Cardiocondyla species groups
The original species groups proposed by Seifert (2003) have been updated and expanded by Seifert (2022, 2023, 2024) and Seifert, Okita, and Heinze (2017).
Cardiocondyla argentea group
Dorsal mesosomal profile evenly convex with absent or only suggested metanotal depression (MGr/CS 0–0.52%) and in dorsal view without pronotal corners. Propodeal spines well-developed (SP/CS 0.208–0.400). Postpetiolar sternite conspicuously bilobate or bicuspidate. Furthermore characterized by short head with rather low postocular index (CL/CW 1.051–1.133, PoOc/CL 0.408–0.436) and a wide frons (FRS/CS 0.242–0.337).
The clearest differences to the C. thoracica and C. wheeleri group are the conspicuously bilobate or bicuspidate postpetiolar sternite, the evenly convex dorsal mesosomal profile and the absence of any pronotal corners.
Six species in the East Orientalic and Australasian zone, no tramp species known.
- Cardiocondyla argentea
- Cardiocondyla argyrotricha
- Cardiocondyla latifrons
- Cardiocondyla micropila
- Cardiocondyla pirata
- Cardiocondyla semiargentea
Cardiocondyla batesii group
Eye very large (EYE/CS 0.263 ± 0.08), postocular distance very small (PoOc/CL 0.368 ± 0.016), head rather long (CL/CW 1.176 ± 0.023), metanotal depression always present (MGr/CS 3.51 ± 0.82%), propodeal spines short (SP/CS 0.100 ± 0.013), pubescence on first gaster tergite rather short (PLG/CS 5.50 ± 0.43%), postpetiolar sternite completely flat, without any protrusions.
Eight species from the southern zone of West Palaearctic, tramp species unknown.
- Cardiocondyla batesii
- Cardiocondyla hashemi
- Cardiocondyla kushanica
- Cardiocondyla nigra
- Cardiocondyla opistopsis
- Cardiocondyla rugulosa
- Cardiocondyla semirubra
- Cardiocondyla tenuifrons
- Cardiocondyla verdensis
Cardiocondyla elegans group
Eye large (EYE/CS 0.250 ± 0.006), postocular distance small (PoOc/CL 0.395 ± 0.009), head rather short (CL/CW 1.156 ± 0.017), metanotal depression always present (MGr/CS 4.50 ± 0.76%), propodeal spines short (SP/CS 0.116 ± 0.013), pubescence on first gaster tergite very long (PLG/CS 7.84 ± 0.51%), postpetiolar sternite without any protrusions.
Four described and one undescribed species (Cardiocondyla sp. code DAOI) from the southern zone of the West Palaearctic.
- Cardiocondyla brachyceps +
- Cardiocondyla dalmatica
- Cardiocondyla dalmaticoides
- Cardiocondyla elegans
+ Seifert (2023) lists Cardiocondyla brachyceps as part of the Cardiocondyla batesii and Cardiocondyla elegans groups (page 8) then later, in taxonomic comments about this species, states it is in the Cardiocondyla elegans group (page 31). When described (Seifert 2003), C. brachyceps was placed in the elegans group.
Cardiocondyla emeryi group
Head elongated with rather high postocular index (CL/CW 1.227–1.246, PoOc/CL 0.454–0.472) and a very narrow frons (FRS/CS 0.200–0.227). Metanotal depression well developed (MGr/CS 2.33–3.22%), Propodeal spines relatively short (SP/CS 0.128–0.207). Postpetiole rather high (PpH/CS 0.292–0.335) and with a bulging sternite that does not show any lobes, cusps or dents. Pubescence on first gaster tergite rather long and dense (PLG/CS 6.7–7.6%, sqPDG 3.8–4.3).
One worldwide tramp species with probably Afrotropical origin.
Cardiocondyla longinoda group
Monotypical group. Assessment based on evaluation of images CASENT09011751 of the holotype in www.antweb.org. The most eye-catching character is petiole shape in lateral view which is not seen in any Afrotropical Cardiocondyla species. Overall, this slender ant shows similarity to members of the Cardiocondyla nuda and C. shuckardi group but it differs from these by a much narrower frons and lower petiole and a more approached spine base. The ratio FRS*PeH/SL is 3.40% in the holotype of C. longinoda but 5.34 ± 0.48 [3.99, 6.88]% in 759 individuals of the C. nuda and C. shuckardi group. The slenderness of C. longinoda is also expressed by the 2nd component of a PCA considering the characters CS, SL, FRS, SPBA and PeH which is −3.80 in the holotype of C. longinoda but 0.005 ± 0.991 [−2.36, 3.59] in 759 individuals of the C. nuda and C. shuckardi group.
