Leptanilloides prometeus

Delsinne et al. (2015) - All the specimens were collected from a single reserve bordering the Podocarpus National Park on the eastern Andean slope of southern Ecuador. The habitat is an evergreen lower montane forest (Homeier et al. 2008) which is in nearly pristine condition. The forest harbours more than 300 tree species, with Lauraceae, Melastomataceae and Rubiaceae being the most species-rich families (Homeier et al. 2012). The mean annual temperature is c. 15 °C and mean annual precipitation is c. 2200 mm, with low seasonality (Bendix et al. 2008). Soils of the sampling area are cambisols, with a very thick (often > 50 cm) leaf litter layer (Homeier et al. 2012). Soil texture is sandy silt loam; proportion of sand, silt and clay is 41%, 52%, and 6%, respectively; mean pH = 3.2 ± 0.1 SD (n = 24 soil samples).

Identification
Delsinne et al. (2015) - Leptanilloides prometeus belongs to the Leptanilloides biconstricta species-group. and can be distinguished by the combination of the following characters: masticatory margin of mandible dentate but teeth extremely minute, blunt and irregularly shaped (Fig. 6C, see below); lateroclypeal tooth present (Fig. 6C); head with piligerous foveolae separated by smooth interspaces equaling, on average, puncture diameters; fine, uninterrupted reticulation on mesopleuron, metapleuron and lateral side of petiole; flange over metapleural gland opening forming a short, blunt projection (Fig. 6D); and subpetiolar process relatively straight (not distinctly bulging), without posterior angle (Fig. 6E).

Leptanilloides prometeus is the largest species of the L. biconstricta species-group. The most similar species in habitus and size is Leptanilloides improvisus, but head of L. prometeus is longer and its mandible has only minute and irregular teeth along the masticatory margin (teeth are conspicuous and regularly spaced in L. improvisus). Moreover, L. prometeus can easily be distinguished from other species in the group by: the presence of a conspicuous lateroclypeal tooth (absent in Leptanilloides caracola), the evenly rounded sternite of abdominal segment III (bulging anteriorly in L. biconstricta), the petiole being as long as the postpetiole (petiole longer than postpetiole in L. biconstricta), the petiolar sternite being higher in its anterior half (bulging medially in Leptanilloides gracilis and Leptanilloides femoralis), the head dorsum with foveolae separated by about their diameter (more densely foveolate in Leptanilloides sculpturatus, with foveolae separated by less than their diameter), and the short, blunt flange over the metapleural gland opening (long and sharply pointed in Leptanilloides atlanticus, Leptanilloides copalinga and Leptanilloides erinys).

Distribution
Known only from the type locality.

Distribution based on Regional Taxon Lists
Neotropical Region: Ecuador.

Castes
Known only from the worker caste.

Nomenclature

 * . Leptanilloides prometea Delsinne & Donoso, in Delsinne, et al. 2015: 12, figs. 4A-D, 5, 6A-F, 7A-C (w.) ECUADOR.
 * Type-material: holotype worker, 67 paratype workers.
 * Type-locality: holotype Ecuador: Zamora-Chinchipe Prov., Res. Biol. San Francisco (RBSF), 2070 m., 3°58’S, 79°05’W, 13.v.2010, leaf litter extract, Winkler (T. Delsinne & T. Arias-Penna); paratypes with same data.
 * Type-depositories: PUCE (holotype); BMNH, CASC, ICNB, ISNB, JTLC, MCZC, PUCE, UTPL (paratypes).
 * Distribution: Ecuador.

Worker
Holotype (3 paratypes): HW 0.4 (0.4–0.44), HL 0.58 (0.61–0.62), SL 0.27 (0.29), PrW 0.27 (0.29), WL 0.71 (0.76–0.78), MH 0.23 (0.24), PL 0.22 (0.22–0.23), PW 0.11 (0.12), PPL 0.22 (0.22–0.23), PPW 0.2 (0.22–0.23), AivL 0.31 (0.31–0.33), AivW 0.37 (0.38–0.4), FFeL 0.38 (0.38–0.4), FFeW 0.11 (0.11), HFeL 0.44 (0.44–0.45), HTL 0.42 (0.44–0.46), CI 69.23 (65.45–71.43), SI 66.67 (66.25–72.22), PI 50.00 (52.5–53.66), MI 32.81 (31.43–32.36).

With the characters typical of the genus (see diagnosis and description in Brandão et al. 1999 and Borowiec & Longino 2011; see here) and of the L. biconstricta species-group (see diagnosis of the group above). Other characters or differences are as follows: Head. Elongate and rectangular with lateral margin nearly straight and parallel. Posterior corner rounded. Posterior margin modestly convex, almost straight. Parafrontal ridge absent. Clypeal lamella strongly convex (Fig. 6C). Masticatory margin of mandible dentate but teeth extremely minute, blunt and irregularly shaped, difficult to discern even under magnifications of about 100× (Fig. 6C). Basal and masticatory margins united by a broad convexity. Basal margin faintly crenulate. Labial palp not readily visible but, at least, one-segmented, maxillary palp two-segmented. Hypostomal anterior border rounded and slightly projected outward but without forming a distinct tooth (Fig. 6A). Scape when laid back reaching about medial distance to posterior margin of head.

