Pycnotarsobrentus inuiae Maruyama & Bartolozzi, 2014

Maruyama, Munetoshi, Bartolozzi, Luca, Inui, Yoko, Tanaka, Hiroshi O., Hyodo, Fujio, Shimizu-Kaya, Usun, Takematsu, Yoko, Hishi, Takuo & Itioka, Takao, 2014, A new genus and species of myrmecophilous brentid beetle (Coleoptera: Brentidae) inhabiting the myrmecophytic epiphytes in the Bornean rainforest canopy, Zootaxa 3786 (1), pp. 73-78 : 74-77

Pycnotarsobrentus inuiae Maruyama & Bartolozzi , sp. nov.

Type material. Holotype, ♂ (DFS), Lambir Hills National Park , Sarawak, E. Malaysia, 22 IX 2011, Itioka et al. leg . Paratypes, 3♂ (KUM), same data, but 28 IX 2011 ; 1♂ ( MZUF, collection number 17085) , 1♀ (DFS), same data but 17 IX 2005 (ex T. Itioka collection) . All the specimens were collected from nests of Crematogaster difformis in domatia of the canopy ferns.

Description. Male. Body ( Figs. 1, 2 ) dark brown, with legs slightly lighter.

Head ( Fig. 3 ) short, eyes totally occupying its lateral sides until basal constriction; vertex connected to mesorostral plate on same plane; surface of vertex with sparse yellow minute setae; metarostrum about as long as head, laterally concave; lateral apophysis preceded by minute tooth; mesorostrum large, flat, laterally rounded; prorostrum short, almost parallel sided; lateral margins of mesorostrum and prorostrum moderately punctuate; underside of meta- and mesorostrum moderately covered with setiferous punctures; antennal segments cylindrical, rather compressed, with rugose surface; segments II-X of antennae all wider than long; segment XI twice as long as wide.

Pronotum ( Fig. 1 ) 1.1× as long as wide, with similar width at anterior and posterior margins, widest at middle; finely punctured on disc, strongly rugose at sides, with some scattered erect golden setae.

Elytra ( Fig. 1 ) 2.4× as long as pronotum; all striae and interstriae present; humeral calli slightly prominent; interstriae 3 and 5 slightly elevated; surface with sparse suberect small setae, denser at sides.

Legs ( Figs. 1, 2 ) with femora weakly dilated from base to apex, laterally compressed basally, then weakly swollen; tibiae ( Fig. 4 ) with inner margin almost straight, serrate; outer margin gently curved; surface smooth but along outer margin with granulate setiferous punctures; tarsi short, segment I slightly longer than II, segment III about twice as long as II, deeply hollowed at apex, last tarsal segment very short, its basal part deeply inside hollow of segment III, surface of segments I-III rugose; underside of segment III with two longitudinal hairy pads.

Female. Body ( Figs. 5, 6 ) more matte, densely micro-reticulate overall. Prorostrum cylindrical, densely and coarsely punctured, punctation denser but smaller than on mesorostrum. Pronotum more coarsely punctured, except along anterior margin. Elytra more densely punctured.

Body length: 8.5–6.2 mm (including rostrum).

Differential diagnosis. No species of Eremoxenini with similar morphological modifications are known from the Oriental region and the new taxon is easily distinguishable from all other Asian Eremoxenini by the generic diagnosis.

Etymology. Dedicated to Dr. Yoko Inui, one of the collectors, for her invaluable contribution to the knowledge of tree canopy ant communities.

Bionomics. The beetles were found exclusively inside the nests of C. difformis in the domatia of the epiphytic ferns ( Figs. 8, 9 ). They were observed to walk slowly when the nests were excavated ( Fig. 10 , 11), and the ants did not pay any attention to them. Ecological studies on the communities of the myrmecophiles in the nests of C. difformis are in progress by the Japanese authors.

Figures

FIGURES 1–7. Pycnotarsobrentus inuiae gen. nov. and sp. nov. 1—Male habitus, dorsal view (paratype; color became paler during preserving in ethanol), 2—same individual, ventral view, 3—ditto, head, dorsal view, 4—right fore tibia and tarsus, 5— female habitus, dorsal view (paratype), 6—same individual, ventral view, 7—ditto, head, dorsal view.

FIGURES 8–10. Habitat of Pycnotarsobrentus inuiae gen. nov. and sp. nov. 8—Platycerium crustacea Copel., 9— Lecanopteris ridleyi H. Christ., 10, 11—living male in a domatia of Lecanopteris sp.