Strumigenys simulans group

Strumigenys simulans group Bolton (2000)

Comprised of two endemic species from Cuba and Hispaniola.

Species

Neotropical

Worker Diagnosis

Booher et al. (2019) – Adapted from Bolton (2000). Basal tooth follows basal lamella without a diastema. Mandibles with 9-10 serially dentate short conical interlocking teeth (in Strumigenys simulans there may be a small space between teeth when mandibles are closed). Basal lamella of mandibles with its anterior margin and part of its mesial margin visible immediately in front of the anterior clypeal margin in full-face view with mandibles fully closed. Lamella slightly taller than basal tooth.

Clypeus with anterior margin between mandible insertions broadly to narrowly concave, the anterolateral angles rounded and the lateral margins weakly divergent posteriorly. Outer margins of mandibles intersect anterior clypeal margin mesad of the anterolateral clypeal angles. Lateral clypeal margins project laterally far beyond outer margins of mandibles and posteriorly are confluent with the expanded frontal lobes, the outline only interrupted by a minute impression where they meet. Clypeal dorsum with numerous very short fine setae that are either erect or adpressed; lateral margins of clypeus fringed with similar setae.

Frontal lobes and frontal carinae strongly expanded laterally, their dorsolateral margins almost straight, weakly divergent posteriorly and in full-face view continuous with the dorsolateral margins of the occipital lobes.

Preocular carina not visible in full-face view, completely concealed by the expanded frontal lobe and frontal carina.

Ventrolateral margin of head not marginate immediately in front of eye, with a shallowly concave margination at the postbuccal impression; the latter forming a conspicuous notch in profile. Cuticle of side of head within the scrobe smooth in the upper half.

Scape short, SI 61, but quite slender, broadening from base to about the midlength and without a subbasal angle; not dorsoventrally flattened and with a weakly defined leading edge. Antenna with only 4 segments (funicular segments 3-5 fused but can be seen under high magnification when backlit). Leading edge of scape without projecting setae of any form. Pronotum not marginate dorsolaterally, the dorsum convex and rounding broadly into the sides.

Propodeum with a pair of triangular teeth that are subtended by a narrow lamella.

Spongiform appendages fully developed, with a ventral curtain and lateral lobes on the petiole, ventral lobes on the postpetiole and a large spongiform pad basally on the first gastral sternite. Lateral lobes of the postpetiole cuticular flanges to cuticular-spongiform flanges.

Notes

Created as a monotypic group for the Cuban species Strumigenys simulans, it now includes the Hispaniola endemic Strumigenys economoi. Both species are known from a small number of specimens.

Booher et al. (2019) – Strumigenys economoi shares a number of key characters (dentition, anterior outline of clypeus, four-segmented antennae, shape of the disc of postpetiole, and spongiform tissue) with Strumigenys simulans. Workers from other groups have a similarly expanded clypeus and frontal lobes e.g. excisa, nitens, and beebei groups but differ as outlined by Bolton (see below). Bolton’s description of the simulans group (Bolton 2000) only required a slight amendment to incorporate pilosity character differences between S. simulans and the new species described here.

Bolton (2000), as noted for the group before the addition of S. economoi - The single small species that currently occupies this group, simulans, is a Cuban endemic. At first glance it resembles species of the excisa, nitens, and beebei group, because of the striking structure of the clypeus and the lateral expansion of the frontal lobes and frontal carinae. These adaptations may be synapomorphies linking all these groups, but the mandibles and dentition seen in simulans are quite different from any of the other groups mentioned. On top of this simulans fails to show the autapomorphies exhibited by the other groups. For instance excisa-group has lost all spongiform tissue from the petiole, ventral postpetiole and first gastral sternite, and the disc of the postpetiole is broadly U-shaped or V-shaped with a deeply concave anterior margin. The nitens-group has extremely short but strongly convex lateral clypeal margins, and has the propodeal spiracle shifted backward. The beebei-group has the head truncated in front and of very characteristic shape.

References

Booher, D.B., Prebus, M.M., Lubertazzi, D. 2019. A taxonomic revision of the Strumigenys nitens and simulans groups (Hymenoptera: Formicidae), two Caribbean radiations of leaf litter ants. Zootaxa. 4656, 335-358. doi:10.11646/zootaxa.4656.2.7
Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.