Oxarthrius spiculatus Gouvea, Valente & Asenjo, 2023

Gouvea, Bruno, Valente, Roberta M. & Asenjo, Angélico, 2023, A new species from the eastern Amazon rainforest with lectotype designations and key for Brazilian Oxarthrius Reitter, 1883 (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 5380 (2), pp. 134-150 : 136-144

publication ID	https://doi.org/ 10.11646/zootaxa.5380.2.2
publication LSID	lsid:zoobank.org:pub:6B51DC3F-67C4-4833-92C7-3387297985A6
DOI	https://doi.org/10.5281/zenodo.10258109
persistent identifier	https://treatment.plazi.org/id/03B087E3-2145-F257-FF29-FB2CA8EC1408
treatment provided by	Plazi
scientific name	Oxarthrius spiculatus Gouvea, Valente & Asenjo
status	sp. nov.

Treatment

Oxarthrius spiculatus Gouvea, Valente & Asenjo , sp. nov.

urn:lsid:zoobank.org:act:4EBD9704-0E09-41D7-8E8B-47D2AB0FA90

( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Type material (4 ♂♂, 4 ♀♀).

Holotype. BRAZIL: Pará: ♂, labeled [dissected]: “STP0599 / BRAZIL: Paragominas, / Mineradora Hydro. CP, / S 03°15’, W 47°44’ [without other data]” “HOLOTYPE [red card] / Oxarthrius / spiculatus sp. nov. / Desig. Gouvea et al. 2023”; ( MPEG). GoogleMaps

Paratypes (3 ♂♂, 4 ♀♀). BRAZIL: Pará : ♂, “STP0266 / BRAZIL: Paragominas, / Mineradora Hydro. AL10, S 03°15’27” W 047°42’28”. / Winkler [without other data]” ( MPEG) GoogleMaps .

♂, [specimen for Scanning Electron Micrographs]; “STP0269 / BRAZIL: Paragominas, / Mineradora Hydro. AL3, / S 03°14’19” W 047°41’55” / 20-VI[June]-18[2018]. Winkler” ( MPEG) GoogleMaps .

♂, [dissected]; “STP0275 / BRAZIL: Paragominas, / Mineradora Hydro. AL3, / S 03°14’19” W 047°41’55” / Winkler.” ( UFPA) GoogleMaps .

♀, [dissected]; “STP0273 / BRAZIL: Paragominas, / Mineradora Hydro. AL9, / S 03°15’43” W 047°42’07”. / 7-V[May]-18[2018]. Winkler” ( MPEG) GoogleMaps .

♀, [MEV] “STP0274 / BRAZIL: Paragominas , / Mineradora Hydro. / Al 9(4), S 03°15’43” / W 047°42’07”. 29-VI[June]-18[2018]. / Winkler ” ( MPEG) GoogleMaps .

♀, “STP0267 / BRAZIL: Paragominas , / Mineradora Hydro. / AL9(2), S 03°15’43” / W 047°42’07”. 20- VI[June]-18[2018]. / Winkler ” ( MPEG) GoogleMaps .

♀, [dissected] “STP0271 / BRAZIL: Paragominas, / Mineradora Hydro. AL9, / S 03°15’43” W 047°42’07”. / 7-V[May]-18[2018]. Winkler” ( UFPA) GoogleMaps .

All paratypes with label “ PARATYPE [yellow card] / Oxarthrius / spiculatus sp. nov. / Desig. Gouvea et al. 2023”.

Diagnosis. Oxarthrius spiculatus sp. nov. is more similar to O. anthicoides due to the rough surface of the pronotum. However, Oxarthrius spiculatus sp. nov. can be distinguished by the thin vertexal sulcus [vs] the lack of carinae on the head, and by pronotum lacking lateral longitudinal sulci [lls]. In O. anthicoides the vertexal sulcus is large and carinate, and the lateral longitudinal sulci [lls] are evident on the pronotum.

