Leptogenys santacruzi

This is an arid zone specialist as conditions on Santa Cruz Island are very dry during most of the year, except for a brief rainy season. The vegetation is deciduous and typically xeric, with the frequent presence of Opuntia, Jasminocereus cacti, and Bursera graveolens Kunth (Triana & Planch.), the incense tree (McCullen 1999).

Identification
Pronotum with fine longitudinal striae in lateral view; propleuron striate; node rectangular and higher than long in lateral view, mostly smooth with scattered piligerous punctae, wider than long in dorsal view; body color brown.

The shape of the node is quite distinctive amongst the arcuata species group with the posterior face not as sharply separated from the lateral node face and distinctly higher than long in lateral view, as well as wider than long in dorsal view. In all other arcuata group species the node is mostly striate laterally, but not in L. santacruzi, which is mostly smooth, and consequently the lateroventral flat smooth area is not as apparent as in the other species. The brown body color is also distinctive in the arcuata group.

Distribution based on Regional Taxon Lists
Neotropical Region: Ecuador.

Castes
Queens and males are unknown.

Nomenclature

 *  santacruzi. Leptogenys santacruzi Lattke, 2011: 151, fig. 9 (w.) ECUADOR (Galapagos Is).

Worker
Metrics, holotype (paratypes, n = 3): HL 1.29 (1.21-1.29); HW 1.06 (0.99-1.09); ML 0.86 (0.76-0.91); EL 0.30 (0.25-0.28); SL 1.34 (1.24-1.37); PW 0.81 (0.76-0.83); WL 2.02 (1.87-2.07); PH 0.81 (0.78-0.86); PL 0.56 (0.56-0.58); DPW 0.56 (0.53-0.61) mm. CI 0.82 (0.81-0.84); MI 0.81 (0.77-0.84); OI 0.29 (0.26-0.27); SI 1.26 (1.26-1.27); LPI 1.45 (1.41-1.55); DPI 1.00 (0.95-1.05).

Head subquadrate in full-face view; lateral margins broadly curved and weakly diverging anterad; posterior margin convex. Eye convex and large, spanning more than one-fourth of lateral cephalic margin, slightly dorso-laterally situated. Cephalic dorsum mostly smooth and shining with sparse piligerous punctae, striate-punctae between eye and antennal sclerite, and anterad of eye. Scape mostly smooth and shining, surpassing posterior cephalic margin by close to one-third its length; length of antennal segment III more than 2 x its width. Anterior clypeal margin laterally converging to median lobe, process about as long as wide, margins translucent, apex with 4 – 3 setae. Mandible slightly arched, parallel-sided with brief and weakly concave edentate masticatory margin, basal angle with short denticle; mandible leaves gap between clypeus when closed, at widest more than twice the mandibular width. Scape with abundant decumbent hairs. Apex of hypostomal tooth just visible in cephalic full-face view.

Mesosoma with prominent metanotal groove in lateral view: pronotal margin convex, mesonotum forms weak convexity, dorsal propodeal margin forms broad convexity, declivitous margin weakly convex to straight, unarmed. Lateral pronotal face with longitudinal striae, except for smooth strip along ventral margin; propleuron striate. Mesometapleural suture well impressed. Mesopleuron with variably sculptured or flat smooth areas; sculpture striate to rugulose, longitudinal or transverse; mesopleural carina developed along anterior half; metapleural-propodeal suture ill-defined. Mesonotum of similar length and width in dorsal view, anterior margin convex, posterior margin straight; metanotal groove scrobiculate. Metapleuron and propodeal lateral face with transverse to oblique striae, and irregular smooth areas, mesosomal dorsum mostly smooth and shining with broad, shallow piligerous punctae; spiracle opening elongate, directed posterolaterally. Tubercle of metathoracic spiracle rugulose.

Petiolar node with strongly convex anterior margin that overhangs anteroventral margin in lateral view, convexity continues to dorsal margin, posterior margin broadly convex; node higher than long. Node with weak longitudinal to oblique striae on side; posterior face mostly smooth and shining, separated from rest of node by strong curvature. Node as wide as long in dorsal view, anterior margin convex, almost as wide as posterior margin, posterior margin weakly convex. Gaster smooth and shining with sparse punctulae. Head, mesosoma and abdomen dark brown; clypeus, mandibles, antennae, and legs ferruginous brown; gastral apex ferruginous brown. Body without appressed pilosity, with numerous decumbent to subdecumbent hairs.

Type Material
Holotype worker. Ecuador, Islas Galapagos, Isla Santa Cruz, 2.5 km from SPNG limit, Pto. Ayora-Baltra Road, 29.iii.1982, Y.D. Lubin 123. Deposited in. – Paratypes. 9 workers with the same data as the holotype. MCZC.

Etymology
The species name alludes to the name of Santa Cruz Island of the Galapagos Archipelago, the locality from which this species has been recorded.

References based on Global Ant Biodiversity Informatics

 * Lattke J. E. 2011. Revision of the New World species of the genus Leptogenys Roger (Insecta: Hymenoptera: Formicidae: Ponerinae). Arthropod Systematics and Phylogeny 69: 127-264