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Strumigenys browni group
Strumigenys browni group Bolton (2000)
Species
Neotropical
Worker Diagnosis
Mandibles in full-face view and at full closure narrowly triangular, serially dentate and the masticatory margins engage throughout their visible length. In profile mandible downcurved near the apex. In ventral view outer margin of mandible without an inflected prebasal angle. MI ca 13.
Dentition. Basally with a row of 8 closely set low small triangular teeth. Basal tooth slightly broader than the succeeding 7 but all of about the same height. These are followed by 4 denticles that are only slightly lower and the margin terminates in an enlarged apical tooth that is easily the largest on the entire margin; total dental count 13.
Basal lamella low broad and subtriangular, its posterior face shallowly convex and its anterior face shallowly concave in full-face view; not visible when mandibles fully closed. Basal lamella about as tall as basal series of teeth , separated from basal tooth by a small diastema whose length is less than the height of the basal tooth.
Labrum terminates in a pair of narrow tapering triangular lobes.
Clypeus with anterior margin broadly evenly shallowly convex, its anterior apron thin, lamellate and translucent. Lateral margins of clypeus weakly divergent posteriorly.
Clypeal dorsum with a number of suberect to subdecumbent fine simple hairs that are acute apically and inclined anteriorly or anteromedially. Anterior and lateral clypeal margins without projecting hairs of any form but some of the simple hairs that arise on the dorsum project beyond the anterior and lateral outlines.
Preocular carina visible in full-face view, short and convex. Frontal carinae in the same view expanded laterally behind the frontal lobes, forming a lamellate flange along the upper scrobe margin ; anteriorly this flange slightly broader than width of frontal lobe, narrowing posteriorly and fading out at apex of scrobe.
Ventrolateral margin of head bluntly marginate from minute eye to base of mandible, the margin shallowly convex ventrally from eye to postbuccal impression; the latter very shallow and inconspicuous.
Cuticle on side of head within scrobe densely reticulate-punctate; the scrobe extensive, long and very broad.
Scape very long, SI 105-110, and very slender, about 10.5 times longer than its maximum width. Scape shaft subcylindrical, slightly broader apically than basally and the subbasal bend extremely shallow; not dorsoventrally flattened and with a rounded leading edge.
Leading edge of scape with somewhat elevated minute pubescence that is inclined toward the apex of the scape; without longer projecting hairs of any form. Funicular segments 2 and 3 much longer than broad.
Propodeum with a pair of triangular teeth that are sub tended by conspicuous lamellae.
Spongiform appendages fully developed on petiole and postpetiole. Base of first gastral stemite in profile with a fine narrow spongiform pad.
Pilosity. Pronotal humeral hair long, flagellate. Upper scrobe margins with several laterally projecting flagellate hairs on each side, and flagellate hairs also present on cephalic dorsum and mesonotum. Dorsal (outer) surfaces of middle and hind tibiae densely clothed with elongate narrowly spatulate hairs that are elevated and strongly curved toward the tibial apices.
Notes
A small group that currently contains only S. browni, from Brazil. The species is easily isolated by the diagnostic characters given above. It exhibits a number of similarities to the mirabilis group and tlaloc group (especially the former), both of which are also monotypic at present. However, comparison of their diagnoses shows fundamental differences in sufficient features that deny them inclusion in a single group. It seems reasonable to expect that several species in each of these groups still await discovery. Certainly any attempt to adduce relationships at present can be no more than guesswork.
References
- Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.