A taxonomic study of the Brazilian turtle ants (Formicidae: Myrmicinae: Cephalotes)

We revise the taxonomy of species of the ant genus Cephalotes occurring in Brazil. Sixty-four species are recognized, distributed in 14 species groups. Five species are described as new: Cephalotes gabicamacho new species, Cephalotes marycorn new species, and Cephalotes monicaulyssea new species (angustus group); Cephalotes liviaprado new species (fiebrigi group); and Cephalotes mariadeandrade new species (pinelii group). The soldier and gyne of C. adolphi (angustus group), and the gyne and male of C. nilpiei (pinelii group) are described for the first time. Cephalotes marginatus is synonymized under C. atratus. The bruchi and the laminatus species groups are synonymized under fiebrigi and pusillus groups, respectively. The new species group manni is proposed, derived from the basalis species group. Distribution maps for each species in Brazil are provided. In addition, we provide an illustrated morphological glossary for the genus and illustrated identification keys for workers and soldiers for species groups and for all Brazilian species. A R T I C L E I N F O Article history: Received 14 March 2021 Accepted 25 June 2021 Available online 13 September 2021 Associate Editor: Eduardo Almeida

according to our proposal (i.e. including the synonymies made here) and present the previous names for the synonymized groups in grey.
The terms for the basic external morphology of Cephalotes were compiled in an illustrated glossary (Fig. 1). The illustrations were made in Illustrator CS6 (Adobe) and Photoshop based on morphological schemes published by Kempf (1951), and Powell et al. (2020). The glossary terms follow De Andrade and Baroni Urbani (1999) and Wilson (1955). Terms for external morphology of alate forms follow Boudinot (2015) and for wing descriptions follow Yoshimura and Fisher (2011). Surface sculpturing follows Harris (1979). Following De Andrade and Baroni Urbani (1999), the reproductive females are here called as gynes; and the small individuals and the specialized large individuals are called workers and soldiers, respectively.
The soldier morphotypes are based on the shape of their heads, according to Powell et al. (2020). They are separated into four morphotypes: square, dome, disc, and dish. The square morphotype is defined by the frontal carinae extending posteriorly to form a continuous carina with the vertexal corners, which gives a square shape to the posterior region of head. The dome morphotype has the frontal carinae terminating over the eyes or posteriorly to the eyes, but not reaching the vertexal corners; while the vertex forms an angle with the dorsum of head, forming a dome. For the disc shape, the frontal carinae extend over the eyes, fusing posteriorly with the median-vertexal teeth, creating a unified dorsal disc shape, so that the vertex corners are in a lower plane than the dorsal disc; the medianvertexal teeth may be absent to strongly visible in the posterior margin of the disc. The dish morphotype is similar to the disc shape, but the frontal carinae are fused anteriorly with the frontal lobes, covering completely the mandible in frontal view. the atratus, basalis, clypeatus and manni groups. The dome morphotype occurs in the basalis, pusillus, and depressus groups. The disc morphotype occurs in the angustus, depressus, grandinosus, pinelii, umbraculatus, and fiebrigi groups. Finally, the dish morphotype occurs only in the pallens group. The soldier for the Brazilian representatives of the coffeae species group (Cephalotes trichophorus) and the solidus species group (Cephalotes solidus) are currently unknown.
Gyne (Figs. 1E, G): Head generally like the soldier; when the soldier caste is absent, gyne's head is similar to the workers but usually larger and more convex. Eyes comparatively large; ocelli always present. Scutum and scutellum weakly convex to flat. Forewings with Sc+R meeting the strongly pigmented stigma; R extends beyond the stigma, not reaching the external margin of wing; Rs meeting R posteriorly and forming a marginal cell with 2r-rs; M+Cu diverging in M and Cu, forming a discal cell with m-cu; M and Cu extends towards margin after discal cell, but spectral for most of its length, not reaching the wing margin; vein A extends beyond the cu-a, which is interrupted, not connecting M+Cu and A; claval furrow marked by a conspicuous notch; length of R, M, Cu, and A can be variable between specimens, but never reaching the margin of wing. Hindwing with R+Rs diverging in R1 and Rs; M+Cu diverging in Cu and rs-m+M; vein A extends beyond the cu-a, which is interrupted, not connecting M+Cu and A; length of R1, Rs, Cu, and A can be variable between specimens, but never reaching the wing margin; hamuli variable in number between species. Gaster longer than mesosoma, with four tergites visible, the first one occupying almost the total length of gaster.
In the morphological phylogeny by De Andrade and Baroni Urbani (1999, see their Fig. 24), this group was considered the sister group to the clade formed by the bruchi, fiebrigi and prodigiosus groups. The current phylogeny confirms the relationships between these groups (Fig. 54). The bruchi, fiebrigi and prodigiosus groups are recovered as monophyletic, but they render the angustus group paraphyletic, suggesting that all these groups might represent a single lineage (Fig. 54).
Morphologically, these groups share the declivous face of the propodeum continuous with its dorsal face, not meeting at a distinct propodeal angle, and with a variable number of spines, but differing by the anterior expansions of the gaster, which are a thin translucent lamella in the angustus group and a thick opaque lamella in bruchi, fiebrigi and prodigiosus groups. Although the phylogenetic data ( Fig. 54) suggests the angustus, bruchi, fiebrigi and prodigiosus groups could be synonymized, we decided to keep angustus as a valid group until a broader phylogeny, including additional species from all these groups, is available. The Argentinian prodigiosus group was not included in the present study, due to its absence in Brazil. The discussion about bruchi and fiebrigi groups is presented in the fiebrigi group section below.
