Tanaemyrmex

Slim Carpenter Ants

Diagnosis: Emery (1925): - "Workers. - Caste polymorphism generally very pronounced in head form and size; polymorphism gradual through extreme forms. Head of majors usually much wider posteriorly than anteriorly, truncated or notched on posteriorly. Head of minors elongated and of very different forms:

(Alpha) sides substantially parallel and posterior margin usually rounded; vertex not depressed.

(Beta) sides converging posteriorly from mouth; vertex evidently depressed and eyes more-or-less distant from posterior margin.

(Gamma) characters in this form become more and more pronounced: posterior half of head, from eyes, cone-shaped and occipital border disappears, reduced to articular border; sometimes, posterior extremity of head extends as neck and more-or-less marked, especially when posterior half of head is not conical but ogival (missile-shaped) (e.g., C. hildebrandtii, Forel, cervicalis, Roger, etc.).

There are, moreover, intermediaries between these forms of minor worker heads. Species in which minors have head forms Beta and Gamma have medias with heads which are more-or-less Alpha-form; head of minors with form Gamma and small medias or majors have head form Beta.

Clypeus generally carinate medially; anterior margin with more-or-less prominant lobe, lobe square or rounded, rarely notched or acute medially; lobe often rounded in minors, and becomes increasingly rectangular in larger workers; medioclypeus (middle portion of clypeus between anterior tentorial pits) not prominent in majors, so that in workers of all sizes clypeus as a whole (excluding anterior lobe and lateral clypeal parts) is trapezoidal. Frontal carinae more-or-less sinuate; antennal insertions usually not far from posterior clypeal margin. Mandibles with simple teeth (usually 6–7), apical tooth longer than others, but not excessively. Mesosomal dorsum never marginate, arched in profile, propodeum rarely hollowed out posteriorly or with saddle-shape. Petiole surmounted by more-or-less high scale, rarely nodiform, rarely with unpaired spine (C. hastifer, Emery, hoplites, Emery). Sculpture and investiture variable; in some American species, gaster covered with fur-like pubescence (e.g., C. chilensis, Spinola). Setae of scapes and tibiae in American species never erect, long and abundant, except in C. cacicus, Emery. Queens. - Head form similar to majors, but not of largest workers in a colony. Males. - Head more-or-less elongated. Antennae long: scape exceeding posterior head margin by at least half its length; pedicel and flagellum composed of more-or-less elongate antennomeres, pedicel nor or only slightly longer than antennomere 3 and not at all pyriform (pear-shaped); rarely antennomeres of flagellum very short and pedicel somewhat pyriform (e.g., C. friedae, Forel, acvapimensis, Mayr, punctulatus, Mayr).

Geographical distribution of species. - Same as genus, except for countries north of polar region.

Remarks on the subgeneric classification of Tanaemyrmex. - I have united in this subgenus most species of the subgenera Myrmoturba and Dinomyrmex of Forel's (1914) classification and my own (1920). It seems, at first sight, easy to differentiate these two groups, whose extreme representatives are, on the one hand, C. solon, Forel and C. natalensis, F. Smith, and on the other hand C. longipes, Gerstacker and C. cervicalis, Roger (to take examples of the Afrotropical and Malagasy faunas). But there are insensible transitions between the form of the head between the Beta minors (Myrmoturba) and Gamma (Dinomyrmex sensu lato), which makes one sometimes embarrassed in the identification of the subgenera. Forel based his classification of Myrmoturba, in effect, on the species C. pompeius, Forel and festinus, F. Smith, whom I regard broadly as Dinomyrmex. How can we classify a Camponotus species for whom we only know the major worker, such as C. perroti, Forel and C. haematocephalus, Emery? In certain forms of the C. maculatus, (Fabricius), group (the type-species of the subgenus Myrmoturba), the true minor workers have the head so narrowed posteriorly that the occipital border is reduced to the articular border [= postocciput], as in the typical species of the subgenus Dinomyrmex. Lumping these two subgenera is necessary, except for C. gigas, Latreille (type species of Dinomyrmex) and C. caesar, Forel, for which I founded the subgenus Myrmoxygenys."

(Translated and edited by B. E. Boudinot, 16 February 2017.)

Tanaemyrmex is currently a subgenus of Camponotus.

