Akarbatrus jelineki, Löbl, 2009

Löbl, Ivan, 2009, Akarbatrus gen. nov., an unusual Batrisitae (Coleoptera: Staphylinidae: Pselaphinae) from Sumatra, Acta Entomologica Musei Nationalis Pragae 49 (2), pp. 661-670 : 664-667

Akarbatrus jelineki sp. nov.

Type material. HOLOTYPE: male, ‘ INDONESIA: Sumatra, W. Sum. Lubuksulasih, 30 km E Padang , 1100 m, 8. XI. 1989, Agosti, Löbl, Burckhardt # 7’ ( MHNG) . PARATYPES: 10 males, with the same data as the holotype ( MHNG).

Diagnosis. Pronotal, elytral and abdominal pubescence long. Antennomeres 2 and 3 short, antennomere 3 expanded apicodorsally to form narrow process. Middle of vertex raised dorsally, prominent apically, forming a process. Posterior part of vertex vertical, with transverse depression. Pronotal excavation deep, delimited by high, smooth lateral laminae. Centre of pronotal excavation with semi-circular tubercle bearing trichomes and bi-dentate process. Elytra with humeral tubercles. Metathoracic wings fully developed. Aedeagus elongate, with strongly sclerotized subapical apophysis and flat, hook-like apex bearing weakly sclerotized lamina.

Description. Length 1.65–1.75 mm. Body uniformly reddish-brown, appendages lighter than body.

Head ( Figs. 1–2 ) rounded triangular, with eyes 0.42 mm wide, wider than long, densely and coarsely punctate. Frontal lobe gradually inflexed and weakly convex, with rounded anterior margin. Frons hardly depressed between antennal tubercles, lacking foveae, sulcus and carina. Pubescence on frons and in middle of vertex fairly short, recumbent, directed apically. Pubescence behind antennal tubercles long, directed obliquely toward mesal axis. Pubescence near eyes long, curved, directed latero-anteriorly. Antennal fossae lying behind the level of anterior third of mesal head length, open toward eyes. Frontoclypeus narrow, overlapped by frontal lobe. Ocular-mandibular carinae extended to anterior eye margins, not extended along eyes. Vertex sexually modified. Centre of vertex raised and expanded apically to form a triangular tooth-like process. Posterior part of vertex large, strongly inclined, almost vertical, with transverse, smooth depression, vertexal foveae about at level of posterior eyes margins, situated on inclined surface and hardly visible in dorsal view. Eyes large, prominent, situated in basal third of head length (without neck), not emarginate, multifaceted, facets small. Tempora short, in dorsal view about as long as half of eye length, rounded. Gular area convex, very finely punctate and bearing recumbent pubescence.

Neck concealed in dorsal view. Ventral side of neck with microsculpture consisting of transverse striae.

Antennae long, reaching abdominal base. Relative length (basal stalk included) / width of antennomeres as: I 20/15: II 9/8: III 10/8: IV 20/6: V 17/7: VI 15/7: VII 17/8: VIII 12/8: IX 19/9: X 13/9: XI 40/11. Scape swollen, bottle-like ( Fig. 5 ), 1.5 times as long as wide, with apical margins not prominent and lacking apical fovea. Antennomere 3 ( Fig. 1 ) subquadrate, about as long as wide and as third of scape length. Antennomeres 3 and 4 sexually modified. Antennomere 3 moderately larger than 2, strongly asymmetrical, with a large and tapering dorsal process. Antennomere 4 narrow, 3 times as long as wide, subcylindrical, with dorsal side slightly concave, ventral side slightly convex. Antennomeres 5 to 8 subcylindrical, shorter and thicker than 4, antennomeres 6 and 8 smaller than antennomeres 5 and 7. Club loosely 3- segmented, antennomere 9 about as long as and slightly wider than antennomere 7, thickened apically. Antennomere 10 shorter than antennomere 9, antennomere 11 strongly elongate, about as long as combined length of antennomeres 8 to 10 and 4 times as long as wide.