Diagnosis: In workers, body with appressed hairs (Fig. 2h). Declivous face of propodeum continuous with dorsal face, not meeting at a distinct propodeal angle, with a variable number of spines (Fig. 2h). If only two pairs of spines are present on propodeum, the anterior one is never the longest, and the posterior one is never longer than the declivous face (Fig. 2h). First tergite of gaster with anterior lamellar expansions translucent (Fig. 2r). In soldiers, propodeum with variable number of spines, if there are two pairs, the anterior one is never longer than the posterior. Anterior gastral expansions with a translucent lamella, usually very thin (Fig. 3o). Key to the identification of Brazilian species of the angustus group of Cephalotes based on soldiers  1 Cephalic disc alveolate with suberect to erect hairs (Fig. 5a) with the apices of the lateral projections yellowish (Fig. 5j). In lateral view, the entire pleurae black to dark brown (Fig. 5h, i) (Fig. 5l)...........C. pallidicephalus 5' First gastral sternite without longitudinal rugosities (Fig. 5m), striae can be present laterally, but the middle of the sternite is smooth (Fig. 5n) (Fig. 5c). In dorsal view, pronotal carina weak and continuous ( Fig. 5e). In lateral view, posterior pair of denticles of propodeum gently bent dorsally with apices not curved anteriorly (Fig. 5i) 15 Holotype: BRAZIL, MT, Coxipó, ix.1900, typus (worker), -15.614986, -56.030674 [MSNG] [examined by images -AntWeb.org CASENT0904906].
Mandibles with appressed canaliculate hairs and erect simple hairs. Head, mesosoma, petiole, postpetiole and legs with appressed canaliculate hairs; frontal carinae with erect simple hairs. Gaster with appressed simple hairs; posterior portion of first sternite and edges of each tergite and sternite of gaster with erect simple hairs (Fig. 6b).
Head longer than wide . Mandibles with a strong longitudinal lateral angle. Clypeus with a pair of denticles (Fig. 6a). Dorsum of head disc shaped, slightly convex anteriorly (Fig. 6b). Frontal carinae crenulate anteriorly. Antennae with a three-segmented club. Roof of antennal scrobes with a lateral carinae and a posterior rounded projection. Lateroventral margins of head without carinae. Vertexal corners forming pointed projections separated of the dorsum cephalic disc (Fig. 6a, b).
In lateral view, pronotum ascending, with a transversal carina raised in a crest; pronotal crest not crenulate, with a median depression (Fig. 6c). In dorsal view, anterior margin of pronotum gently rounded, lateral margins with two pairs of denticles, the anterior one acute, the second one obtuse. Mesonotum and propodeum discontinuous and flat (Fig. 6b); mesonotum with a pair of blunt rounded denticles; propodeal groove impressed; dorsal and declivous faces of propodeum meeting in a distinct propodeal angle; in dorsal view, lateral margins of propodeum with a pair of median spines and obtuse denticles strongly bent dorsally, with the apices curved anteriorly (Fig. 6b). Femora not angulated dorsally, mid, and hind basitarsi not flattened, with subparallel dorsal and ventral faces.
Gaster elongate, with narrow anterior lamellar expansions (Fig. 6c). ( Gyne (first description): Body black; dorsum and lateral of head, lateral margins of pronotum and propodeum, central disc of anepisternum, and legs yellowish to ferruginous. First gastral tergite with an anterior and a posterior pair of yellowish spots, each one occupying more than one third of the first tergite length; posterior margins of each tergite and sternite yellowish (Fig. 7).
Pilosity of head as in the soldier. Mesoscutum, axillae and legs with some short erect hairs. First gastral tergite with sparse appressed simple hairs and some short erect hairs; first gastral sternite with short and long appressed simple hairs, and short erect hairs ( Fig. 7c) Head as in the soldier, but shorter (HL 1.80) (Fig. 7a).

Cephalotes gabicamacho new species
Worker measurements (   Worker description: Body black; frontal lobes, anterior spots on gastral tergite, apices of each segment of legs, and external face of tibiae yellowish (Fig. 8).
Head slightly wider than long (CI 95.1-120), dorsum slight convex (Fig. 8b). Mandibles with weakly developed lateral angle. Anterior margin of clypeus concave, without lateral denticle. Frontal carinae notched anteriorly to eyes, not bent dorsally over eyes (Fig. 8c). Antennae with three-segmented club. Lateroventral margins of head with posterior carinae extending posteriorly to eyes until vertexal corners. Vertexal corners with narrow, irregular lamellar expansion (Fig. 8a).  Mesosoma weakly convex in lateral view (Fig. 8b). In dorsal view, lateral margins of pronotum with three denticles, anterior two acute, posterior broad and sometimes bifid, almost forming fourth denticle; promesonotal groove absent (Fig. 8c). Mesonotum with a pair of short denticles. Propodeal groove impressed only laterally. Dorsal and declivous faces of propodeum continuous, not meeting in a distinct propodeal angle; lateral margins of propodeum with variable number of denticles (Fig. 8c). Femora not angulated dorsally, mid and hind basitarsi not flattened, with subparallel dorsal and ventral faces.
dorsal and declivous faces of propodeum meeting in a distinct propodeal angle (Fig. 9b); in dorsal view, lateral margins of propodeum with two pairs of projections, the anterior obtuse, the posterior acute, short, not curved anteriorly (Fig. 9b). Legs as in the worker.
In dorsal view, anterior margin of petiole slightly concave, laterally with a pair of spines curved backwards (Fig. 9c), dorsum with a pair of denticles (Fig. 9b), subpetiolar process broader anteriorly with an acute projection. Postpetiole wider and longer than petiole (Fig. 9c), with a pair of spines broader than spines of petiole and curved anteriorly, dorsum of postpetiole with a transversal elevation (Fig. 9c), subpostpetiolar process pronounced and compressed anteroposteriorly (Fig. 9b).
Gaster elongate, protruding anteriorly, without anterior lamellae or carinae (Fig. 9c). Soldier measurements (N=10): HL 1.  Soldier description: Body black; dorsum and lateral of head, apices of femora and external face of tibiae ferruginous. First gastral tergite with an anterior and a posterior pair of yellowish spots, each one occupying less than one third of the first tergite length; posterior margins of each tergite and sternite yellowish (Fig. 9).
Sculpturing as in the workers, except by propleura with striae not fully occupying the propleura, often on the lower part of the surface (Fig. 9b). Pilosity as in the workers, expect by gaster, which has appressed simple hairs (Fig. 9b, c).
