Bledius spectabilis Kraatz, 1857
This strictly coastal species occurs sporadically around the Mediterranean from Asia Minor to Portugal and along the Atlantic and Baltic coasts north to the Irish and North Seas and is also widely distributed around the Black and Caspian seas; in the UK it is locally common north to the Wash and Anglesey although generally absent from the West Country. Adults are active from spring until the autumn; they generally occur abundantly in extensive colonies near seawater, often along the intertidal zone but also on wet sand or mud in salt marshes, below cliffs and on tidal estuary mudflats, they occur on all but the most recently exposed substrates and are generally absent from poorly drained areas or those where vegetation is encroaching. They are notable among staphylinids, although not unique e.g. see Platystethus arenarius, in exhibiting care for their eggs and first instar larvae; after mating the female digs a brood chamber which both sexes will inhabit, usually in regularly flooded substrate, consisting of a narrow entrance about 2-3mm wide so that surface tension will prevent the ingress of tidal water for a while during which time they quickly block the opening with sand, and a ventral chamber about 5mm in diameter. Eggs are laid over an extended period in crevices scraped around the inside of the chamber by the female and they begin hatching after a month or so. Larvae remain in the chamber until half-way through the first instar stage and during this time they feed on algae which is provisioned by the parents but also collected and replenished by the them during forays between tides, adults also ventilate the chambers by unblocking the entrances during low tides and fight off parasites and predators e.g. ground beetles will attack larvae in the absence of adults. The half-grown first instars leave the chamber by burrowing through the substrate and construct a chamber of their own in which they will develop and pupate, and it is during the remaining first instar period that the larva is most vulnerable to attack by the specialist parasitic wasp Barycnemis blediator (Aubert, 1970); wasps rarely attack chambers occupied by parents and larvae or by later instar larvae but among young larvae the proportion of parasitized chambers may reach 15% and chambers containing wasp pupae may reach one hundred per square metre.
Bledius spectabilis 1
Bledius spectabilis 2
Bledius spectabilis 3
Bledius spectabilis 4
Bledius spectabilis 5
Adults are very successful in preventing wasps and predators from entering their chambers, they also aerate them and so help reduce the threat of fungal infection of the eggs, and they collect food on a regular basis and so ensure their survival in a relatively safe but otherwise harsh environment e.g. chambers without regular ventilation become anoxic within about four days, and young larvae abandoned in the parental chamber may have an increased chance of survival in dense colonies due to more efficient drainage and a higher oxygen tension provided by numerous adjacent chambers. During immersion the occupants of a chamber survive within a bubble of air but chambers occasionally become inundated and this may be lethal for the larvae, adults become comatose when immersed and either die within a short time or recover when the water recedes and leave the chamber and take flight. The cycle from egg to adult usually takes about three months and some continental populations are thought to produce two generations each year. During immersion the occupants of a chamber survive within a bubble of air but chambers occasionally become inundated and this may be lethal for the larvae, adults become comatose when immersed and either die within a short time or recover when the water recedes and leave the chamber and take flight. Observing and sampling this species is straightforward but colonies are usually very dense and extensive and so may be damaged by inexperienced or thoughtless recorders.
A relatively large species which is generally distinctive due to the red elytra with a dark scutellary mark that extends laterally to, or almost to, the shoulders, sexual dimorphism is very strong and males are obvious from the thoracic horn. 6-8mm. Entirely black with elytra bicoloured and the appendages variously pale. Head transverse with large convex eyes, basally constricted temples that are mostly hidden under the thorax, and short, triangular antero-lateral lamellae. Antennae inserted laterally in front of the eyes; basal segment long and gradually thickened to the apex, 2-4 elongate and 5-10 becoming gradually more transverse, basal segment glabrous, the remainder densely pubescent. Pronotum strongly bordered to at most weakly produced anterior angles, the disc vaguely impressed either side of a median longitudinal impression and quite strongly though generally sparsely punctured, lateral margins sub-parallel in apical half then rounded or weakly angled to a narrow basal margin. Anterior margin produced in the male into a long horizontal horn which is slightly longer than the pronotum and far overlaps the head. Pronotum and elytra separated by a short pedicel upon which the scutellum is obvious. Elytra quadrate or nearly so, with prominent shoulders, gradually broadened towards the apex and separately rounded apically; randomly and quite strongly punctured, on the disc the punctures separated by at a little more than their diameter. Pubescence sparse and very short. Abdomen entirely shiny black or the posterior margins of the apical segments narrowly pale, the surface of tergites 1-5 sparsely punctured and pubescent, the lateral margins strongly bordered. Legs long and robust; all tibiae with strong apical spurs, pro- and meso-tibiae densely spinose; the pro-tibiae with two distinct rows of spines along the outer margin (a diagnostic character of Bledius among the UK fauna). Tarsi 3-segmented, the terminal segment longer than the others combined.