Description. Holotype male, body length: 2.81 ( Figs 1–2 View FIGURE 1 View FIGURE 2 ). Head and pronotum dark reddish-brown, tegument densely rough. Antennae, legs, elytra and abdomen light reddish brown, tegument of elytra and abdomen shiny and polished. Tarsi and mouthparts paler. Body covered with sparse long setae. ( Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 , 5 View FIGURE 5 ).

Head: slightly oval (length 0.32: width 0.41) with small antennal tubercles at lateral margin of frontal ridge. Antennal insertions of head not visible in dorsal view. Eyes prominent, situated at posterior half of head with sparse interfacetgal setae between ommatidia, genal area small and rounded. Neck strongly constricted (neck width 0.20). Head with two deep vertexal foveae [dorsal tentorial pits] [vf] connected by a slightly distinguished U-shaped vertexal sulcus [vs] that extends to a depression between antennal tubercles ( Figs 2B View FIGURE 2 , 3A View FIGURE 3 ). Median longitudinal carina extending from base of constricted neck to anterior margin of head ( Fig. 3A View FIGURE 3 ). Ocular-mandibular carina present, extending from anterior margin of eyes to base of clypeus. Maxillary palpi four-segmented pubescent, distal segment longer and wider than others with unscarred external face. Gular carina absent. Gular foveae [gf] present in posterior region of head. Antenna thick and long (length 0.92) with antennal club formed by last three antennomeres, antennal length exceed their middle body length ( Figs 1A View FIGURE 1 , 2A–D View FIGURE 2 ). Scape subcylindrical ( Figs 2A View FIGURE 2 , 3A View FIGURE 3 , 5B View FIGURE 5 ), longer than wide (length 0.14: width 0.08), base curved, apex notched at dorsal and ventral view. Rounded pedicel, thinner and shorter than scape (length 0.06: width 0.06). Segment 3–7 slightly longer than wide ( Figs 1A View FIGURE 1 , 2A–D View FIGURE 2 ): 3 (length 0.05: width 0.04); 4 (length 0.06: width 0.05); 5 (length 0.07: width 0.05); 6 (length 0.07: width 0.05); 7 (length 0.07: width 0.06). Segment 8 (length 0.07: width 0.06). Segment 9–11 forming distinctive antennal club ( Figs 1A View FIGURE 1 , 2A–D View FIGURE 2 ): 9 subcylindrical, straight angles (length 0.09: width 0.07); 10 subquadrate, straight angles (length 0.08: width 0.09); 11 fusiform, straight angles at base and obtuse at apex (length 0.19: width 0.09). All antennal segments covered with microsetae, segments 9–11 with microsetae denser.

Thorax: Cordiform shape, similar in length (0.34) and width (0.34), edges of anterior half very tumescent, edge of posterior half tapering posteriorly; basal margin almost right; posterolateral angles almost right angle. Integument densely rough almost like wave pattern, with posterior half less rough ( Fig. 3B View FIGURE 3 ). Pair of conspicuous basolateral spines next to one deep lateral antebasal foveae [laf] on external side ( Fig. 3B View FIGURE 3 ). Outer basolateral foveae [oblf] and inner basolateral foveae [iblf] at basal margin present ( Fig. 3B View FIGURE 3 ). Prosternum ( Fig. 2A View FIGURE 2 ) with anteroprosternal foveae [apsf], lateral procoxal foveae present [lpcf] proepimeral foveae [pef] all present. Mesoventrite ( Figs 1C View FIGURE 1 , 2A View FIGURE 2 ) with pair of lateral mesosternal foveae [lmsf] and pair of lateral mesocoxal foveae [lmcf]. Metaventrite with pair of lateral metasternal foveae [lmtf] and median oval excavation ( Figs 1C View FIGURE 1 , 2E View FIGURE 2 ) impressed by pattern of transverse grooves.

