Camponotus

Hita Garcia, Wiesel and Fischer (2013) - Camponotus is an extremely large and complex, globally distributed genus. At present, more than 1000 species and nearly 500 subspecies belonging to 45 subgenera are described (Bolton, 2012) and it could well be the largest ant genus of all. The enormous species richness, high levels of intraspecific and geographic variation and polymorphism render the taxonomy of Camponotus one of the most complex and difficult. Revisionary studies on Camponotus are generally confined to species groups and/or small geographical regions (e.g. Robertson & Zachariades, 1997; Snelling, 2006; McArthur, 2007; Shattuck & Janda, 2009). These ants live in a variety of habitats and microhabitats and the sheer size of the genus makes any characterisation of their biology challenging. Nests are built in the ground, in rotten branches or twigs, or rarely into living wood (Bolton, 1973a) and most species possess a highly generalistic diet.

Recently, Blaimer et al. (2015) found that Camponotus is paraphyletic with respect to Phasmomyrmex and Forelophilus, and that Colobopsis is sister to the remainder of the Camponotini while Dinomyrmex is nested outside of Camponotus. For this reason, Ward et al. (2016) revised the generic delimitation of the Camponotini; see the genus links included in this blurb for more detail.

Identification
Camponotus is a hyperdiverse genus (> 1,000 species, > 400 subspecies) that is rife with taxonomic problems and puzzles. Various subgenera, complexes, and informal groupings have either been defined in taxonomic publications or have been informally recognized. All of this sorting of species at the level between the genus and species level is an attempt to introduce some order to the genus and/or allow for a more workable framework for understanding Camponotus diversity within a particular region. The Camponotus species groups page provides links to some of the Antwiki pages that include Camponotus species groupings and information. See, particularly, Emery's (1925) keys to the subgenera of Camponotus, as well as related pages linked therein.

Note that female "Camponotus" are usually distinguishable from "Colobopsis" by their antennal sockets, which are placed in the anterior half of the frontal carinae (see the Colobopsis taxon account for more detail.

Emery's keys to the subgenera from Genera Insectorum
Emery's (1925) key to subgenera from Genera Insectorum

Species Groups
Table of Camponotus species by subgenus

Species richness
Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data



Nomenclature

 *  CAMPONOTUS [Formicinae: Camponotini]
 * Camponotus Mayr, 1861: 35. Type-species: Formica ligniperda, by subsequent designation of Bingham, 1903: 347.
 * [Type-species not Formica herculeana, unjustified subsequent designation by Forel, 1914a: 259, repeated in Arnold, 1922: 612.]
 * Camponotus (subgenus not given) senior synonym of †Shanwangella: Hong & Wu, 2000: 20.
 * Camponotus senior synonym of †Paleosminthurus: Snelling, R.R. (pers. comm., unpublished).
 * Subgenera of Camponotus (alphabetical order with synonyms indicated): nominal plus Colobopsis (= Campylomyrma, = Condylomyrma, = Dolophra), Dendromyrmex, Dinomyrmex (= Myrmogigas), Hypercolobopsis (= Neocolobopsis), Karavaievia, Manniella, Mayria (= Myrmosaga), Myrmacrhaphe, Myrmamblys, Myrmaphaenus (= Neomyrmamblys, = Paracolobopsis), Myrmentoma, Myrmepinotus, Myrmepomis (= Myrmolophus), Myrmespera, Myrmeurynota, Myrmisolepis, Myrmobrachys, Myrmocladoecus, Myrmodirachis, Myrmogonia, Myrmomalis, Myrmonesites (= Myrmensites), Myrmopalpella, Myrmopelta, Myrmophyma (= Myrmocamelus), Myrmopiromis, Myrmoplatypus, Myrmoplatys, Myrmopsamma, Myrmopytia, Myrmosaulus, Myrmosericus, Myrmosphincta, Myrmostenus, Myrmotarsus, Myrmotemnus, Myrmothrix, Myrmotrema, Myrmoxygenys, Orthonotomyrmex (= Orthonotus (junior homonym), Paramyrmamblys, Pseudocolobopsis, Rhinomyrmex, Tanaemyrmex (= Myrmoturba), Thlipsepinotus.
 * [All subgenera were given as provisional junior synonyms of Camponotus by Brown, 1973b: 179-185. The list was repeated in Hölldobler & Wilson, 1990: 18 with all subgenera listed as junior synonyms. They reverted to subgeneric status in Bolton, 1994: 50; see under individual entries. The entry of Myrmophyma and Thlipsepinotus under the synonymy of Camponotus by Taylor & Brown, D.R. 1985: 109, is not accepted as confirmation as not all taxa were included.]
 * †PALEOSMINTHURUS [junior synonym of Camponotus]
 * †Paleosminthurus Pierce & Gibron, 1962: 146. Type-species: †Paleosminthurus juliae (junior synonym of Formica festinata) [Snelling, R.R. pers. com., unpublished], by monotypy [in order Collembola].
 * †Paleosminthurus incertae sedis in Formicidae: Najt, 1987: 152; Bolton, 2003: 76.
 * †Paleosminthurus junior synonym of Camponotus: Snelling, R.R. (pers. comm., unpublished).
 * †SHANWANGELLA [junior synonym of Camponotus]
 * †Shanwangella Zhang, J. 1989: 307. Type-species: †Shanwangella palaeoptera, by original designation.
 * †Shanwangella junior synonym of Camponotus: Hong & Wu, 2000: 20.

