Rogeria exsulans

Rogeria exsulans has been collected only at 600-700m on a single island in the middle of the South Pacific. Most collections specify a rain forest habitat, where it has been found under dead bark, in rotten logs, in moss and ferns on trees and in berlesate of moss on logs and tree trunks.

Identification
Kugler (1994) - creightoni species group. WL 0.68-0.84mm. Eye fairly large, oval. Propodeal spiracle faces posterolaterally. Petiole with lamellate keel and dentate inferior process. Terminal segments of gaster rotated ventrad. Sides of head areolate-rugose; posterior head and promesonotum strongly areolate. Scapes with decumbent and a few short, suberect hairs. No erect hair on extensor surfaces of legs. Mostly abundant decumbent to subdecumbent hair on dorsa of head, mesosoma, nodes and gaster T1 (sparse erect hair on head and mesosoma); not sorting into two distinct kinds of pilosity.

The only other Pacific species, Rogeria stigmatica and Rogeria megastigmatica are easily distinguished from Rogeria exsulans by their lack of a petiolar keel and inferior process, as well as other features listed above.

The species most similar to exsulans is Central American. Rogeria belti has some members with similar size, habitus, eye size, clypeus shape, a distinct petiolar keel, strong areolate sculpture, and intergrading types of hairs on mesosoma. However, belti workers still differ in having generally longer propodeal spines (PSI 0.19-0.24), less prominent petiolar keel, and distinct long/erect and short/decumbent pilosities on the gaster.

Distribution
Only known from the island of Upolu, (Samoa).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Samoa.

Castes
Known only from workers.

Nomenclature

 *  exsulans. Rogeria exsulans Wilson & Taylor, 1967: 74, fig. 60 (w.) SAMOA. See also: Kugler, C. 1994: 64.

Worker
Kugler (1994) - TL 2.5-3.0, HL 0.62-0.71, HW 0.52-0.64, EL 0.08-0.11 (20-26 facets), PW 0.37-0.45, WL 0.68-0.84, SpL 0.10-0.15, PetL 0.26-0.33, PpetL 0.15-0.17mm, CI 0.84-0.90, OI 0.19-0.21, SI 0.81-0.85, PSI 0.14-0.19. N=4

Some mandibles with 6 teeth (5 decreasing in size then a large basal), but usually the small penultimate basal tooth is replaced by 2 denticles, or by a gap and 1 denticle. Pal pal formula 3,2. Clypeal apron medially emarginate. Back of head in dorsal view convex or flat medially; temples broadly rounded. Promesonotal profile may be evenly rounded, but more often angular. Metanotal groove usually distinct, producing a step between promesonotum and propodeum, but weak in two specimens. Propodeal spiracles more than one diameter from nearest edge of infradental lamella. Node short, evenly convex. Postpetiolar sternum relatively long, flat; postpetiole from above subtrapezoidal, as in Fig. 51. Sting apparatus as in creightoni-group diagnosis.

Longitudinal rugae of frontal lobes and median head gradually change to strongly areolate on posterior head. Cheeks and laterodorsa longitudinally areolate-rugose. Intervals on head dorsum vaguely undulate, but shiny; intervals on sides and posterior head smooth and shiny. Promesonotum for the most part strongly areolate, but several elongate cells may occupy the midline of the pronotal disc, and often the pronotal sides have weaker areolate sculpture. Meso- and metapleura confused areolate-rugose. Mesosoma microsculpture reduced; intervals in macrosculpture uneven, but very shiny. Petiolar node with weak to vestigial areolate macrosculpture and vague microareolate background. Postpetiolar node shiny, nearly smooth throughout.

Head, mesosoma dark reddish-brown, waist and anterior and posterior ends of gaster somewhat lighter. Mandibles, clypeus, antennae, and legs yellowish-brown.

Type Material
Kugler (1994) - Holotype SAMOA: Upolu (T. E. Woodward) (Holotype ; paratypes, MCZ) [Holotype and 30 paratypes examined].

References based on Global Ant Biodiversity Informatics

 * Dlussky G.M. 1994. Zoogeography of southwestern Oceania. Zhivotnoe naselenie ostrovov Iugo-Zapadnoi Okeanii ekologo-geograficheskie issledovanii 48-93.
 * Kami K.S., and S. E. Miller. 1998. Samoan insects and related arthropods: checklist and bibliography. Bishop Museum Technical Report 13, pp 121.
 * Kami KS & Miller SE. 1998. Samoan insects and related arthropods: checklist and bibliography. Bishop Museum Technical Report No. 13.
 * Kugler C. 1994. A revision of the ant genus Rogeria with description of the sting apparatus (Hymenoptera: Formicidae). Journal of Hymenoptera Research 3: 17-89.
 * Wetterer, James K. and Vargo, Donald Vargo L. 2003. Ants (Hymenoptera: Formicidae) of Samoa. Pacific Science. 57(4):409-419.
 * Wilson E. O.; Taylor, R. W. 1967. The ants of Polynesia (Hymenoptera: Formicidae). Pacific Insects Monograph 14:1-109.
 * Wilson E.O., and G.L. Hunt. 1967. Ant fauna of Futuna and Wallis islands, stepping stones to Polynesia. Pacific Insects 9(4): 563-584.
 * Wilson EO, Hunt GL. 1967. Ant fauna of Futuna and Wallis Islands, stepping stones to Polynesia. Pacific Insects 9.4: 563-584.
 * Wilson EO, Taylor RW. 1967. The ants of Polynesia. Pacific Insects Monograph 14:1-109.
 * Wilson, Edward O. and George L. Hunt. 1967. Ant Fauna of Futuna and Wallis Islands, Stepping Stones To Polynesia. Pacific Insects. 9(4):563-584.
 * Wilson, Edward O. and Hunt, George L. Jr. 1967. Ant Fauna of Futuna and Wallis Islands, Stepping Stones to Polynesia. Pacific Insects. 9(4):563-584