Additions to the taxonomy of Pheidole (Hymenoptera: Formicidae) from the southern grasslands of Brazil

The ant genus Pheidole is the most species-rich lineage of ants in the world and one of the dominant organisms in tropical regions. However, the knowledge of Pheidole diversity in the southern half of the Neotropical Region is fragmentary. Here, we offer contributions to the Pheidole taxonomy considering the species that occur in the grassland formations of South Brazil. The following species are revived from synonymy: P. idiota Santschi rev. stat., P. obscurior Forel rev. stat., P. paranana Santschi stat. rev. et n. stat. and P. strobeli Emery rev. stat. The following synonyms are proposed: P. idiota (= P. laticornis Wilson n. syn.), P. obscurior (= P. partita Mayr n. syn., = P. incisa evoluta Borgmeier n. syn.) and P. strobeli (= P. rufipilis divexa Forel n. syn., = P. nitidula daguerrei Santschi n. syn., = P. perversa Forel n. syn., = P. perversa richteri Forel n. syn., = P. strobeli misera Santschi n. syn.). Finally, six new species are described: P. abakytan n. sp., P. abaticanga n. sp., P. cangussu n. sp., P. curupira n. sp., P. mapinguari n. sp., and P. obapara n. sp. A R T I C L E I N F O Article history: Received 13 July 2020 Accepted 20 September 2020 Available online 23 November 2020 Associate Editor: Jeffrey Sosa-Calvo


Introduction
Among ant genera, Pheidole Westwood is the most species-rich with 1,151 species and 129 subspecies currently described (Bolton, 2020) and likely contains well over 1,500 species. Pheidole is a cosmopolitan genus, first diversifying in the New World approximately 29 Mya, with diversification in the Old World beginning around 11 Mya (Economo et al., 2019). More than 700 described Pheidole species inhabit the New World, with nearly 620 species recorded from the Neotropical Region and around 150 recognized in Brazil (AntWeb.org). Thanks to Wilson's (2003) monograph, considered the most important single taxonomic contribution to the genus thus far, and the works by Longino (2009Longino ( , 2019, our knowledge on diversity and taxonomy of Pheidole has increased significantly for the New World. However, as expected for such a hyperdiverse genus, recent works did not cover all the diversity for the genus and had particularly sparse coverage in some areas of the Neotropics. Among these, the Pheidole fauna of the southern half of South America is far from thoroughly documented. Due to this knowledge deficit, it is expected that the biomes of Brazil harbor a high number of undescribed Pheidole species. Among Brazilian phytophysiognomies, the non-forest ecosystems (e.g. grasslands, savannas, shrublands, and open woodlands) are widespread. These ecosystems cover large portions of four different biomes (i.e. Caatinga, Cerrado, Pampa, and Pantanal) and occur to a lesser extent in other two forest biomes (i.e. Amazon Forest and Atlantic Rainforest) (Overbeck et al., 2015). In South Brazil, which encompasses the states of Rio Grande do Sul, Santa Catarina, and Paraná, the non-forest ecosystems are known as Campos Sulinos, and are naturally widespread over two different biomes, the Pampa in the southernmost region (Overbeck et al., 2007) and patches of grasslands within the Atlantic Forest in the northern portions .
Grassland physiognomy in this region is not homogeneous and can vary strongly regarding vegetation coverage, elevation, and the anthropic influence (Overbeck et al., 2007). Campos Sulinos can be composed of noticeably short vegetation, mainly formed by grasses, to tall and complex vegetation composed by shrub and treelet species (Overbeck et al., 2007). The southern part of the grasslands in Brazil encompasses the Pampa biome, an open ecosystem with an average elevation of 800 m a.s.l., exclusive for the state of Rio Grande do Sul in Brazil and also distributed in Argentina and Uruguay. This is considered one of the most species-rich grasslands in the world, despite being more intensively grazed when compared to the highland grasslands of Santa Catarina and Paraná that are included in the Atlantic Forest biome (Overbeck et al., 2007;Dröse et al., 2017). The highland grasslands in the Atlantic Forest biome are mainly distributed from about 800 to 1,000 m a.s.l., with highest peaks up to 1,800 m, eventually forming mosaics with Araucaria forests .
In the Paraná state, the non-forested ecosystems, commonly referred as Campos Gerais (Franco & Feitosa 2018), are characterized by the combination of savannas (Cerrado), in the northern portion, and open grasslands permeated by gallery forests with Araucaria angustifolia (Bertol.) Kuntze covering rocky soil with canyons, caves, and shallow rivers (Maack, 1981;Melo et al., 2001). Additionally, these highland grasslands are adapted to frequent burnings concentrated at the end of the winter, resulting in a dominance of highly fire-resilient grass tussock species (Boldrini, 2009).
