Strumigenys epinotalis

The species was described from "1 female and 4 workers ... collected by Dr. George C. Wheeler from Talia Farm, Estrella Valley, Costa Rica, June 18, 1924 (Weber 1934)." Dozens of sifted litter samples from Atlantic slope wet forest, including sites near the type locality, have not produced examples of this species. The species skwarrae, synonymized with epinotalis by Brown (1953), was "described from 15 specimens representing four colonies, all taken by Dr. Skwarra in Tillandsia streptophylla in two localities: Tlacocintla (type locality; 487 and 494) and Mirador (153 and 290) [Wheeler 1934]." Bolton (2000) reports Mexican collections by Dressler and by Dejean, both researchers who work with epiphytes. These observations all suggest the species is arboreal. (Longino, Ants of Costa Rica)

Identification
Bolton (2000) - A member of the Strumigenys schulzi-group. A very distinctive small species that is immediately characterised by its dentition and pilosity. Unlike most species in this group the postpetiole disc is completely smooth and the petiole ventrally has a distinctly spongiform longitudinal crest. The curved row of spoon-shaped hairs that adorn the top of the mid -pronotal arched-transverse ridge is very distinctive in dorsal view and is a unique development of this species.

Longino (Ants of Costa Rica) - Mandibles in side view straight, not broadly curved ventrally; mandibles relatively short, subtriangular, much of the apical portion meeting along a serially toothed masticatory margin when closed (former Smithistruma); leading edge of scape with a row of conspicuous projecting curved hairs, of which those distal to the subbasal bend distinctly curve toward the base of the scape; pronotal humeral hair absent; dorsal surfaces of middle and hind tibiae with decumbent to appressed short spatulate hairs; face punctate; side of mesosoma completely punctate; petiole with ventral spongiform appendage; postpetiole disc completely smooth; mid-pronotal arched-transverse ridge with row of spoon-shaped hairs, most visible in dorsal view; first gastral tergite smooth behind the basigastral costulae, the latter distinct and extending at least the basal fifth to quarter of the length of the tergite, not masked by dense sculpture; infradental lamella of propodeum strongly developed.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Argentina, Brazil, Costa Rica, Ecuador, Mexico, Panama, Paraguay.

Biology
Chen, et al. (2012) - Although the vast majority of dacetine ants nest in soil and leaf litter, members of the schulzi species group are typically associated with plants, and several species have been recorded from epiphytes or plant cavities (Bolton 2000). Many species in this group also differ in that workers have enlarged compound eyes, as compared with their epigeic and hypogeic relatives. Similar to most members of this group, P. epinotalis also has enlarged eyes and is thought to be an arboreal species. Weber described this species in 1934 from specimens collected by GeorgeWheeler in 1924 in an Atlantic slope wet forest in Costa Rica, but he did not indicate whether the ants were collected arboreally or in litter (Weber 1934a). Collecting in the same region years later, Longino reported that multiple litter samples from near the type locality did not yield specimens of this species, which suggests that perhaps this species might be arboreal (Longino, Ants of Costa Rica). In 1934, Wheeler reported that Dr. Skwarra discovered four colonies of this species (reported as Strumigenys skwarrae Wheeler) in Tillandsia streptophylla at two localities in Mexico in 1929 (Wheeler 1934g). Bolton (2000) reported that collections of this species were made in Mexico by Dressler and by Dejean, both of whom worked with epiphytes, which implies they collected their specimens from epiphytes. More recently, Rider reported collections of this species in the canopy in Ecuador, which further validates its status as an arboreal species (Blogspot: The Ant Room, 2007, "Tiputini Pyramica and Strumigenys")

Here we report the first records of P. epinotalis for the United States. A single alate female was collected by Mark Deyrup in Highlands County, Florida, on 14 August 2009 using a Townes Malaise trap (M. Deyrup, pers. comm.). Five females and 14 workers were collected in Ascension, Jefferson, and Saint James Parishes in Louisiana on various dates from 8 to 21 September 2009 and from 30 May to 23 September 2011. The Louisiana locations are all within the Mississippi River deltaic plain in coastal Louisiana. These collections were made in Cypress-tupelo swamps using floating pitfall traps placed directly upon the surface of the water and with cup traps, bottle traps and trunk traps placed on trunks and branches of three species of trees: bald cypress (Taxodium distichum), water tupelo (Nyssa aquatica) and red maple (Acer rubrum var. drummondii). [see the publication for additional specimens and their collection details. These records significantly extend the northward distribution of S. epinotalis].

