Tinotus morion (Gravenhorst, 1802)

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POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

STAPHYLINIDAE Latreille, 1802

ALEOCHARINAE Fleming, 1821

ALEOCHARINI Fleming, 1821

Tinotus Sharp, 1883

Native to the Western Palaearctic region, this species is now Holarctic in distribution; it has long been known from western Siberia but has more recently been reported from eastern Siberia and Japan although whether these are from western imports is not known, it was introduced into the United States from Europe and is now widespread and has been known from Canada since 1975. The species is generally common throughout Europe north to the UK and central Fennoscandia and east into Western Russia and Asia Minor, it is known from most of the Mediterranean islands and is widespread across North Africa, it is generally a species of lowlands and low mountain altitudes but is synanthropic into the alpine zone in Europe. In the UK it is common throughout southeast and central England and Wales and more local and scattered in the southwest and further north to the Scottish Highlands and the western Isles. Adults occur year-round; they overwinter in tussocks or among decaying vegetation and are active from March until late in the autumn, peaking in abundance during May and June. The species is very adaptable and may be found among decaying organic matter generally; often among fairly dry dung of all kinds but also in compost, straw, decaying fungi and carrion, it is often common on pasture or in gardens and other ruderal areas but also occurs in woodland, moorland and on coastal dunes and beaches. Adults fly well, they sometimes swarm on warm spring and summer evenings and may appear at light or in flight-interception traps, they are often quick to colonize new material such as dung or carrion and often do so in numbers. Breeding occurs in spring and early summer and larvae are known to be parasitic on a range dipteran pupae; species of Drosophilidae, Sepsidae and Sarcophagidae having so far been recorded, hence the species eurytopic occurrence. Sampling adults is usually a matter of sieving or going through samples of likely material but they sometimes occur in moss or by sweeping or beating foliage or grass, they are often active in straw etc. through the winter and may occur in numbers in decaying fungi during the autumn.

Tinotus morion 1

Tinotus morion 1

© Lech Borowiec

Tinotus morion 2

Tinotus morion 2

© U.Schmidt

For many years this species was included in the tribe Myrmedoniini Thomson, 1867 due to its 4-5-5 tarsal formula, it has since found its way into the Hoplandriini Casey, 1910 or Aleocharini Fleming, 1821 due to the reduced terminal maxillary and labial palpomere, but despite such ambiguity the close relationship with Aleochara  Gravenhorst, 1802 is based on several morphological characteristics including the compact and somewhat cylindrical habitus, broad, truncate and fully carinate mesosternal process which reaches to the apex of the intercoxal metasternal process, the median lobe of the aedeagus with a developed flagellum, and the spermatheca coiled basally and without an apical invagination of the head. The form of the maxillary palpi is unusual and seen otherwise only in Aleochara , they appear four segmented but the long, narrow and tapering terminal segment has a tiny extra segment (or pseudosegment) at the very tip (requires X50 with good light). Coupled with this the parasitic lifestyle of the larvae also suggests a close relationship. Among the UK fauna several species of Aleochara also have a completely carinate mesosternal process but these are mostly larger and readily separated on general morphology.

1.9-2.6 mm. Compact and fusiform, weakly shiny, dark brown to black, often with the abdominal apex becoming paler, antennae dark brown or paler towards the base, legs brown, entire dorsal surface finely punctured and pubescent, lateral margins without outstanding setae. Head transverse and broadly rounded, with weakly convex eyes that more-or-less follow the outline and long, smoothly rounded temples. Antennae gradually widened from the base; segments 2 & 3 elongate with 2 distinctly longer than 3, 4 weakly transverse, 5-10 strongly so and the terminal segment elongate and rounded apically. Pronotum much broader than the head, transverse, broadest near the base and strongly narrowed to a rounded apical margin (from above), surface evenly convex and with pubescence obliquely back from the centreline. From above the metasternal epimera are distinctly visible laterally beyond the elytral apex. Elytra transverse, slightly wider than the pronotum and weakly curved laterally from rounded shoulders to distinct posterior angles, basal margin strongly sinuate, pubescence oriented slightly obliquely backwards. Abdomen long and gradually tapering in the apical half, basal tergites depressed across the base and the penultimate tergite finely toothed across the apex. Legs long and slender; femora simple, tibiae with paired, very fine apical spurs, finely pubescent but without outstanding setae on the external margin. Tarsi 4-5-5 in both sexes, the basal segment of the hind tarsi almost as long as the next two combined.. Claws smooth and without a basal tooth. Aedeagus and spermatheca distinctive.