Mesosoma. Flange over metapleural gland opening conspicuous and posteriorly forming short, blunt projection, not surpassing propodeum declivity margin (Fig. 6D). Femur not conspicuously enlarged, relatively slender. Midtibia with one short (i.e., half size of foretibia strigil), pectinate spur (Fig. 6B), although pectination may be difficult to observe even at high magnification. Hindtibia with one broadly pectinate spur roughly as long as strigil. Metatibial gland present, visible at high magnification and good lighting as translucent oval area at apex of tibia, behind spur insertion (Fig. 4D). Metatibial gland pore plate observable in SEM (Fig. 7A–C).

Metasoma. Long and relatively slender. In dorsal view, petiole uniformly rectangular, twice as long as wide, as long as abdominal segment III (postpetiole). Anterior face concave, posterior face straight. In lateral view, petiole height approximately 1/4 smaller than height of abdominal segment III. Petiolar tergite dome-shaped, with short and poorly differentiated anterior and posterior faces, maximum height situated in posterior half. Short tubulated portion present posteriorly. Petiolar spiracle inconspicuous, not in excavation, set near anterior rim of tergite, similar in form and slightly smaller in diameter than propodeal spiracle. Subpetiolar process with ventral margin relatively straight (not distinctly bulging), and without posterior angle (Fig. 6E). Anterior projection of subpetiolar process variable in shape, acute to rounded (Figs 5, 6E). Maximum height of petiolar sternite situated in its anterior half. In dorsal view, abdominal segment III (postpetiole) trapezoid, with straight, parallel anterior and posterior faces. Posterior face almost twice as long as anterior face. In lateral view, tergite evenly convex, without well-differentiated posterior face. Sternite evenly rounded, slightly bulging anteriorly. In dorsal view, abdominal segments IV–VI subequal in length.

Pilosity and sculpture. Mandible smooth and shiny, with few scattered piligerous punctures. Head with abundant deep piligerous punctures and smooth interspaces on average equaling puncture diameter, except on ventral side and front where punctures are sparser, separated by more than their diameter. Mesosoma and abdomen more finely and sparsely punctate. Fine reticulate sculpture present laterally on lower pronotum, entire mesopleuron, propodeum, and petiole. Body and appendages with abundant, short and subdecumbent to suberect hairs. Body color brownish to reddish, with head and mesosoma tending to be darker than petiole and gaster. Legs and antennae yellowish.

Type Material
Holotype. ECUADOR: Worker, Zamora-Chinchipe Prov., Reserva Biológica San Francisco (RBSF}, 2070 m, 3°58’ S, 79°05’ W, 13 May 2010, within 0.5 m2 of leaf litter extracted with a mini-Winkler apparatus for 96 h, coll. Thibaut Delsinne and Tania Milena Arias-Penna (, sc 4267803). Paratypes (n = 67). ECUADOR: Same data as holotype except that specimens were captured after 48 h of Winkler extraction: 30 workers, 96% ethanol (, General Inventory Number 33044: sc 4052302 [1 specimen with DNA data], sc 4052314 [1 specimen with DNA data], sc 4052316 [21 specimens without DNA data]; [1 specimen, sc 4052317];  [1 specimen, sc 4052318];  [1 specimen, sc 4052319];  [1 specimen, sc 4052320];  [1 specimen, sc 4052321];  [1 specimen, sc 4052322];  [1 specimen, sc 4052323]); 3 workers, pinned (MUTPL), sc 4052310, 4052315; RBINS, sc 4052313); 2 workers, 96% ethanol after non-destructive DNA extraction (RBINS, sc 4052311, 4052312); 1 worker, gold-coated for SEM (RBINS, sc 4052301). – Same data as holotype except 21 Mar. 2010, within upper 5 cm of organic layer of a core (Ø 5 cm) extracted by heat using a modified high gradient extractor for 4 days: 28 workers, 96% ethanol (RBINS, sc 4060601); 2 workers, 96% ethanol after non-destructive DNA extraction (RBINS, sc 4060602, 4060603); 1 worker, pinned (MUTPL, sc 4060604). GenBank accession numbers: KT601698–KT601703 and KT750331.

Etymology
Name in apposition, in honour of the Prometeo initiative of the Ecuadorian government that seeks to strengthen research and knowledge transference by getting national and international experts to work together. This project is aligned to the Ecuadorian “National Development Plan for Good Living”, which has the objective, among others, of guaranteeing the rights of Nature and promoting a healthy and sustainable environment. Furthermore, the species is the largest of the L. biconstricta species-group and its name nicely reminds us of ‘Prometheus’, the Titan in Greek mythology who brought fire, a symbol of enlightenment, to mankind. We hope that this new ant species will symbolize the promise of a bright future for Ecuadorian biodiversity.