Elytra ( Figs 1A View FIGURE 1 , 3C View FIGURE 3 ): wider than long (EL: 0.53; EW: 0.60), slightly wider than pronotum, sides rounded and gradually widening from the anterior to the posterior region, anterior margin straight, posterior margin sinuous. Humeri slightly prominently. Each elytron with one deep basal elytral fovea [bef] near scutellum ( Fig. 3C View FIGURE 3 ). Sutural stria [ss] complete, evident ( Fig. 3C View FIGURE 3 ).

Legs: Thin and long. Procoxae and mesocoxae ( Figs 1C View FIGURE 1 , 2A View FIGURE 2 ) conical, prominent, contiguous; metacoxae ( Figs 1C View FIGURE 1 , 2A, 2E View FIGURE 2 ) transversely elongated, slightly prominent, separated. Protrochanter and mesotrochanther smaller, triangular shape; metatrochanter bigger, with minute black spine on the apex ( Figs 1C View FIGURE 1 , 5A View FIGURE 5 ). Femora thickening near the apex, mesofemur with acute and prominent spine on basal half, also one median crest posteriorly to the spine ( Fig. 1C View FIGURE 1 ). Tibiae elongated, slim, narrow. Tarsi 3-segmented, first tarsomere small, the last two elongated.Tarsal claws simple, with other minute claw on each tarsi.

Abdomen: Rounded (length 0.67), constricted on base. At dorsal view, paratergites visible only in tergite IV; intersegmental membranes with minute rectangular sclerites. Tergite IV ( Fig. 3D View FIGURE 3 ) (length 0.20: width 0.56) longer than tergite V, with pair of basolateral foveae [blf] and pair of mediobasal foveae [mbf]. Tergite V (length 0.08: width 0.48) and VI (length 0.06: width 0.41) very short. Tergite VII (length 0.13: width 0.31) longer than tergite V– VI and shorter than tergite IV, transverse, angles slightly converging from the base to the apex, base with projections that extends below tergite VI. Tergite VIII large, U-shaped ( Fig. 4D View FIGURE 4 ), concave centrally on anterior. Sternite III very short, with one deep mediobasal foveae [mbf] evident on the center. Sternite IV longer than III. Sternites V-VII short. Sternite VIII ( Fig. 4F View FIGURE 4 ) large, transverse, slightly sinuous on anterior margin, protrude centrally on posterior margin, with large medial depression and subapical curved keel ( Figs 2E View FIGURE 2 , 4F View FIGURE 4 ).

Aedeagus: Slightly asymmetrical (length 0.3 mm). Median lobe bulbous; apex almost straight with one central plate (cp) divided into two short opposite branches ( Figs 4A, 4C View FIGURE 4 ), ventrally with two poorly defined spots of setae, median pointed projection (mpp) ventrally facing on each side of aedeagus, discrete ( Figs 4A, 4B View FIGURE 4 ), parameres not observed.

Pubescence: Thin and long setae [ts] are the most common and found all over the body ( Fig. 5B, 5D View FIGURE 5 ), flattened setae [fs] present on the anterior edge of the head ( Fig. 5C View FIGURE 5 ) and dorsal surface of the abdomen, hollow setae present on the antennae.

Female. Similar to male, except for: mesofemora ( Fig. 1D View FIGURE 1 ), without spine and median crest; metatrochanter without any spine ( Fig. 1D View FIGURE 1 ); metaventrite with median longitudinal sulcus ( Fig. 2F View FIGURE 2 ) instead of excavation as in the male ( Figs 1D View FIGURE 1 , 2E View FIGURE 2 ). Tergite VIII ( Fig. 4E View FIGURE 4 ) trapezoidal, straight on anterior margin, rounded on posterior margin. Sternite VIII ( Fig. 4G View FIGURE 4 ) large, rounded, slightly sinuous on posterior margin, no keel, no depression. Genital complex ( Fig. 4H View FIGURE 4 ) trapezoidal, weak sclerotized; posterior margin rounded, projecting laterally, narrowed; anterior margin membranous; median region with one evident transversal curved carina, centrally with one pair of transversal sclerites, slightly elongated anteriorly.