In lateral view, pronotum ascending, with a transversal carina not raised in a crest; pronotal carina weakly developed, not crenulate, medially interrupted (Fig. 9c). In dorsal view, anterior margin of pronotum gently rounded, lateral margins subparallel, with a pair of anterior denticles. Mesonotum and propodeum discontinuous and flat (Fig. 9b); mesonotum with a pair of blunt rounded projections; propodeal groove well impressed;  HBW 0.12; Gyne description: Body black; head predominantly black, with the edges of dorsum and part of lateral face yellowish. Apices of femora, tarsi and external face of tibiae yellowish. First gastral tergite with an anterior and a posterior pair of yellowish spots, each one occupying about one fifth of the first tergite length; posterior margins of each tergite and sternite yellowish (Fig. 10).
Sculpturing and pilosity as in the soldiers, except by some erect hairs on mesoscutum and first tergite of gaster.
Petiole and postpetiole as in the soldier, but longer (Fig. 10b, c). Gaster elongated, protruding anteriorly, without anterior lamellae or carinae (Fig. 10c). Comments: This species differs from C. marycorn new species and C. monicaulyssea new species by the anterior portion of the first tergite of gaster, near of the postpetiolar insertion, not striate, while the two first species present short striae in this portion. Also, the first gastral tergite in C. gabicamacho is covered by appressed canaliculate hairs anteriorly and posteriorly, with a narrow central portion with appressed simple hairs, while C. marycorn new species has appressed canaliculate hairs only laterally on anterior portion and posterior edges of tergite, the central portion has sparse appressed simple hairs, and C. monicaulyssea new species has abundant appressed canaliculate hairs evenly distributed over the tergite. Cephalotes gabicamacho is the species C. sp. 3 in the molecular phylogenies of Price et al. (2014Price et al. ( , 2016, where it is placed as sister to the clade containing all other members of the angustus, fiebrigi and prodigious groups and thus contributes to the paraphyly of the angustus group (Fig. 54 Powell, 2008Powell, , 2016. In both cases, discovery occurred during a transect baiting approach, designed to maximize the discovery of Cephalotes forager recruitment (See Powell, 2008 for explanation). For each colony, all occupied nests were located using dense baiting within the home tree and visually tracking recruits back to their nest (following methods of Powell, 2009). Collections were made by sealing each nest in the early morning, when foragers are not active, and then removing the intact branches for dissection in the laboratory (following methods of Powell, 2009). The colonies occupied six and eleven nests, respectively.
The two colonies occupied different tree species, indicating no tree species preference. Nevertheless, nest entrance size was limited to sizes that closely fit a single soldier head (see data for C. sp3 in Powell, 2016), characteristic of species with a disc-headed soldier morphology (Powell et al., 2020).  Head wider than long (CI 111-123), dorsum slight convex (Fig. 11b).
Mandibles with a weakly developed lateral angle. Anterior margin of clypeus concave without a pair of denticles. Frontal carinae sinuous anterior to the eyes, not bent dorsally over the eyes (Fig. 11c). Antennae with a three-segmented club. Lateroventral margins of head with posterior carinae extending beyond the eyes until vertexal corners.
Mesosoma convex in lateral view (Fig. 11b). In dorsal view, lateral margins of pronotum with three denticles, the anterior two acute, the posterior broad and sometimes bifid, almost forming a fourth denticle; promesonotal groove absent (Fig. 11c). Mesonotum with a pair of short denticles. Propodeal groove impressed only laterally.
Dorsal and declivous faces of propodeum continuous, not meeting in a distinct propodeal angle; lateral margins of propodeum with variable number of denticles (Fig. 11c). Femora not angulated dorsally, mid and hind basitarsi not flattened, with subparallel dorsal and ventral faces.
In dorsal view, anterior margin of petiole concave, laterally with a pair of spines (Fig. 11c), petiolar dorsum with a pair of tiny denticles ( Fig. 11b), subpetiolar process broader anteriorly (Fig. 11b). Postpetiole wider and longer than petiole (Fig. 11c), with a pair of spines curved backwards, broader than the spines of petiole. Dorsum of postpetiole without carinae or denticles ( Fig. 11c), subpostpetiolar process pronounced and compressed anteroposteriorly (Fig. 11b). compared with other adjacent areas at different levels of regeneration. That area is a transition zone between three Brazilian biomes: Cerrado and Caatinga (Brazilian savanna), and Mata Atlântica (Brazilian Atlantic Forest). That locality is at almost 500 m a.s.l., with average annual temperature of 25ºC, and average annual precipitation of 818 mm, the rainiest months are November and April (Antoniazzi et al., 2019).
Workers were sampled in arboreal pitfalls which contained water and soap, on the canopy of two tree species, between 10 and 23 meters. Handroanthus chrysotrichus (Mart. Ex DC.) (Bignoniaceae), known as Golden trumpet tree (in Brazil, ipê), is found in open formation of Atlantic Forest, in dry forests, on top of hills, disturbed areas, associated with sandy soils, and is widely used as ornamental tree in urban areas (Bittencourt Junior and Moraes, 2010). This species presents extrafloral nectaries located on leaves (Gonzalez, 2013), which is highly attractive for ants, and Cephalotes genus are often sampled on these trees. Myracrodruon urundeuva Allemão (Anacardiaceae), known as Aroeira, has an ethnobotany role, as an important species for communities in northeastern Brazil, because of its use for medicinal, construction, fuel and forage purposes (Barros et al., 2016). However, precisely because of its importance for the community, this species was evaluated as one of the ten most priority for conservation, in comparation with almost 150 species with medicinal use endemic from Brazil (Campos and Albuquerque, 2020).
Distribution: Minas Gerais, Brazil. Etymology: This species is named, in apposition, after Mary Lynne Corn, an early pioneer in the study of Cephalotes ants. Her dissertation on Cephalotes atratus from 1976 was groundbreaking in its detailed examination of Cephalotes biology. Her work represents as an essential contribution to our knowledge of this remarkable group of ants and stands as an inspiration to all students of Cephalotes biology. Diagnosis: A member of angustus species group. Workers with incomplete striae on the propleura. First gastral tergite with short striae near of postpetiole insertion, and with evenly distributed appressed canaliculate hairs, without simple hairs (Fig. 12c). In soldiers, in dorsal view, lateral margins of pronotum convex and converging posteriorly (Fig. 13c). Propodeal groove weakly impressed, marked on the sides but absent medially (Fig. 13c). First sternite of the gaster with striae laterally (Fig. 5n).
