Strumigenys schleeorum

The general cephalic morphology, the small clavate hairs and the size of the eyes would indicate a close relationship between Strumigenys schlee­ orum and S. studiosi WEBER, known only from Costa Rica. S. schleeorum, however, differs in a remarkable way from any other known dacetine by its mandibular mor­phology.

Identification
A Strumigenys species with extremely reduced mandibular denti­ tion and mandibles touching each other only at an undifferentiated apex when closed.

Distribution
This taxon was described from Dominican Amber (Miocene).

Nomenclature

 * † schleeorum. †Strumigenys schleeorum Baroni Urbani, in Baroni Urbani & De Andrade, 1994: 35, figs. 19, 22, 23 (q.) DOMINICAN AMBER (Miocene). Combination in Smithistruma: Bolton, 1995b: 385; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 127.

Description
Head (Fig. 23) with anteriorly strongly converging sides, rounded posteriorly and occipital border moderately concave. Eyes very protruding, their maximum diameter as long as the masticatory border of the mandibles; their exact position in relation to the antennal scrobe could not be precisely located in the single available specimen. Preocular laminae convex and slightly crenulate externally, running backwards from the postero-lateral sides of the clypeus without reaching the eyes. Clypeus slightly longer than broad, with convex sides, and acute posterior margin. A marked medial line between the posterior margin of the clypeus and the median ocellus. Antennae with 6 antennomeres. Scapes 1/z of the head length, not reaching the occipital border posteriorly when folded backwards, short, broad, flattened, bent very close to the base, its external border slightly convex and crenulated, and the internal border nearly straight. Last funicular joint nearly as long as the sum the preceding ones. Mandibles 1/3 of head length, touching each other only at the apex when opposed, with slightly convex external sides; internal border with a basal lamella followed by a set of 8-9 minute denticles decreasing apically in size and only superficially differentiated; mandibular apex continuing the row of denticles without fork or other differentiate structures, constituted only by a single spiniform tooth. Labrum with a pair of anteriorly projecting lobes easily visible between the mandib­les. Trunk: pronotum with poorly marked humeral angles. Mesonotum adjecting medially and cranially over the pronotum, slightly convex on the sides, and straight posteriorly. Scutellum rounded posteriorly. Propodeal spines straight, directed backwards, slightly shorter than the petiole width. A faint median line visible on the mesonotum and scutellum. Petiole bell shaped in dorsal view, 113 longer than broad. Postpetiole 1h broader than the petiole, with rounded anterior face. Spongiform appendages absent. Gaster round in dorsal view, truncated anteriorly. Wings : fore wings with marked pterostigma. R +Sc complete. 2r ending in a trace of Rs+ M. Mf l equally marked. Only traces of other veins. Hind wings with clearly visible costal vein only. Sculpture: clypeus deeply and finely reticulate, the same structure broader  and more accentuated on the cephalic dorsum; trunk and abdominal peduncle with effaced reticulation superimposed by irregular, light striation; gaster, mandibles and appendages superficially punctuated. Median area of the anterior portion of  the gaster with three effaced costulae. Colour: dark brown, opaque with slightly lighter antennae and legs. Pilosity: dorsum of the head with sparse, short, subdecumbent spatulate hairs slightly longer towards the sides; longer, pointed subdecumbent hairs on the antero­ lateral sides of preocular laminae, the edges of clypeus and, more scattered, on the mandibles; vertex with a pair of standing setae directed upwards three times longer than the spatulate hairs on the rest of the cephalic dorsum; a pair of standing setae, longer than the maximum diameter of the eyes on the postocular sides; scapes equally covered by spatulate hairs slightly longer than those on the head on the superior and anterior border, comparable in length to the smallest cephalic ones on the posterior border; sides of pronotum and mesonotum with short, appressed spa­ tulate hairs; pronotal humeri with a pair of long, filiform hairs; two pairs of similar but slightly shorter hairs are present on the sides of the mesonotum; another  two pairs of similar but still shorter hairs on the scutellum; petiole and postpetiole with a pair of filiform hairs each. Gaster and legs with rare, short, acuminate hairs similar to those on the mandibles.