Only a single Afrotropical species known.
Cardiocondyla minutior group
Head elongated with rather high postocular index (CL/CW 1.182–1.263, PoOc/CL 0.463–0.490) and a narrow frons (FRS/CS 0.221–0.246). Metanotal depression weak or absent (MGr/CS 0–1.25%), propodeal spines short (SP/CS 0.089–0.133). Postpetiole with a flat sternite and low (PpH/CS 0.230–0.274). Pubescence on first gaster tergite rather long and dense (PLG/CS 6.6–8.3%, sqPDG 2.8–4.0).
Eight species with distributional center in the Orientalic and Australasian region of which two are worldwide tramp species.
- Cardiocondyla britteni
- Cardiocondyla carbonaria
- Cardiocondyla goa
- Cardiocondyla minutior
- Cardiocondyla opaca
- Cardiocondyla parvinoda
- Cardiocondyla schulzi
- Cardiocondyla tjibodana
Cardiocondyla monardi group
(Subgenus Loncyda Santschi, 1931)
Monotypical group. Head, mesosoma, waist and gaster on whole exposed surface with a rich silvery glinting pubescence having flattened hairs. Dorsal profile of mesosoma from anterior part of pronotum to caudal part of propodeum continuously convex, the latter without any suggestions of spines or dents. Petiole extremely slender, with a very long peduncle and a long and narrow node with a feebly convex dorsal profile. Postpetiole narrow and low, distinctly longer than wide, in dorsal view its anterior half conically narrowing frontad.
Only a single Afrotropical species known.
Cardiocondyla nivalis group
Very small (CS 357–402 µm). With exception of the dark brown to jet black gaster, whole body whitish or whitish-yellowish. Metanotal groove notable (MGr/CS 1.6–2.6%) and overall dorsal mesosomal profile more straight. Frons wider than in the former three species groups (FRS/CS 0.290–0.314). Head and scape rather short (CL/CW 1.095–1.149, SL/CS 0.787–0.857).
One species of Australasian-Polynesian origin.
Cardiocondyla nuda group
Promesonotal and anterior propodeal profiles usually not forming evenly convex curvatures—as result, metanotal depression, if present at all, not as wide and with steeper anterior and posterior slopes. Propodeal spines short, appearing in lateral view as smaller angles of 60–95°. Postpetiole in dorsal aspect frequently with angulate-convex sides—the outlines of postpetiole thus resembling a hexagon. 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.
There are similarities to the C. shuckardi group questioning if a separation in different groups by subtle differences in mesosoma profile and postpetiole shape are reasonable. Yet, the morphometric separation of the C. shuckardi and C. nuda group is clear. Individual workers of seven available species in the C. shuckardi group and of all eight species of the C. nuda group were correctly classified by a linear discriminant function in 98.8% of the cases. With all linear measures in mm and sqPDG as square root of the µm value, the discriminant 195.98∗MGr + 0.29∗sqPDG − 9.636∗CW − 24.69∗FRS + 48.59∗SPBA − 71.61∗SP + 58.30∗PeW − 77.64∗PpW + 56.53∗PpH + 2.367 was −1.343 ± 0.973 [−4.100, 1.430] in 540 workers of the C. nuda group and 3.342 ± 1.065 [0.465, 6.606] in 217 workers of C. shuckardi group.
Eight species from the tropical to south temperate zones of the Old World, with one species introduced to the Americas.
- Cardiocondyla atalanta
- Cardiocondyla compressa
- Cardiocondyla itsukii
- Cardiocondyla kagutsuchi
- Cardiocondyla mauritanica
- Cardiocondyla nuda
- Cardiocondyla paranuda
- Cardiocondyla strigifrons
Cardiocondyla shuckardi group
Dorsal profile of promesonotum and of propodeum frontal of spine base feebly but continuously convex—as result, the always developed and rather deep metanotal depression is formed by very shallow anterior and posterior slopes (MGr/CS 1.6–6.3%). Propodeal spines always short (SP/CS 0.029–0.088), reduced do blunt dents or obtusely angled corners. Petiole node in dorsal view always globular. Postpetiole rather narrow (PpW/CS 0.399–0.490), its sides in dorsal view rounded, outlines of postpetiole thus never not forming a hexagon.