Comments: This species differs from C. gabicamacho and C. monicaulyssea new species by the anterior portion of the first tergite of gaster, near the postpetiolar insertion, which presents short striae and sparse appressed simple hairs, while in C. gabicamacho this portion is not striate and covered by abundant, appressed canaliculate hairs, and in C. monicaulyssea new species this portion has short striae, but the hairs are canaliculate and evenly distributed.
Natural history: The only series of this species known so far was collected at the Parque Estadual da Mata Seca, an area of successional stages where had no anthropogenic intervention for at least 60 years. There are trees exceeding 20 m in height and fewer new trees and lianas when  with some short striae in the anterior portion, near to the postpetiolar insertion; first sternite medially smooth and shiny, laterally striatemicroalveolate (Fig. 12b, c).
Head wider than long (CI 105-117), dorsum slightly convex (Fig. 12b). Mandibles with a weakly developed lateral angle. Anterior margin of clypeus concave with a pair of denticles. Frontal carinae sinuous to notched anteriorly the eyes, in frontal view (Fig. 12a), gently bent dorsally over the eyes, in posterior view (Fig. 12c). Antennae with three-segmented club. Lateroventral margins of head with posterior carinae extending posteriorly to vertexal corners, in lateral view. Vertexal corners with a narrow irregular lamellar expansion (Fig. 12a).
Mesosoma convex in lateral view (Fig. 12b). In dorsal view, lateral margins of pronotum with variable number of denticles, often three, the posterior one bifurcate or trifurcate; promesonotal groove absent (Fig. 12c). Mesonotum with a pair of short denticles. Propodeal groove impressed only laterally. Dorsal and declivous faces of propodeum continuous, not meeting in a distinct propodeal angle; lateral margins of propodeum with a pair of anterior denticles and row of minor denticles posteriorly near petiolar insertion (Fig. 12c). Femora not angulated dorsally, mid and hind basitarsi not flattened, with subparallel dorsal and ventral faces.
In dorsal view, anterior margin of petiole concave; lateral margin with posteriorly curved spine, dorsum with a pair of denticles, subpetiolar process in lateral view with an anterior angle (Fig. 12b). Postpetiole wider and longer than petiole (Fig. 12c), with lateral spines broader than petiolar spines and curved backwards, dorsum without carinae or denticles, subpostpetiolar process in lateral view pronounced and compressed anteroposteriorly (Fig. 12b).
Gaster suboval, deeply concave anteromedially with broad anterior anterolateral lamellar expansions, not extending posteriorly as a carina (Fig. 12c).    Soldier description: Body mostly black; anterolateral face and edges of the dorsum of head ferruginous, only central portion of the cephalic disc black. Lateral margins of pronotum with ferruginous spots. Apices of femora, tarsi and dorsal face of tibiae ferruginous. First gastral tergite with an anterior and a posterior pair of weakly yellowish spots, each one occupying less than one fourth of the first tergite length (Fig. 13).
Sculpturing and pilosity as in workers, except by the presence of appressed simple hairs on the first tergite of gaster, and the erect short hairs on the posterior edge of the tergites and sternites (Fig. 13b).
Head slightly wider than longer (CI 106-111). Mandibles with strong longitudinal lateral angle. Clypeus slightly concave with a pair of denticles (Fig. 13a). Dorsum of head disc shaped and concave anteriorly. Frontal carinae crenulate anteriorly. Antennal club ill-defined. Roof of antennal scrobe with lateral carinae and posterior denticle. Lateroventral margin of head without carina. Vertexal corners forming pointed projections separated of the dorsum cephalic disc (Fig. 13a, b).
In lateral view, pronotum ascending, with a transversal carina not raised in a crest; pronotal carinae weakly developed, not crenulate ( Fig. 13c). In dorsal view, anterior margin of pronotum gently rounded, lateral margins slightly concave and converging posteriorly, with anterolateral denticle. Mesonotum and propodeum continuous and flat (Fig. 13b); mesonotum with blunt rounded posterolateral projection; propodeal groove impressed only laterally; dorsal and declivous faces of propodeum meeting in a distinct propodeal angle; in dorsal view, lateral margin of propodeum with three projections, the anterior one obtuse, the median one broad and acute, the posterior one acute and long, with the apices curved anteriorly. Legs as in worker.
Petiole and postpetiole as in worker, except for the presence of a transverse elevation of dorsum of postpetiole.
C. gabicamacho by the first tergite of gaster with abundant appressed canaliculate hairs evenly distributed. While C. gabicamacho has appressed canaliculate hairs anteriorly and posteriorly, with a narrow central portion with appressed simple hairs, and C. marycorn has appressed canaliculate hairs only laterally of anterior portion and posterior edge of tergite, the central portion has sparse appressed simple hairs.
Natural history: This species was collected at the same locality in three different years (2017, 2018 and 2019), at Serra do Cipó, the southern part of the mountainous system of Serra do Espinhaço, Minas Gerais state. The local climate is well-defined, with fresh and rainy summers and dry season, the annual average temperature is 18°C, and the annual average precipitation is 1,600 mm.
The dominant vegetation of the region is the Cerrado, a Neotropical savanna (Callisto et al., 2001). The specimens were only collected in altitudes above 1200m, in a phytophysiognomy know as Campo Rupestre, despite targeted Cephalotes sampling at nearby locations at 1000m and 800m. Campo Rupestre is characterized by occurring exclusively on top of mountains, above 900m, with rocky outcrops, shallow soils, and vegetation herbaceous-shrubs (Vasconcelos, 2011). It has been inferred that 30% of the taxa occurring in campos rupestres are restricted to this formation (Lousada et al., 2011).     Gyne description: Color, sculpturing and pilosity as in soldiers, except for some erect hairs on mesoscutum (Fig. 14).
Petiole and postpetiole as in the soldier, but longer (Figs. 14b, c).
Comments: This species is very similar to C. angustus, differing by the presence of striae on the first sternite of gaster and the gastral anterior lamellae not extending posteriorly as a carina.
