Megalomyrmex fungiraptor

The natural history of this species is unknown but the numerous unique shared morphological characters of the narrow symmetochus complex strongly suggest that M. fungiraptor are guest ants like Megalomyrmex symmetochus and Megalomyrmex adamsae, the former associating with Sericomyrmex species and that latter with Trachymyrmex species (Longino 2010; Adams, Shah et al. 2012). Although Sericomyrmex aztecus was collected at the same baiting station (using Keebler Pecan Sandies) as the type series of M. fungiraptor, suggesting it a likely host, other Attini were collected at baits in the same locale, including Trachymyrmex cornetzi (host of Megalomyrmex wettereri), Cyphomyrmex rimosus sensu lato (host to Megalomyrmex mondabora), and Cyphomyrmex costatus (host to Megalomyrmex mondaboroides and Megalomyrmex silvestrii). Sericomyrmex amabilis—the host of Megalomyrmex symmetochus—build tunnels in the leaf litter, and the Megalomyrmex are often found in the tunnels. If this is also true for the M. fungiraptor host, this might explain why they were able to be baited and do not always remain subterranean. Alternatively, this species may be a facultative social parasite like M. silvestrii and may nest and forage independent of their host colony. The only known queens were collected at a blacklight at the La Selva Biological Station in Costa Rica. Wheeler (1925) reported that Sericomyrmex groom the tarsi of their M. symmetochus guests. Future work could examine possible function of the unique compressed basitarsi of M. fungiraptor and M. symmetochus.

Identification
Boudinot et al. (2013) - Worker uniquely identified by the combination of two characters: (1) meso- and metabasitarsi strongly compressed; (2) postpetiole about twice as wide as tall. Identification supported by the following: (1) katepisternum costate; (2) dorsal face of mandible striate; (3) dorsal and posterior faces of propodeum meeting at a blunt angle; (4) subpostpetiolar process strong, long, fang-like. Queen similarly identifiable as worker, alate.

Megalomyrmex fungiraptor is the most robust species in the symmetochus complex and has been collected in sympatry with Megalomyrmex symmetochus in Nicaragua and Honduras. In terms of gross morphology, M. fungiraptor shares several characteristics which distinguish Megalomyrmex adamsae from Megalomyrmex symmetochus and vice versa. The most compelling character uniting M. fungiraptor to M. symmetochus is the anteroposterior compression of the basitarsi—a unique trait, at least within the Central American Megalomyrmex fauna. At least one character, beyond body size, is shared between Megalomyrmex fungiraptor and M. adamsae: the meeting between dorsal and posterior faces of the propodeum is angular. For a discussion of separating M. fungiraptor from M. adamsae, see the “Comments” section of the latter species.

This species is immediately distinguishable from M. adamsae by the anteroposteriorly flattened meso- and metabasitarsi. It is distinct from M. symmetochus by the following: (1) posterior face of postpetiole subopaque, roughened by fine rugulose sculpture (vs. smooth and shining above carinae); (2) sternal process of postpetiole projecting anteroventrally as a long fang-like process in profile (vs. short); (3) dorsal margins of petiole and postpetiole weakly convex in posterior view (vs. strongly convex); (4) postpetiole relatively broader; (5) anterior and posterior faces of postpetiole parallel in profile view (vs. posterior face evenly sloping to base); (6) petiolar node relatively narrow; (7) foraminal carina entire (vs. medially obsolescent); (8) setae on antennomeres 3–8 decumbent (vs. appressed); (9) head dorsum and temple roughened by fine, sometimes weak, carinulae extending from piligerous punctures (vs. smooth and shining between piligerous punctures); (10) setae stouter and less erect.

Key to Central American Megalomyrmex workers

Distribution
Nicaragua to Costa Rica; 50-310 m elevation.

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

Nomenclature

 *  fungiraptor. Megalomyrmex fungiraptor Boudinot, Sumnicht & Adams, 2013: 35, figs. 17, 19, 115–118, 238 (w.q.) NICARAGUA.

Worker
(holotype): HW 0.85, HL 0.90, SL 0.84, OMD 0.18, EL 0.26, ML 1.25, CI 94, SI 96, EI 30, OMI 68. (n=7): HW 0.81-0.87, HL 0.84–0.94, SL 0.79–0.87, OMD 0.17–0.20, EL 0.25–0.27, ML 1.25–1.36, CI 92-94, SI 90–93, EI 30–32, OMI 67–74.

Head Palpal formula 3,2. Basal and masticatory margins of mandibles distinct. Mandible with 6-8 teeth: apical tooth largest; tooth size decreasing towards basal margin. Dorsal surface of mandible coarsely striate. Clypeus convex in profile. Frontal carina with 2–3 proximal parallel carinulae extending posteriorly to about anterior margin of compound eye. Antennal fossa surrounded by 1–2 fragmented carinulae. Malar area with coarse carinulae. Compound eye with medium-long ocular setae. Occipital carina thin; not visible in full-face view; extending on ventral surface about one third distance to hypostomal margin. Mesosoma Katepisternum, anepisternum, and lower lateral sides of propodeum with longitudinal rugae. Metapleural carinulae reaching meso-metapleural suture. Dorsal face of propodeum meeting posterior face at a blunt angle. Posterior face of propodeum with 1–3 transverse carinulae. Foraminal carina entire. Meso- and metabasitarsi anteroposteriorly compressed. Posterior base of petiole and posterior face of postpetiole with several pronounced transverse carinae. Metasoma Ventral keel of petiole a low translucent flange, forming a short angular tooth anteriorly. Keel splitting into two small subparallel carinulae posteriorly in ventral view. Postpetiolar sternum produced as a long, sharp, anteriorly projecting tooth. Lancets of sting apparatus longer than sting shaft, narrow, broadening to truncate apex; sting shaft apically spatulate. Setation Uniformly dense, suberect to subdecumbent coarse setae present on: femora, tibiae, scape, head, mandible, mesosoma, and first gastric tergum. Most of cuticle smooth and shining although face, dorsal surface of head, clypeus, promesonotum, dorsal petiole and dorsal postpetiole with uniformly distributed piligerous punctae tilted such that one side of each puncta is raised above the other. General body and appendage color deep orange; mandibles dark brown; first gastric tergum with a wide black band wrapped wrapped around the posterior two thirds.

Queen
(n=3): HW 0.93–0.95, HL 0.96–0.94, SL 0.84–0.87, EL 0.34–0.35, ML 1.52–1.59, CI 102–103, SI 90–92, EI 37.

Similar to worker; differing by having an alate-condition mesosoma, with coarser sculpturation, and denser setation. Forewing with pterostigma; crossvein 1m-cu present; submarginal cell 1 between four and five times longer than width; apical abscissa of M branching from Rs+M basad 2r-rs, becoming spectral around where it curves apicad.

Type Material
Holotype worker NICARAGUA, Región Autónoma del Atlántico Norte: PN Cerro Saslaya, 13.77036°N 84.98102°W ±100 m, 320 m, 9 May 2011, tropical wet forest at bait (LLAMA#Ba-D-02-1-05-01) CASENT0629661,.

Paratype workers: (9) same data as holotype (CASENT0629666, ; CASENT0629662, ; CASENT0629664, ; CASENT0629256,; CASENT0629663, ; CASENT0629665, ; CASENT0629667, ; CASENT0629660, ; CASENT0629781, ).

Etymology
Stems are from Latin, meaning “fungus thief.” The specific epithet is a noun in apposition, and thus invariant.