Strumigenys silvestrii

A South American species that has spread to other areas of the Neotropics. Strumigenys silvestrii likely has similar food habits as the three highly successful Old World tramp dacetine ants, Strumigenys membranifera, Strumigenys emmae, and Strumigenys rogeri, preying on tiny soil arthropods, such as Collembola (Wetterer, 2011, 2012a, b). The ecological importance of these dacetine invaders, however, remains largely unstudied.

Strumigenys silvestrii is a native to tropical and subtropical South America and has been introduced to the USA, Mexico, and Portugal (MacGown et al. 2012; Guénard et al. 2017). Although ranging across all southeastern Atlantic Gulf states, it is not commonly collected across its USA range. This species inhabits drier more open habitats than most Nearctic species and is often picked up in pitfall traps or flight traps in areas with little leaf litter accumulation. Fewer collectors have recorded this species occurring in heavily forested habitats. Both males and queens have been collected for this species, with mating flights in Texas between late May and mid-July (estimated from alate collections). The earliest record from Texas is 1969 and from California is 1996 (MacGown et al. 2012) (Booher, 2021).

Identification
Bolton (2000) - A member of the Strumigenys silvestrii-group. Within the silvestrii-group 6 species have pilosity on the first gastral tergite that is not predominantly or entirely of fine elongate or flagellate hairs. In these 6 the pilosity of the first gastral tergite is of spatulate, remiform or simple stiff hairs. One such species, Strumigenys ascita, has two narrowly spiniform preapical teeth on each mandible, as opposed to one tooth and a minute denticle in the remainder. Three species of Central American origin (Strumigenys calamita, Strumigenys perdita, Strumigenys nastata) retain spongiform tissue on the ventral surface of the petiole and have two pairs of short erect hairs on the cephalic dorsum. In the last two species, Strumigenys epelys and silvestrii, the petiole lacks spongiform tissue ventrally and the cephalic dorsum bears only a single pair of short erect hairs. Of these two species epelys lacks the projecting hairs on the head and alitrunk that are listed above for silvestrii. Finally, silvestrii is the only species of the 6 to have its distal preapical tooth set very close to the apicodorsal tooth.

Distribution
Apparently from South America and subsequently spread to the southern US and the West Indies. Strumigenys silvestrii has recently been found for the first time in the Old World, from the island of Madeira, mainland Portugal, and Macau. (MacGown et al. 2012)

Argentina to Guyana; introduced in USA, Mexico, most Caribbean Islands and Portugal; in eastern USA from Florida to North Carolina and west to Louisiana; in western USA occurs in California and Texas (Booher, 2021).

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Argentina, Bahamas, Brazil, Cuba, Dominican Republic, Greater Antilles, Grenada, Paraguay. Palaearctic Region: China, Iberian Peninsula, Portugal.



Biology
Not much is known about the biology of this species. In general, (for species in this genus)

Florida (USA)
Deyrup et al. (2000) - A rare but widely distributed species, known from a few sites from the keys north to Gadsden County. Found in leaf litter in woods. Members of this genus feed on small organisms, especially Collembola. First published Florida record: Johnson 1986; earlier specimens: 1984.

Nomenclature

 *  silvestrii. Strumigenys silvestrii Emery, 1906c: 168, fig. 27 (w.q.) ARGENTINA. Senior synonym of caribbea: Brown, 1959f: 25. See also: Bolton, 2000: 559.
 * caribbea. Strumigenys (Strumigenys) caribbea Weber, 1934a: 43, fig. 12 (w.q.) CUBA. Junior synonym of silvestrii: Brown, 1959f: 25.