In the recent years, ant surveys have been conducted in the Brazilian southern grasslands in Paraná (e.g. Franco & Feitosa 2018;Martins et al., 2020), Santa Catarina (e.g. Martins et al., 2020), and Rio Grande do Sul (e.g. Diehl et al., 2005;Albuquerque & Diehl, 2009;Pinheiro et al., 2010;Rosado et al., 2012;Diehl et al., 2014;Dröse et al., 2017), all of them revealing a considerable number of unidentified Pheidole species. Several limitations have led to this taxonomic impediment, including: (1) the absence of a comprehensive and user-friendly key to the identification of the Brazilian Pheidole species, (2) the difficulty in understanding the species limits within the genus, (3) and the high number of undescribed species from the southern part of the Neotropics.
Besides the species described by Longino (2009Longino ( , 2019 from the Mesoamerican fauna, a single Pheidole species was recently described from Bahia in Brazil (Pheidole protaxi Oliveira, et al., 2015). Thus, considering the scarcity of taxonomic studies on Pheidole in the southernmost areas of the Neotropical Region, and the accumulation of specimens from recent surveys, here we offer additions to the taxonomy of Pheidole known from natural grasslands of South Brazil. To visually improve the taxonomic descriptions, we provide images, 3D models, and 3D videos based on surface volume renderings of microtomography (micro-CT) scans for all new species. A synopsis of the species recognized for these environments is also provided, as well as updated taxonomic keys based on Wilson's (2003) monography. This is the first study focusing on the Pheidole species from a single ecosystem in Brazil.

Specimen examination and imaging
The specimens examined here were obtained from different published and ongoing surveys carried out in the natural grasslands of South Brazil (Dröse et al., 2017;Franco & Feitosa 2018;Dröse et al., 2019;Martins et al., 2020) and sent for identification and/or deposit in the Coleção Entomológica Padre Jesus Santiago Moure of the Universidade Federal do Paraná (DZUP). Also, to improve our species delimitation hypotheses and examine type-specimens, we have visited some of the most representative ant collections for Pheidole in the New World, including the Museu de Zoologia da Universidade de São Paulo, the myrmecological collection of the Centro de Pesquisas do Cacau in Bahia, and the Museum of Comparative Zoology of the Harvard University, Cambridge. In total, approximately 1,550 specimens were examined.
A considerable part of the material examined here derives mainly from three large projects carried out in South Brazil, of which voucher specimens were deposited in DZUP. The first project, coordinated by RMF at the Laboratório de Sistemática e Biologia de Formigas (UFPR), aimed a comprehensive survey of the ant fauna inhabiting the natural savannas and grasslands of the state of Paraná. In this project, ants were collected using pitfall traps and Winkler extractors in four different reserves of the state, representing the first standardized inventory of ants in the natural grasslands of Paraná (for further details see Franco & Feitosa (2018)).
The second project, namely SiSBiota, was conducted by Embrapa Floresta (Colombo, Paraná, Brazil) and the Universidade Estadual de Santa Catarina (UDESC). This project focused on verifying the effect of different land use systems on the composition of epigaeic and hypogaeic invertebrates. Samplings encompassed several vegetational formations, including natural and anthropic grasslands (Martins et al., 2020). In total, ants were collected in seven municipalities with representative areas of grasslands, one in the Paraná state, and six in the Santa Catarina state.
The last project, developed by the research group of the Laboratório de Ecologia de Interações of Universidade Federal do Rio Grande do Sul (UFRGS), investigated how ant communities are locally assembled in natural forest-grassland ecotones distributed over the south Brazilian region (Dröse et al., 2017(Dröse et al., , 2019. In this project, a total of six natural grassland areas under traditional cattle grazing in the state of Rio Grande do Sul were sampled.
Examinations were made at 80x magnification with a Zeiss SteREO DiscoveryV8 dissecting microscope. High-resolution images were obtained with an Axiocam 305 color coupled in Zeiss SteREO Discovery. V20, extended depth focus was made in the software Zen Blue v.2.6, and subsequently treated to correct for brightness and contrast.

X-ray micro-computed tomography and 3D images
The use of Micro-CT in systematic and taxonomic research is becoming more common. Recent studies have demonstrated its utility for generating high-resolution, virtual, and interactive three-dimensional reconstructions of whole ant specimens (e.g. Fischer et al., 2016;Sarnat et al., 2016;Hita Garcia et al., 2017). One of the main advantages of the approach is the generation of an openly available cybertype dataset to accompany the physical type, thus protecting the original exemplar from deterioration (Faulwetter et al., 2013;Hita Garcia et al., 2017). Here, micro-CT/μCT scans were created with a ZEISS Xradia 510 Versa and the ZEISS Scout and Scan Control System software. Scan settings were selected according to yield optimum scan quality: 4x objective, exposure times between 0.6 and 3 seconds, source filter "Air", voltage between 40 and 50 kV, power between 3 and 4W, and field mode "normal" (Table 1). The combination of voltage, power and exposure time was set to yield intensity levels of between 15,000 and 17,000 across the whole specimen. Scan times varied from 27 to 50 minutes, depending on exposure times. Full 360-degree rotations were done with a number of 801 projections. The resulting scans have resolutions of 1013x992x999 (HxWxD) pixels and voxel sizes range between 2.25 μm and 5.39 μm. 3D reconstruction of the resulting scans was done with XMReconstructor and saved in DICOM file format.

