Gnamptogenys Species Groups of the New World

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The following classification is based on Lattke (1995), at a time when our taxonomic concept of Gnamptogenys was much broader. The revision of the subfamily containing this genus by Camacho et al. (2022) has drastically changed our understanding of these ants and scattered the species once place here into five separate genera; these species are listed below in the original species groups proposed by Lattke (1995).

concinna group

Head subquadrate; scapes surpassing vertex in frontal view; median clypeal carina frequently present; body sculpture densely striate; small pit frequently situated medianly on weakly impressed promesonotal suture; metasternal process slender to acicular; row of stout setae on base of foretarsus opposite strigil present; petiolar node with no anterior peduncle; metacoxae and propodeum unarmed. All three members of the group are large species. This group is nevertheless heterogeneous and its three members were considered individually in the matrix.

minuta group

Head subquadrate; frontal carinae broadly expanded laterad; row of stout setae on base of foretarsus opposite strigil present; petiolar spiracles facing directly ventrad and sunken within a pit.

Dias & Lattke (2019) - The morphological similarities of Alfaria piei with Alfaria caelata and Alfaria striolata mostly agree with the characters used by Lattke (1992:125) to consider Alfaria caelata and Alfaria striolata as forming a small sub-group within the minuta-group.

mordax group

Antennal scapes usually do not reach vertex and are compressed, smooth and shining; mandibles subtriangular to subfalcate with front smooth and shining; head subquadrate to elongate; mesosoma mostly parallel sided; small propodeal lobes frequently present, denticles absent (except one species); metacoxal denticles or lobes frequently lacking; second gastric segment straight, without ventral arching. Considerable interpopulation variability in the average size is observed in species of this group. The group can be divided into 4 subgroups:

regularis subgroup

Mandibles subtriangular; anterior clypeal border straight and usually with laterally acutely pointed lamella; no transverse dorsal mesosomal sutures; petiolar node lacking anterior peduncle; subpetiolar process subquadrate. Within this subgroup three species complexes are recognizable.

hartmani complex

Mandibles triangular to subtriangular, frontal surface partially sculptured; vertical sculpturing on declivitous propodeal face;

regularis complex

Mandibles subtriangular, their frontal sides smooth and shining; vertical sculpturing on declivitous propodeal face;

annulata complex

Mandibles subtriangular, front smooth and shining; horizontal sculpturing on propodeal declivity.

mordax subgroup

Mandibles subfalcate, frontal surface smooth and shining; anterior clypeal margin concave with rounded lamellar sides; well impressed metanotal groove; petiolar node slightly pedunculate; subpetiolar process projects anterad.

alfaroi subgroup

Mandibles triangular, head prominently elongate; denticles on propodeum. The elongate head and armed propodeum makes this subgroup quite distinct from the others.

levinates subgroup

Subtriangular mandibles, frontal surface sculptured; scapes surpassing vertex; subpetiolar process subquadrate. Its clypeus projects anterad more than in any extant species of the group.

rastrata group

Head subquadrate or wider anterad than posterad in frontal view; anterior clypeal margin usually straight; mandibular front usually striate or rugulose, sometimes smooth; scapes usually surpassing vertex, sometimes with longitudinal rugulae, vermiculate or smooth and shining; promesonotal suture feebly impressed to absent, never totally dividing sculpture; metanotal suture well impressed; propodeum usually armed with denticles or spines; petiolar node low; subpetiolar process shape variable, usually projecting anterad but sometimes subquadrate; metacoxal teeth always present, usually acicular; second gastric segment ventrally arched. The ants of this group are specialized millipede predators and can be subdivided into two subgroups.

rastrata subgroup

Mandibles triangular. Within the subgroup two complexes are defined:

bispinosa complex

Large species, anterior clypeal margin convex, propodeal teeth above level of spiracles; anterior lobe of subpetiolar process prominent.

rastrata complex

Smaller species; anterior clypeal margin straight; propodeal teeth at same level as spiracles; subpetiolar process subquadrate.

banksi subgroup

Mandibles subfalcate to falcate. Two species complexes are defined.

banksi complex

Meta coxae and propodeum with denticles.

semiferox complex

Metacoxae and propodeum lacking denticles. In a study of the sting apparatus of several species of Gnamptagenys Kugler (1991) grouped triangularis and bispinosa, the only members of the rastrata group as defined above, into one group.

striatula group

Mandibles triangular with rugulae or striae on frontal surface; convex anterior clypeal margin; scapes usually surpassing vertexal margin, sculpturing punctate or vermiculate, never smooth and shining; eyes slightly behind cephalic midlength; head wider posterad than anterad; propodeal spiracle close to declivity; anterolateral propodeal declivity without spines or tubercles; anterior prosternal process broadly concave medianly; metacoxal dorsum always with denticle or lobe; high petiolar node; relatively wide anteroventral postpetiolar process; second gastric segment ventrally arched . Most seem to be generalist predators, but nothing is yet known about the diet of the strigata subgroup species.

Three subgroups are recognizable:

striatula subgroup

Petiolar node erect and sessile; subpetiolar process variably shaped, either subquadrate or triangular and projecting anterad in lateral view.

porcata subgroup

Petiolar node posteriorly inclined, with short anterior peduncle; subpetiolar process lobe-like, projecting anterad in lateral view.

strigata subgroup

Petiolar node variably shaped ; subpetiolar process subquadrate with a cuneiform ventral edge as opposed to the uniformly parallel sides of the other striatula group species. Many of the species have their propodeal spiracles elevated on small prominences. Most species are smaller in size than those of other subgroups and all are cryptobiotic leaflitter inhabitats. Two species complexes can be pointed out in this subgroup:

strigata complex

Cephalic vertex sculptured; no distinct propodeal lobes; petiolar node not parallel-sided in lateral view, anterior margin usually convex. All species inhabitat cloud forests, mostly of the Andes, with the exception of one found in the Cordillera de la Costa of Venezuela.

haytiana complex

Cephalic vertex mostly smooth and shining; small propodeal lobes present; petiolar node strongly compressed with subparallel anterior and posterior faces; some species have modified sculpturing from the usual costulate patterns of the genus. Most species inhabitat the Amazon-Orinoco river basin, except for one species found on Hispaniola Island. Kugler (1991) obtained similar results studying the sting apparatus of brunnea, nr. strigata, porcata, moelleri and gracilis. They were the only members of the striatula group included, as defined above, and were grouped together.

sulcata group

Mandibles subtriangular, front smooth and shining; head subquadrate; anterior clypeal border usually straight; lamella usually laterally angular; scapes smooth and shining; metacoxal denticles wanting in some species; usually no transverse mesosomal sutures; petiolar node low, lacking peduncle; metasternal process acicular and arched; second gastric segment relatively straight; anteroventral postpetiolar process relatively narrow and bluntly pointed, in contrast with wider process of other species. Two subgroups can be pointed out.

sulcata subgroup

Posterior face of petiolar node with horizontal costulae. Two species complexes are recognizable:

fernandezi complex

Mandibles triangular; clypeal lamella convex.

sulcata complex

Mandibles subtriangular; clypeal lamella straight.

ericae subgroup

Posterior node face with longitudinal costulae. This subgroup is made up of three complexes.

ericae complex

Clypeal lamella laterally acutely angulate; mandibles subtriangular.

lucaris complex

Clypeal lamella laterally rounded; mandibles subtriangular.

volcano complex

Clypeal lamella laterally obtusely angulate; mandibles triangular.

References

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