Rogeria

The rarely collected myrmicine ant genus Rogeria has a disjunct distribution, with 37 species known to occur in the New World and 3 species that are known from the Australasian region (Kugler 1994). Rogeria ants are cryptic in habit and specimens are primarily collected from leaf litter and rotten wood, usually through Berlese or Winkler sampling. Not much is known about their biology, except that nests have been taken in rotting logs, under rocks, and from the trunks of cacao trees (Kugler 1994, LaPolla, J. S. and J. Sosa-Calvo, 2006).

Identification
Kugler (1994) - Monomorphic myrmicines. Antenna 12-segmented; scape not reaching posterior margin of head; distinct 3-segmented club longer than rest of funiculus; apical antennomere longer than combined lengths of other two club segments. No antennal scrobes or fossae. Clypeus projects narrowly between frontal lobes at least to posterior edge of antennal insertions. Body of clypeus with one or more pair of longitudinal carinulae. Lateral clypeus not raised into a ridge in front of antennal insertions. Nuchal grooves present on posteroventral corners of head. Anteroventral corners of pronotum angular to dentate and fitting into nuchal grooves. Propodeal spiracle 3 diameters or less from the edge of the propodeum below the propodeal spines. Metapleural lobes not sharply pointed.

Some members of Temnothorax have antennae like Rogeria and some have a narrow posterior lobe of the clypeus, but these have rounded anteroventral corners of the pronotum and no nuchal grooves. Of 65 species of Temnothorax examined at the, only one had an angular inferior corner of the pronotum, but in that species the scapes extend beyond the head, the posterior lobe of the clypeus is wider, and nuchal grooves are absent.

Some species of Lordomyrma, a genus sometimes confused with Rogeria in pacific islands, have similar antennal and clypeal features, but have a rounded anteroventral corner of the pronotum and lack nuchal grooves.

Stenamma workers are similar in form of clypeus, including narrow posterior portion between frontal lobes, and some have 3-segmented antennal clubs, but in that case the apical segment is shorter than the combined length of the other two segments. Also, Stenamma has no nuchal grooves, the anteroventral corner of the pronotum is rounded, and the metanotal groove is generally more distinct than in Rogeria species.

A number of Rogeria are highly variable and species level identification may be difficult for any particular collection or specimens.

Kugler (1994) organized species into groups (Rogeria species groups), stating "Some species can be assembled into more or less distinct species groups. Others can not be placed easily in any group, or seem to link several groups. These incertae sedis species are described with the group to which they may be most related." The diagnostic characters of these groups can be helpful in making species determinations.

Distribution
Kugler (1994) - Members of the genus Rogeria are distributed from Buenos Aires to southern Texas and Arizona, and in the Pacific between 10°N and 25°S from Tahiti to the western end of the island of New Guinea. So far it is unknown in Australia or southeastern United States. In the North American region, most species occur below the Isthmus of Tehuantepec, but two species (Rogeria creightoni, Rogeria cuneola) extend northward through the eastern lowlands of Mexico. Only Rogeria foreli and Rogeria creightoni have been collected in the United States. The North American region contains 8-10 endemic species (depending on the uncertain distributions of Rogeria innotabilis and Rogeria leptonana); the Caribbean, two endemic species; South America (including Trinidad), 19 endemic species and the Pacific, three endemic species. Only 5-7 species (depending on Rogeria innotabilis and Rogeria leptonana) are found in both Central America and northern South America.

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



Biology
Kugler (1994) provided the following summary: Little is known of the biology of these cryptic ants. Collection records usually range from sea level to 1000m, but five species extend higher and two (Rogeria unguispina and Rogeria merenbergiana) can be found at 2000m. Rogeria species are generally collected in moist forests (primary or secondary forests, coffee or cacao plantations), but at higher elevations can be found in pastures (Rogeria leptonana, Rogeria merenbergiana). Several species (Rogeria creightoni, Rogeria cuneola, Rogeria foreli) have been found in both moist and dry climates. Rogeria foreli is the most unusual, with some members dwelling at over 1800m in the temperate mountains of southern Arizona.

Most Rogeria species have only been collected as strays or by Berlese or Winkler sampling, usually in leaf litter and rotten wood, but occasionally among epiphytes and moss (Rogeria belti, creightoni, Rogeria exsulans). Nests of several species (belti, Rogeria blanda, merenbergiana) have been found under loose bark of rotten logs. Nests of blanda and Rogeria tonduzi have been taken from the trunks of cacao trees. A nest of Rogeria leptonana was found at 1750m under a rock in a pasture.