Taxonomic procedures
Taxonomic units (morphospecies) were delimited using characters of external morphology such as body shape, surface sculpturing, and pilosity. The delimited morphospecies were compared with the type material of valid species and junior synonyms to confirm their identities. All morphospecies not corresponding to available names were described as new, and for those that have been recognized among synonyms, the name status was revived. The revived species were redescribed so that the important features for each one could be updated and standardized. LucidBuilder software (LucidTeam) was used to generate a list of characters, which served as the basis for the descriptions in a semiautomatic method.
Considering the noteworthy diversity of Pheidole and the limitations of making available an identification key that included only the species of this study, we included the species treated here in the last couplet required to access them in the keys provided by Wilson (2003).

Measurements and index abbreviations
Measurements were adapted from Sarnat et al. (2016) and Longino (2019) and were taken from at least one specimen of each worker subcaste. Specimens were measured with a dual-axis micrometer stage with output in increments of 0.001 mm. All measurements are presented in mm.
EL Eye length. Maximum eye length in lateral view. FL Metafemur length. Length of metafemur measured along its long axis.
HL Head length. Maximum distance from the midpoint of the anterior clypeal margin to the midpoint of the posterior margin of the head, measured in full-face view. In majors, measured from midpoint of tangent between the anterior-most position of clypeus to midpoint of tangent between the posterior-most projection of posterolateral lobes.
HW Head width. Maximum width of the head in full-face view, excluding the eyes.
ML Mesosomal length. Maximum length of mesosoma measured in lateral view as the diagonal length of the mesosoma from the point at which the pronotum meets the cervical shield to the apex of the propodeal lobe.
PeW Petiole width. Maximum width of the petiole measured in dorsal view.
PeL Petiole length. Maximum length of petiole measured from anteroventral junction with propodeum to posterodorsal junction with postpetiole.
PpW Postpetiole width. Maximum width of the postpetiole measured in dorsal view. SL Scape length. Length of the antennal scape, including the lamella encircling the base of the scape but excluding the basal condyle.
IHP Inner hypostomal projection. Distance measured between the inner hypostomal projection in ventral view considering the approximate midpoint of the base of the projection. Apply to major workers and queens.
OHP Outer hypostomal projection. Distance measured between the outer hypostomal projection in ventral view considering the approximate midpoint of the base of the projection. Apply to major workers and queens.

Terminology
The terminology follows Wilson (2003) and Longino (2019) for the morphological structures, Wilson (1955) for pilosity, and Wilson (2003) and Longino (2019) for surface sculpturing. Regarding the latter, a common sculpture pattern in Pheidole is the areolate one. In some cases, it can be superficially marked and hardly recognized; however, it can be seen by using indirect light. Major and minor workers are referred as ♃ and ☿ in the examined material, respectively.

Data availability
All the type specimens examined in this study have been databased and the data is freely accessible on AntWeb (http://www.antweb.org; Table 1 Overview of micro-CT scanning data presenting specimen data, scan settings, and voxel sizes for the resulting scans (all specimens are workers and all files are in DICOM format).   Additions to Wilson (2003)  Major worker. Head: head side, in dorsal view, broadly convex, with dense appressed setae; head dorsal profile forming a broadly, continuous convexity, and vertexal margin deeply emarginate. Hypostoma with median tooth vestigial; inner teeth distinct, narrow and slightly curved, converging apically, and widely spaced. Median clypeal carina absent; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, surpassing midheight between eye and vertexal margin but not reaching the margin, with a combination of appressed setae and standing. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface, in frontal view, smooth. Mesosoma: pronotum dorsally strongly areolate with a reticulate-rugose area anteriorly, and promesonotal dorsum, in lateral view, presenting two pairs of stiff standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin narrowly concave, and petiolar node, in lateral view, broad and apically rounded. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting stiff standing setae, two of them longer than the adjacent. First gastral tergum finely areolate; dorsally with a combination of stiff standing and appressed setae, no more than 1.5× the eye length. Color reddish-brown.
Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, not visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina strongly areolate, with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae finely areolate with a smooth median patch. Vertexal surface finely areolate. Mesosoma: pronotal surface strongly areolate, dorsally with a reticulate-rugose patch anteriorly, and promesonotal dorsum, in lateral view, presenting two pairs of stiff standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection triangular; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, with straight side, dorsally smooth, and presenting a combination of a pair of stiff standing setae, with shorter and appressed setae. First gastral tergum smooth; dorsally with a combination of stiff standing and appressed setae, no more than 1.5× the eye length. Color reddish-brown.
Comments. Similar species are P. laevifrons Mayr, P. lemur Forel, and P. zelata Wilson. All these species, which are included in the diligens group, present majors with lateral margins of the head with appressed setae, space between eye and frontal carina with a small reticulaterugose patch, and vertexal surface smooth. Pheidole abakytan can be differentiated from P. laevifrons by first gastral tergum with a combination of stiff standing and appressed setae, while in P. laevifrons these setae are flexuous. Pheidole lemur has the first gastral tergum finely areolate, and P. abakytan has a smooth gastral surface. The main difference between P. zelata and P. abakytan is that the propodeal projection is spiniform in P. zelata while in P. abakytan this projection is triangular. Minors of P. abakytan have the head surface predominantly areolate, and in P. laevifrons and P. zelata the surface is smooth.
This species was collected in pitfall traps in a savanna area at 917 m. The type-locality, Parque Estadual do Cerrado in Jaguariaíva, Paraná state, represents the southernmost fragment of the Cerrado biome in Brazil, where the prevailing vegetation are the open woodlands.
Etymology. From Tupi-Guarani, Old Tupi, ába = hair, akytan of akytã = short (de Carvalho, 1987), in apposition, referring to the hairs on the head of the major worker. The Old Tupi (also known as as língua brasílica "Brazilian language") was the main language spoken by the ethnic groups that inhabited the Brazilian coast before the conquest by the Portuguese settlers. Vocabulary available on http://www.oocities. org/indianlanguages_2000/.   Major worker. Head: head side, in dorsal view, slightly convex, nearly straight, with standing setae; head dorsal profile with a strong convexity just anterior to the vertexal region, and vertexal margin deeply emarginate. Hypostoma with median tooth vestigial; inner teeth distinct and broad, in mid-distance from outer teeth. Median clypeal carina absent; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, not surpassing midheight between eye and vertexal margin, with standing setae. Space between eye and frontal carina reticulate-rugose, with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae longitudinally rugulose that gradually become reticulate-rugose at about the posterior half of head dorsum. Vertexal surface, in frontal view, strongly reticulate-rugose. Mesosoma: pronotum dorsally reticulaterugose, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, without an anterior concavity and with a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, apically narrow and rounded. Postpetiole, in dorsal view, wider than long and trapezoidal, and dorsally presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, more than 1.5× the eye length. Color light yellow.
Minor worker. Head: vertexal margin, in dorsal view, emarginate and rounded; occipital carina, in dorsal view, not visible; postgenal bridge, in lateral view, areolate. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina strongly areolate, with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae strongly areolate. Vertexal surface strongly areolate. Mesosoma: pronotal surface strongly areolate, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile continuous, without a distinctly produced median area, and dropping almost vertically to the propodeum. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, with smoothly rounded side, dorsally smooth, and presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color light yellow.
Comments. Majors can be differentiated from similar species in the flavens group by the head dorsal profile anteriorly convex and depressed near the vertexal portion, and the head surface strongly reticulate-rugose, including the space between eye and antennal fossa, frons, and vertexal surface. Minors of P. abaticanga are similar to several species included the flavens group, so that the complete description must be employed to distinguish it.
The type-series of this species was collected in a leaf-litter sample at a small fragment of semideciduous forest near a stream. The typelocality, Parque Estadual do Guartelá, Tibagi, is one of the last wellpreserved remnants of the grassland formation known as Campos Gerais, exclusively found in the Paraná state, within the Atlantic Forest domain. The landscape consists of large areas of grasslands and shrublands with small enclaves of semideciduous forests.