Common Names for Camponotus Subgenera
A mnemonic list of common names for the subgenera of Camponotus may be found here.

Subgenus Camponotus
True Carpenter Ants

Diagnosis of subgenus: Emery (1925) - "Worker and queen. - Large species; caste polymorphism and other characteristics as in the subgenus Tanaemyrmex, except for the following differences: Head of minors Alpha-form (see Tanaemyrmex for head shape classification), but head generally shorter and posterior head margin straighter; head of major worker much less enlarged and less emarginate posteriorly; head of queens similar to those of majors. Clypeus lacking medial carina nor usually with anterior lobe, although weakly-produced and more-or-less rectangular (C. japonicus, Mayr) or rounded (C. sansabeanus, Buckley) lobe may be present [note: C. sansabeanus is currently classified as Tanaemyrmex]; anterior margin of clypeus entire, lacking medial notch. Mandibles strongly arched, usually with 4 or 5 teeth, sometimes with 6. Mesosomal dorsum arched, always continuous in profile; pronotal dorsum rounded or sometimes depressed in majors, with slightly prominent humeri. Male. - Caracteres of Tanaemyrmex.

Note that the subgenera Camponotus, Tanaemyrmex, Myrmosericus, and Myrmothrix constitute a group: they are separated by characters of little importance and often offer transitions from one group to another.

Geographical distribution of species. - Holarctic region, except Mediterranean Africa; C. punctatissimus, Emery, is found in the north of Indomalaya."

(Translated and edited by B. E. Boudinot, 15 February 2017.)

Taxonomic History of Camponotus
The taxonomic history of Camponotus may be divided into four phases, or eras, based on the kind of work published during these time periods.

Phase I ("Archaic Era")

1861–1896 (Beginning: Mayr 1861; end: Emery 1896).

The beginning of subgeneric work on Camponotus started with Mayr's (1861) key to the European ant fauna, wherein he recognized the cork-head ants, Colobopsis, as a distinct genus for the first time. Most of the work during this period was regional in nature, treating Europe, the Mediterranean, Madagascar, Russia, India, Sri Lanka, and North America. Only one explicit subgenus, Mayria was designated, while two taxa currently treated as subgenera were described: the American weaving ants, Dendromyrmex, and big-nose carpenter ants, Rhinomyrmex. In 1896, Emery proposed the first global, synoptic classification of Camponotus; previously no higher classification was in place, excepting recognition Mayria. In this work, all of the groups Emery distinguished were treated informally. Specifically, Emery recognized three principal groups (cohorts), which he divided into 26 subgroups which he termed manipoli. This work marked the beginning of the second phase of higher classification within Camponotus, wherein formal treatments of these groups were published.