Cephalotes monicaulyssea differs from new species C. marycorn and Figure 16 Distribution maps of angustus group in Brazil "part 2". White stars: type locality. Black circles: material examined. Red squares: new records. Blue triangles: records not examined from literature. (Literature source : 13, 14, 40, 47 48, 49, 56, 64). (Figs. 17,18) The atratus group was proposed for the first time by De Andrade and Baroni Urbani (1999). Before that, the species C. alfaroi, C. atratus and C. serraticeps belonged to the genus Cephalotes, while the species C. oculatus, C. opacus and C. placidus belonged to the genus Eucryptocerus. The species C. alfaroi was not included in this study since it does not occur in Brazil. In the morphological phylogeny by De Andrade and Baroni Urbani (1999, see their Fig. 24), the Central American hamulus group is the sister group of all other groups in Cephalotes, followed by the atratus group. In the recent molecular phylogenies (Price et al., 2014) this relationship is inverse, and the atratus group is the sister-most group in the topology (Fig. 54). The atratus and hamulus groups share the absence of the soldier caste in some species of atratus and all species of hamulus. The species C. alfaroi, C. opacus, and C. serraticeps have known soldiers, while the species C. atratus, C. oculatus, and C. placidus do not have soldiers, as far as we know. Of these, large colony series of C. atratus have revealed that while this species certainly lacks morphologically differentiated soldiers and any pronounced allometric morphological scaling, the worker caste is highly variable in size within mature colonies (Corn, 1980). This species is broadly distributed, and frequently collected (Fig. 18), and is the second most common species of the genus in Brazil, after C. pusillus. The other species without soldiers are not highly variable in size, and their distribution is more restricted (Amazon/Atlantic Forest (Fig. 18)).

The atratus species group
Diagnosis: In workers and soldiers vertexal corners of head, in lateral view, with a pair of spines (Fig. 2a). Pronotum always with a pair of long dorsolateral spines; a pair of short median spines can be present in some species, sometimes weakly developed. Postoccipital carinae with ventral expansions (Fig. 17a-b). Obsolete combination: Cryptocerus placidus = Cephalotes fenestralis (Smith, 1876) Obsolete combination: Cryptocerus fenestralis. Cephalotes serraticeps (Smith, 1858) Obsolete combination: Cryptocerus serraticeps Note: The synapomorphies so far accepted for C. marginatus include abundant suberect pilosity on the first gastral sternite, instead of sparse as in C. atratus, and median pronotal spines at least with ¼ of the size of the dorsolateral ones, instead of minute or absent as in C. atratus (De Andrade and Baroni Urbani, 1999).
Cephalotes marginatus was described by Fabricius (1804), synonymized under C. atratus by Klug (1824), and then revived by De Andrade and Baroni Urbani (1999). In the latter study, the species C. decemspinosus Santschi, 1920 was synonymized under C. marginatus. Kempf (1951) has already argued that the status of this species should be changed, as there were individuals in series of C. atratus with the same characteristics of C. decemspinosus.

Diagnosis:
In workers and soldiers, margin of pronotum with lamellar expansions, without denticles or spines. Declivous face of propodeum and anterior face of petiole truncate (Fig. 19c-d). Hind femora with a median projection dorsally (Fig. 2j). In dorsal view, the anterior lamellar expansions of the gaster with apices distally directed in relation to the postpetiole insertion.

Cephalotes cordiae (Stitz, 1913)
Obsolete combination: Cryptocerus cordiae Cephalotes ramiphilus (Forel, 1904) Obsolete combination: Cryptocerus complanatus ramiphilus   The clypeatus species group (Figs. 22,23) The clypeatus group was proposed by De Andrade and Baroni Urbani (1999) to include three species from the former genus Zacryptocerus. The authors stated that the diagnostic characters of this group (triangular vertexal angles, and pronotal and propodeal spines fused by lamella) could indeed be enough to keep them in a separated genus from Cephalotes. However, this would render Cephalotes paraphyletic since the phylogeny shows this group as a clade within the genus Cephalotes (Fig. 54). All species in this group are exclusively South American.

Diagnosis:
In workers, declivous and dorsal faces of propodeum continuous, not meeting at a distinct propodeal angle. Propodeum with two pairs of denticles, the posterior one longer than the anterior one, but never longer than the declivous face. Postpetiole wider than petiole. Gaster with a narrow anterior lamella; first tergite with erect hairs; first sternite with longitudinal striae.

5' In frontal view, distance between the anterior and posterior margins
of the dorsum of head shorter than or equal to the distance between the eyes (Fig. 28b) (Fig. 28k) In frontal view, the long hairs posterior to the eyes are as long as the length eyes (Fig. 28d). Dorsum of head with comparatively small foveae, and canaliculate suberect hairs present only anteriorly (Fig. 28d) Diagnosis: A member of fiebrigi species group. Workers with long flexuous hairs (Fig. 29b). In frontal view, frontal carinae with a lateral projection anteriorly to the eyes (Fig. 27d). In soldier, first gastral tergite, with erect hairs, few and sparse appressed hairs can be present (Fig. 30).
Mandibles, dorsum of head, mesosoma, petiole and postpetiole foveate-rugose, space between foveae microalveolate (Fig. 29a, c). Mesosoma strongly convex in lateral view (Fig. 29b). In dorsal view, lateral margins of pronotum with three pairs of denticles, the anterior one acute and the two posterior obtuse; promesonotal groove absent (Fig. 29c). Mesonotum with a pair of short blunt denticles. Propodeal groove absent. Dorsal and declivous faces of propodeum continuous, not meeting in a distinct propodeal angle; lateral margins of propodeum with an anterior pair of short blunt denticles, followed by a pair of large and acute and a row of minor acute denticles near petiolar insertion, the number and degree of development of the denticles vary even between sides of the same specimen (Fig. 29c). Femora not angulated dorsally, mid and hind basitarsi not flattened, with subparallel dorsal and ventral faces.
Gaster oval, with a pair of well-developed thick opaque anterior expansions, not extending posteriorly forming a lateral lamella (Fig. 29c).   Soldier description: Body black; frontal lobes and apices of each segment of legs brownish to ferruginous (Fig. 30).