Study area and sampling notes. All specimens of O. spiculatus were collected in the area of the Mineração Paragominas S.A. Company of the Norsk Hydro ASA, located approximately 70 km (coordinates: 3˚15’53”S, 47˚423’06”W) from the municipal headquarters of Paragominas, state of Pará, in the eastern Brazilian Amazon ( Fig. 6 View FIGURE 6 ). Paragominas represents one of the largest bauxite reserves of the World, having estimated reserves of 1 billion tonnes ( Veredict Research 2008). Its main soils are Yellow Latosols, Yellow Argisols, Plinthsols, Gleysols and Neosols ( Rodrigues et al. 2003).

In this region the climate is tropical wet and dry (Aw type, Köppen-Geiger’s Climate classification), with a pronounced dry season occurring from June to November besides a wetter season (from February to May) and a transition season (from December to January) ( Bastos 2005; Dubreuil et al. 2018). The precipitation varies a lot throughout the year, ranging from 28 mm (August and September) to 357 mm (March; average annual 1,800 mm), whereas relative humidity (76% to 85%; annual average 81%) and air temperature (25.6°C to 27°C; annual average 26.3°C) are relatively stable throughout the year ( Bastos 2005). The predominant vegetation is dense Amazon Rainforest showing different levels of degradation and deforestation, resulting in a landscape mosaic ( Uhl & Vieira 1989).

In the study area, the mining activity due to bauxite extraction has changed the landscape due to total vegetation suppression through total topsoil and soil removal. The bauxite mined areas are later reforested with native species according to the Degraded Area Rehabilitation Plan (PRAD) which incorporates three different systems of rehabilitation implemented by the Mineração Paragominas: “nucleação”, spontaneous natural regeneration and planted forest species ( Martins et al. 2018; Cerqueira et al. 2021). Therefore, the landscape of the study area is mainly composed of Forest, bauxite mining areas and PRAD areas ( Fig. 6 View FIGURE 6 ).

The bauxite mining areas were not sampled. The field collections occurred between 2017 and 2019: November to December 2017 (dry season to transition season), May 2018 (wet season), June 2018 (dry season), and February 2019 (wet season). The sampling points were randomly scattered in the study area to represent its environmental variability, with about 60% of the points in forest. In the PRAD areas, sampling points were spread out close to the edge of the forest. The sampling unit was not established.

All specimens of Oxarthrius collected belong to O. spiculatus . They were recorded exclusively in the forest, at elevations from 100m to 140m, between the end of the wet season (May 2018) and the beginning of the dry season (June 2018). Different sampling methods were used for the collections: Classical Light Trap (white cloth, with mercury-vapor or blacklight lamps), Winkler extractor, Yellow Pan Trap (or Moericke), Butterfly Sweep Net, Sweep Net, Quadrate Beating Sheet or white Umbrella, and active search under decaying logs, leaves, flowers and logs. However, all specimens of O. spiculatus were gathered exclusively from Winkler extractor samples. Here, the Winkler samples consisted of litter with some part of the topsoil. Each Winkler litter sample were put in coarsemesh bags suspended inside a large closed cloth bag suspended over a collection 100 ml bottle containing 75 ml of 80% ethanol, and left to dry at controlled temperature of 25ºc for three days. We believe that O. spiculatus lives as a ground-dwelling rove beetle living in the leaf litter of the Amazon forest. It seems to be unable to colonize the local PRAD areas during this study.

Distribution. Only known from the type locality.

Etymology. The specific epithet refers to the Latin term spiculatus , meaning equipped with small spines, in reference to the spines on the male metatrochanter.