Oxarthrius (Oxarthrius) aurora Asenjo, 2018

Asenjo, Angélico, Zampaulo, Robson De Almeida & Ferreira, Rodrigo Lopes, 2018, Two new troglobitic species of Oxarthrius Reitter (Coleoptera, Staphylinidae, Pselaphinae) from Brazil, Zootaxa 4462 (3), pp. 404-414 : 409-413

Oxarthrius (Oxarthrius) aurora Asenjo sp. nov.

( Figs. 12–22 )

Type material (2 ♂♂, 5 ♀♀). Holotype: BRAZIL: ♂, labeled “BRAZIL: Tocantins, / Aurora do Tocantins, / Gruta Lage I, 12.ii [February].2016, / R.L. Ferreira leg.”; “HOLOTYPE / Oxarthrius (Oxarthrius) / aurora Asenjo sp. nov. / Desig. Asenjo et al., 2018” (ISLA).

Paratype: (1 ♂, 5 ♀), labeled: “ BRAZIL: Tocantins, / Aurora do Tocantins, / Gruta Lage I, 12.ii [February].2016, / R.L. Ferreira leg.” (1 ♂, 5 ♀ ISLA). All paratypes with label “ PARATYPE / Oxarthrius (Oxarthrius) / aurora Asenjo sp. nov. / Desig. Asenjo et al., 2018”.

Other specimens. BRAZIL: Tocantins: Aurora dos Tocantins, Gruta das Rãs, 12°41’19.07”S, 46°24’34.15”W, 8.i.2009, R. A. Zampaulo leg. (1♂, 1♀ CEMT).

Diagnosis. The new species Oxarthrius aurora sp. nov. differs from O. bispinosus and O. inexpectatus sp. nov. by characters cited under the diagnosis of O. inexpectatus sp. nov.

Description. Holotype male, BL: 2.69. Body brown, mouth parts, antennae, and tarsi reddish-brown ( Figs. 12– 13 ). Tegument polished and shiny with sparse long setae, granulated at their base.

Head ( Figs. 14–15 ): slightly oval (HW: 0.50; HL: 0.55), with large antennal tubercle at lateral margin of frontal ridge. Antennal insertions of head not visible in dorsal view. Region of lateral margins before eyes narrowing and lateral genal edge rounded. Eyes prominent, situated at middle of head length. Neck strongly constricted (NW: 0.23) of curved sides. Head with two vertexal fovea [vf] connected by one straight transverse sulcus. Small and fine longitudinal carina between vertexal fovea [vf] and another on neck dorsally. Ocularmandibular carinae present, starting at the superior edge of eyes; another fine carina present that starts between eyes and joints with ocular-mandibular carinae at anterior region of head. Median gular sulcus shallow almost imperceptible. Gular foveae [gf] present in posterior region of head.Antenna thin and long, with scape short and base curved, apex of scape with one emargination in dorsal and ventral side, last three antennomeres gradually thickening. Scape with base thicker than apex (length 0.20: width 0.11), pedicel thinner and shorter than scape (length 0.09: width 0.06), segment 3–11 longer than wide: 3 (length 0.15: width 0.06), 4 (length 0.18: width 0.06), 5 (length 0.25: width 0.06), 6 (length 0.24: width 0.06), 7 (length 0.28: width 0.06), 8 (length 0.22: width 0.05), 9 (length 0.24: width 0.07), 10 (length 0.20: width 0.06), 11 (length 0.48: width 0.08); all antennomeres covered with microsetae; segment 9–11 with microsetae denser.

Thorax ( Figs. 14–15 ): Pronotum of cordiform shape about as long as wide (PL: 0.53; PW: 0.51), edge of anterior half almost semicircular, posterior half with sides slightly convergent and posterior margin concaved, postero-lateral angles with right angle. In posterior half with pair of prominent basolateral spines adjacent to elongate lateral antebasal foveae [laf], median antebasal fovea [maf] absent. Outer [oblf] and inner basolateral foveae [iblf] at basal margin are present. Prosternum with lateral procoxal fovea [lpcf], proepimeral fovea [pef], and distinct paranotal carinae. Transversae sulcus with long setae at anterior margin of mesoventrite and into the anterior sulcus with one pair of median mesosternal foveae [mmsf]. Metaventrite with lateral mesocoxal fovea [lmcf].

