Halacritus punctum (Aubé, 1843)
POLYPHAGA Emery, 1886
HYDROPHILOIDEA Latreille, 1802
ABRAEINAE MacLeay, 1819
Halacritus Schmidt, J., 1893
This exclusively maritime species is locally common from Portugal to Greece and Turkey and on many of the Mediterranean islands, it occurs on the northern coast of the Black Sea and is sometimes quoted from North Africa but this needs to be verified, to the north, where it is generally very local and rare, it extends to the UK and Germany but is absent from the Baltic coast. The nominate subspecies occurs throughout this range while in Italy it is also represented by ssp. viennai Gomy, 1978. In the UK it occurs at a few sites on the South and South-West coasts of England, South and North-West Wales and on Anglesey; there are very few modern records and it is likely the species suffered from commercial development and maintenance of at least some of its previous sites, but given its tiny size and concealed lifestyle it is likely to be under-recorded. Adults occur between March and October and have been recorded in December, they peak in abundance during April and May and again in late summer and so it is likely they breed in the spring and overwinter as adults although little is known of the biology. Typical habitats are among buried decaying seaweed and tidal refuse on sandy beaches and dunes but adults also occur under stranded driftwood and seaweed, and some modern records are from rocks on pebble-beaches. In Northern Europe they sometimes occur in dune systems some distance from the sea.
Very small, 1.0-1.4 mm, but quite distinctive due to the general appearance, and of course only likely to be encountered in coastal habitats. Broadly elongate-oval, continuous in outline with a characteristic sinuate margin where the pronotum and elytra meet, glabrous and shiny, body brown or reddish-brown, appendages usually paler brown. Head finely and rather sparsely punctured, transverse and strongly produced in front of dorsal antennal insertions, vertex convex but rather strongly impressed laterally and anteriorly, eyes weakly convex but distinctly protruding, their surface with small but conspicuous tubercles, clypeus smoothly curved anteriorly and with strong cellular microsculpture towards the lateral margins. Mandibles robust, smoothly curved and with a strong dorsal ridge, terminal maxillary palpomere elongate, pointed and narrower than the penultimate segment. Antennal scape strongly curved and only moderately expanded from the middle, segments 2 and 3 quadrate to slightly elongate, 4-9 transverse and the club large, rounded and apparently single-segmented. Pronotum transverse, broadest near the base and narrowed to slightly projecting anterior angles, lateral margin finely bordered and basal margin gradually produced, surface finely and sparsely punctured throughout; without a transverse series of punctures in front of the base. Scutellum very small but always obvious. Elytra elongate, broadest behind the shoulders and narrowed to almost truncate apical margins, without striae but often with short longitudinal impressions along the basal margin and sometimes traces of an oblique basal stria, finely and rather sparsely punctured throughout. Front tibiae very strongly broadened and with five or six small teeth towards the apex, middle and hind tibiae gradually broadened towards the apex, tarsi 5-5-4 in both sexes, without expanded segments.
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