Phase II ("Classical Era")

1896–1928 (First classificatory publication of era for Camponotus: Emery, 1898; last: Santschi, 1928).

In addition to the continuation of global exploration marked by regional works (South America, India, Sri Lanka, Myanmar, Palearctic [numerous], North America, Afrotropics [particularly South Africa], and the Malagasy region), this period is distinguished by greater focus on the subgenera, with Forel (1914), Emery (1920), Wheeler (1922), Santschi (1921), and Arnold (1922) expanding upon and refining Emery's system. In 1912, Forel formalized the Emery's (1896) higher classification by recognizing 16 subgenera, but without designating types. Wheeler (1913) sought to correct this by explicitly designating type species, but unfortunately this work was overlooked when Forel (1914) redundantly designated type specimens for his subgenera. This error of omission was replicated by Emery (1920), wherein he revised his initial classification, recognizing a total of 34 subgenera, as well as excluding Phasmomyrmex and species belonging to Notostigma (Melophorini), which he described as new. Wheeler (1921) put the nail in the coffin for the issue of confusion over subgeneric type species in a pointedly titled article, Professor Emery's subgenera of the genus Camponotus Mayr. The capstone to this second phase was Emery' (1925) final ,monumental contribution to Wytsmann's Genera Insectorum, which is still the most significant work on the internal classification of Camponotus to date. In this work, Emery synthesized all previous taxonomic works on Camponotus, particularly those of Forel and Wheeler, revised the delimitation of all subgenera, including subgroups, and provided keys to and diagnoses of all subgenera, all of which amounted to an effort which has not been matched. Moreover, Emery proposed his final phylogenetic hypothesis for the genus (see Emery's Phylogenetic Hypothesis below), which is distinguished from hypotheses he proposed for other groups by the strong biogeographic structure he postulated for the group. In 1926 and 1928, Santschi published the final two works formally altering Emery's (1925) system; both of these works were minor acts of splitting, and neither revised Emery's keys.

Phase III ("Modern Era")

1928–2006 (Beginning: Santschi, 1928; end: Moreau et al. and Brady et al. 2006)

After Emery (1925) and Santschi (1926, 1928), no further works were published which formally modified the subgeneric system of Camponotus until the fourth era of the internal classification of the genus (see Phase IV below). For almost 90 years, there has been, effectively, no major attempt to understand the diversity of Camponotus globally, with the major publications of the era for the genus being regional catalogs (Kempf 1972 Neotropics (followed by Brandao’s update in 1991), Taylor & Brown 1985 Australia (followed by Shattuck 1999), and Bolton’s 1995 global catalog). Virtually all of the taxonomic work on Camponotus during this time were regional, which in sum span the globe, but with global revisions restricted to minor groups of species (i.e., the groups or complexes of herculeanus, nigriceps, fulvopilosus, weiderkehri, and perjerus), as well as regionally-restricted and well-defined or easily-recognizable subgenera (e.g., Dendromyrmex, Karavaievia, Myrmentoma, Myrmostenus, Myrmothrix). In the late ‘90s and early 2000’s, Shattuck and McArthur treated a number Australian groups which they recognized morphologically but in which they disregarded the subgeneric classification. The end of this era is marked by the first global phylogenies of the Formicidae based on molecular data, published by Moreau et al. (2006) and Brady et al. (2006).

Phase IV ("Molecular Era")

2006–present.

