Crematogaster

Hita Garcia, Wiesel and Fischer (2013) - One of the most species-rich and widely distributed genera, with approximately 470 valid species and 300 subspecies (Bolton, 2012). Despite its cosmopolitan distribution, most species are found in the tropics. The extreme species richness together with the high intraspecific and geographical variability provides serious obstacles for the taxonomic understanding of this genus. Thus, it is not surprising that revisionary treatments are very scarce and have been thoroughly avoided in the past. Some regional faunas have been revised on genus or subgenus level (Buren, 1959; Longino, 2003; Hosoishi & Ogata, 2008, 2009; Blaimer, 2010, 2011). In tropical regions, most members of this genus are arboreal (Longino, 2003), although a minority of species nest and forage on the ground (Quinet et al., 2009; Hosoishi et al., 2010). Crematogaster can be found in a diversity of habitats, such as forests, woodlands, savannahs or shrublands (Blaimer, 2010) and they often play a dominant, aggressive and territorial role within the local ant fauna (Longino, 2003). Most Crematogaster seem to be highly generalistic and omnivorous (Longino, 2003), although the most important resource for many species is homopteran honeydew.

Identification
Crematogaster species can be difficult to identify. There are many parts of world where Crematogaster are quite abundant but the diversity and taxonomy of the genus is poorly known. A number of recent revisions have greatly improved our understanding of a few species groups and regions. Unfortunately there is no comprehensive revision that can provide any coherent accounting of the genus as a whole.

Eguchi, Bui and Yamane (2011) - Worker monomorphic, but sometimes varying widely in size; head round, subrectangular or subtrapezoidal; frontal carina and antennal scrobe absent; median portion of clypeus roundly expanded anteriad, partly overhanging basal part of mandibles when fully closed; posteromedian portion very broadly inserted between frontal lobes; no isolated, median seta on anterior clypeal margin; mandible narrow; masticatory margin oblique, with 4 teeth; antennae 11-segmented, with a 2-, 3-, or 4-segmented club, or gradually incrassate; eye medium sized or rarely consisting of a few ommatidia; promesonotum more or less raised; promesonotal suture absent or weakly present dorsally; metanotal groove usually distinctly impressed, sometimes margined laterally by a longitudinal carina or lamella; propodeal spine usually (but not always) present, varying in size and shape; propodeal spiracle located well posteriorly on posterolateral margin of propodeum, just below base of propodeal spine; petiole depressed dorsoventrally, without node; postpetiole with rounded node which often bears median longitudinal impression, attached to dorsal surface of gaster; gaster in dorsal view triangular or cordate; sting spatulate.

Crematogaster is easily distinguished from all other myrmicine genera known from Vietnam by the morphology of the waist and gaster. The worker of species belonging to the subgenus Orthocrema of Crematogaster is a little similar to that of Recurvidris, but in the latter the propodeal spines are weakly to strongly recurved, the propodeal spiracle is located far in front of the base of the propodeal spine, the postpetiole, in dorsal view, is broadly attached to the first gastral segment, and the first gastral segment behind the postpetiole is extremely dorsoventrally compressed in lateral view. Antennal club is 2-segmented in Orthocrema, but 3-segmented in Recurvidris.

Species Groups

 * Asian Crematogaster ranavalonae group
 * Malagasy Crematogaster Species by Subgenus and Species Group

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



Biology
Eguchi, Bui and Yamane (2011) - Many species are arboreal foragers, and nest in decayed parts of standing trees and hollows of tree trunks and branches or build carton nests. Some species nest in soil or rotting logs on the ground. Species of the subgenus Orthocrema forage both on and under the ground.