In lateral view, pronotum ascending, pronotal carina weakly marked and crenulate (Fig. 30b, c). In dorsal view, anterior margin of pronotum rounded, lateral margins with two pairs of denticles, the anteriorly one acute, the posterior one obtuse. Mesonotum and propodeum continuous and flat (Fig. 30b); mesonotum with a pair of blunt rounded projections; propodeal groove impressed; dorsal and declivous faces of propodeum meeting in a distinct propodeal angle, in dorsal view, lateral margins of propodeum with a pair of median obtuse denticles and a pair of well-developed spines, directed upwards (Fig. 30c). Legs as in the worker.
Natural history: Cephalotes liviaprado was collected in the Chaco formation. This ecosystem is part of the diagonal zone of seasonallydry open areas in South America. The so called "Gran Chaco" occurs in northern Argentina, western Paraguay, southeastern Bolivia, and the extreme western of Mato Grosso do Sul state in Brazil, exclusively in the city Porto Murtinho (Prado, 1993). The vegetation is represented by shrub, deciduous, and spinous vegetation, usually associated with saline soils (Silva et al., 2000). The Chaco extends from tropical latitudes (18° S) to subtropical zones (31° S), and the climate is marked by strong seasonality, with more severe summers, and winter frosts (Werneck, 2011). The Brazilian Chaco (Chaco sensu stricto) occupy a subregion of the Pantanal biome, and extends over about 7% of its territory (Silva et al., 2000). Despite its relatively small area in Brazil, this formation is considered of high priority for conservation (Tálamo and Caziani, 2003). However, the anthropic use in this area for agriculture and logging has been a serious threat for the maintenance of this ecosystem and the species that live in it (Pott and Pott, 2003).
Cephalotes liviaprado was collected in the thorns of the tree species Prosopis ruscifolia Griseb. (Fabacea: Mimosoideae), which is endemic to the Chaco (Fuster, 2012). This tree species is adapted to edaphic conditions, and marshy and salty environments, and is known as a pioneer and colonizer plant. It has large stem thorns (10 to 30 length and 2 cm diameter) and extrafloral nectaries (Vilela and Palacios, 1997) which favors nesting by arboreal ants, like Cephalotes (Fuster, 2012). So far, C. liviaprado has been collected only in this location exclusively associated with P. ruscifolia. If these species are intimately related and endemic of Chaco, they must be extremely threatened.
Distribution: Mato Grosso do Sul, Brazil. Etymology: The specific epithet, in apposition, is in honor of Livia Pires do Prado, a Brazilian myrmecologist and passionate historian of science, for her contributions to the taxonomy of Brazilian ants and the rescue of extremely relevant names and facts involving the history of Brazilian entomologists of all generations. Her work and dedication to science stands as an inspiration to female myrmecologists and students of the history of science alike.  Comments: This species is similar to C. pilosus but can be distinguished by the frontal carinae notched anterior to the eyes, forming a lateral angle and by the less abundant and shorter pilosity; in C. pilosus the frontal carinae is evenly straight to slightly depressed anterior to the eyes, but never forming a lateral angle and the pilosity is long and dense.
Grandinosus and pinelii are sister groups in the morphological phylogeny (De Andrade and Baroni Urbani, 1999, see their Fig. 24), sharing many characters, as the strongly dorsoventrally flattened body, dorsum of mesosoma continuous, and lamellar expansions on mesosoma, petiole, postpetiole and gaster. Both groups differ only by the presence of a lamella on hind femora and the lighter color in grandinosus.
In the molecular phylogeny (Price et al., 2016, see their Fig. S3), the grandinosus and pinelii groups are recovered as paraphyletic. Cephalotes foliaceus (grandinosus group) is sister to C. sp. 2 (here described as C. mariadeandrade new species, of the pinelii group). The clade formed by the other species of the grandinosus group (C. grandinosus¸ C. klugi, C. persimplex and C. persimilis) is the sister group of a clade formed by some of the previously designated species of the pinelii group (C. maculatus, C. liepini, C. nilpiei, C. pinelii and C. pileini) (Fig. 54).
The morphological similarities and phylogenetic association between species of the pinelii and grandinosus groups suggest they likely represent a single evolutionary lineage (Fig. 54). Even being paraphyletic, these groups are morphologically diagnosable, thus we kept it separate here, since we have not examined the species occurring outside Brazil in this study, what would help to better understand the relationships and limits between these species and redefine these groups.
Diagnosis: In workers, body strongly flattened dorsoventrally. In dorsal view, dorsum of mesosoma continuous, with lamellar lateral expansions. In workers and soldiers, hind femora with a ventral and/or

Key to the identification of Brazilian species of the grandinosus group of Cephalotes based on soldiers (Figs. 34a-f)
Note: Cephalotes klugi is known only for the gyne.
Cephalotes manni differs from the species in the basalis group by many characters. All species in the basalis group have lamellar expansions on the margins of the pronotum, in dorsal view, while C. manni has three pairs of dentiform projections. The declivous face of propodeum and anterior face of petiole are flat in the species of the basalis group, and concave in C. manni. The species in the basalis group have a median dorsal projection on the hind femora, which is absent in C. manni. In dorsal view, the anterior lamellar expansions of the gaster of species of basalis group have their apices distant to the postpetiole insertion, while in C. manni the apices of the lamellar expansions are near the postpetiolar insertion.
In the morphological phylogeny, C. manni is the sister species of the rest of the basalis group (De Andrade and Baroni Urbani, 1999, see their Fig. 24), but this species was not included in the molecular phylogeny (Price et al., 2016), which could corroborate its phylogenetic position.
In Brazil, C. manni occurs only in the North Region, in the Amazon Forest, like some species of basalis group, but not in sympatry with other members of this group.
Diagnosis: In workers, in lateral view, eyes occupying more than 1/3 of the length of the head. In dorsal view, margin of pronotum with three pairs of lamellar dentiform projections. Fore femora very increased in size relative to the mid and hind femora. Lateral margins of the declivous face with broad lamellar expansion extending to the posterior dorsal spines of propodeum towards to petiolar insertion (Fig. 2m). In soldiers, mesonotal spines curved dorsally. Posterior femora without projections, metatibiae never marginated.