Etymology. From Tupi-Guarani, Old Tupi (see details about the language at the description of P. abakytan above), abati = corn, canga of akánga = head (de Carvalho, 1987), in apposition, referring to the head shape of the major worker. This name was chosen for the way that my labmate Mila Martins typically recognizes and diagnoses this species.  Major worker. Head: head side, in dorsal view, broadly convex, with standing setae; head dorsal profile forming a smooth, continuous convexity, nearly straight, and vertexal margin deeply emarginate. Hypostoma with median tooth absent; inner teeth distinct and broad, diverging apically. Median clypeal carina distinct; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, not surpassing midheight between eye and vertexal margin, with standing setae, and anterior margin with some of them longer than the adjacent. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae longitudinally rugulose. Vertexal surface, in frontal view, smooth. Mesosoma: pronotum dorsally smooth, and promesonotal dorsum, in lateral view, presenting stiff standing setae. Mesonotal profile continuous, with a distinctly produced median area. Katepisternum finely areolate with smooth median patch and few rugulae. Propodeal projection triangular. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, apically narrow and acute. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting stiff standing setae. First gastral tergum smooth; dorsally with stiff standing setae, no more than 1.5× the eye length. Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface smooth. Mesosoma: pronotal surface finely areolate, laterally with a smooth posterior patch, dorsally with the pronotal disc smooth, and promesonotal dorsum, in lateral view, presenting stiff standing setae. Mesonotal profile slightly sinuous, without a distinctly produced median area, and gradually inclining to the propodeum. Katepisternum strongly areolate with a smooth anteroventral patch. Propodeal projection triangular; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, with smoothly rounded side, dorsally smooth, and presenting stiff standing setae. First gastral tergum smooth; dorsally with stiff standing setae, no more than 1.5× the eye length. Color light yellowish-brown.
Comments. P. cangussu resembles P. schwarzmaieri Borgmeier. Majors of P. cangussu have the mesosoma surface predominantly smooth, while P. schwarzmaieri has the surface areolate. Minors of P. cangussu have the head smooth and mesosoma finely areolate; P. schwarzmaieri has the head and mesosoma distinctly areolate.
The type-series comes from pitfall traps installed at 804 m in the Parque Estadual do Cerrado, Jaguariaíva, Paraná (see details about the locality at the description of P. abakytan above).
Etymology. From Tupi-Guarani, Old Tupi (see details about the language at the description of P. abakytan above), cang of akánga = head, ussu of uçu = big (de Carvalho, 1987), in apposition, referring to the large head of the major worker. Major worker. Head: head side, in dorsal view, broadly convex, with standing setae; head dorsal profile forming a smooth, continuous convexity, nearly straight, and vertexal margin moderately emarginate. Hypostoma with median tooth vestigial; inner teeth vestigial, closely spaced. Median clypeal carina vestigial; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, not surpassing superior limit of the eye, with standing setae. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae longitudinally rugulose. Vertexal surface, in frontal view, smooth. Mesosoma: pronotum dorsally smooth, anteriorly with transverse, straight to slightly curved rugulae, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile continuous, without a distinctly produced median area, and dropping almost vertically to the propodeum. Katepisternum finely areolate with smooth median patch. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, apically narrow and rounded. Postpetiole, in dorsal view, wider than long and trapezoidal, and dorsally presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color yellowish-brown.
Measurements Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface smooth with few piligerous punctures. Mesosoma: pronotal surface finely areolate, laterally with a smooth posterior patch, dorsally with the pronotal disc smooth, and promesonotal dorsum, in lateral view, presenting stiff standing setae. Mesonotal profile slightly sinuous, without a distinctly produced median area, and gradually inclining to the propodeum. Katepisternum strongly areolate. Propodeal projection vestigial; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, trapezoidal, dorsally smooth, and presenting stiff standing setae. First gastral tergum smooth; dorsally with stiff standing setae, no more than 1.5× the eye length. Color yellowish-brown.
Comments. Pheidole curupira resembles P. gigaflavens Wilson, 2003. Majors of P. curupira have the pronotal surface mostly smooth, while P. gigaflavens has this surface areolate. Minors of P. curupira have the head mostly smooth, and P. gigaflavens has the head strongly areolate.
The P. curupira type-series was collected with pitfall traps in the Parque Estadual de Vila Velha, Ponta Grossa, Paraná. The landscape consists of vast extensions of grasslands and shrublands, with small forest enclaves within the Atlantic Forest domain.
Etymology. In apposition, from Brazilian folklore, the curupira has many representations throughout the country, but the common depiction refers to him as a dwarf with red hair, feet in reverse and heels forward so that footprints confound those who are looking for him in the jungle. The name was chosen to honor Brazilian culture, in addition to referring to the small size of this species.  Major worker. Head: head side, in dorsal view, broadly convex, with standing setae; head dorsal profile forming a broadly, continuous convexity, and vertexal margin deeply emarginate. Hypostoma with median tooth vestigial; inner teeth distinct, narrow and straight, widely spaced. Median clypeal carina absent; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, surpassing midheight between eye and vertexal margin but not reaching the margin, and basally terete; with a combination of appressed setae and standing. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface, in frontal view, smooth. Mesosoma: pronotum dorsally smooth, anteriorly with transverse, straight to slightly curved rugulae, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection triangular. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, broad and apically rounded. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color dark brown. Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface smooth. Mesosoma: pronotal surface finely areolate, and promesonotal dorsum, in lateral view, presenting stiff standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection triangular; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, with straight side, dorsally smooth, and presenting stiff standing setae. First gastral tergum smooth; dorsally with stiff standing setae, no more than 1.5× the eye length. Color dark brown.
