Metopiellus painensis, Asenjo, Angélico, Ferreira, Rodrigo Lopes & Zampaulo, Robson De Almeida, 2017

Asenjo, Angélico, Ferreira, Rodrigo Lopes & Zampaulo, Robson De Almeida, 2017, Description of Metopiellus painensis sp. nov. (Coleoptera, Staphylinidae), first troglobitic Pselaphinae from Brazil, Zootaxa 4269 (1), pp. 115-123 : 116-117

Metopiellus painensis new species

( Figs 1–23 )

Type material (2♂). Holotype: BRAZIL: ♂, labelled: “Brasil (MG)[Minas Gerias] — ISLA // Pains— 21/ III [March]/2009 // Loca dos Negros [Loca dos Negros 2: 20°26’7”S, 45°39’34”W, WGS84] (seca) // Pselaphidae sp.14— Troglo // col. Zampaulo, R. A. ”; “ ISLA 367 [record number collection]”; “ HOLOTYPE / Metopiellus / painensis sp. nov. / Desig. Asenjo et al., 2017” . Paratype: 1♂ [teneral specimen], labeled: “ Brasil (MG)[Minas Gerais] — ISLA // Pains— 03/IV [April]/2009 // Grutas das Cerâmicas [20°24’16”S, 45°35’52”W, WGS 84] // Pselaphidae sp. 13 (Troglo) // Col. Zampaulo, R. A. ”; “ ISLA 368[record number collection]”; “ PARATYPE / Metopiellus / painensis sp. nov. / Desig. Asenjo et al., 2017”

Diagnosis. Metopiellus painensis can be distinguished from the other species of Metopiellus by the following combination of characters: eyes nearly absent (one ommatidium) and pedicel nearly one-half length of scape.

Description. Holotype male, BL: 3.25. Body, mouthparts, antennae, and tarsi dark reddish-brown, abdomen and elytra light brown ( Figs. 1–3 ).

Head: pyriform ( Figs. 1–2 , 13 ), longer (HL: 0.59) than wide (HW: 0.48), anterior region distinctly narrower, apex ending and slightly raised at the antennal tubercle. Posterior margin of head narrowing, with posterolateral angles rounded. Neck almost half width of head, with margins rounded. Head with two vertexal foveae [VF] ( Figs. 1–2 , 13 ), foveae connected by a transverse sulcus near posterior margin. Vertex longitudinally impressed, with weak sulcus running from anterior margin of antennal tubercle to neck. Ventral surface of head with shallow, long gular sulcus, interrupted at posterior third by two gular foveae [GF] that are connected by curved sulcus. Eyes ( Fig. 3 ) composed of one ommatidium situated at middle of head length in lateral view. Antennae ( Figs. 2, 5 , 13 ) 2/3 body length, scape almost half antenna length, last three antennomeres gradually broadening. Scape length (without peduncle) 1.15 mm, width (maximum) 0.11 mm, pedicel shorter than scape (0.60: 0.07), antennomere 3 (0.09: 0.06) longer than wide, antennomere 4 (0.08: 0.06) longer than wide, antennomere 5 (0.11: 0.05) longer than wide, antennomere 6 (0.07: 0.06) longer than wide, antennomere 7 (0.07: 0.06) longer than wide, antennomere 8 (0.04: 0.05) subquadrate, antennomere 9 (0.08: 0.09) subquadrate, antennomere 10 (0.08: 0.10) subquadrate, antennomere 11 (0.20: 0.12) longer than wide; all antennomeres covered by long microsetae.

Thorax: pronotum ( Figs. 1, 3 , 13 ) subquadrate (PL: 0.55; PW: 0.53) widest at anterior half. Pronotum convex with weak median longitudinal sulcus, each side withlateral sulcus, with antebasal sulcus. Pronotum with basal and anterior margins weakly emarginated; with lateral antebasal fovea [laf]. Prosternum with lateral procoxal fovea [lpcf]. Mesoventrite with prepectal fovea [ppf], median mesocoxal fovea [mmsf], lateral mesosternal foveae [lmsf] lateral mesocoxal foveae [lmcf], and with lateral metasternal foveae [lmtf].

Elytra: subquadrate (EL: 0.76; EW: 0.82), sides gradually broadening apically ( Figs. 1, 3 , 13 ). Posterior margins concave, discal stria [ds] and sutural stria [ss] present. Elytron with two basal elytral foveae [bef] at anterior margin, one close to the elytral suture, second near middle of elytral width at base. Apico-lateral margin of elytra weakly notched. Flight wings absent.

Legs: Legs long and slender ( Fig. 13 ). Femora thickened in apical half. Tibiae curved and similar in length to femora, all tibiae thickened at apex. Protibiae lacking microsetae on concave, mesial face, which is carinate and open at base ( Fig. 4 ). Tarsi 3-segmented ( Fig. 4 ), first tarsomeres very short, last 2 tarsomeres longer, tarsomere 2 longer that segment 3; all tarsi with single claw and minute accessory seta. Procoxae conical and prominent, mesocoxae rounded and prominent, metacoxae transverse, region that articulates with trochanter conical in shape. Procoxae with small, apically pointed prosternal process, mesocoxae weakly separated, metacoxae contiguous.

