Caucanthobium mirandum, Assing, 2018

Assing, Volker, 2018, An enigmatic new genus and species of Anthophagini from Georgia (Coleoptera: Staphylinidae: Omaliinae), Linzer biologische Beiträge 50 (2), pp. 969-976 : 974-975

Caucanthobium mirandum nov.sp. ( Figs 1-11 , Map 1 )

T y p e m a t e r i a l: Holotype ♂: " N41°40'16 E42°02'37, Georgien Adjara (62), Gobroneti 1280 m, 24.5.2018, Brachat & Meybohm / Holotypus ♂ Caucanthobium mirandum sp. n. det. V. Assing 2018" (cAss) . Paratypes: 1♀ [in ethanol]: "AKH-GE18-2f, Georgia Guria, Chokhatauri, W of Bakhmaro, 41°50'50.0''N, 42°17'10.2''E, 5.VI.2018, h 1950m, sifting alder litter, grazed fields, rhododendron, scrubs, and forest patches, leg. A.K. Hansen NHMD " ( ZMUC); 2♀♀ [one in ethanol]: "AKH-GE18-5b, Georgia Guria, Chokhatauri , N of Bakhmaro, 41°53'19.4''N, 42°21'40.2''E, 8.VI.2018, h 1640m, sifting oak litter and mouse nest in hollow tree, Pontic oak forest, leg. A.K. Hansen NHMD " ( ZMUC, cAss) .

E t y m o l o g y: The specific epithet (Latin, gerundivum of the verb mirare: to be admired) alludes to the conspicuous appearance (size and coloration) of this species.

C o m m e n t: The two paratypes preserved in concentrated ethanol were not used for the measurements in the description.

D e s c r i p t i o n: Body length 4.7-5.0 mm; length of forebody 4.1 mm. Habitus as in Fig. 1 . Coloration: head blackish-brown with all, or the anterior portion of, the frons and the lateral portions of the posterior constriction reddish-yellow to red; pronotum uniformly dark-yellowish or dark-yellowish with the median portion slightly darker; elytra dark-yellowish, each with two large infuscate spots, one slightly anterior to middle and one in posterior portion; abdomen reddish-yellow; legs yellow; antennae reddish with antennomeres V-IX slightly to distinctly darker.

Head ( Figs 4-6 ) transverse, median portion somewhat elevated and with irregularly distributed punctation, between this elevation and dorsal margins of eyes with a deep and densely punctate impression on either side; frons with transverse microsculpture and with very fine and rather sparse punctation. Antenna ( Fig. 2 ) 1.9-2.0 mm long; antennomeres IV-X oblong.

Pronotum ( Fig. 4 ) approximately 1.4 times as broad as long and 1.55 times as broad as head; lateral margins broadly explanate and weakly serrulate, sinuate near the sharply marked posterior angles; antero-lateral angles rather weakly projecting anteriad; median portion in anterior three-fifths with an oblong median impression and an oblong elevation on either side of this impression, in posterior portion with a median impression and with an elevation on either side of this impression; punctation very coarse and rather dense, somewhat irregularly distributed in median portion; interstices with micropunctation, otherwise without microsculpture.

Elytra ( Fig. 1 ) approximately 1.05 times as long as combined width, about 1.2 times as broad and 1.8 times as long as pronotum; lateral margins broadly explanate and serrulate; punctation coarse and dense, laterally and posteriorly seriate. Hind wings completely reduced. Legs long; metatibia 1.25-1.30 mm long. Abdomen ( Fig. 8 ) with dense and distinct punctation; posterior margin of tergite VII without palisade fringe.

♂: protarsomeres I-IV ( Fig. 3 ) distinctly dilated; posterior margin of tergite VIII broadly concave; aedeagus ( Figs 9-10 ) of highly derived morphology, small in relation to body size, 0.67 mm long (including parameres), weakly sclerotized, strongly asymmetric with the right paramere much longer and larger than the left paramere (ventral view), and with a conspicuous dark internal structure apically extending beyond apex of ventral process.

♀: protarsomeres I-IV weakly dilated, much less so than in male; posterior margin of tergite VIII truncate; posterior margin of sternite VIII broadly convex, in the middle weakly concave; gonocoxites ( Fig. 11 ) short and broad, with short styli and very long terminal seta.

C o m p a r a t i v e n o t e s: Caucanthobium mirandum is readily distinguished from other Anthophagini distributed in the Caucasus region by the generic characters, as well as by its coloration and the unique morphology of the aedeagus.

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: This species is currently known from three localities in Adjara and Guria regions, Southwest Georgia. It seems remarkable that a conspicuous species like C. mirandum should have remained undiscovered up until today. Possible explanations could be a very restricted distribution and/or a special habitat. The holotype was sifted from leaf litter in a mixed deciduous forest with beech, chestnut, hornbeam, alder, hazelnut, laurel, and rhododendron undergrowth (MEYBOHM pers. comm.). Two of the paratypes were sifted from litter and a mouse nest in a hollow tree. The altitudes range from 1280 to 1950 m.

Figures

Map 1: Distribution of Caucanthobium mirandum.

Figs 1-3: Caucanthobium mirandum nov.sp.: (1) habitus; (2) antenna; (3) male protarsus. Scale bars: 1-2: 1.0 mm; 3: 0.2 mm.

Figs 4-8: Caucanthobium mirandum nov.sp.: (4) head and pronotum; (5) head in dorso-lateral view; (6) head in ventral view; (7) thorax in ventral view; (8) apical portion of abdomen. Scale bars: 7: 1.0 mm; 4-6, 8: 0.5 mm.

Figs 9-11: Caucanthobium mirandum nov.sp.: (9-10) aedeagus in lateral and in ventral view; (11) female genital segment. Scale bars: 0.2 mm.