Forelius damiani

Described from specimens from a dry forest of the Sierra Nevada de Santa Marta, Colombia, and additional collections from Costa Rica and Texas (USA).

Identification
Guerrero & Fernandez (2008) - Worker. Mandible with four teeth and two denticles. Pronotum in profile relatively low and flat, with 2 erect setae. Dorsum of mesonotum and propodeum with very fine punctation. Mesopleural and metapleural regions shining, with sparse pubescence. Propodeal spiracle circular ≤ 0.02 mm diameter.

Forelius damiani and Forelius pruinosus are the first species of the genus Forelius known from Colombia. Both species have been collected in the lowland dry forest of the Sierra Nevada de Santa Marta while F. damiani has also been collected in Zambrano (Bolívar), northern Colombia. The Zambrano specimens do not differ from those of the type locality. The workers of F. damiani from Costa Rica differ somewhat in size (TL 1.50-1.68 mm in Costa Rica vs. TL 1.40-1.58 mm in Colombia) and the length of the scapes (exceeding the vertexal margin by 0.04 mm in Costa Rica, not exceeding the vertexal margin in Colombia). While the TL of the workers showed differences between the populations of Costa Rica and Colombia, the length of mesosoma is less variable and the measurements for the two countries broadly overlap (MsL 0.46-0.56 mm in Costa Rica vs. MsL 0.44-0.58 mm in Colombia). Specimens from Costa Rica are darker brown than those from Colombia.

Forelius damiani is relatively similar to F. pruinosus, but F. damiani has only two erect pronotal hairs while F. pruinosus can have two to four erect pronotal hairs; the promesonotum of F. damiani is lower compared with F. pruinosus; the dorsal face of the propodeum is longer than the declivitous face in F. damiani, moreover it lacks propodeal hairs; and F. damiani is smaller than F. pruinosus in some measurements such as TL, HL, HW and SL (see measurements above and Cuezzo (2000) for comparison). Forelius damiani is similar to Forelius pusillus, however several characters show differences: the mandibles of F. damiani have four teeth while those of F. pusillus have five; the propodeum of F. pusillus has four conspicuous setae but F. damiani has none; the workers in F. pusillus are a little larger (TL 1.6-1.8 mm in F. pusillus vs. 1.40-1.68 mm in F. damiani). Characters that distinguish Forelius damiani from most other Forelius species are the circular propodeal spiracle and the absence of erect hairs on the dorsal face of the propodeum.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Colombia, Guatemala, Mexico.

Biology
Guerrero & Fernandez (2008) - Forelius damiani was collected in lowland dry forest of the Sierra Nevada de Santa Marta, a tropical forest with an open canopy dominated by Bursera simaruba (L.) Sarg. (Burseraceae), Bursera glabra (Jacq.) Triana & Planch and Pereskia colombiana Britton & Rose (Cactaceae). The habitat is subjected to occasional human disturbance resulting from the extraction of timber. It was also collected in the dry forest of Zambrano (Bolívar, Colombia), but we have no specific information about floristic composition from this site. However, this locality is a transition zone between gallery forest and tropical dry forest. This species is restricted to lowland forest and scrub vegetation, from sea level to 650 m elevation.

The specimens from Costa Rica were collected in open tropical dry forest, xeric scrub, and synanthropic habitats in wet forest areas. Although the genus is generally adapted to dry climates, this species can extend into wet climate areas in the presence of frequent human disturbance.

Although no complete nest of F. damiani has been collected, the large number of specimens collected from the type locality with only one pitfall trap (150 workers) indicates that its colonies could be composed of more than one hundred workers, foraging in large numbers.

Jack Longino: This species occurs in open areas with bare soil or sparse vegetation cover. It favors roadsides and pastures. For example, it has been collected once at La Selva Biological Station, in the grassy area around the dining hall, yet in spite of long-term intensive collecting activity it has never been collected in the adjacent forested habitats. Ward (2005) discussed this species in his treatment of California ants (Guerrero and Fernández (2008) subsequently described it). It is broadly sympatric with Forelius pruinosus. Ward found both species sympatrically in an area just east of Playa Nancite in Santa Rosa National Park.

Nomenclature

 *  damiani. Forelius damiani Guerrero & Fernández, 2008: 53, figs. 1-3 (w.) COLOMBIA.

Worker
Holotype. TL 1.56, HL 0.48, HW 0.38, EL 0.10, EW 0.08, IOD 0.24, COD 0.10, SL 0.40, PSW 0.01, PSL 0.01, ISPD 0.10, PL 0.10, PHM 0.08, MsL 0.44, CI 79, OI 125, SI 105.

Paratypes and non types (n= 38): TL 1.40-1.68, HL 0.42-0.50, HW 0.36-0.42, EL 0.10-0.12, EW 0.08-0.10, IOD 0.22-0.32, COD 0.04-0.10, SL 0.36-0.44, PSW 0.01-0.02, PSL 0.01-0.02, ISPD 0.10-0.16, PL 0.08-0.14, PHM 0.06-0.10, MsL 0.44-0.58, CI 79-90, OI 120-150, SI 95-132.

Head flattened dorsoventrally, longer than wide (full face view). Vertex of head weakly concave. Palpal formula 6:4. Anteromedial clypeal plate with shallow concavity and long, ventrally curved setae about same length as closed mandibles. Clypeal margin with a long median seta and two long lateral setae projecting forward. Long erect seta on middle inner margin of each torulus; long seta behind each torulus. Scape short, reaching posterior margin of head. Mandible with apical tooth elongate, twice as long as subapical tooth; subapical tooth followed by a denticle, a tooth, another denticle, and a basal tooth separating masticatory margin from basal margin. Mesosoma (lateral-view) straight with slight mesonotal groove. Mesonotum and propodeum with decumbent scattered pubescence; very fine punctuation on dorsum of mesonotum and dorsum of propodeum. Mesopleuron and metapleuron shining, with sparse pubescence. Propodeal spiracle circular. Posterior face and dorsal face of propodeum convex; dorsal face longer than posterior face. Outer face of anterior coxa with two setae; proximal seta longer than distal seta; inner face of middle and posterior coxae with distal setae; femora and tibiae with dense pilosity. Scale present and strongly inclined anteriorly; petiolar spiracle at base of scale. Dorsum of gaster with abundant pubescence; first gastric (third abdominal) tergite without setae, second gastric tergite bearing 2 setae, third gastric tergite bearing 4 setae and fourth tergite bearing 6 setae. Head and mesosoma dark brown; gaster, petiole, legs, scape and mandible light brown; teeth of mandibles slightly darker than mandible; funicular segments darker than scape.

Type Material
Holotype worker. Colombia: Magdalena; Santa Marta; Vda. Mosquito; 11°10'23.6" N 74°10'45" W 96 m; pitfall; 24-26.Feb.2007; D. Ramírez, coll. Deposited in ICN Insect Collection, Instituto de Ciencias Naturales, Universidad Nacional de Colombia, (Bogotá D.C., Colombia). Paratypes: 22 workers, all from the same locality and date as the Holotype, deposited in (1w),  (4w), CEUM (2w),  (1w),  (1w),  (2w), ICN (2w),  (2w),  (1w),  (1w),  (1w),  (1w),  (1w),  (1w),  (1w).

Etymology
The species name honors our colleague and friend Damian Ramírez, who collected and loaned the ants from his thesis research.

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Guerrero R. J., and F. Fernández. 2008.  A new species of the ant genus Forelius (Formicidae: Dolichoderinae) from the dry forest of Colombia. Zootaxa. 1958: 51-60.
 * Longino, J.T. 2010. Personal Communication. Longino Collection Database