About nine species occurring in Africa, the Arab Peninsula and Iran of which one species was introduced to the Caribbean and Hawaii.
- Cardiocondyla fajumensis
- Cardiocondyla longiceps
- Cardiocondyla melana
- Cardiocondyla sekhemka
- Cardiocondyla shuckardi
- Cardiocondyla unicalis
- Cardiocondyla venustula
- Cardiocondyla zoserka
Cardiocondyla sima group
(Subgenus Prosopidris Wheeler, 1935)
Antennae with 11 segments instead of 12 in all other species of the genus. Collective length of the three apical antennal segments 57–63% of whole funiculus length, in other species shorter. Anterior part of postpetiole in dorsal view conic. Petiole with a very long peduncle and well-developed node. Scape very long in terms of the genus (SL/CS 0.937–0.981).
At least two polymorphic Australasian species, no tramp species known.
Cardiocondyla stambuloffii group
True foveolae on vertex completely absent. Instead the bases of pubescence hairs are placed in the center of flat tubercles or flat pits of small diameter, giving a finely punctate surface appearance at lower magnifications, dFov 8.13 ± 0.78 [5.0, 10.0]. Frons very wide, FRS/CS 0.320 ± 0.015 [0.269, 0.353]. Propodeal spines reduced to blunt dents, SP/CS 0.070 ± 0.013 [0.027, 0.096]. Metanotal depression deep, MGr/CS 3.57 ± 0.83 [1.63, 6.16]%; all numeric data from 153 worker individuals of five species.
The members of the C. batesii, C. elegans and C. ulinanini groups as proposed are morphologically similar. This grouping is confirmed by an LDA considering all morphometric characters with positive checks in wild-card runs for rare species with very few samples available.
SE Europe across Asia Minor eastwards to Tibet and Mongolia.
- Cardiocondyla gibbosa
- Cardiocondyla koshewnikovi
- Cardiocondyla rolandi
- Cardiocondyla stambuloffii
- Cardiocondyla tibetana
Cardiocondyla sulcata group
Monotypical group. Metanotal groove very deep and with an extremely steep posterior slope that forms with the anterior slope a distinct angle of 90–100°. Petiole with a very long peduncle, in dorsal view more than twice as long than wide and with a small circular node, in profile the node is low with a convex dorsum. Postpetiolar sternite almost flat, only with suggested and very rounded anterolateral corners.
Only a single Orientalic species known from Malaysia.
Cardiocondyla thoracica group
Pronotal corners in dorsal and lateral view very prominent and sharp. Dorsal mesosomal profile not evenly convex and with an absent to well-developed metanotal depression (MGr/CS 0–7.6%). Postpetiolar sternite differently shaped but not distinctly bilobate or bicuspidate, without any prominent structures. Spine base narrower and spines shorter than in the C. wheeleri group (SPBA/CS 0.237–0.368, SP/CS 0.230–0.365).
Three Australasian species, all occurring east of the Wallace Line, no tramp species known.
Cardiocondyla ulianini group
Eye large (EYE/CS 0.248 ± 0.012), postocular distance larger (PoOc/CL 0.407 ± 0.031), head longer (CL/CW 1.160 ± 0.022), metanotal depression always present (MGr/CS 3.85 ± 0.84%), propodeal spines short (SP/CS 0.114 ± 0.015), pubescence on first gaster tergite rather long (PLG/CS 6.55 ± 1.06%), postpetiolar sternite without any protrusions.
Seven described and one undescribed species (Cardiocondyla sp. code CASP) from the southern zone of the West and Central Palaearctic.
- Cardiocondyla bulgarica
- Cardiocondyla caspiense
- Cardiocondyla gallilaeica
- Cardiocondyla israelica
- Cardiocondyla littoralis
- Cardiocondyla persiana
- Cardiocondyla sahlbergi
- Cardiocondyla ulianini
Cardiocondyla wheeleri group
Pronotal corners in dorsal view developed but blunt. Dorsal mesosomal profile not evenly convex with a small metanotal depression (MGr/CS 1.4–3.0%). Postpetiolar sternite flat or shallowly convex and without any prominent structures. Spine base very broad and spines rather long (SPBA/CS 0.341–0.374, SP/CS 0.296–0.418).
