Abax Bonelli, 1810
This small genus of ground beetles is native to Europe and Asia Minor, the seventeen species have a relatively restricted distribution with the greatest diversity in the Alps and many are present as distinct subspecies. They typically occur in woodland and moorland habitats and especially in upland areas. They are medium to large carabids, all are unmetallic black and most are of a characteristic appearance which soon becomes obvious with experience, at least among the European fauna; several Nearctic genera are closely similar. They are typically rather parallel-sided and flattened, broadly elongate and with long robust appendages. The head is proportionally large, and the pronotum quadrate to transverse with well-developed and often deep basal fovea. The elytra are characteristic; the shoulders are toothed, the seventh interstice is raised and often carinate- in all but one species-and the ninth stria is well impressed posteriorly. In the U.K. they are most similar to some Pterostichus species but all Abax species lack setiferous punctures or fovea in the elytral interstices and striae. The wings are reduced or absent and the male pro-tarsal segments are dilated in all species.
A. parallelepipedus (Piller & Mitterpacher, 1783)
This is the most widely distributed species of the genus; it occurs throughout central Europe from Spain to Greece-where it is represented by ssp. subpunctus Dejean, 1820 - extending north into southern Scandinavia and the U.K. There are nine subspecies, most of which have a restricted and well-defined distribution, three of these occur in Italy. This is the only species to occur in the Nearctic zone; an adventive recorded from Atlantic Canada. The species is generally common throughout the U.K. except for the north eastern Scottish Highlands, Orkney and Shetland. The typical habitats are neglected gardens, parkland and damp, shaded woodland where the adults may be found by day under logs and among leaf-litter etc., often alongside other common carabids. In northern and western areas they also occur among long and dense vegetation on moorland, and in this situation they may be abundant. They are active at night and so readily occur in pitfall traps but they tend to avoid open areas e.g. pathways and lawns etc. Adults occur year-round, they are active from April to October, and spend the winter beneath logs or in the soil beneath leaf-litter etc.
The large size, 18-22mm, entirely black colouration and broad, flattened form should make this species immediately recognizable in the field. The head is large with prominent convex eyes and robust mandibles, the clypeus is expanded laterally in front of the eyes and beneath the antennal insertions and there is a series of furrows and two setiferous punctures beside each eye. The antennae are pubescent from the fourth segment. The pronotum is impunctate, slightly transverse and has well-developed lateral beads, the basal fovea are broad and long; almost reaching the middle. The elytra have a distinct ‘shoulder tooth’, eight well-impressed striae which are complete to the apex and a ninth which is well-impressed in the posterior half. The interstices are convex and lack punctures, the seventh is carinate towards the base. The legs are long and robust; all tibiae have short spines along the margins and a well-developed apical spur. The tarsi are smooth and glabrous above, and the under surface of the terminal segment of the meta-tarsus is clothed with fine setae. Males are shiny and have the basal pro-tarsal segments dilated; females lack the dilated tarsal segments and are dull, a character readily appreciated in the field.
A. parallelus (Duftschmid, 1812)
This species has sometimes been included on the British list on the strength of a single specimen found in 1913 at St. Mary’s, Scilly. It is now generally accepted to have been the result of human introduction, is classed as a non-established introduction and has not been included in modern carabid keys. On the continent it is a widespread but local insect of mountain forests from France to Ukraine but does not extend into Scandinavia. It is represented by two subspecies, A. p. zoufali Maran, 1927 occurring in Serbia. A little narrower and smaller than parallelipipedus, 14-18mm, it has the typical form of the genus. Both sexes are shiny and in both the seventh interstice is raised but not carinate, and the shoulder tooth is less developed than that in parallelipipedus; it is readily distinguished by the lack of setae beneath the terminal meta-tarsal segment.
Elytra generally less shiny.
Interstices with setiferous punctures.
9th striae not carinate towards base.