Cardiocondyla argentea

So far this species is only found east of the Wallace Line in North and Central Sulawesi as well as Maluku from sea level to 800 m. Its biology is unknown but should be, at least regarding male morphology and behavior, similar to the situation in the well studied, closely related Cardiocondyla argyrotricha.

Identification
Worker (Figure 10, Table 2): Medium-sized, CS 491 µm. Head extremely short, CL/CW 1.051. Postocular distance rather small, PoOc 0.420. Scape moderately long, SL/CS 0.826. Eye small, EYE 0.211. Anterior clypeal margin between the level of frontal carinae concave. Occipital margin slightly concave or straight. Frontal carinae converging immediately posterior of the FRS level, FRS/CS 0.311. Mesosoma extremely thickset and short; its length without neck shield only 1.1 of CL. Dorsal profile of mesosoma hump-backed, strongly and evenly convex, without any metanotal groove. Spines of medium length (SP/CS 0.258), acute, in lateral view feebly upcurved and their axis deviating by 25° from longitudinal axis of mesosoma, spine bases widely distant, SPBA/CS 0.392. Petiole in lateral view high (PeH/CS 0.335), with a short peduncle a concave frontal and convex caudodorsal profile; the node in dorsal view wider than long, PeW/CS 0.300. Postpetiole in dorsal view narrow (PpW/CS 0.413), extremely short and with a concave anterior margin; in lateral view very low (PpH/CS 0.254), with a semicircular ventral profile that is produced by prominent bilateral lobes of the sternite which strongly protrude compared to median level. Whole surface of head and mesosoma densely foveolate-microreticulate, thus appearing at lower magnifications perfectly matt. The foveolae on vertex and dorsal pronotum are larger with a foveolar diameter of 11–15 µm but are not salient because of partial covering by pubescence. Petiole and postpetiole microreticulate and matt; postpetiole in the holotype series mildly shiny and weakly microcorrugated. First gaster tergite shiny, with a delicate, fragmentary microreticulum. Cephalic and mesosomal pubescence hairs flattened and appearing silvery (Figure 10D), their larger diameter 4 µm (normal in Cardiocondyla are 1.7–2 µm), the smaller diameter about 2.5 µm. Gastral pubescence not flatted, rather long and dense (PLG/CS 6.08%, sqPDG 4.12). Whole body rather concolorous dark to medium brown.

There are three similar Indo-Malayan species sharing a silvery pubescence, a thickset, hump-backed mesosoma and an extremely low postpetiole with prominent bilateral sternal lobes: Cardiocondyla argentea, Cardiocondyla semiargentea and Cardiocondyla argyrotricha. The former two species occur east of the Wallace Line and the latter one west of it. These species can be separated by a PCA and LDA. The PCA was run considering the 15 characters CS, CL/CW, SL/CS, SPBA/CS, PeW/CS, PpW/CS, SP/CS, FRS/CS, EYE/CS, PeH/CS, PpH/CS, sqPDG, PLG/CS, PoOc/CL and MpGr. The first three components of this PCA where then used as variables in a LDA in order to avoid an overfitting of the discriminant function due to low class size (only 11 specimens in the smallest class). Both the LDA and the leave-one-out cross-validation LDA confirmed all 47 species hypotheses (Figure 29).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia.

Nomenclature

 * . Cardiocondyla argentea Seifert, 2022: 37, fig. 10 (w.q.) INDONESIA.

Type Material
Holotype worker and 5 paratype workers labelled “Banggai Arch., Potil Kecil 1°28′ S-123°34′ E 12–19.ii.1980\M.J.D.Brendell B.M. 1980-280”, BMNH London; 2 worker and 1 gyne paratype with identic labelling, SMN Görlitz; 3 worker paratypes labelled “INDONESIA: N.C.Seram\Manusela N.P., Wae Mual Plain 25.vii-9.ix.1987\Op. Raleigh M.J.D.Brendell. B.M. 1987-262”, BMNH London; 3 paratype workers labelled “Indonesia-05, Sulawesi, Prov. Minasha, Dumoga Bone N.P., E-side, vic. Duluduo, 0°35′ N 124°54′ E, 100mH, 04.-09.12.2000, Leg. A Schulz”, SMN Görlitz.