Strumigenys precava group

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Strumigenys precava group Bolton (2000)

Species

Neotropical-Nearctic

Worker Diagnosis

Apical fork of mandible without intercalary teeth or with a small tooth, denticle, tubercle or minute tumulus that arises at, or slightly distal of, the midlength of the upper margin of the apicoventral tooth. Mandible with a short triangular preapical tooth, close to apicodorsal tooth. MI 41-72.

Leading edge of scape either with two or more hairs that are curved toward the base of the scape, or with a series of short stubbly hairs in the basal third that are roughly at right-angles to the long axis of the scape; never with all hairs curved or inclined toward the apex of the scape. Scape slender, sub cylindrical or slightly flattened; moderate to long, SI 72-94.

Preocular carina in profile terminating in front of the level of the eye, not extending back above the eye nor curving down toward the anterior margin of the eye.

Ventrolateral margin of head, and vertical side of head in front of eye, deeply concave so that the head appears strongly constricted in front of the eyes.

Propodeum with teeth or spines, subtended by a carina or narrow lamella on the declivity; without a sharp tooth or spine at base of declivity although a small rounded lobe may occur.

Ventral surface of petiole with a partial or complete spongiform curtain; other spongiform appendages of waist segments also present.

Pilosity. Pronotal humeral hair present. Apicoscrobal hair present. Cephalic dorsum with at least one pair of standing hairs, always a pair near the occipital margin. Mesonotum with a pair of standing hairs. Pilosity otherwise very variable among species.

Sculpture. Head and alitrunk reticulate-punctate or reticulate; overlying rugulose sculpture may be present, especially on head.

Notes

This small group contains the four fairly large species (HL 0.75-1.30, HW 0.64-1.03) discussed below. Apart from sharing the characters listed above they are all quite distinctive and easy to recognise, although precava seems to be the only one that is widely distributed.

The intercalary tooth of the apical fork, when present, is very variable in size but its location, at least halfway along the upper margin of the apicoventral tooth, is characteristic. It is present and quite distinct in all specimens of Strumigenys princeps and Strumigenys thomae that have been seen but is extremely variable in size in different populations of Strumigenys precava. At maximum in this species it is a small but obvious inclined tooth that is acute apically. From this maximum there is a gradual morphoclinal reduction to a denticle, a small blunt tubercle, a low tumulus, a mere rounded prominence in the outline, to wholly absent. An intercalary tooth is absent in the three workers of Strumigenys formicosa that are known.

References

  • Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.