Leptogenys tiobil

Found in humid forests.

Identification
Key to Leptogenys of the New World

Lattke (2011) - L. tiobil is the only ingens group species with a triangular petiolar node. Large black species with blue iridescence; body with abundant appressed pubescence; petiolar node triangular in lateral view with blunt point that overhangs posterior margin. Mandibles slightly triangular, brown with fine striae on dorsum; median clypeal lobe prominent with longitudinal strigae.

Distribution
This taxon is known from northcentral Venezuela.

Biology
Lattke (2011) - It has a spotty distribution in Venezuela’s Cordillera de la Costa, with almost all records from the mountains next to the Rancho Grande field station, and a single record 100 km to the East. Both sites have abundant humid forests, with records in the former locality ranging from 1000 to 1300 m altitude, and a single worker at 350 m in the latter site. The type series nest was found along an earthen embankment, and consisted of a single chamber some 30 cm in the earth. Some ants reacted to disturbance by hiding in nearby crevasses, others fled rapidly into the surrounding litter. Single workers have been observed foraging during day light hours. Series 1054 was found in a vertical earthen embankment with a single nest entrance some 50 cm from the ground. A pile of bleached isopod remains fanned out from the entrance. The nest entrance seemed excessively large in proportion to the ants, pointing to the possibility that they were using a previously excavated cavity. Since several nest series have been taken and none of the captured ants could be identified as a queen, the possibility exists that queens in this species are morphologically almost indistinct from the workers.

This species was collected by William Brown along the trails close to the Rancho Grande research station during 1971 and in correspondence he mentioned their presence there as common. I started collecting in the same site in the early 1980s and was able to corroborate the frequent presence of nests close to the station yet in the course of time, particularly during the 1990s, these ants became quite rare close to the station and were more noticeable at higher altitudes. At present they are quite infrequent from the station surroundings and are now found close to 1300 m.

Castes
Queen, male. Unknown.

Nomenclature

 *  tiobil. Leptogenys tiobil Lattke, 2011: 177, fig. 32 (w.) VENEZUELA.

Worker
Metrics, holotype (paratypes, n = 5): HL 2.05 (2.05 – 2.15); HW 1.4 (1.45 – 1.5); ML 1.05 (1.05 – 1.15); EL 0.5 (0.5 – 0.55); SL 2.6 (2.45 – 2.6); PW 1 (1.2 – 1.45); WL 3.55 (3.4 – 3.65); PH 1.1 (1.05 – 1.1); PL 1.5 (1.45 –1.55); DPW 0.65 (0.6 – 0.7) mm. CI 0.68 (0.69 – 0.71); MI 0.75 (0.72 – 0.79); OI 0.36 (0.34 – 0.38); SI 1.86 (1.63 – 1.86); LPI 0.73 (0.68 – 0.76); DPI 0.43 (0.41 – 0.47).

Head in full-face view elongate, wider anterad than posterad, posterior margin broadly convex, lateral margin almost straight, median clypeal lobe prominent, in full-face view longer than half the straight line distance from the anterior edge of the antennal sclerite to the anterior-most mandibular edge; lobe apically roughly triangular with bluntly pointed apex, expanding abruptly laterad towards base; lateral clypeal lobe broadly triangular, median lobe meets lateral lobe at an angle. Scape surpasses posterior cephalic border by almost one-half its length; third antennal segment about 2 x length of either second or fourth segments. Compound eye convex and slightly bulging, situated dorsolaterally, interrupting lateral cephalic margin; ED more than one-fourth LCM. Mandible elongate and mostly semi-parallel, widening slightly towards apex; a small gap remains between mandible and clypeus when shut tight; mandible with small basal tooth and larger pre-apical denticle. Mandibular dorsum with fine strigulae and shallow piligerous punctae. Hypostomal tooth not visible in cephalic full-face view. Antennal fossa surrounded by concentric striae, frons mostly reticulate punctuate, densely punctate towards vertex; area posterad of eye striate-punctate; sculpture tends to smoothen on ventral cephalic surface with sparse punctae and shallow arching, fine strigulae. Vertexal carina distinctly visible in cephalic full-face view, carina well developed ventrally, becoming a perpendicular flange at least as wide as half the greatest scape width.

Mesosoma with promesonotal margin forming single convexity in lateral view, metanotal groove well impressed, dorsal propodeal margin slightly convex to almost straight, declivity convex with outline made jagged by transverse striae. Pronotum mostly punctate in lateral view, punctae-striate posterolaterally, dorsum densely punctate; prosternum mostly smooth and shining. Mesopleuron transversely striate, striae fine medially, coarser dorsad and ventrad; metapleuron and lateral propodeum posterad of spiracle transversely striate; mesopleuron separated from mesosternum by carina, carina widest anterad; propodeal spiracle elongate, posterolaterally directed. Metapleural-propodeal suture weakly impressed. Mesonotum and propodeal dorsum transversely striate

Petiole in lateral view triangular, with single anterodorsal broadly convex margin, apex with short blunt tooth that slightly overhangs the slightly convex posterior margin; ventral margin sinuate with anterior tooth. Node punctate laterally, punctae become sparse ventrad; posterior face medially with transverse strigulae and ventrad with coarse striae. Node in dorsal view with elongate tear-drop shape, the slender anterior section gradually becoming wider posterad. Abdominal segments III – IV densely punctulate; segment V sparsely punctulate. Pygidium with median longitudinal crest; hypopygidium with lateral row of setae and ventrally with 2 pairs of arching setae close to base of sting. Body covered with abundant appressed pilosity, standing and decumbent hairs also present. Lateral face of procoxa mostly smooth and shining; posterior face of protibia with 3 – 5 setae, the longest at apex. Body black with blue iridescence; antennae, mandible, femora and tarsi brown; coxae and tibiae dark brown with weak blue iridescence.

Type Material
Holotype worker. Venezuela, Aragua, Parque Nacional Henri Pittier, Rancho Grande via La Cumbre, 1300 m, 22.vii.2001, J. Lattke 2444. One worker deposited in. – Paratypes. From the same nest as the holotype: 4 workers deposited in MIZA, 1w, 1w , 1w , 1w , 1w.

Etymology
The species name is a tribute to William L. Brown, Jr. (1922 – 1997), myrmecologist and mensch. It is an indirect patronym derived from the Spanish “Tío Bill”, and is a translation of “Uncle Bill”. (He eschewed patronyms) Gracias por todo Tío Bill.