Comments. Pheidole idiota can be easily recognized by the basally broad scape which surpasses the midheight between the eyes and the vertexal margin, not reaching the margin. The only morphologically similar species is Pheidole porcula Wheeler. Both species can be distinguished by the gaster pilosity, which in P. idiota the setae have no more than 1.5× the eye length, while in P. porcula the setae are more than 1.5× the eye length. Minors of P. idiota are similar to several species included in the diligens group and the complete description is necessary to distinguish them. This species has been a junior synonym of Pheidole vafra since Wilson (2003). Wilson (2003) described Pheidole laticornis and considered the scape basally broad of majors as the main diagnostic character of the species. However, P. idiota presents the same character and lacks any significant morphological difference when compared to P. laticornis. In a recent publication, Longino (2019) synonymized P. laticornis under Pheidole vafra, considering the similarity between the images of both types. After examining a large number of specimens, including the sympatric populations of Paraná state (see Franco & Feitosa (2018) for the records), as well the type series and its synonyms, we consider that P. vafra can be securely distinguished from P. idiota by the consistency of the diagnosis above. We revive P. idiota to species with P. laticornis as its junior synonym.
The current disjunct distribution of P. idiota is probably an artifact from the fact that several records for the species in Mesoamerica and southern South America have been attributed to P. laticornis and P. vafra, respectively.    Major worker. Head: head side, in dorsal view, broadly convex, with standing setae; head dorsal profile forming a broadly, continuous convexity, and vertexal margin shallowly emarginate. Hypostoma with median tooth vestigial; inner teeth distinct, narrow and slightly curved, converging apically, and widely spaced. Median clypeal carina absent; clypeal disc predominantly smooth, with few rugulae. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, surpassing midheight between eye and vertexal margin but not reaching the margin, with a combination of appressed setae and standing. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe with interspaces finely areolate. Vertexal surface, in frontal view, smooth. Mesosoma: pronotum dorsally finely areolate with humeral area reticulate-rugose, and with few sparse rugulae, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, broad and apically rounded. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting flexuous standing setae. First gastral tergum finely areolate; dorsally with flexuous standing setae, more than 1.5× the eye length. Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, not visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin emarginate; clypeal disc smooth. Space between eye and frontal carina strongly areolate, with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae finely areolate with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface finely areolate. Mesosoma: pronotal surface finely areolate, laterally with a smooth posterior patch, dorsally with few transverse rugulae anteriorly, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, with smoothly rounded side, dorsally smooth, and presenting flexuous standing setae. First gastral tergum finely areolate; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color reddish-brown.
Comments. Pheidole mapinguari is similar to P. longiseta Wilson. Majors and minors of P. mapinguari have the pronotal dorsum areolate with few rugulae anteriorly; and P. longiseta has the pronotal dorsum smooth. This is one of the most common species found in the Parque Estadual de Vila Velha, Ponta Grossa, Paraná. Specimens were mostly collected with pitfall traps in different phytophysiognomies, including open grasslands and shrublands.
Etymology. In apposition, from Brazilian folklore, the mapinguari is a large, black creature, with long hands, clawed nails, and long hair covering its body like a cloak. This name was chosen to honor Brazilian popular culture, in addition to making reference to the dark color and the long gastral pilosity of major workers, with more than 1.5× the eye length. Major worker. Head: head side, in dorsal view, slightly convex, nearly straight, with standing setae; head dorsal profile with a strong convexity just anterior to the vertexal region, and vertexal margin deeply emarginate. Hypostoma with median tooth distinct; inner teeth distinct and broad, in mid-distance from outer teeth. Median clypeal carina absent; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, not surpassing midheight between eye and vertexal margin, with standing setae. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae with curved rugulae extending from one frontal lobe to another and that gradually become transverse posteriorly, with interspaces finely areolate. Antennal scrobe, in frontal view, shallow and areolate, delimited posteriorly by a curved rugulae. Vertexal surface, in frontal view, transversally rugulose with few reticulate-rugose areas. Mesosoma: pronotum dorsally transversally rugulose, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, without an anterior concavity and with a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, apically narrow and rounded. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color light yellowish-brown.
Minor worker. Head: vertexal margin, in dorsal view, emarginate and rounded; occipital carina, in dorsal view, not visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina strongly areolate, with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae strongly areolate with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface strongly areolate. Mesosoma: pronotal surface strongly areolate, and promesonotal dorsum, in lateral view, presenting stiff standing setae. Mesonotal profile continuous, without a distinctly produced median area, and slightly inclining to the propodeum. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, trapezoidal, dorsally smooth, and presenting stiff standing setae. First gastral tergum smooth; dorsally with stiff standing setae, no more than 1.5× the eye length. Color light yellowish-brown.
