Cardiocondyla species groups

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The following is based on Seifert, 2003.

Characters such as position and size of eyes, basic type of sculpture, basic shape of mesosoma and waist, and ventral postpetiolar structures were considered as important to establish groups of related species. The phylogenetic significance of these characters, and how the species are associated in these species groups, is not known.

Cardiocondyla elegans group

Small postocular index (PoOc/CL 0.368 - 0.418), large eyes (EYE 0.235 - 0.261), long scape (SL/CS 0.790 - 0.881), long pubescence (PLG/CS 6.54 - 8.73 %). Anterior postpetiolar sternite in the median portion significantly more produced than in paramedian portions; in lateral view this anteromedian bulge forming a small obtusely rounded corner and changing into helcium with distinct angle. Accessory characters: flat and frequently bicoronate foveolae on paramedian vertex with 16 - 21 mm diameter and shining interspaces; dorsal mesosoma showing a distinct metanotal depression and appearing smooth and shining at lower magnifications. The group is distributed from Tberia to West Asia.

Cardiocondyla bulgarica group

Equal to Cardiocondyla elegans group in structure of postpetiolar sternite and similar in having flat and frequently bicoronate foveolae on paramedian vertex with 12 - 21 mm diameter and shining interspaces, similar mesosomal sculpture, and rather large eyes (EYE 0.219 - 0.258). Differing from former group by larger postocular index (PoOc/CL 0.40 - 0.47), shorter scape (SL/CS 0.75 - 0.85), and shorter, more dilute pubescence (PLG/CS 4.5 - 6.8 %, sqrtPDG 4.4 - 6.2). The group is distributed in SE Europe, N Africa, and W Central Asia.

Cardiocondyla batesii group

Eyes large (EYE 0.249 - 0.283). Postocular index small (PoOc/CL 0.311 - 0.420). Postpetiole rather narrow (PPW/CS 0.463 - 0.551). Anterior postpetiolar sternite completely flat, in medial portion as flat as in more lateral portions; in lateral view its anterior profile changing into helcium without distinct angle. Foveolae on paramedian vertex usually flat but of diverse structure. Gastral pubescence short (PLG/CS 4.5 - 6.9 %) and rather dilute (sqrtPDG 4.1 - 6.0). Allopatric and parapatric occurrence makes taxonomic decisions most difficult in this group. The known distribution includes Siberia, N Africa, the S Balkans, Asia Minor, the Arab Peninsula and W Asia. No tramp species are known in this group though the occurrence of C. nigra on the Cape Verde Islands should be caused by introduction.

Cardiocondyla nuda group

Basic type of sculpture on paramedian vertex and mesosoma microreticulate, though varying in strength. Postocular index large (PoOc/CL 0.413 - 0.492). Eyes rather small (EYE 0.218 - 0.246). Postpetiole rather narrow (PPW/CS 0.434 - 0.539), its sides in many species angulate-convex giving it a slightly hexagonal dorsal outline. Dorsal profiles of promesonotum and anterior propodeum not evenly shallowly convex; linear portions predominate which may curve down quite abruptly to a rather shallow metanotal groove, if such groove is present at all (MGr/CS 0.2 - 3.4 %). If propodeal spines are reduced to short dents, their dorsal and caudoventral profiles usually form an angle of less than 90°. The members of the group are distributed around the globe. The native distribution centres are hypothetic but probably in the S Palaearctic, Oriental, and Polynesian faunal regions. The S Nearctic and Neotropic populations have most probably been founded by anthropogenic introduction.

Seifert et al. (2017) - The Cardiocondyla nuda group can be separated from other species of the genus by the following character combination: Propodeal spines short, appearing in lateral view as smaller angles of 60–95° (in the Cardiocondyla shuckardi group forming blunt corners of 95–120°). Postpetiole in dorsal aspect frequently with angulate-convex sides—the outlines of postpetiole thus resembling a hexagon. Promesonotal and anterior propodeal profiles usually not forming evenly convex curvatures: as result, metanotal depression not as wide or completely absent (a difference to the C. shuckardi group). Eyes small (EYE/CS 0.231± 0.05), postocular index rather large (PoOc/CL 0.454±0.013) and postpetiole rather narrow (PPW/CS 0.487±0.030). Basic type of sculpture on paramedian vertex and mesosoma microreticulate, though varying in strength. The six known species of the Cardiocondyla minutior group are rather similar in shape of head, mesosoma and spines as well as in type of microsculpture but have significantly smaller absolute body size and a much lower absolute postpetiolar height PPH which is 111 ± 8 [92,130] μm in 207 workers of the C. minutior group but 153 ± 12 [123,188] μm in 577 workers of the C. nuda group.

Cardiocondyla shuckardi group

Ddiffering from C. nuda group by overall mesosomal profile; the promesonotal and anterior propodeal profiles form shallow, convex curvatures, which together forming broad and rather deep metanotal depression (MGr 1.9 - 6.4 %). In lateral view propodeal spines appearing as blunt angles of usually > 90°. Postpetiole very narrow (PPW/CS 0.40 - 0.49), its sternite with an indication of 2 paramedian longitudinal carinae. Eyes small (EYE 0.199 - 0.239). Postocular index large (PoOc/CL 0.43 - 0.47). The radiation centre of this group is most probably Africa.

Cardiocondyla stambuloffii group

Reduction of foveolae on vertex; pubescence hairs originating from either flat tubercles or flat pits of 4 – 10 mm diameter, at lower magnifications with a finely punctate surface appearance. Propodeal spines reduced to blunt dents. Frons very wide (FRS/CS 0.280 - 0.353). Metanotal depression deep. Except for the more distantly related Cardiocondyla tibetana, the species in this group share the following accessory characters: petiole much higher than wide, postpetiole twice as wide as petiole, eyes small (EYE 0.203 - 0.235). The group is distributed from SE Europe across Asia Minor eastwards to Tibet and Mongolia.

Cardiocondyla wroughtonii group

Minute. Head short, CL/CW 1.06 - 1.17. Frons wide, FRS/CS 0.256 - 0.294. Anterior postpetiolar sternite on each side with a prominent longitudinal carina ending in an anteroventral dent or curved semiconvex angle. As result, anteroventral postpetiole concave in dorsofrontal view. Petiole relative to postpetiole rather wide (PEW/PPW 0.60 - 0.71). The group includes cosmopolitan species and two species with apparently restricted range.

Cardiocondyla emeryi group

Minute. Head elongated, CL/CW 1.17 - 1.28. Frons narrow, FRS/CS 0.199 - 0.248. Postpetiolar sternite never completely flat, either with prominent bulge or with anterolateral dents or corners. Africa is the most probable radiation centre of this group.

Cardiocondyla minutior group

Minute. Head much elongated, CL/CW 1.21 - 1.32 and with very large postocular index, PoOC/CL 0.46 - 0.49. Frons rather narrow, FRS/CS 0.223 - 0.258. Postpetiolar sternite completely flat, very low postpetiole (PPW/CS 0.25 - 0.29); petiole much higher (PEH/PPH 1.15 - 1.42). Metanotal groove shallow or absent (MGr 0 - 1.9 %). Propodeal spines moderately long to short, SP/CS 0.089 - 0.147. The biggest diversity in this group is found in the Indomalayan region. The cosmopolitan tramp species C. minutior is the only species frequently found outside this area. It can be expected worldwide in all regions with tropical or subtropical climate.