The pallens species group (Figs. 37,38,39) The pallens group was proposed by De Andrade and Baroni Urbani (1999) with 10 species. It includes C. jamaicensis, C. pallens, C. patellaris, C. porrasi, C. varians and the new species described by De Andrade in De Andrade and Baroni Urbani (1999) (C. decolor, C. decoloratus, C. pallidoides, C. pallidus, and C. pellans). Of these species, only five occur in Brazil -C. pallens, C. pallidoides, C. pallidus, C. patellaris, and C. pellans. This is the most morphologically homogeneous group of Cephalotes. Therefore, is the most challenging group regarding species delimitation, especially if the workers are the only caste available. In the identification key for workers, De Andrade and Baroni Urbani (1999) provided a note about this difficulty and recommended verification of the soldier's identification key before applying a name.
In addition to the characters employed by De Andrade and Baroni Urbani (1999), here we provide an illustrated identification key for workers based on characters as the shape of frontal carinae in relation to eyes, and sculpture patterns on pleura. Regarding the identification key for soldiers, the most informative characters are the sculpture and pilosity patterns.
The pallens group is sister to the clade formed by the grandinosus and pinelii groups (Fig. 54), with all of these groups sharing a worker body shape that is strongly flattened dorsoventrally.
Diagnosis: In worker, body strongly flattened dorsoventrally. Body color reddish brown. In frontal view, vertexal corner extending laterally overhanging the eye (Fig. 2d). In soldier, in frontal view, cephalic dorsum completely covering the mandibles to form a "dish" head type (Fig. 38).
Head slightly wider than long , dorsum very convex medially, with two longitudinal elevations posteriorly, and depressions in front of eyes. Mandibles with a weakly developed lateral angle. Anterior margin of clypeus concave without denticles. Frontal carinae strait anteriorly of eyes; pointed upwards over eyes (Fig. 42c). Antennae with a two-segmented club. In dorsal view, petiole compressed anteroposteriorly, anterior margin with a discrete median concavity, with lateral lamellar expansions broader posteriorly, dorsally with pair of obtuse denticles, subpetiolar process broader and rounded anteriorly (Fig. 42b). Postpetiole narrower than petiole ( Fig. 42b), with lateral lamellar expansions, dorsum of postpetiole with a transverse elevation (Fig. 42c), subpostpetiolar process pronounced and compressed anteroposteriorly (Fig. 42b).
Gaster suboval, deeply concave anteromedially, with broad anterior lamellar expansions, not extending posteriorly in a carina (Fig. 42c).   Soldier description: Body dark brown; frontal lobes and lamellar expansions of pronotum, propodeum, petiole, postpetiole and gaster yellowish to translucent. Gaster dark brown with an anterior and a posterior pair of small yellowish spots (Fig. 43).
Legs, and gaster as in the workers (Fig. 43c).
Pilosity as in the workers, except by anterior portion of head with erect clavate hairs, dorsum of head with canaliculate hairs on tubercles, and dorsum of pronotum with sparse canaliculate hairs.
Head slightly wider than longer . Mandibles with a strong longitudinal lateral angle. Clypeus without denticles (Fig. 43a).
Dorsum of head disc shaped and convex, strongly tuberculate with a posteriorly pair of distinct larger tubercle (Fig. 43a, b). Frontal carinae crenulate laterally. Antennae with a two-segmented club. Roof of antennal scrobes with a lateral crenulate carinae. Lateroventral margins of head with a posterior carinae extending beyond the eyes until vertexal corners. Vertexal corners forming a pair of broad projections pointed upwards (Fig. 43b, c).
Mesonotum, propodeum, legs, petiole, postpetiole and gaster as in workers; except by the narrow lamellar expansions on the declivous face of propodeum (Fig. 43c). Gyne measurements (N=4): HL 1.  Gyne description: Body black; frontal lobes anteriorly translucent; dorsum of head, pronotum and legs brownish to yellowish. First gastral tergite with an anterior and a posterior pair of whitish spots, each one occupying less than one third of the first tergite length; posterior margins of each tergite and sternite yellowish (Fig. 44).
Pilosity as in the soldier, but hairs more abundant on propodeum.
Head as in the soldier (CI 106-110). The two posterior ocelli positioned in the posterior tubercular elevations (Fig. 44a).
In dorsal view, anterior margin of pronotum slightly rounded, narrower than in the soldiers, lateral margins with a pair of denticles pointed forwards, pronotal carina weakly developed, crenulate, medially interrupted (Fig. 44c).
Body with long and flexuous hairs, more abundant on mandibles, dorsum of head and mesosoma. Legs with long hairs only in the internal face of coxae and femur. Hairs shorter on gaster (Fig. 45b).
Head wider than longer (CI 130-138), broader posteriorly. Mandibles with one apical tooth, lateral angle weakly developed to absent. Clypeus with a median elevation, posterior margin rounded. Frontal carinae not extending posteriorly. The central portion of head strongly elevated. Eyes occupying more than half of head length (Fig. 45a). Ocelli positioned at a central elevation. Antenna as the genus description.
In dorsal view, petiole and postpetiole concave anteriorly, with lateral acute projections near to the anterior margin, without dorsal projections, subpetiolar and subpostpetiolar process weakly developed (Fig. 45c).
First tergite of gaster as broad as mesosoma, occupying half or less than the total length of gaster (Fig. 45b), without anterior projection (Fig. 45c).
Comments: This species differs from others in pinelii group by the presence of two longitudinal elevations on the posterior portion of head dorsum, lack of lateral lamellar expansions on dorsum of propodeum declivous face, and body robust, not strongly flattened dorsoventrally. Cephalotes mariadeadrade is the species C. sp. 2 in the molecular phylogenies by Price et al. (2014Price et al. ( , 2016, recovered at the base of the paraphyletic grouping formed by the grandinosus and pinelii groups (Fig. 54).