Comments. Pheidole obapara is similar to Pheidole transversostriata Mayr. In both species, majors have curved rugulae in the space between the frontal carinae, which extend from one frontal lobe to the other, becoming gradually transversal posteriorly. Majors of P. obapara have the head dorsal profile anteriorly convex and depressed near the vertexal portion, and the interspaces among the face rugulae areolate; P. transversostriata has the dorsal profile broadly convex, and the interspaces smooth.
Specimens of P. obapara described here were collected in a leaflitter sample within a small fragment of semideciduous forest beside a stream in the Parque Estadual do Guartelá. See details about the type-locality under the description of P. abaticanga above.
Measurements Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc predominantly smooth, with few rugulae. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and interspaces finely areolate. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface finely areolate. Mesosoma: pronotal surface finely areolate, laterally with a smooth posterior patch, and promesonotal dorsum, in lateral view, presenting a combination of few flexuous standing and comparatively longer setae, with dense, shorter, thin and apically curved setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, trapezoidal, dorsally strongly areolate, and presenting flexuous standing setae. First gastral tergum finely areolate; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color light reddish-brown.
Comments. Similar species are P. cardinalis Wilson and P. susannae Forel. Majors of P. obscurior have the vertexal surface smooth, while in P. cardinalis it is sculptured. In addition, the pronotal dorsum of P. obscurior is strongly areolate, with few rugulae in majors, and with a combination of few standing flexuous and comparatively longer hairs, with dense, shorter, thin and apically curved hairs; while the pronotal surface of P. susannae is finely areolate in majors, bearing standing hairs only. Finally, sympatric populations between both species are unknown.
In previous studies (Forel 1886;Wilson, 2003), the authors recognized that differences between P. obscurior and P. susannae were mainly related to the color pattern. Longino (2009) synonymized P. obscurior under P. susannae considering that the color pattern is variable in this widespread species. However, P. obscurior presents a very distinct pilosity pattern and pronotal sculpture, which was not recognized by previous authors. The same pilosity pattern and the overall morphology of P. obscurior is shared with P. partita Mayr and P. incisa evoluta Borgmeier. We revive P. obscurior to species with P. partita and P. incisa evoluta as its junior synonyms. Pheidole triconstricta paranana Santschi, 1925Santschi, [1924: 13 (major worker Major worker. Head: head side, in dorsal view, broadly convex, with dense appressed setae; head dorsal profile forming a broadly, continuous convexity, and vertexal margin shallowly emarginate. Hypostoma with median tooth vestigial; inner teeth distinct, narrow and slightly curved, converging apically, and widely spaced. Median clypeal carina absent; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, surpassing midheight between eye and vertexal margin but not reaching the margin, with appressed setae. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae longitudinally rugulose, with interspaces finely areolate. Vertexal surface, in frontal view, smooth. Mesosoma: pronotum dorsally strongly areolate with a reticulate-rugose area anteriorly, and promesonotal dorsum, in lateral view, presenting sparse appressed setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin narrowly concave, and petiolar node, in lateral view, broad and apically rounded. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting stiff standing setae, two longer than the adjacent, and two shorter and appressed. First gastral tergum smooth; dorsally with a combination of stiff standing and appressed setae, no more than 1.5× the eye length. Color reddish-brown.
Measurements Minor worker. Head: vertexal margin, in dorsal view, emarginate and rounded; occipital carina, in dorsal view, not visible; postgenal bridge, in lateral view, areolate. Anterior clypeal margin emarginate; clypeal disc overlain with several rugulae with interspaces areolate. Space between eye and frontal carina strongly areolate, with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae strongly areolate with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface strongly areolate. Mesosoma: pronotal surface strongly areolate, dorsally with a reticulate-rugose patch anteriorly, and promesonotal dorsum, in lateral view, presenting sparse appressed setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection triangular; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, with smoothly rounded side, dorsally smooth, and presenting a combination of a pair of stiff standing setae, with shorter and appressed setae. First gastral tergum smooth; dorsally with a combination of stiff standing and appressed setae, no more than 1.5× the eye length. Color reddish-brown.
Comments. Similar species are P. geraesensis Santschi and P. triconstricta Forel. Majors of P. paranana have the vertexal lobe smooth and the anterior surface of head strongly sculptured with an areolaterugose patch between eye and frontal carina; and pronotal dorsum areolate with a reticulate-rugose patch anteriorly; P. geraesensis has the head almost entirely smooth; and P. triconstricta has the pronotal dorsum uniformly areolate throughout its distribution in Brazil (Mato Grosso do Sul, Minas Gerais, Paraná, Pernambuco, Rio Grande do Sul, Santa Catarina, São Paulo).
