Thinodromus arcitenens (Fauvel, 1907)

Makranczy, György, 2014, Review of the Thinodromus circulus species group (Coleoptera: Staphylinidae: Oxytelinae), Acta Entomologica Musei Nationalis Pragae 54 (2), pp. 539-554 : 552-553

Thinodromus arcitenens (Fauvel, 1907)

( Figs 4 , 29–30 , 35 )

Trogophloeus (Thinodromus) arcitenens Fauvel, 1905: 78 (original description), BERNHAUER & SCHUBERT (1911): 94 (catalogue).

Thinodromus arcitenens: HERMAN (1970) : 387 (catalogue), HERMAN (2001): 1761 (catalogue).

Type locality. Indonesia, W-Java, Kota Bogor, 6°36ƍS, 106°48ƍE.

Type material examined. LECTOTYPE (here designated): J, ‘ Buitenzorg ; 2-3 [II-III. 1904] (Java) [leg. K. Kraepelin & J.C. Koningsberger] \ arcitenens; Fvl. \ Coll. et det A. Fauvel; R. I.Sc. N.B. 17.479 \ Lectotypus; Trogophloeus ; arcitenens Fauvel ; des. Makranczy, 2013 \ Thinodromus ; arcitenens (Fauvel) ; det. Makranczy, 2013 ’ ( ISNB).

Redescription. Measurements (in mm, n = 1): HW = 0.35; TW = 0.34; PW = 0.41; SW = 0.45; AW = 0.51; HL = 0.25; EL = 0.10; TL = 0.06; PL = 0.29; SL = 0.46; SC = 0.44; FB = 1.04; BL = 1.96. Lustre and colour. Body with moderate lustre; ¿ne but dense punctation and/or more or less distinct microsculpture on all body parts providing uniformly greasy lustre. On head epistomal suture as a dark transversal line and two dark spots on vertex near neck mark remnants of ocelli, otherwise reddish medium brown, mouthparts, antennae, legs and pronotum light brown, latter with ¿ne darker edges. Elytra and abdomen medium brown with some reddish tint; basal ridge of tergites marked by a darker line. Shape and sculpture. Forebody as in Fig. 4 . Head rather transverse, well developed bulging temples more than half the length of eye. Neck delineated by a very slight and indistinct groove, more apparent by change of microsculpture to more alveolate. Antennae rather elongate, antennomeres 4 and 5 approximately 1.30× and 1.45× longer than broad, respectively; article 9 just imperceptibly longer than broad, antennomere 10 as long as broad. Pronotum very transverse, even more accentuated by arcuate lateral margin weakly rounded at 1/3 length, much less rounded than side anteriad. In posterior half pronotal sides gently concave: anterior corners so strongly obtuse-angled that they are hard to observe, posterior corners weakly rounded, more prominent and protruding than in the other species. Middle of disc with a pair of large, confluent impressions (with slight, gently oblique longitudinal ridges running outside of it), posteriorly with a similarly strongly impressed horseshoe-shaped impression more of a transverse oval shape very close to posterior pronotal margin, anteriorly connected to more shallow impressions behind anterior corners. Fine marginal bead of pronotum observable on lateral and hind margins, laterally also marked by darker colour. Elytra combined 1/5–1/6× broader than long, gently dilated towards apex, with a pair of small, slightly oval impressions continuing posteriorly in shallow longitudinal depressed areas along suture. Posterior elytral margin (slightly oblique) with very thin bead and in outer half with thin membranous, protruding lobe. Apex of abdominal tergite VII with palisade fringe. Punctation and microsculpture. Head and pronotum with indistinct coriaceous microsculpture, ¿nely, moderately densely punctate yet interspaces (almost the size of puncture diameters) signi¿cant, giving the surface a moderate lustre. Around pronotal hind corners, temples and in depressions (e.g. along ridge from supra-antennal tubercles) microsculpture can be dense and more rough, scabrous. Elytral punctures slightly larger, yet interspaces also proportionally larger, so lustre not differing from that of head and pronotum, in spite of indistinct coriaceous microsculpture. Abdomen with isodiametric, slightly imbricate or coriaceous microsculpture, a little more rough behind basal ridges. Punctation very scattered, punctures insigni¿cant. Pubescence. Body setation short, ¿ne and medium dense, setae on abdomen especially near apices of segments only slightly longer. Primary and secondary sexual features. Male sternite VIII as in Fig. 29 , male tergite X as in Fig. 30 , aedeagus as in Fig. 35 .

Differential diagnosis. Thinodromus arcitenens is distinguishable from the other here discussed species by its pronotal shape. None of the other species have such weakly rounded arcuate pronotal sides at 1/3 their length.

Distribution. The species is still only known from its original type material from Java.

Remarks. The light (yellowish-reddish) colours of the single male specimen may be partly due to its old age. There possibly exists other syntypes (of unknown whereabouts), the lectotype chosen is the only specimen (male) known to the present writer and designated to ¿x the interpretation of this species.

Figures

Figs 1–4. Forebodies of Thinodromus species. 1 – T. circulus (Bernhauer, 1922); 2 – T. chagosanus (Bernhauer, 1922); 3 – T. palustris (Bernhauer, 1922); 4 – T. arcitenens (Fauvel, 1905).

Figs 25–30. 25–26 – Thinodromus chagosanus (Bernhauer, 1922): 25 – male sternite VIII, 26 – male tergite X. 27–28 – T. palustris (Bernhauer, 1922): 27 – male sternite VIII, 28 – male tergite X. 29–30 – T. arcitenens (Fauvel, 1905): 29 – male sternite VIII, 30 – male tergite X. Scale bar: 0.07 mm for 30; 0.08 mm for 28–29; 0.1 mm for 26–27; 0.11 mm for 25.

Figs 31–35. 31 – Thinodromus velutinus (Sharp, 1887), female ringstructure. 32 – T. circulus (Bernhauer, 1922), female ringstructure. 33–34 – T. palustris (Bernhauer, 1922): 33 – male sternite IX, 34 – aedeagus. 35 – T.arcitenens (Fauvel, 1905), aedeagus. Scale bar: 0.1 mm for 31; 0.12 mm for 32, 35; 0.15 mm for 33; 0.2 mm for 34.