Natural history: A complete colony of C. mariadeandrade species was collected in Uberlândia (Minas Gerais) in a region of Neotropical savanna (biome Cerrado). The colony occupied four individual nests on the same tree occupied by an aggressive species of Crematogaster of similar size and dark brown color. Workers of C. mariadeandrade were observed running in the well-established foraging trails of the Crematogaster species, which could indicate a parasitic relation between these species, like that described to Cephalotes specularis and Crematogaster ampla Forel, 1912. In that case, C. specularis mimics the behavior and posture of their host C. ampla, so they can use the foraging networks and exploit food resources of their hyperaggressive host without being notice . Cephalotes mariadeandrade workers also moved like the Crematogaster workers whose trails they integrated with and they were similarly undetected by the Crematogaster foragers.
Distribution: Minas Gerais, Brazil. Etymology: The specific epithet, in apposition, is in honor of Maria de Andrade, a Brazilian taxonomist, who dedicated years of work conducting the most comprehensive study of the genus Cephalotes to date. This seminal contribution provided the basis for the development of the present study and the foundation upon which all current Cephalotes research is based. head disc shaped, slightly concave anteriorly. Frontal carinae crenulate anteriorly. Antennae with a three-segmented club. Roof of antennal scrobes with lateral carinae without projections. Lateroventral margins of head without carinae. Vertexal corners forming a pair of broad projections (Fig. 46c).   OI 22.6; Worker and soldier descriptions can be found in De Andrade and Baroni Urbani, 1999, page 381. Gyne (first description): Body black to brownish; frontal lobes, lateral margins of pronotum and propodeum, and legs brownish to ferruginous. First gastral tergite with an anterior and a posterior pair of yellowish spots, each one occupying more than one third of the first tergite length (Fig. 46).
Male (first description): Body predominantly black; apices of femora, tibiae and tarsi, and edges of each sternite and tergite brownish to yellowish (Fig. 47b).
Head wider than longer (CI 153-166), broader posteriorly. Mandibles with one to three apical teeth, lateral angle absent (Fig. 47a). Clypeus with a median elevation, posterior margin rounded. Frontal carinae not extending posteriorly. The central portion of head slightly elevated. Eyes occupying more than half of head length (Fig. 47a). Ocelli positioned at a central elevation. Antenna as the genus description.
In dorsal view, petiole and postpetiole wider than longer, laterally rounded, without lateral or dorsal projections, subpetiolar and subpostpetiolar process weakly developed (Fig. 47c).
Gaster as long as mesosoma. The first tergite narrower than mesosoma and occupying half or less than the total length of gaster (Fig. 47b), without anterior projection. (Fig. 47c). (Figs. 49,50,51) The spinosus group by Kempf (1951) comprised the De Andrade and Baroni Urbani's laminatus and pusillus groups, which share the following characters: anterolateral pronotum angulate, separate from the pronotal expansions; propodeum with two pairs of spines or denticles, with the posterior one longer than anterior; dorsal and declivous faces of propodeum differentiated, meeting in a distinct propodeal angle; gaster with distinct anterolateral lamellate borders.

The pusillus species group
Despite the shared characters, De Andrade and Baroni Urbani (1999) separated the former Kempf's spinosus group in laminatus and pusillus groups. The synapomorphy for the pusillus group is the absence of fine reticulation on the cephalic ventral face and the absence of angulate hind femora. However, both characters are the same in the laminatus group, which includes the remaining species of Kempf's spinosus group and C. duckei, that had been considered an isolated species by Kempf (1951). The synapomorphy for laminatus group, according to De Andrade and Baroni Urbani (1999), is the vertexal corners with a truncate lamella, but this character is also present in other groups, including the pusillus group. The characters used by Kempf (1951) to join the members of the pusillus and laminatus groups within the spinosus group seem more robust. Concordantly, the molecular phylogeny by Price et al. (2016, see their Fig. S3) recovered C. pusillus and C. columbicus within the laminatus group, rendering the laminatus group paraphyletic. Based on this molecular and morphological evidence, we here recognize the members of pusillus and laminatus groups as a unique group, under the name "pusillus", since C. pusillus is the oldest species in the group (Fig. 54).
Most species in this group occur in Brazil, except for C. christopherseni, known so far only from Colombia, Venezuela, and Panama, and for C. columbicus, known from Colombia and Venezuela.
The angustus and solidus groups share the dorsal and declivous faces of propodeum continuous, not meeting in a distinct propodeal angle, but differ by the mesonotum and propodeum unarmed in solidus, while in angustus there is a pair of denticles on the mesonotum and a series of denticles on propodeum.
In the morphological phylogeny by De Andrade and Baroni Urbani (1999, see their Fig. 24), C. solidus is not related with the angustus group species, being more closely related to the pusillus group. Nevertheless, most of the characters used in their morphological analysis are based on soldiers. However, C. solidus is a rarely collected species, with only five workers known so far from northern Brazil (Fig. 52). This species was not included in the molecular phylogeny (Price et al., 2016).

Brazilian species of solidus group
Cephalotes solidus (Kempf, 1974) Obsolete combination: Zacryptocerus solidus separated from them. Kempf's proposal was corroborated by the morphological and molecular phylogenies (De Andrade and Baroni-Urbani, 1999, see their Fig. 24;Price et al., 2014, both phylogenies recover this species as a monophyletic lineage. The recent molecular phylogenies by Price et al. (2014Price et al. ( , 2016 recovered umbraculatus as a sister group of the clade formed by the angustus, fiebrigi and prodigiosus groups (Fig. 54). Cephalotes umbraculatus is broadly distributed in Central America and north of South America.

Diagnosis:
In workers, body with appressed hairs. Dorsal and declivous face of propodeum continuous, not meeting in a distinct propodeal angle, with a variable number of spines. Dorsum of petiole without denticles. Gaster yellowish with a cross-shaped dark macula, anteriorly with lamellar expansions (Fig. 2p). In soldiers, in dorsal view, pronotum crest with pointed edges (Fig. 3f).
He discussed the position of the species, which shares characters with the angustus and pinelii groups, but is different enough to be

Figure 54
The maximum clade credibility tree from phylogenetic analyses performed by Price et al. (2016) based on morphological and molecular data. The tree has been trimmed to include only those species known from Brazil. The labels for the species groups follow our proposals, including the synonymies, and the previous names for the synonymized groups are shown in grey.