Nomenclature

 *  CREMATOGASTER [Myrmicinae: Crematogastrini]
 * Crematogaster Lund, 1831a: 132. Type-species: Formica scutellaris, by subsequent designation of Bingham, 1903: 124.
 * [Type-species not Formica acuta, unjustified subsequent designation by Emery, 1912d: 272; this error repeated in, for example, Emery, 1914c: 39, Arnold, 1920a: 482, Emery, 1922e: 128, Gallardo, 1934: 4; Soulié, 1965: 78.]
 * Crematogaster senior synonym of Acrocoelia: Roger, 1863b: 36; Mayr, 1863: 404; Dalla Torre, 1893: 79 (see also Buren, 1959: 125; Kempf, 1972a: 81).
 * Crematogaster (as subgenus) senior synonym of Atopogyne, Colobocrema, Decacrema, Oxygyne, Nematocrema, Paracrema, Physocrema, Sphaerocrema, Xiphocrema: Blaimer, 2012: 52.
 * Subgenera of Crematogaster: nominal plus  Orthocrema. .
 *  CREMASTOGASTER Mayr, 1861: 74 (and many later authors), incorrect subsequent spelling. Discussion of spelling: Emery, 1912d: 272 (footnote); Wheeler, W.M. 1913a: 78; Donisthorpe, 1941f: 36 and Buren, 1959: 125.
 * ACROCOELIA [junior synonym of Crematogaster]
 * Acrocoelia Mayr, 1853a: 147. Type-species: Acrocoelia ruficeps (junior synonym of Formica scutellaris), by subsequent designation of Wheeler, W.M. 1911f: 158.
 * Acrocoelia junior synonym of Crematogaster: Mayr, 1863: 404; Wheeler, W.M. 1911f: 158; Wheeler, W.M. 1922a: 828.
 * Acrocoelia revived from synonymy as subgenus of Crematogaster: Emery, 1922e: 140.
 * Acrocoelia junior synonym of Crematogaster: Buren, 1959: 126.
 * Acrocoelia revived from synonymy as genus: Soulié, 1964: 398.
 * Acrocoelia junior synonym of Crematogaster: Brown, 1973b: 178. [The type-species of Acrocoelia and Crematogaster are synonymous, the generic synonymy is therefore absolute.]
 * TRANOPELTOIDES [junior synonym of Crematogaster]
 * Tranopeltoides Wheeler, W.M. 1922e: 10. Type-species: Tranopelta huberi, by original designation.
 * Tranopeltoides junior synonym of Crematogaster: Kempf, 1960c: 173.
 * NEMATOCREMA [junior synonym of Crematogaster]
 * Nematocrema Santschi, 1918d: 182 [as subgenus of Crematogaster]. Type-species: Crematogaster stadelmanni, by original designation.
 * Nematocrema raised to genus: Soulié, 1964: 398.
 * Nematocrema junior synonym of Crematogaster: Hölldobler & Wilson, 1990: 13.
 * Nematocrema subgenus of Crematogaster: Bolton, 1995b: 38.
 * Nematocrema junior synonym of Crematogaster: Blaimer, 2012: 249.

North America
Deyrup and Cover (2007) - The first useful account of the North American Crematogaster was Creighton’s (1950) treatment of the genus in the “Ants of North America.” From the past Creighton inherited a confusing list of ill-defined taxa, the customary legacy to modern taxonomists from the “Bronze Age” of Ant Taxonomy (1750 - 1950), an era characterized by much honest descriptive effort that was critically undermined by the lack of a biologically realistic conceptual framework. Creighton began the process of bringing order to the North American ant fauna, and to the Crematogaster in particular, by employing the newly popularized biological species concept to elicit meaning from what seemed to be an intractable morass of names and morphological variation (see Buhs, 2000 for a discussion of this development). Expanding on this pioneering work, Buren (1958, 1968) revised the North American Crematogaster again, incorporating much newly available information. Like Creighton, Buren made extensive use of distributional data and natural history observations in making taxonomic decisions and, as a result, his work still forms the basis for our modern understanding of the genus in North America. Not much has been added since Buren’s studies. Johnson (1988) reviews the eastern species and presents a key to them. In an excellent new revision of the Crematogaster of Costa Rica, Longino (2003) makes several taxonomic changes that affect the North American fauna.