As noted, this species is thought to be primarily an arboreal species. Similarly, collections in Louisiana were all made from arboreal traps except for a single worker that was collected using a floating pitfall trap, which was in the same habitat type. Xuan Chen also collected ants in leaf litter and quadrats on ground cover in both locations, yet S. epinotalis was not found. Although the single Florida collection was made in scrub habitat, the alate female could have flown there from nearby bayhead habitat. The sum of the collection records suggests this species prefers wetland forest habitats, which includes the swampy, wetland habitats of the Louisiana collections.

It seems likely that P. epinotalis is an introduced species. Evidence for this includes the large geographical gap between the known distribution and the new records of this species from Florida and Louisiana. Nonetheless, If S. epinotalis is truly associated with wetland forests, this species may easily be overlooked. Collections along the eastern edge of Mexico and into Texas could greatly enhance our knowledge of this species’ distribution and provide information on whether or not it is truly an introduced species. Until such time as these collections can be made, we tentatively consider this species to be an exotic species to the US.

Brown (1964) - Two new records from southern Mexico further confirm the tendency of this species to nest, like other schulzi-group members, in plant cavities: Veracruz, Veracruz, in hollow twigs (N. L. H. Krauss leg.); Laguna Ocotal Grande, 950 m. Ocosingo Valley, Chiapas, in epiphytic Tillandsia bulb in pine forest (R. L. Dressler leg.).

Nomenclature

 *  epinotalis. Strumigenys (Cephaloxys) studiosi subsp. epinotalis Weber, 1934a: 46 (w.q.) COSTA RICA. Combination in Smithistruma: Brown, 1953g: 101; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 119. Raised to species and senior synonym of skwarrae: Brown, 1953g: 101. See also: Bolton, 2000: 219.
 * skwarrae. Strumigenys (Cephaloxys) skwarrae Wheeler, W.M. 1934g: 177 (w.) MEXICO. Junior synonym of epinotalis: Brown, 1953g: 101.

Worker
Bolton (2000) - TL 1.9-2.1, HL 0.49-0.56, HW 0.39-0.42, CI 73-79, ML 0.11-0.12, MI 20-22, SL 0.25-0.27, SI 62-66, PW 0.25-0.28, AL 0.50-0.56 (to measured). Tooth 3 from the base elongate and spiniform, longer than 1-2 or 4-5, all of which are about of equal length and acute. Anterior clypeal margin evenly shallowly convex. Eye with 5-6 (rarely 7) ommatidia in the longest row. Scape broad in dorsal view, ca 4.5 X longer than its maximum width. Ground-pilosity of head of conspicuous medially curved spoon-shaped hairs. Vertex behind highest point with a transverse row of 4 longer, more erect and somewhat stouter hairs. Apicoscrobal hair thick, anteriorly curved and spoon-shaped, longer and more strongly laterally prominent than any other hair on the margin. Pronotal humeral hair absent. Pronotal dorsum at its midlength with a broadly arched low transverse ridge that bears a row of anteromedially curved spoon-shaped hairs. Mesonotum with curved spoon-shaped ground-pilosity but without standing hairs of any form. Head and alitrunk usually densely reticulate-punctate on every surface, but rarely the katepisternum with a small shining patch. Lamella on propodeal declivity broad. Petiole node markedly broader than long in dorsal view; in profile with a narrow but distinct longitudinal spongiform crest ventrally. Disc of postpetiole smooth and shining, the lateral and ventral postpetiolar spongiform lobes large. Basigastral costulae extending over the basal quarter to third of the sclerite, sharply defined; tergite otherwise smooth and shining. Hairs on first gastral tergite numerous, suberect to erect, stout straight and thickened or remiform apically. First gastral stemite in profile with narrow but distinct basal spongiform pad.

Type Material
Bolton (2000) - Syntype workers and queen, COSTA RICA: Estrella Valley, Talia Farm, 18.vi.1924 (G. C. Wheeler) [examined].

References based on Global Ant Biodiversity Informatics

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 * Maes, J.-M. and W.P. MacKay. 1993. Catalogo de las hormigas (Hymenoptera: Formicidae) de Nicaragua. Revista Nicaraguense de Entomologia 23.
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 * Weber N. A. 1934. Notes on neotropical ants, including the descriptions of new forms. Revista de Entomologia (Rio de Janeiro) 4: 22-59.