Eurhopalothrix circumcapillum

This species inhabits mature wet forest from near sea level to lower cloud forest. It is known from 200–1110 m elevation. All specimens are from Winkler samples of sifted litter and rotten wood from the forest floor. On Cerro Saslaya in Nicaragua, it occurs in less than 5% of Winkler samples and occurs more or less evenly from 300–1100 m. In Costa Rica it occurs sporadically on the Atlantic slope. (Longino 2013)

Identification
Mandible with single tooth row; face with 14 or 16 specialized spatulate setae (anterior row 6 or 8, middle row 4, posterior row 4); ground pilosity of face spatulate, decumbent, weakly differentiated from specialized projecting setae, in discrete patches on posterolateral face, leaving median strip bare, anterior border of ground pilosity abrupt, at level of anterior row of specialized projecting setae; posteromedian vertex with shallow depression; pronotum with 1 pair spatulate setae, lacking on mesonotum; first gastral tergite typically lacking erect setae. Similar to Eurhopalothrix machaquila, Eurhopalothrix megalops, Eurhopalothrix ortizae, Eurhopalothrix oscillum, Eurhopalothrix schmidti, Eurhopalothrix semicapillum. (Longino 2013)

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Nicaragua.

Nomenclature

 *  circumcapillum. Eurhopalothrix circumcapillum Longino, 2013: 116, figs. 14E, 17, 36 (w.q.) NICARAGUA.

Worker
HW 0.66–0.75, HL 0.63–0.69, SL 0.36–0.39, SLL 0.04–0.05, CI 103–108, SLI 10–14 (n=6). Anterolateral gibbosities of basal portion developed as sharply right-angled, ventrally-directed teeth, apical portion elongate, flexed dorsally, relatively narrow, distinctly bilobed at apex; apex with a fringe of short, non-capitate translucent setae; mandible triangular, dorsal surface convex, smooth and shining apically, grading to punctate basally, rounding into ventral surface; interior surface concave, smooth and shining; masticatory margin a single row of 11 flattened acute triangular teeth; scape with moderately developed basal lobe; scrobe deep, sharply delimited dorsally and ventrally, abutting deep antennal socket; surface of scrobe shallowly foveolate anteriorly, smooth and shiny posteriorly; eye small, about 5 ommatidia across greatest diameter; clypeus approximately planar, uniformly covered with small puncta; sides of head above eyes moderately angulate; surface of face with longitudinal median impression; entire surface of face punctate, puncta larger and sparser posteromedially, with smooth interspaces, becoming more confluent anteriorly and laterally; occipital carina indistinct; undersurface of head uniformly punctate; postgenal suture a well-developed longitudinal trough, darker than surrounding cuticle.

Promesonotal profile convex, with weakly differentiated anterior, dorsal, and posterior faces, meeting flat dorsal face of propodeum at obtuse angle; metanotal groove a narrow impressed groove; dorsal and posterior faces of propodeum distinct, meeting at obtuse angle, dorsal face shorter than posterior face; propodeal spine laminar, translucent, triangular, acute, ventral margin rounding into narrow infradental lamella that extends down posterior face to propodeal lobe; propodeal spiracle small, directed posteriorly in small concavity between base of propodeal spine and dorsum of metapleural gland bulla; all of mesosoma except posterior face of propodeum uniformly punctate with smooth interspaces; posterior face of propodeum smooth to very faintly sculptured; no transverse carinae between bases of propodeal spines; puncta on promesonotum larger than those on katepisternum and side of propodeum; interspaces sublucid on promesonotum, more matte on katepisternum and side of propodeum.

Petiolar peduncle joins anterior face of petiolar node at rounded obtuse angle; anterior face of node meets sloping flat dorsal face at rounded right angle; posterior face of node very short; ventral margin of petiole with short, acute, anteroventral tooth; postpetiole low and broad, with a broad longitudinal sulcus dorsally; first gastral sternite lacking anterior sagittal keel; petiole, postpetiole, and gaster densely punctate, puncta on anterior portions of first gastral tergite and sternite separated by smooth interspaces subequal in width to width of puncta, puncta becoming smaller and more confluent posteriorly.

Dorsal surface of scape covered with uniform short, decumbent, spatulate setae; leading edge of scape with projecting clavate setae, short near apex of scape, gradually lengthening to longest setae on basal lobe; ground pilosity on clypeus obsolete; conspicuous ground pilosity of face composed of large setae, similar in shape and slightly larger than those on scape, decumbent, distributed in two sharply delimited patches, delimited anteriorly at anterior row of projecting specialized setae, delimited medially to leave bare median furrow, extending laterally to posterolateral margins of head; projecting specialized setae spatulate, about twice as long as wide, curved, about twice as large as ground pilosity (and thus not highly differentiated from it), full complement typically 16, with curved anterior row of 8 (occasionally 6), transverse median row of 4, and posterior row of 4 on vertex margin; ground pilosity obsolete on dorsal mesosoma and metasoma; typically one pair of projecting small spatulate setae on pronotum, similar to those on face; legs with ground pilosity similar to that on face, dense on apices of femora, dorsal and anterior faces of mid and hind tibia, weaker on dorsal and posterior face of fore and midtibia, sparser to absent elsewhere; apex of foretibia with 1 larger spatulate seta, apices of mid and hind tibia with 2; basitarsus with 3–5 pairs suberect clavate setae, remaining tarsomeres each with pair of suberect clavate setae, tarsal setae smaller on foretarsus than on mid and hind tarsus; hind margin of dorsal face of petiolar node usually lacking setae; hind margin of postpetiole usually with pair of small spatulate setae laterally, usually lacking median pair; first gastral tergite usually lacking specialized setae, rarely one or two irregularly distributed.

Color dark brown.

Queen
HW 0.68–0.71, HL 0.66–0.67, SL 0.38–0.39, SLL 0.05, CI 103–107, SLI 13–14 (n=3). Similar to worker in most respects; ocelli present; compound eye much larger than worker eye; anepisternum separated from katepisternum by U-shaped groove; metapleuron separated from propodeum by broad U-shaped groove; puncta fading on anterodorsal katepisternum, leaving small smooth patch; pronotum with 1 pair spatulate setae; mesoscutum with 4–6 straight, erect, narrowly clavate setae; axilla with clavate seta; scutellum with 1 pair spatulate setae; petiolar node with or without pair of spatulate setae; posterior margin of postpetiole with lateral pair spatulate setae, with or without smaller median pair; first gastral tergite lacking specialized setae.

Type Material
Holotype worker: Nicaragua, Región Autónoma del Atlántico Norte: PN Cerro Saslaya, 13.77216 - 84.99613, ±20 m, 670 m, 8 May 2011, montane wet forest, ex sifted leaf litter (LLAMA Wm-D-02-1-08), unique specimen identifier CASENT0639417. Paratype workers, queens: same data as holotype CASC, CASENT0639420 (dealate queen);, CASENT0639416; ECOSCE, CASENT0639418; , CASENT0639414; , CASENT0639413; , CASENT0639411; , CASENT0639412; , CASENT0639419; , CASENT0639410, CASENT0639421 (dealate queen); , CASENT0639415.

Etymology
The name is in reference to the sharply delimited patches of ground pilosity on the face. It is a noun in apposition and thus invariant.

References based on Global Ant Biodiversity Informatics

 * Longino J. T. 2013. A review of the Central American and Caribbean species of the ant genus Eurhopalothrix Brown and Kempf, 1961 (Hymenoptera, Formicidae), with a key to New World species. Zootaxa 3693(2): 101-151.
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/