Oxarthrius Reitter, 1883

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 : 147-148

Key to Brazilian species of Oxarthrius Reitter, 1883

1. Antennal segments 3–9 slightly longer than wide, or subquadrate ( Fig. 2D ). Vertexal sulcus [vs] present ( Fig. 3A )........ 2

- Antennal segments 3-9 extremely elongate, at least twice as long as wide ( Asenjo et al. 2018; figs 1–2, 12–13). Vertexal sulcus [vs] absent ( Asenjo et al. 2018; figs 3, 14)................................................................. 4

2. Carina connecting pronotal setae lacking. Pronotum lacking median basal carina........... Oxarthrius bispinosus (Reitter)

- Pronotum with sinuous carina connecting base of setae ( Fig. 3B ). Pronotum with median basal carina ( Fig. 3B ).......... 3

3. Lateral antebasal foveae [laf] wide ( Fig. 7D ). Vertexal sulcus [vs], deep and wide, laterally carinate ( Figs. 7A–B )............................................................................ Oxarthrius anthicoides (L.W.Schaufuss)

- Lateral antebasal foveae [laf] narrow ( Fig. 3B ). Vertexal sulcus [vs] narrow, not laterally carinate ( Fig. 3A )......................................................................................... Oxarthrius spiculatus sp. nov.

4. Antennal segment 10 twice as long as wide ( Asenjo et al. 2018; figs 1–2). Basal half of male mesofemora with an elongated and sinuated spine ( Asenjo et al. 2018; fig. 5)..................................... Oxarthrius inexpectatus Asenjo

- Antennal segment 10 three times as long as wide ( Asenjo et al. 2018; figs 12–13). Basal half of male mesofemora with a truncate spine ( Asenjo et al. 2018; fig. 16)............................................. Oxarthrius aurora Asenjo

Discussion

Taxonomy

The new species described here belongs to the genus Oxarthrius due to the pronotum having a pair of antebasal spines, and lacking an antebasal transverse sulcus. It is placed in the subgenus Oxarthrius as defined by Park (1942) based on the characters “maxillary palpi with simple unscared external face” and “each elytron with a single basal fovea”. Currently, only Oxarthrius aurora Asenjo, 2018 and Oxarthrius inexpectatus Asenjo, 2018 have the male genitalia described. Photographs of type specimens of O. bispinosus and O. anthicoides were fundamental for definition of O. spiculatus as a new species considering that they are very similar, and the original description was insufficiently detailed to distinguish the two species. For first time the female genital complex is described for a species of Oxarthrius so it is not possible to compare it with any described species. As far as is known, this is the first species of Oxarthrius that the male have a spine on the metatrochanter since the male is unknown for O. anthicoides , O. forticornis , O. simplexides .

Distribution of Oxarthrius

The genus is widely distributed throughout South America ( Argentina, Bolivia, Brazil, Paraguay and Peru) and also in Central America it is known from Guatemala and Panama ( Park 1942; Asenjo et al. 2018). The northernmost record is for O. hamaticollis , which was collected at an elevation of 3,000 feet at Las Mercedes, Guatemala ( Sharp 1887; Park 1942). From the Panama Canal Zone (Barro Colorado Island, Gatun Lake) specimens of O. sternadens were collected from beneath bark of a log, and specimens of O. escharus were taken from a decaying log and galleries of termites (probably Coptotermes niger Snyder, 1922 ) in a fallen tree ( Park 1942). The southernmost record for the genus is of O. attaphilus , which was collected at Loreto, Misiones, Argentina in an ant nest ( Atta sexdens L.) ( Bruch 1933; Park 1942). The southwest record is for O. rugosicollis from “ Asunción ” ( Paraguay) ( Raffray 1918).

Four species were collected from Bolivia: O. armatides , O. simplexides , O. rugosus ( Raffray, 1898) and O. forticornis ( Raffray, 1898) , but there is no precise information about their type localities since they were recorded as “ Haute-bolivie: triubu des Yuracaris” ( Raffray 1898; Park 1942). We believe that these species occur in the Bolivian Amazon, because the Yuracaré indigenous people lived until the 1940s in a large area of tropical rainforest at the foot of the Andes Mountains and along rivers from Santa Cruz to Cochabamba ( D’Orbigny 1839: 354-355, Metraux 1948: 485), which belongs to the Bolivian Amazon region ( Plaza Martinez 2011). Additionally, one female of O. simplexides was subsequently collected from Peru at an elevation of 2,000 feet from Colonia el Perené “El campamiento” (Chanchamayo, Junín Department) ( Fletcher 1928; Park 1942; Rasmussen 2016), which is situated in the Peruvian Amazon region ( IGN 2018).

Previously, four species had been recorded from Brazil. The species O. aurora was taken in the state of Tocantins and O. inexpectatus was collected in the state of Minas Gerais, both being the first troglobitic species of Oxarthrius , and which were taken from caves ( Asenjo et al. 2018) situated in the Cerrado Biome ( IBGE 2019). The distribution of O. anthicoides is problematic, since it is recorded from “Brasilia” (L.W.Shauffus 1887), and the distribution of O. bispinosus is uncertain also since it was based on material from “Brasilia; Santa-Rita; September (Salhb.[Reinhold Ferdinand Sahlberg])” ( Reitter 1883: 376). However, in same work Reitter (1883: 379) mentioned in a key “bispinosus Rttr. Petropolis ”, Petropólis is a municipality in the state of Rio de Janeiro. Subsequently, Raffray (1898:438, 1908:134) and Park (1942:246) mentioned the locality of O. bispinosus as “Santa Rita, Blumenau”. According to Papavero (1973), Sahlberg was in Rio de Janeiro in August 1850 and collected for about 3 months, however, in the same paper it is mentioned that Sahlberg also collected in the municipality of Minas Gerais from Chapéu d’Uvas to Diamantino, presenting the possibility of Santa Rita being on his itinerary. Considering that there is no mention of Santa Rita during Sahlberg’s visit to Rio de Janeiro, it is possible that Santa Rita corresponds to the current district of Santa Rita Durão, in the state of Minas Gerais.

Therefore, Oxarthrius spiculatus sp. nov. recorded from Paragominas, State of Pará, is the first species of the genus recorded from the Brazilian Amazon. Herein we expand the distribution of the genus to eastern Amazonia .

Figures

FIGURE 2. Oxarthrius spiculatus sp. nov. (A-E. Male holotype - STP0599; F. Female paratype – STP0267) A. Habitus, ventral view. B. Head, dorsal view. C. Habitus, lateral view. D. Antennae. E. Abdomen ventral view. F. Abdomen ventral view. Scale bars = 1 mm (A, C); 0.5 mm (B, E, F); 200 µm (D).

FIGURE 3. Oxarthrius spiculatus sp. nov., paratype male- STP0269. A. Head, dorsal view. B. Pronotum, dorsal view. C. Elytra, dorsal view. D. Abdomen, dorsal view. Scale bars = 100 μm (A, B, D); 200 μm (C). Abbreviations: vf, vertexal foveae; laf, lateral antebasal foveae; oblf, outer basolateral foveae; iblf, inner basolateral foveae; bef, basal elytral foveae; ss, sutural stria; mbf, mediobasal foveae; blf, basolateral foveae.

FIGURE 7. Oxarthrius anthicoides (L.W.Schaufuss, 1887), Lectotype (MNHN, EC21543). A. habitus, dorsal view. B. habitus, ventral view. C. original labels. D. habitus, lateral view. Credits of the photographs: Christophe Rivier (Muséum National d’Histoire Naturelle, Paris, France). Scale bars = 1 mm (A, B, D)