Pronotum ( Figs. 3–4 ) strongly sexually modified, wider than head and wider than long, at widest point twice as wide as at base. Anterior margin prominent, extended over neck, slightly narrower than basal margin. Contours subhexagonal ( Fig. 6 ). Basal margin transverse. Narrow antebasal area uneven, with small, shallow foveiform impressions, lacking foveae. Basal, upper parts of hypomera delimited by short carinae. Laterobasal foveae large, situated below hypomeral ridges. Anteromesal area of disc deeply excavated. External sides of excavation raised to form two high, sharply delimited ridges. Inner surface of ridges glabrous. Outer surface of ridges glabrous on anterior surface and near upper and lower margins, reticulate and opaque on remaining surface. Centre of excavation with small bi-dentate ridge and low, semicircular tubercle bearing setal patches. Pronotal disc depressed behind lateral ridges and mesally. Depressions situated behind ridges oblique, coarsely and densely punctate. Mesal depression widened anteriorly, almost impunctate. Pubescence long, curved, rather recumbent, one pair of very admesal macrosetae present.

Elytra convex dorsally, combined moderately wider than long, strongly narrowed toward base. Basal sulcus present, concealed by pronotal base. Lateroapical cleft present. Lateral contours arcuate between humeral tubercles and apical angles, oblique between humeral tubercles and basal angles. Humeral tubercles low. Sutural striae present, partly faint. Punctation consisting of very small, shallow punctures. Pubescence long, erect, pair of macrosetae present on each elytron. Metathoracic wings fully developed.

Metasternum with shallow mesal impression ending apically by deep foveiform impression, convex in admesal area, with arcuate, narrowly notched metacoxal process. Metacoxae moderately separated. Metasternal punctation sparse, pubescence short at middle, long laterally, with a pair of macrosetae.

Mesotrochanters ( Fig. 7 ) each with simple, tooth-like process situated near trochanteral bases. Metatrochanters ( Fig. 8 ) each with two overlapping tooth-like processes, ventral process bearing few very short apical sensilla. Femora and tibiae lacking obvious sexual characters. Dorsal side of tibiae with long, erect setae. Metatibiae with apical tuft of robust setae. Tarsomeres 2 and 3 long, narrow, tarsomere 2 subcylindrical, tarsomere 3 cylindrical. Protarsomeres 2 and 3 subequal in length, tarsomere 2 hardly curved. Mesotarsomere 2 slightly arcuate, shorter than tarsomere 3. Metatarsomes 2 and 3 straight, subequal in length.

Abdomen with five exposed tergites, weakly and gradually narrowed apically. Tergite 1 horizontal, with single pair of basal foveae situated close to lateral margin. Tergites 2 to 4 lacking sharply defined lateral margins. Tergite 1 about 1.5 times as long as tergite 2, tergites 2 and 3 similar, slightly inflexed, tergite 4 almost as long as tergite 1, strongly inflexed, tergite 5 almost vertical. Abdominal punctation and pubescence similar to that on elytra, setae about as long as length of tergite 2, tergites 1 to 4 each with two pairs of macrosetae. Sternite 1 in middle weakly convex and moderately longer than sternite 2. Sternites 2 to 4 flattened in middle. Sternites 2 and 3 in middle equally long, each slightly longer than sternite 4.

Aedeagus ( Figs. 9–10 ) 0.30 mm long, moderately flattened. Paramere strongly sclerotized, gradually narrowed apically, with obtuse tip. Median lobe and parameres loosely connected by membranes. Median lobe with one subapical, strongly sclerotized, stylet-like apophysis, apex flattened, hook-like, bearing wide and weakly sclerotized lamina. Diaphragm present. Basal part of internal sac associated with basal spine, extruded part of internal sac membranous.

Variation. The variation in the total body length from 1.65 to 1.75 mm may be in part an artifact produced while mounting the specimens. Pronotal length: 0.40–0.41 mm, pronotal width 0.47–0.50 mm, elytral length 0.56–0.58 mm, combined elytral width 0.58–0.63 mm. Differential diagnosis. See under Akarbatrus diversicornis sp. nov.

Habitat. An evergreen secondary forest on a steep slope.

Etymology. This species is dedicated to Josef Jelínek, Prague, in a friendship covering half a century.

Figures

Figs. 1–4. Akarbatrus jelineki gen. nov.et sp. nov., SEM micrographs. 1–2 – head (1 – dorsal view; 2 – lateral view); 3–4 – pronotum (3 – dorsal view; 4 – lateral view).

Figs. 5–10. Akarbatrus jelineki gen. nov. et sp. nov. 5 – antennomeres 1 to 4, scale bar = 0.1 mm; 6 – pronotum in ventral view, scale bar = 0.2 mm; 7 – mesotrochanter, scale bar = 0.1 mm; 8 – metatrochanter, scale bar = 0.1 mm; 9–10 – aedeagus (9 – ventral view, 10 – lateral view; scale bar = 0.1 mm).