Strumigenys emeryi group

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Strumigenys emery group Bolton (2000)

Species

Neotropical-Nearctic

Worker Diagnosis

Apical fork of mandible with one intercalary tooth or denticle. Mandible with preapical dentition variable: either without preapical teeth or denticles, or with one small acute preapical tooth or denticle near the apicodorsal tooth; a minute proximal denticle may also be present. MI 56-66.

Leading edge of scape with two or more hairs curved or directed toward the base of the scape. Scape slender, the subbasal curve shallow; moderate to very long, SI 79-105.

Preocular carina in profile straight, running above eye and extends back beyond level of anterior margin of eye; usually terminating at about level of midlength of eye but may be slightly longer or shorter.

Ventrolateral margin of head not indented nor deeply concave in front of eye, at most very shallowly concave. Postbuccal groove obtuse and shallow.

Propodeum with teeth or spines subtended by a carina or lamella on the declivity; some species with a propodeal lacuna (see below) but none with a sharp tooth or spine at base of declivity.

Ventral surface of petiole usually with spongiform tissue (absent in one species).

Pilosity. Pronotal humeral hair flagellate. Ground-pilosity of head and alitrunk of curved spatulate hairs. Apicoscrobal hair present. Cephalic dorsum with two pairs of standing hairs, one close to highest point of vertex, the other near occipital margin.

Mesonotum with a pair of standing hairs.

Sculpture. Head and alitrunk predominantly but rarely entirely reticulate-punctate; one or both often also with rugulose or costulate sculpture. Mesopleuron, metapleuron, or both usually with a smooth area (completely sculptured only in one species).

Notes

The core-species of this group were examined by Brown (1959a). Later he discussed further samples of some species (Brown, 1961), and established in particular that preapical dentition could be very variable. All his species are still included except Strumigenys boneti, now treated elsewhere because of its lack of hairs on the leading edge of the scape that curve toward the base of the scape. The species are almost entirely of Central American origin (Mexico to Panama) though the recent discoveries of Strumigenys nevermanni in the U. S. A., of Strumigenys humata in Venezuela and of Strumigenys moera in Ecuador implies that the group may be more widely distributed but under-represented in collections.

Several of the species show a strange modification of the propodeal lamella, that Brown (1959a: 97) called the propodeal lacuna. He defined these as “. . . oval pits, one in each lateral face of the propodeal lamellae, which may or may not be filled with a light-colored incrustation, probably representing a hardened secretion.” This structure is most apparent in Strumigenys emeryi, humata, Strumigenys lacacoca and Strumigenys micretes where it is associated with a broad lamella on the declivity. In other species of the group either the propodeal lacuna is smaller (to absent), or the lamella is narrow, sometimes reduced to a mere carina, or both.

Five species of the group (Strumigenys diaptyxis, humata, lacacoca, micretes, moera) have relatively long scapes and narrow head s (range of SI 92-105, of CI 67-75). The remaining species (Strumigenys eversa, emeryi, nevermanni, Strumigenys sevesta) have shorter scapes and broader heads (range of SI 79-89, of CI 75-83).

References