The current era of classification, with respect to Camponotus, is nascent. Blaimer et al. (2015) published two phylogenies of the Formicinae using “traditional” Sanger sequencing and “next-gen” Illumina sequencing of ultraconserved elements (UCEs). This work was followed shortly by a formal reclassification of the subfamily by Ward et al. (2016), in which a number of taxonomic changes were made to relieve Camponotus and particular subgenera of paraphyly (i.e., Colobopsis and Dinomyrmex revived status as genera, Myrmogonia synonymized with Colobopsis, Phasmomyrmex made subgenus of Camponotus).Bill MacKay is still working on his revision of Camponotus of the Americas, and at present, no major phylogenetic work is underway for Camponotus, beyond refining the placement of species belonging to Colobopsis.

(Section by B. E. Boudinot, 19 February 2017.)

Emery's Phylogenetic Hypothesis for Camponotus
In Emery's (1925) treatment of Camponotus in Genera Insectorum, he proposed a final, revised hypothesis of the internal relationships of the genus; an earlier version was published in Emery (1920). An important facet of this hypothesis, translated from p. 61, is Emery's "opinion that Camponotus underwent independent evolution in the Old and New Worlds". Emery postulated seven genus groups within Camponotus, with explicit morphologically-transitional lineages. These groups are indicated below:



Group I: Myrmopiromis

(Afrotropical and Malagasy regions, a few species from India)

1. Myrmopiromis

2. Myrmotrema

3. Myrmisolepis

4. Orthonotomyrmex

5. Myrmepinotus

Group II: Myrmosaulus

(Malaysia, Australia, Madagascar)

1. Myrmosaulus

Group III: Myrmamblys

Myrmopsamma subgroup (Africa)

1. Myrmopsamma

Karavaievia subgroup (Indomalaya, etc.)

1. Karavaievia

2. Myrmotarsus

3. Myrmoplatys

Mayria subgroup (Afrotropical, Malagasy)

1. Mayria

2. Myrmonesites

3. Myrmopytia

Miscellaneous subgroup

1. Myrmentoma

2. Colobopsis [note: revived status as genus, Ward et al. (2015)]

3. Myrmogonia [note: synonymized with Colobopsis, Ward et al. (2015)]

Subgroup transitional to Myrmaphaenus via Tanaemyrmex

1. Myrmamblys (Old World) [note: split into Myrmespera, Myrmopelta, Myrmotemnus, Paramyrmamblys, and Myrmamblys sensu stricto by Santschi (1926).]

2. Myrmophyma [note: split into Thlipsepinotus and Myrmophyma sensu stricto by Santschi (1928).

Group IV: Tanaemyrmex

(Cosmopolitan)

1. Tanaemyrmex [note: Emery's species groups may be particularly useful for understanding, and dividing, this probably "plesiotypic" taxon]

Group V: Myrmoxygenys group

(Transitional between Myrmamblys and Myrmaphaenus groups via Tanaemyrmex)

1. Myrmoxygenys (Afrotropics)

2. Dinomyrmex (Malaysia) [note: revived status as genus, Ward et al. (2015)]

3. Myrmosericus (Afrotropics, India)

4. Myrmothrix (Neotropics)

Group VI: Myrmaphaenus

Subgroup transitional to Myrmamblys group via Tanaemyrmex

1. Camponotus (Holarctic) (sensu lato, including Nearctic Tanaemyrmex and caryae and lateralis groups of Myrmentoma, in part.

2. Myrmaphaenus (New World)

Neotropical subgroup, transitional to Myrmobrachys group

1. Pseudocolobopsis

2. Myrmostenus

3. Hypercolobopsis

4. Manniella

5. Myrmosphincta

Group VII: Myrmobrachys

Subgroup transitional to Myrmaphaenus group

1. Myrmobrachys

2. Myrmocladoecus

3. Myrmomalis

4. Myrmeurynota

5. Myrmodirachis

6. Myrmoplatypus

7. Myrmepomis

(Section by B. E. Boudinot, 19 February 2017.)