Abdomen: strongly margined ( Figs. 1, 2 , 13 ), with five visible tergites (morphological tergites IV–VIII), tergite III reduced to small plate beneath elytra, tergite VIII with apex straight. Tergites IV–VII bordered by distinct paratergites. Sternite III with transverse depressed plate completely bare and beneath metacoxae, transverse plate with longitudinally projecting carina at middle. Tergum IX divided into two plates; right plate ( Fig. 8 ) larger and more sclerotized than left ( Fig. 9 ). Sternite VIII ( Fig. 7 ) with apex deeply emarginate.

Aedeagus: asymmetric with parameres fused to form elongate plate, median lobe slightly bulbous at base, elongate and narrow, curved laterally at apex ( Figs. 10–12 ).

Female. Unknown.

Distribution. Only known from the type locality.

Etymology. The specific epithet refers to the locality “pains” in Minas Gerais, where all known specimens were collected.

Habitat. The karst regions of Arcos, Pains, and Doresópolis are located in the central west of Minas Gerais, Brazil ( Fig. 16 ), comprising the largest concentration of caves in the country and probably in South America . This area is located in the southern part of the São Francisco craton, on a Neoproterozoic metapelitic sequence from the Bambuí geological Group (the main carbonate rock formation of Brazil) ( Fig. 16 ) (reference). The exokarst of the region presents a strongly eroded aspect, with steep limestone outcrops, besides an extremely well-developed endokarst. There are around 2,200 caves registered by environmental agencies and these are the main speleological entities of the country ( CECAV 2016 ; SBE 2016). Despite the great concentration of caves, most of them do not exceed 100 meters of linear development, being considered of small size when compared to limestone caves from other Brazilian regions. The caves known from the area represent around 17% of the total caves known for Brazil .

A specimen each of Metopiellus painensis sp. nov. was found in two caves: Loca dos Negros II cave ( Figs. 17– 20 ) and Cerâmicas cave ( Figs. 21–23 ). The Loca dos Negros II cave is located approximately 6.5 km from the urban area of the municipality of Pains ( Fig. 16 ), being part of a complex underground system composed of a large number of small cavities that are interconnected by epigean (diaclasis and skylights) and hypogean (conduits) features within a limestone outcrop. The Loca do Negros II cave has approximately 85.5 m of linear development. Its main entrance is small, and the inner portion of the cave is reachable after a descending slope, which favors the input of a small amount of vegetable debris. On the opposite side of the cave, there is a second entrance formed by an open diaclasis, allowing the input of a considerable amount of vegetable debris, though this region is comparatively light and highly influenced by the epigean environment. The cave is, in general, a low-ceiling cave, presenting a single moist area. The remaining areas are extremely dry, being covered by fine sediment deposits. Guano piles (from bat colonies) were not observed. The cave can be considered oligotrophic, with few aphotic and more stable zones, as was the case of the area where the Metopiellus specimen (Paratype) was found. In this same area, other troglomorphic invertebrates were found, such as spiders, harvestmen, springtails, and millipedes.

The Cerâmicas cave ( Figs. 21–23 ) is a labyrinthine cave with five entrances ( Figs. 21–23 ). It is located about 7.5 km from the main city of Pains. The cave has two distinct levels, each of them presenting different environmental and trophic conditions. Near the main entrances (for the lower level), there are some deposits of organic matter (especially vegetable debris) brought in by the wind. However, to access the upper level (the main part of the cave) there is an abrupt uplift of approximately three meters, that prevents the organic matter from reaching the inner portion of the cave. Accordingly, the upper level is mainly oligotrophic and dry. During the rainy season, a few moist areas appear in the upper level due to dripping water. The only specimen of Metopiellus painensis sp. nov. caught from this cave was found in a dry area at the upper level, in a place full of rocks ( Figs. 21–23 ).

Figures

FIGURE 16. Localization of the karst regions of Arcos, Pains and Doresópolis, Minas Gerais, Brazil.

FIGURES 1 – 12. Metopiellus painensis sp. nov., holotype, 1, habitus, dorsal view: 2, habitus, left lateral view; 3, head, pronotum and elytra, dorsal view; 4, first leg; 5, left antenna, lateral view; 6, Tergum VIII (T 8); 7, Sternum VIII (S 8); 8, right tergum IX (T 9); 9, left tergum IX (T 9); 10, aedeagus, ventral view; 11, aedeagus, lateral view; 12, aedeagus, dorsal view. Scale bars: 0.2 mm.

FIGURES 13 – 15. Habitus, 13, Metopiellus painensis sp. nov.; 14, Metopiellus silvanicus; 15, Metopiellus hirtus. (13, Paratype; 14, after Bruch 1933; 15, after Reitter 1885; slightly modified).

FIGURES 17 – 20. Plan of the cave Loca dos Negros II; 17, main entrance of cave Loca dos Negros II; 18, one of many skylights that there is in the carbonate rock formation; 19, place where were collected the holotype; 20, cave room in the side of place were collected the holotype in aphotic region. Photographs R. de A. Zampaulo.

FIGURES 21 – 23. Plan of the cave Grutas das Cerâmicas; 21, main entrance of cave gruta das Cerâmicas; 22, secondary entrance with a big skylight; 23, main canal in the floor there are many rocks of different size. Photographs R. de A. Zampaulo.