Because nests are so rarely found, males are known for only four species (belti, blanda, leptonana and Rogeria stigmatica), and queens associated through nest series for only nine species.

Nomenclature

 *  ROGERIA [Myrmicinae: Stenammini]
 * Rogeria Emery, 1894c: 188. Type-species: Rogeria curvipubens, by subsequent designation of Wheeler, W.M. 1911f: 172.
 * Rogeria senior synonym of Irogera: Kempf, 1965: 185; Kugler, C. 1994: 23.
 * IROGERA [junior synonym of Rogeria]
 * Irogera Emery, 1915i: 191 [as subgenus of Rogeria]. Type-species: Rogeria procera, by original designation.
 * Irogera raised to genus: Brown, 1953h: 4 (in text); Kempf, 1961d: 436.
 * Irogera junior synonym of Rogeria: Kempf, 1965: 185; Kugler, C. 1994: 23.

Worker
Kugler (1994) - Mandibles usually triangular. Except in some ciliosa and foreli, mandibles with 5-7 teeth (3 apical teeth decreasing in size basad, followed by 2-3 smaller basal teeth). Additional denticles may occur among basal teeth or any basal tooth may be replaced by a pair of denticles. Palpal formula usually 3,2 or 2,2, but 3,3 in some stigmatica-group, and 2,1 in the very tiny minima. Scape neither elbowed nor ridged at the base, nor with an apron around the peduncle. Clypeus in profile usually with a very narrow anterior apron. Body of clypeus rises near vertically in most species, but occasionally projecting beyond the clypeal apron. Frontal lobes narrow; but covering antennal insertions; at most feebly notched behind. Frontal triangle small, depressed slightly. Eyes with 1-100 facets; located on sides, in the anterior half of the head (excluding mandibles). Sides of head widest just behind the eyes, forming rounded corners with the posterior head, which is weakly concave to weakly convex in full face view.

Mesosoma generally compact, broad shouldered. Anterior face of pronotum rises nearly vertically from the neck and usually forms a distinct, rounded angle with the dorsal surface. Mesosoma dorsum without sutures; no mesonotal groove; metanotal groove absent to distinct. Anterior edge of propodeum often marked by a transverse carina. Propodeal spines absent to long. Metapleural lobes low carinae to rounded triangular. Legs not incrassate. No tibial spurs on middle or hind legs. Tarsal claws simple.

Petiolar peduncle with or without a ventral keel; inferior process dentate except in stigmatica group. Node unarmed; poorly to well differentiated from peduncle. Postpetiole with short peduncles and a low node that is broader than long. Terminal segments of gaster rotated ventrad in all but the stigmatica group.

All pygidia dissected have a pair of small pygidial gland reservoirs and/or paired microareolate patches present on anterior edge, except in the stigmatica group. Common features of the sting apparatus are: 1) medial connection of spiracular plate incompletely sclerotized, 2) gonostylus single-segmented, 3) dorsoterminal chaeta present, 4) at least one companion seta (except gibba), 5) each lancet with a single moderate to large valve, 6) sting bulb large, with arched sting base.

Mandibles usually predominantly smooth, with piligerous punctures and vestigial carinulae at insertions, but carinulae stronger and more extensive in some members of the stigmatica-group. In all but ciliosa, the body of the clypeus is smooth with a pair of carinulae extending from the frontal lobes and stopping short of the clypeal apron; these are sometimes accompanied laterally by 1-2 shorter, weaker carinulae. Lateral extremities of clypeus and adjacent cheeks with longitudinal carinulae. Frontal triangle smooth, except in ciliosa. If macrosculpture present, frontal lobes and mid dorsum with diverging longitudinal rugae; rest of body areolate, rugose, or occasionally carinate. Microsculpture when present usually microareolate, appearing granular or punctured at lower magnifications. Posterior face of propodeum smooth, except in gibba. Legs smooth and shiny. First segment of gaster smooth and shiny; less so in prominula, and minima. Pygidium and sometimes other terminal terga with microscopic areolate sculpture on exposed posterior surfaces; pygidium may also possess minute piligerous tubercles.

Short appressed or decumbent pilosity common, most dependably on legs (except blanda and procera) and antennae. Terminal segments of gaster with erect hair. No erect hair on laterodorsa of head (under sweep of scapes). Body of clypeus just above apron with pairs of erect hairs; members of stigmatica group each with an additional median hair.

Color from brownish yellow to black, with mandibles, antennae, and legs lighter. Most species also with a lighter triangle on clypeus, cheeks, and frontal area.