Thinodromus palustris (Bernhauer, 1922)

Makranczy, György, 2014, Review of the Thinodromus circulus species group (Coleoptera: Staphylinidae: Oxytelinae), Acta Entomologica Musei Nationalis Pragae 54 (2), pp. 539-554 : 551-552

Thinodromus palustris (Bernhauer, 1922)

( Figs 3 , 27–28 , 33-34 )

Trogophloeus (Carpalimus) palustris Bernhauer, 1922b: 167 (original description), SCHEERPELTZ (1933): 1082 (catalogue).

Thinodromus palustris: HERMAN (1970) : 387 (catalogue), HERMAN (2001): 1772 (catalogue).

Type locality. Seychelles, Mahé, approx. 4°38ƍS, 55°27ƍE.

Type material examined. LECTOTYPE (here designated): J, ‘[on mounting card:] 81 \ Mahe, 1908-9; Seychelles Exp. \ palustris; Bernh.; Cotypus \ Chicago NHMus; M. Bernhauer; Collection \ Lectotypus; Trogophloeus ; palustris Bernhauer ; des. Makranczy, 2013 \ Thinodromus ; palustris (Bernhauer) ; det. Makranczy, 2013 ’ ( FMNH).

Other material examined. PALAU ISLANDS: Babelthuap I., Ngiwal, 7°33ƍ18ƎN, 134°37ƍ59Ǝ, 20.V.1957, leg. C.W. Sabrosky, at light (2 JJ 3 ♀♀ BPBM, 1 J 1 ♀ HNHM, 1 ♀ NHMW) ; Babelthuap I., Ngaremlengui, 7°31ƍ12ƎN, 134°30ƍ04Ǝ, 1.VI.1957, leg. C.W. Sabrosky, at light (1 J BPBM) .

Redescription. Measurements (in mm, n = 8): HW = 0.44 (0.41–0.47); TW = 0.43 (0.39– 0.46); PW = 0.465 (0.42–0.48); SW = 0.56 (0.53–0.59); AW = 0.63 (0.57–0.66); HL = 0.31 (0.28–0.33); EL = 0.155 (0.14–0.17); TL = 0.07 (0.06–0.07); PL = 0.35 (0.33–0.37); SL = 0.55 (0.52–0.58); SC = 0.52 (0.50–0.55); FB = 1.25 (1.18–1.33); BL = 2.40 (2.28–2.62). Lustre and colour. Slightly dull due to not so strong but rather dense punctation of the foreparts. Head very dark brown, pronotum and elytra dark brown with reddish tint (pronotal marginal bead darker), abdomen blackish dark brown (basal part of tergites behind basal ridge darker. Mouthparts, legs, antennae reddish medium to dark brown, ¿rst antennomere often a little lighter. Shape and sculpture. Forebody as in Fig. 3 . Head transverse, eyes rather large, temples slightly bulging, almost reaching 1/2 eye length. Neck delineated primarily by different, alveolate microsculpture, but with a trace of a transversal groove. Antennae moderately elongate, antennomeres 4 and 5 1.40–1.46× and 1.63–1.80× longer than broad, respectively, antennomere 9 1.03–1.05× longer than broad while antennomere 10 just imperceptibly broader than long. Pronotum less transverse than in the other species, only abut 1/3 broader than long. Pronotal sides arcuate, more strongly at 1/4 length (the broadest point), posteriorly only slightly arcuate, almost straight; posterior corners obtuse-angled and broadly rounded, inconspicuous. Horseshoe-shaped impression rather wide, strongly impressed, connected to slight anterolateral depressions. Middle of disc bearing pair of roundish, slightly connected depressed areas slightly connected. Pronotal marginal bead thin (marked also by blackish line), observable on sides and posterior margin. Elytra combined almost 1/3 broader than long, gently dilated and slightly arcuate towards apex, Behind scutellum with a pair of small, rounded impressions connected to longitudinally elongate depressed areas along suture. Posterior elytral margin (slightly oblique) with very thin marginal bead and in outer 1/3 with small membranous lobe protruding. Apex of abdominal tergite VII with palisade fringe. Punctation and microsculpture. Punctation on head and pronotum strong, interspaces only a fraction of puncture diameters. On head epistomal suture marked by somewhat shinier surface, smaller and more sparse punctures. Elytral punctation also strong, 1.5× stronger than on pronotum, interspaces also only a fraction of puncture diameters, therefore microsculpture on forebody not very apparent, but pronotal sides, scutellar area on elytra and depressions have more conspicuous and scabrous microsculpture. Abdominal punctures strong and rather dense, slightly less strong on apices of segments; traces of imbricate microsculpture but not very prominent. Pubescence. Body setation short, ¿ne, but rather dense, hair sizes vary more on abdomen, apices of segments with longer hairs. Setae on elytra appear particularly dense. Primary and secondary sexual features. Male sternite VIII as in Fig. 27 , male sternite IX as in Fig. 33 , male tergite X as in Fig. 28 , aedeagus as in Fig. 34 .

Differential diagnosis. Thinodromus palustris is distinguishable from the other discussed species by its abdomen with unusually strong punctation, similar in density and depth to elytral punctation. Eye margin posteriorly appears conspicuously shiny (unsculptured) partly because of its widening remarkably on the hind part above the dorsal longitudinal midline of eye – such a shiny eye margin is present in the other species, but mostly very thin and not widened. Distribution. This species seems to be widespread across tropical islands of the Old World. Remarks. The type locality of T. palustris is Mahé Island, the main island of the Seychelles. The geographical distance from Palau Island is enormous, yet the internal sclerites of the aedeagi are identical between the two samples, leaving little doubt about their conspeci¿ty. SCOTT (1922) notes that the original material came from ‘the lower levels in the Seychelles’. Of numerous existing syntypes in depositories, the lectotype is a male with clear genital traits and chosen 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.