, extending north into Central Fennoscandia and the UK where it is common across Wales and Central and Southeast England. Before its discovery in 1947 this species was identified as A. impressa and so older keys such as that of Joy have since become very limited in usefulness.
Autalia impressa 1
Autalia impressa 2
Autalia impressa 3
Autalia impressa 4
© Lech Borowiec
Autalia longicornis 1
Autalia longicornis 2
Autalia longicornis 3
Autalia longicornis 4
© Lech Borowiec
Autalia puncticollis 1
Autalia puncticollis 2
Autalia rivularis 1
Autalia rivularis 2
Autalia rivularis 3
Autalia rivularis 4
© Lech Borowiec
A. rivularis (Gravenhorst, 1802) is the most widespread member of the genus; it occurs throughout the Palaearctic region including China and Japan and is widespread in both the Nearctic and Neotropical regions. It is common throughout Europe and extends north into Central Fennoscandia and the UK where it occurs throughout England and Wales and is widespread across the Scottish Highlands.
A. puncticollis Sharp, 1864 is more restricted; it is locally common in central and Southern Europe, being more prevalent in mountain areas, and extends sporadically east to the Black Sea and north into Northern Fennoscandia and the UK where it is very local and known from widely scattered records in Northern Wales, Northern England and Scotland. In the New World, however, it is widespread in North America and also known from South America.
We include this genus because, especially among the Aleocharinae, it is very distinctive and specimens will frequently occur when working most types of organic material, it therefore offers a good opportunity to become familiar with a few of the more obscure groups of staphs. The species will often key out readily but impressa and longicornis will need to be dissected in order to examine the genitalia, in this way both males and females of all species may be identified with certainty. The genus may be recognized by the following characters. Tarsi 4-4-5 in both sexes. Antennae filiform, compact and only very slightly widened towards the apex. Head rounded from behind the eyes to a narrow neck. Anterior margin of mentum narrowly and deeply emarginate, ligula long, narrow and divided into two divergent lobes apically. Pronotum flat across the base, broadest about the middle and strongly narrowed to a straight apical margin, surface with a median longitudinal furrow (which may only be visible anteriorly) and an oblique furrow either side from the base. Mesonotum with a complete median carina. Elytra each with two strong longitudinal basal impressions. For practical purposes, and among our UK fauna, they are recognized by the form of the head coupled with the pronotal and elytral impressions. But the overall appearance will soon become familiar and the generic assignment will be taken for granted. They are small staphs; 1.5-3.2 mm, elongate and sometimes appearing ant-like, with the rounded and exposed head about as wide as the pronotum and the pronotum much narrower than the elytra. The elytra are quadrate or slightly transverse, they lack striae and are very finely and rather sparsely punctured, the inner margins do not overlap and the apical margins are sinuate just before the posterior angles. Abdomen long and strongly bordered, usually bulging about the middle and tapering only towards the apex, basal abdominal tergites transversely impressed across the base and with, variable but usually strong, median and lateral longitudinal carinae. The dorsal surface is sparsely pubescent throughout, the microsculpture varies but is usually weak and most specimens will appear shiny, and species are either black with pale appendages, or have a dark, almost black, head and subapical abdominal segments, brown elytra and pale pronotum and basal and apical abdominal segments and pale appendages. These two colour patterns cannot be confused and so our species are readily separated as follows:
Body entirely black.
Body bicoloured, head black, pronotum pale brown, elytra darker brown, abdomen pale with the subapical tergite(s) dark.
Smaller species, 1.7-2.1 mm. Pronotum with the central longitudinal impression extending from the basal transverse impression into the apical quarter, often reaching the apical margin, pronotal punctures extremely fine.
Larger species, 2.1-2.6 mm. Pronotum with the central longitudinal furrow confined to the apical half, punctures much stronger and slightly raised from the surface.
The following species are only reliably separated by genitalia examination. Both sexes are easily recognized; in males the internal and external curvature and the form of the median lobe and parameres (in lateral view) are distinctive whereas in females the form of the spermathecal duct and the orientation of its insertion are characteristic. The following morphological characters are subtle but when series of specimens are compared they become obvious.
On average a little larger, 2.6-3.2 mm. Temples more strongly narrowing from behind the eyes to the neck. Antennae more elongate and slender; the fourth segment distinctly elongate and the penultimate segment only slightly transverse.
On average a little smaller, 2.5-3.0 mm. Temples more rounded from behind the eyes to the neck. Antennae less elongate and more compact, the fourth segment not or only very slightly elongate and the penultimate segment more transverse, at least 1.5X wider than long.
Little is known of the biology of our species but they seem to occur year-round and they are generally associated with damp compost, humus, litter, dung and decaying fungi, this is fairly typical of the genus although a few Afrotropical species are myrmecophilous. Dung is likely to be productive at any time but older and drier samples are probably most productive, and during autumn and winter decaying terrestrial fungi may host large numbers of a mixture of species. There seems to be no clear preference as most species occur widely in various habitats but it is probably true to say that A. impressa is more frequent in decaying fungi, A. puncticollis more so in compost, and A. puncticollis in dung.