Four Australasian species, all occurring east of the Wallace Line, no tramp species known,
Cardiocondyla wroughtonii group
Head rather short with comparably low postocular index (CL/CW 1.099–1.189, PoOc/CL 0.415–0.440) and a variably wide frons (FRS/CS 0.219–0.282). Scape short to very short (SL/CS 0.682–0.825). Metanotal depression well developed (MGr/CS 3.25–3.65%). Propodeal spines rather short (SP/CS 0.184–0.201). Postpetiole higher (PpH/CS 0.276–0.337) with a bilobate or bicuspidate sternite. Pubescence on first gaster tergite variable.
Seifert (2024) - The bilobate shape of the postpetiolar sternite (see next paragraph) is considered here as a leading indicator of the C. wroughtonii group. However, when clustering attempts are made considering all 16 phenotypical characters, Cardiocondyla yemeni Collingwood & Agosti 1996, C. yoruba Rigato 2002, C. weserka and C. neferka Bolton 1982, which all show a bilobate postpetiolar sternite, do not cluster with the remaining species of the C. wroughtonii group. In this context it should be noted that the six species from Africa and the Arabian Peninsula show diverging frontal carinae with FL/FR > 1.040 whereas the five species with Orientalic- Australasian origin have FL/FL < 1.040. Thus it seems that the C. wroughtonii group sensu stricto has to be reduced to the latter five species. Anyway, to clear up the relatedness of these species, we have to wait for an analysis of adequate nuDNA markers done on the basis of an extended sample size.
In the absence of better solutions and aiming at a simple keying in a worldwide context, I characterize here the C. wroughtonii group as follows: postpetiolar sternite anterolaterally with a rounded lobiform protrusion on each side which clearly elevates above the level of median surface of sternite; the surface of the sternite thus appearing deeply concave in frontal view. Mesosoma not stout (ratio ML/MH >2.2); dorsal mesomal profile not humpbacked, instead it is feebly convex with a metanotal depression, if the latter is nearly absent then dorsal profile rather linear; ratio SPBA/CS <0.314. The shape of postpetiolar sternite characteristic for the wroughtonii group is also seen in the following species restricted to the Orientalic-Australasian-Polynesian zoogeographical region: Cardiocondyla argentea Seifert 2023, Cardiocondyla semiargentea Seifert 2023, Cardiocondyla argyrotricha Seifert 2023, Cardiocondyla latifrons Seifert 2023, Cardiocondyla micropila Seifert 2023, Cardiocondyla pirata Seifert 2013. These species are easily separable, among other characters, by their stout, humpbacked mesosoma with a ratio ML/MH < 2.2 and broad spine bases with SPBA/ CS > 0.314.
Five described and two undescribed species (Cardiocondyla sp. code HEIN, Cardiocondyla sp. code AFRI) with origin in the tropics of the Old World, two of these occur as worldwide tramp species.
- Cardiocondyla allonivalis
- Cardiocondyla heinzei
- Cardiocondyla nana
- Cardiocondyla neferka
- Cardiocondyla obscurior
- Cardiocondyla shagrinata
- Cardiocondyla weserka
- Cardiocondyla wroughtonii
- Cardiocondyla yemeni
- Cardiocondyla yoruba
References
- Seifert, B. 2003. The ant genus Cardiocondyla (Insecta: Hymenoptera: Formicidae) - a taxonomic revision of the C. elegans, C. bulgarica, C. batesii, C. nuda, C. shuckardi, C. stambuloffii, C. wroughtonii, C. emeryi, and C. minutior species groups. Annalen des Naturhistorischen Museums in Wien Serie B Botanik und Zoologie. 104:203-338.
- Seifert, B. 2022. The ant genus Cardiocondyla (Hymenoptera: Formicidae): The species groups with Oriental and Australasian origin. Diversity 15, 25 (doi:10.3390/d15010025).
- Seifert, B. 2023. A revision of the Palaearctic species of the ant genus Cardiocondyla Emery 1869 (Hymenoptera: Formicidae). Zootaxa 5274(1), 1–64 (doi:10.11646/zootaxa.5274.1.1).
- Seifert, B. 2024. A taxonomic revision of the ants of the Cardiocondyla wroughtonii group (Hymenoptera: Formicidae) with a checklist of the Cardiocondyla species of the world. Soil Organisms 96 (2):113-144. (doi:10.25674/415)
- Seifert, B., Okita, I., Heinze, J. 2017. A taxonomic revision of the Cardiocondyla nuda group (Hymenoptera: Formicidae). Zootaxa 4290: 324–356 (doi:10.11646/zootaxa.4290.2.4).