Minors of P. paranana have the clypeal disc overlain with several rugulae with interspaces areolate; P. geraesensis has the surface strongly areolate while in P. triconstricta this surface is smooth. This same key character occurs in sympatric populations of P. paranana and P. triconstricta in the state of Paraná (see Franco & Feitosa (2018) for the records).
This species was first described as a variety of P. triconstricta by Santschi (1925). The author described P. paranana in comparison with P. rosariensis Forel based on the denser head sculpture in P. paranana. The sculpture on the pronotal surface can also readily differentiate these species, while P. paranana has the dorsum reticulate rugose, P. rosariensis has the dorsum areolate. Wilson (2003) synonymized P. paranana under P. radoszkowskii, without further justification. The head sculpture morphologically distinct in both species, with  Major worker. Head: head side, in dorsal view, broadly convex, with appressed setae except in the vertexal margin with few standing setae; head dorsal profile forming a broadly, continuous convexity, and vertexal margin shallowly emarginate. Hypostoma with median tooth distinct; inner teeth distinct, narrow and straight, widely spaced. Median clypeal carina absent; clypeal disc smooth. Frontal lobe, in lateral view, projected and rounded. Scape, in frontal view, surpassing midheight between eye and vertexal margin but not reaching the margin, with a combination of appressed setae and standing. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally, and with a reticulate-rugose patch. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface, in frontal view, smooth with few piligerous punctures. Mesosoma: pronotum dorsally smooth, anteriorly with transverse, straight to slightly curved rugulae, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum. Metasoma: petiolar peduncle, in profile, with dorsal margin broadly concave, and petiolar node, in lateral view, broad and apically rounded. Postpetiole, in dorsal view, as wide as long and trapezoidal, and dorsally presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color light yellowish-brown.
Measurements Minor worker. Head: vertexal margin, in dorsal view, not emarginate and strongly rounded; occipital carina, in dorsal view, visible; postgenal bridge, in lateral view, smooth. Anterior clypeal margin not emarginate; clypeal disc smooth. Space between eye and frontal carina with sparse concentric, and a few longitudinal rugulae laterally. Space between frontal carinae smooth with few longitudinal rugulae extending posteriorly from frontal lobe. Vertexal surface smooth. Mesosoma: pronotal surface smooth, dorsally with few transverse, straight to slightly curved rugulae anteriorly, and promesonotal dorsum, in lateral view, presenting flexuous standing setae. Mesonotal profile sinuous, with an anterior concavity and a distinctly produced median area. Katepisternum strongly areolate. Propodeal projection spiniform, not as long as posterior face of propodeum; and propodeal dorsum finely to strongly areolate. Metasoma: postpetiole, in dorsal view, trapezoidal, dorsally smooth, and presenting flexuous standing setae. First gastral tergum smooth; dorsally with flexuous standing setae, no more than 1.5× the eye length. Color light yellowish-brown.
Comments. Pheidole strobeli resembles Pheidole nitidula Emery and Pheidole dione Forel. Majors of P. strobeli have the lateral margin of head with appressed hairs except in the vertexal margin with standing hairs, while P. dione has standing hairs that extend laterally, and P. nitidula has appressed hairs only. Minors of P. strobeli have the vertexal margin of the head strongly rounded, and mesosoma with stiff standing hairs; P. nitidula has the margin slightly rounded; and P. dione has the mesosoma with flexuous standing hairs.
Pheidole strobeli and P. nitidula occur sympatrically in the state of Paraná (see Franco & Feitosa (2018) for the records), presenting a diagnosis consistent with the described above. Regarding P. dione, only known from Corrientes and Jujuy in Argentina, it is not possible to confirm its sympatry with P. strobeli in a local scale in Argentina, considering that P. strobeli occurs in La Plata and Alta Gracia (Bruch, 1931) as well as Missiones and Buenos Aires (junior synonym distribution).
Based on the head shape and sculpture pattern, this species was considered a subspecies of P. nitidula by . Later, Wilson (2003) synonymized all the subspecies described for P. nitidula under this name. Pheidole strobeli can be recognized by the distinctly different head pilosity. We revive P. strobeli to species with three of the former subspecies of P. nitidula as its junior synonyms (Pheidole nitidula daguerrei Santschi, 1931, P. perversa Forel, 1908, and Pheidole perversa richteri Forel, 1909. Forel (1908) described Pheidole rufipilis divexa, a name subsequently synonymized under Pheidole rufipilis by Wilson (2003). The head sculpture in P. rufipilis (reticulate-rugose extending from the frontal lobe) is notably different from that of P. rufipilis divexa, (only a few rugulae extending from the frontal lobe). We consider P. rufipilis divexa a junior synonym of P. strobeli by the lack of any important morphological differences.