Atheta (Anopleta) digitalis ASSING, 2019

Assing, Volker, Brachat, Volker & Meybohm, Heinrich, 2019, Monograph of the Staphylinidae of Crete (Greece). Part II. Descriptions of new species (Insecta: Coleoptera), Beiträge Zur Entomologie = Contributions to Entomology 69 (2), pp. 239-289 : 243

Atheta (Anopleta) digitalis ASSING spec. nov.

urn:lsid:zoobank.org:act:E1F1F8FC-708F-4C1B-AF02-5A83EC6E5A0D

( Figs 12–19 )

Type material: Holotype ♂: “ N35°19'10 E23°54'46, GR Westkreta (16), Omalos 1110 m 16.3.2018, l. Brachat & Meybohm / Holotypus ♂ Atheta digitalis sp. n. det. V. Assing 2018” (cAss) . Paratypes: 1 ♀: same data as holotype (cAss); 1 ♂: “GR – Crete [17a], NW Dikti Oros, Limnakaro , 35°08'08"N, 25°29'00"E, 1170 m, sifted, 30.III.2012, V. Assing ” (cAss) .

Etymology: The specific epithet (Latin, adjective: of a finger) alludes to the shape of one of the internal structures of the aedeagus.

Description: Body length 2.2–2.3 mm; length of forebody 0.9–1.1 mm. Habitus as in Fig. 12 . Coloration: body black; legs dark-brown to blackish-brown with the bases and apices of the tibiae and all of the tarsi pale yellowish; antennae black.

Head ( Fig. 13 ) weakly transverse, with or without very shallow impression in the middle; punctation moderately dense and extremely fine, barely visible even at a magnification of 100 x; interstices with pronounced microreticulation. Eyes large, as long as, or slightly longer than postocular portion in dorsal view. Antenna ( Fig. 14 ) approximately 0.6 mm long; antennomere IV weakly transverse; antennomeres V–X of gradually increasing width and increasingly transverse, X approximately 1.5 times as broad as long.

Pronotum ( Fig. 13 ) small, approximately 1.2 times as broad as long and 1.1 times as broad as head; punctation and microsculpture similar to those of head; pubescence white, directed transversely laterad in lateral portion and apparently (difficult to assess in type specimens) anteriad in anterior third and posteriad in posterior two-thirds of midline.

Elytra ( Fig. 13 ) approximately 1.2 times as long as pronotum; punctation and microsculpture similar to those of head and pronotum.

Abdomen ( Fig. 15 ) narrower than elytra, broadest at segment VI; punctation fine, denser on anterior than on posterior tergites; all tergites with pronounced isodiametric microsculpture, but glossy; posterior margin of tergite VII with palisade fringe; tergite VIII subject to sexual dimorphism.

♂: posterior margin of tergite VIII ( Fig. 16 ) truncate to weakly concave and crenulate; sternite VIII with moderately convex posterior margin; median lobe of aedeagus ( Figs 17–18 ) small, 0.23 mm long; crista apicalis pronounced; internal structures of distinctive shape, the less sclerotized one shaped like a finger in lateral view.

♀: posterior margin of tergite VIII of similar shape as in male, but posterior margin not crenulate; posterior margin of sternite VIII less convex than in male; spermatheca ( Fig. 19 ) small and of highly distinctive shape, distal portion strongly dilated.

Comparative notes: Based on the similar sexual characters, A. digitalis appears to be closely allied to A. puberula (SHARP, 1869) . It is distinguished from this species by significantly smaller size ( A. puberula : body length 2.5–2.8 mm), shorter antennae, the coloration of the legs (yellow in A. puberula ), and by the primary and secondary sexual characters. In A. puberula , the posterior margin of the male tergite VIII is more concave and has a distinct lateral tooth on either side, the posterior margin of the male sternite VIII is strongly convex, the median lobe of the aedeagus is much larger ( A. puberula : median lobe approximately 0.35 mm long) and has differently shaped internal structures, the posterior margin of the female sternite VIII has a pronounced median concavity, and the spermatheca is much larger and of different shape.

Distribution and natural history: This species is currently known from two localities, one in West Crete and one in the east of the island. The specimen from East Crete was recorded as Atheta (Microdota) sp. by ASSING (2013). The specimens were sifted from litter at an altitude of 1110 m (specimens from the type locality) and from grass, litter, and moss near snowfields at an altitude of 1170 m (male from Dikti).

Figures

Figs 1–19: Amischa cretia (1–11) and Atheta digitalis (12–19): habitus (1, 12); forebody (2, 13); antenna (3, 14); male tergite VIII (4, 16); male sternite VIII (5); median lobe of aedeagus in lateral and in ventral view (6–8, 17–18); female tergite VIII (9); female sternite VIII (10); spermatheca (11, 19); abdomen (15). Scale bars: 1, 12: 1.0 mm; 2, 13, 15: 0.5 mm; 3–5, 9–10, 14, 16: 0.2 mm; 6–8, 11, 17–19: 0.1 mm.