Strumigenys xenochelyna

One of the few specimens of this species was collected at a tree pitfall between 1.5-2m from the ground.

Identification
Bolotn (2000) - A member of the Strumigenys appretiata-group. The Brazilian specimens are more strongly sculptured, with distinct reticulate-punctation on posterior mesonotum, propodeal dorsum and dorsum of petiole node. Also in these the petiole node, though broader than long, is not as strikingly transverse as in the type-series. This species is immediately characterised by its complete lack of a ventral spongiform lobe on the postpetiole, coupled with the presence of short straight hairs at the pronotal humeri and on the first gastral tergite, and its possession of a transversely rectangular petiole node with a concave anterior margin. All other species in the group have at least a vestige of the ventral postpetiolar lobe remaining. In most (Strumigenys deinomastax, Strumigenys glenognatha, Strumigenys halosis, Strumigenys raptans, Strumigenys teratrix, Strumigenys wheeleriana) the lobe is large and conspicuous; in one species (Strumigenys siagodens) it is small, and in two (Strumigenys appretiata, Strumigenys hadrodens) it is reduced to an anteroventral vestige but still discernable.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil, Paraguay.

Nomenclature

 *  xenochelyna. Pyramica xenochelyna Bolton, 2000: 165, fig. 125 (w.) PARAGUAY. Combination in Strumigenys: Baroni Urbani & De Andrade, 2007: 130

Worker
Holotype. TL 2.3, HL 0.58, HW 0.54, CI 93, ML 0.10, MI 17, SL 0.21, SI 39, PW 0.28, AL 0.58. Pronotal humeral hair fine, short straight and simple, not flagellate. Mesonotum with a pair of similar hairs. Dorsal surfaces of petiole, postpetiole and first gastral tergite with sparse fine short hairs that are simple and erect. Dorsal alitrunk glossy, with faint vestiges of sculpture; upper half of propodeal declivity finely reticulate-punctate. Dorsum of petiole node feebly sculptured; postpetiole disc glassy smooth. Propodeal spines triangular, very broad basally and tapering rapidly to an acute apex. Petiole in profile with a narrow longitudinal ventral carina (not spongiform) and a tiny lateral lobe that is set posteriorly and very low down on the side. Postpetiole with a lateral spongiform lobe; without any trace of a ventral lobe, the sternite bare. Node of petiole in dorsal view transversely rectangular, nearly two times broader than long, with acute anterolateral angles and a shallowly concave anterior margin; lateral margins straight and feebly convergent posteriorly. Lateral lobes of petiole narrow but prominent, restricted to posterolateral corners. Postpetiole in dorsal view much broader than long, the anterior margin much wider than the posterior so that the sides strongly converge posteriorly. Lateral spongiform lobes of postpetiole extensive and very conspicuous. Basigastral costulae weakly defined and surface of the first gastral tergite with very faint, almost effaced, superficial reticular patterning.

Paratypes. TL 2.0-2.3, HL 0.54-0.60, HW 0.50-0.57, CI 93-95, ML 0.08-0.11, MI 15-18, SL 0.20-0.22, SI 39-40, PW 0.26-0.30, AL 0.50-0.58 (6 measured). Mainly as holotype but in some the promesonotum is almost completely smooth, the feeble sculpture nearly entirely effaced.

Type Material
Holotype worker, Paraguay: Canendiyu, Ype Jhu, 28.x. 1 979, no. 39 (V. Mahnert). Paratypes. 10 workers with same data as holotype (MHN,, ).

References based on Global Ant Biodiversity Informatics

 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Silva T. S. R., and R. M. Feitosa. 2019. Using controlled vocabularies in anatomical terminology: A case study with Strumigenys (Hymenoptera: Formicidae). Arthropod Structure and Development 52: 1-26.
 * Silvestre R., M. F. Demetrio, and J. H. C. Delabie. 2012. Community Structure of Leaf-Litter Ants in a Neotropical Dry Forest: A Biogeographic Approach to Explain Betadiversity. Psyche doi:10.1155/2012/306925
 * Wild, A. L. "A catalogue of the ants of Paraguay (Hymenoptera: Formicidae)." Zootaxa 1622 (2007): 1-55.