Elytra ( Fig. 12 ): wider than pronotum (EL: 0.87; EW: 0.79), sides gradually narrowing anteriorly. Anterior margin straight and each elytron with two small basal elytral foveae [bef], humeri prominent, shallow sutural stria [ss] complete and small shallow discal stria [ds]. Elytron with epipleural carina that vanishes at anterior third, with small apicolateral clefts. Metathoracic wings longer than elytra but not reach apex of abdomen.

Legs ( Figs. 16–17 ): thin and long. Procoxae and mesocoxae conical, prominent and contiguous. Metacoxae transversely elongate and moderately separate. Femora thickened medially; mesofemora with a truncate spine in the basal half of posterior edge ( Fig. 16 ). Tibiae similar in length to femora, all tibiae thickening the apex; metatibiae concaved in anterior edge. Tarsi 3-segmented, first segment very short and last two segments relatively long; protarsi and mesotarsi with second and third segments subequal in length, metatarsi with second segment longer than third; all tarsi with a single claw and a minute accessory seta.

Abdomen ( Fig. 12 ): slightly wider medially, segments IV–VI with terga and sterna fused and without paratergite, with fine lateral carina; the intersegmental membranes with pattern of minute rectangular sclerites like brick wall. Tergite IV (first visible tergite) longest, V–VI very short in their lengths. Tergite IV with strong inner marginal carinae (imc); mediobasal fovea [mbf] and basolateral fovea [blf] connected internally; both mediobasal foveae [mbf] connected by deep longitudinal basal sulcus. Tergite IV at anterior margin with weak curved impressed line. Tergite VII and IV similar in length. Tergite VIII at half of apical region with a small protuberance. Sternite IV with one basolateral fovea [blf] at each side, one mediobasal fovea [mbf] and one medial fovea at each side, all connected by a deep longitudinal basal sulcus. Sternite V–VII very thin in its length. Sternite VIII transverse, with flat region at middle; posterior margin emarginated. Tergum IX visible ( Fig. 21 ).

Aedeagus ( Figs. 18–20 ): strongly asymmetric, with parameres fused to form slim elongate plate that is curved at apex; median lobe bulbous at base and with apical plate bifurcated and both curved at apex.

Female. Characters of head, eyes, pronotum and elytra as described in male. Mesofemora without basal. Tergite VIII with apical margin slightly emarginated, with dorsal small pointed protuberance. Sternite VIII with central area almost flat, apical margin curved.

Etymology. The specific epithet refers to the name of the municipality “Aurora do Tocantins ” where the species was collected. This in a noun in apposition.

Distribution. Known from two iron-rich caves located in Aurora do Tocantins municipality, Tocantins state, Brazil.

Habitat and ecological notes. Specimens were collected in only two caves, although eight other caves were sampled in the area ( Zampaulo & Ferreira, 2009). However, it is important to point stand out that this region is quite unexplored, and the species may be discovered in other caves in the future. Most of the known caves in the area are too dry to be suitable habitat for the species. Two caves where specimens of Oxarthrius aurora sp. nov. were found are quite moist, especially in the deeper zones, where individuals were collected. The specimens were observed walking on muddy substrate on the cave floors or on the moist cave walls ( Fig. 31 ). Visible organic resources were bat guano and vegetable debris brought by water. Although the areas surrounding the limestone outcrops are preserved, considerable portions of the forests have been removed for agriculture and cattle pasture. Furthermore, there are no conservation units in the area, protecting caves and their inhabitants. However, the caves are not frequently visited by humans, hence, they are quite preserved. Despite the fact that specimens were only observed in two caves, it is plausible to assume that other populations might exist, given the huge number of nonprospected limestone outcrops in the area.

Figures

FIGURES 12–22. Oxarthrius (Oxarthrius) aurora sp. nov., holotype, 12, habitus, dorsal view; 13, habitus, lateral view; 14, head and pronotum, dorsal view; 15, head and pronotum, ventral view; 16, meso leg, external face; 17, meta leg, external face (coxa absent); 18, aedeagus, ventral view; 19, aedeagus, lateral view; 22, aedeagus, dorsal view; 21, tergum IX; 22, tergum VIII (T8) and sternum VIII (T8), lateral view. Scale bars: 1 mm (12–13); 0.5 mm (14–17); 0.2 mm (18–22).

FIGURES 28–31. 28, Elevation map of South America, Tocantins state, Bambuí geological group in lead color, star blue the localities; 29, rock outcrop Lage I; 30, Gruta das Rãs; 31, Oxarthrius (Oxarthrius) aurora sp. nov. in Lage I.