Tanaemyrmex

Narrow-head 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 reunited in this subgenus most species of the subgenera Myrmoturba and Dinomyrmex of Forel's (1914) classification and mine (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 head form between Beta of minors (Myrmoturba) and the form Gamma (Dinomyrmex sensu lato), which makes one sometimes embarrassed in the identification of the subgenera. Forel based his classification Myrmoturba, in effect, on the species C. pompeius, Forel and festinus, F. Smith, whom I regard as Dinomyrmex. How can we classify a Camponotus species for whom we only know the major worker, for example C. perroti, Forel and C. haematocephalus, Emery? In certain forms of the group C. maculatus, (Fabricius), 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 the 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. Please see Camponotus for further information.

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.