Worker
Bolton (2000) - TL 1.6 - 2.0, HL 0.42 - 0.49, HW 0.33 - 0.37, CI 76 - 80, ML 0.22 - 0.26, MI 50 - 57, SL 0.24 - 0.31, SI 76 - 86, PW 0.21 - 0.25, AL 0.38 - 0.48 (6 measured). Apical fork of mandible usually with a minute intercalary denticle, may be very difficult to see; absent in some. Mandible with preapical tooth located very close to apicodorsal tooth; the two almost adjacent and the length of the preapical tooth greater than the distance between it and the apicodorsal. A minute denticle also present on inner margin of mandible, often difficult to see, located close to midlength. Ground-pilosity of head and leading edge of scape fine and slender, narrowly spatulate. Specialised projecting hairs on head and alitrunk stiff, feebly remiform or somewhat flattened apically: in apicoscrobal position; a short pair on cephalic dorsum close to occipital margin; at pronotal humerus; a pair on mesonotum. All hairs on first gastral tergite narrowly remiform and elevated, inclined toward midline in dorsal view, in profile appearing curved or inclined posteriorly. Petiole node in dorsal view slightly broader than long; ventral surface of petiole without spongiform tissue and lateral spongiform lobe vestigial to absent, at most nothing more than a slight expansion at apex of the posterior collar. Disc of postpetiole mostly or entirely smooth, at most with some faint superficial vestiges of sculpture.

Type Material
Bolton (2000):

Syntype workers and queen, ARGENTINA: Santa Catalina, Buenos Aires (F. Silvestri) [examined].

Strumigenys (Strumigenys) caribbea Weber, 1934a: 43, fig. 12. Syntype workers and queens, CUBA: Soledad, Cienfuegos, 15.viii.1933 (queens) (N.A. Weber); Soledad, Cienfuegos, 4.xi.1927 (workers) (W.S. Creighton) [examined].

References based on Global Ant Biodiversity Informatics

 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * Brown W. L., Jr. 1959.  The neotropical species of the ant genus Strumigenys Fr. Smith: group of silvestrii Emery. Studia Entomologica. (n.s.)2: 25-30.
 * Cuezzo F. 1999. Nuevas citas de hormigas de las tribus Dacetini y Basicerotini (Hymenoptera: Formicidae) para la República Argentina. Rev. Soc. Entomol. Argent. 58(3/4): 209-210.
 * Favretto M. A., E. Bortolon dos Santos, and C. J. Geuster. 2013. Entomofauna from West of Santa Catarina State, South of Brazil. EntomoBrasilis 6 (1): 42-63.
 * Fleck M. D., E. Bisognin Cantarelli, and F. Granzotto. 2015. Register of new species of ants (Hymenoptera: Formicidae) in Rio Grande do Sul state. Ciencia Florestal, Santa Maria 25(2): 491-499.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * MacGown J. A., J. K. Wetterer, and J. G. Hill. 2012. Geographic spread of Strumigenys silvestrii (Hymenoptera: Formicidae: Dacetini). Terrestrial Arthropod Reviews DOI 10.1163/18749836-05031051
 * Medeiros Macedo L. P., E. B. Filho, amd J. H. C. Delabie. 2011. Epigean ant communities in Atlantic Forest remnants of São Paulo: a comparative study using the guild concept. Revista Brasileira de Entomologia 55(1): 7578.
 * Rosa da Silva R. 1999. Formigas (Hymenoptera: Formicidae) do oeste de Santa Catarina: historico das coletas e lista atualizada das especies do Estado de Santa Catarina. Biotemas 12(2): 75-100.
 * Siqueira de Castro F., A. B. Gontijo, W. Duarte da Rocha, and S. Pontes Ribeiro. 2011. As comunidades de formigas de serapilheira nas florestas semidecíduas do Parque Estadual do Rio Doce, Minas Gerais. MG.BIOTA, Belo Horizonte 3(5): 5-24.
 * Vittar, F. 2008. Hormigas (Hymenoptera: Formicidae) de la Mesopotamia Argentina. INSUGEO Miscelania 17(2):447-466
 * Vittar, F., and F. Cuezzo. "Hormigas (Hymenoptera: Formicidae) de la provincia de Santa Fe, Argentina." Revista de la Sociedad Entomológica Argentina (versión On-line ISSN 1851-7471) 67, no. 1-2 (2008).
 * Wild, A. L. "A catalogue of the ants of Paraguay (Hymenoptera: Formicidae)." Zootaxa 1622 (2007): 1-55.