Species groups
Emery (1925) divided Tanaemyrmex into 12 species groups––four from the New World, and eight from the Old World––plus a number of "anonymous" (unnamed) groups of uncertain affinity. Below are his diagnoses of these groups, all based on workers:

"SPECIES GROUPS OF AMERICA

Group I: chilensis-punctulatus

Diagnosis. - Head of minors of form Alpha; species more-or-less stocky, especially majors. Color generally black or dark, rarely pale; gasters of some species covered with more-or-less dense pubescence. Transition more or less marked to Camponotus sensu stricto and Myrmaphaenus.

Group II: picipes-fumidus

Diagnosis. - Head of minors of form Alpha. Species not stocky. Color variable, rarely uniform yellow. In some species tibial setae more-or-less detached erect (transitioning to Myrmothrix).

Group III: Iandolti-agra

Diagnosis. - Head of minors of form Beta or Gamma; species medium-sized to very large; elongate to very elongate, especially minors; legs not hairy. Includes American species of subgenus Dinomyrmex sensu Forel.

Group IV: cacicus

Diagnosis. - As for previous group, but with numerous standing setae.

American species of uncertain placement

C. abunanus, Mann ''C. fryi, Mann

SPECIES GROUPS OF THE OLD WORLD

Group V: maculatus-gouldi

Diagnosis. - Head of minors of form Beta or Gamma. Medium-sized to very large ants. Species of Africa and Madagascar; includes type species of subgenus (C. longipes, Gerstaecker), as well as species of Dinomyrmex (part) and Myrmoturba (part) sensu Forel.

Group VI: dorcyus-extensus

Diagnosis. - Same as previous group. Indomalayan and Australasian species. Includes species of Dinomyrmex and Myrmoturba, sensu Forel.

Group VII: irritans-thraso

Diagnosis. - Head of minors of form Alpha. Medium to small species. Dimorphism well marked, but majors neither stocky nor with massively wide head. Ventral surfaces of tibiae without bristles (at most 2–3 bristles near apex). Includes species of Myrmoturba sensu Forel.

Group VIII: aethiops

Diagnosis. - Similar to previous group, but bristles more-or-less numerous on ventral surface of tibiae. Propodeum sometimes impressed or lower than mesonotum/metanotum. Species mainly inhabiting Southern Europe.

Group IX: compressus-sylvaticus

Diagnosis - Head of minors of form Alpha. Species generally large or medium; dimorphism well marked. At least a row of bristles on ventral surface of tibiae. Species of Mediterranean Basin, Africa, and Asia.

Group X: arrogans-testaceipes

Diagnosis. - Head of minors of form Alpha; major workers stocky, often with enormous heads; propodeum sometimes impressed.

Group XI: nigriceps

Diagnosis. - Workers and queens - Clypeus widely and deeply notched anteromedially. Species of Australia.

Group XII: gambeyi-nasica

Diagnosis. - Head of minors of form Alpha, but more-or-less conical posteriorly. Dimorphism little marked: majors either unknown or with small heads. Pronotum and mesonotum forming raised bump, while dorsal face of propodeum inclined and declivitous (posterior) face remarkably short and forming curve with dorsal face. (Myrmocamelus [part], Forel.)"

(Translated and edited by B. E. Boudinot, 16 February 2017.)

Revisions
Camponotus nigriceps species group Adams and MacArthur, 1996

Salata, Khalili-Moghadam, and Borowiec (2020) newly defined the Camponotus samius complex for six Tanaemyrmex species occurring in the Turano-Balkan region. The defining characters of the complex and its distribution are consistent with Emery's compressus-sylvaticus group. Taxonomic problems and a lack of good collections for species in the compressus-sylvaticus group in Asia and Africa prevented further study of the relationship between this group and the samius complex.

Nomenclature

 *  TANAEMYRMEX [subgenus of Camponotus]
 * Tanaemyrmex Ashmead, 1905b: 384. Type-species: Formica longipes (junior primary homonym in Formica, replaced by Camponotus etiolipes), by original designation.
 * Tanaemyrmex senior synonym of Myrmoturba: Emery, 1925b: 75.
 * MYRMOTURBA [junior synonym of Tanaemyrmex]
 * Myrmoturba Forel, 1912i: 91 [as subgenus of Camponotus]. Type-species: Formica maculata, by subsequent designation of Wheeler, W.M. 1913a: 82.
 * Myrmoturba junior synonym of Tanaemyrmex: Emery, 1925b: 75.