Cephalotes atratus
Creators: name: Oliveira, Aline Machado
name: Powell, Scott
name: Feitosa, Rodrigo Machado
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Cephalotes
Cephalotes atratus

description: Theatratus speciesgroup
(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 tothe genus Cephalotes, while the species C.oculatus, C.opacusandC.placidus belongedto thegenusEucryptocerus. 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 theatratus group. In the recent molecular phylogenies (Price et al., 2014, 2016, see their Fig. S 3) this relationship isinverse, and theatratus group is the sister-mostgroup in the topology (Fig. 54). Theatratus and hamulus groups share the absenceof 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 ofC. atratus have revealed that while this species certainly lacks morphologically differentiated soldiers and any pronounced allometric morphological scaling, the worker caste is highly variable insize 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)).
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. 17 a-b).
Brazilian species of atratus group
Cephalotes atratus (Linnaeus, 1758)
Obsolete combinations:Cryptocerus atratus, Formica atrata = Cephalotes atratus crassispina Santschi, 1920 = Cephalotes atratus erectus Kempf, 1951 = Cephalotes atratus nitidiventris Santschi, 1920 = Cephalotes atratus quadridens (De Geer, 1773) Obsolete combinations: Cephalotes quadridens, Formica quadridens = Cephalotes atratus rufiventris (Emery, 1894) Obsolete combination: Cryptocerus atratus rufiventris = Cephalotes dubitatus (Smith, 1853) Obsolete combination: Cryptocerus dubitatus = Cephalotes marginatus (Fabricius, 1804) new synonym Obsolete combination: Cryptocerus marginatus
Cephalotes oculatus (Spinola, 1851) Obsolete combination: Cryptocerus oculatus = Cephalotes aethiops (Smith, 1853) Obsolete combination: Cryptocerus aethiops
Cephalotes opacus Santschi, 1920 = Cephalotes abdominalis Santschi, 1929
Cephalotes placidus (Smith, 1860) Obsolete combination: Cryptocerus placidus = Cephalotes fenestralis (Smith, 1876) Obsoletecombination: Cryptocerus fenestralis.
Cephalotes serraticeps (Smith, 1858) Obsolete combination: Cryptocerus serraticeps
Note: The synapomorphiesso far accepted for C.marginatus include abundant suberect pilosity onthefirst 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 Andradeand 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 synonymizedunder 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.
After a careful examination of both species based on specimens from a wide range of distribution, we found great variation of the putative synapomorphic characters of C. marginatus among samples of C. atratus. Cephalotes marginatus is known only for the Amazonian arch in South America, while C. atratus is widely distributed from Mexico to north of Argentina and isone of the most commonly sampled species of Cephalotes.
Therefore, consideringmorphological and geographic evidence, we here propose the synonymy of C. marginatus under C. atratus.
Key to the identification of Brazilian species of the atratus group of Cephalotes based on workers and soldiers
(Figs. 17 a-g)
1 In lateral view, eyes positioned ventrally to the antennal scrobes (Fig. 17a)...................................................................................................................2
1’ In lateral view, eyes positioned posteriorly the antennal scrobes (Fig. 17b)..................................................................................................................3
2 Body shiny. In lateral view, postpetiolar dorsal spines shorter than the subpostpetiolar process (Fig. 17d)............................................. C.atratus
2’ Body opaque. In lateral view, postpetiolar dorsal spines longer than the subpostpetiolar process (Fig. 17e)…............................…. C. serraticeps
3 In dorso-oblique view, dorsal and lateral faces of mesonotum and propodeum meeting in a carina, not necessarily extending to the propodeal spines (Fig. 17f)............................................................... C. oculatus
3’ In dorso-oblique view, dorsal and lateral faces of mesonotum and propodeum continuous, without carina (Fig. 17g)....................................4
4 Propodeal spines shorter than the declivous face of propodeum (Fig. 17c).................................................................................................... C.opacus
4’ Propodeal spines longer than the declivous face of propodeum (Fig. 17d, e)............................................................................................ C. placidus
description: Published as part of Oliveira, Aline Machado, Powell, Scott & Feitosa, Rodrigo Machado, 2021, A taxonomic study of the Brazilian turtle ants (Formicidae: Myrmicinae: Cephalotes), pp. 1-52 in Revista Brasileira de Entomologia 65 (3) on pages 18-19, DOI: 10.1590/1806-9665-RBENT-2021-0028, http://zenodo.org/record/5512220