Cardiocondyla atalanta

Colony structure and behavior does not seem to differ from Cardiocondyla nuda. Multiple fertile queens were present in four of six colonies excavated in 2014 in Kutini Payamu National Park near Lockhart. Males are ergatoid, kill callow males and fight with adult males (observation in the laboratory of J. Heinze). Slightly larger, ergatoid males with stubby wings, as previously described for related taxa (Yamauchi et. al. 2005), may occasionally occur. (Seifert et al., 2017)

Identification
A member of the Cardiocondyla nuda group.

This species differs from Cardiocondyla nuda by a less elongated head and scape, a higher petiole and a higher and wider postpetiole. The main difference to the sister species Cardiocondyla paranuda is the longer pubescence on the gastral tergites (Seifert et al., 2017).

Seifert et al. (2017) - There is no doubt that species separation in the C. nuda group is difficult. It requires careful consideration of character definitions and the use high-resolution optical and measurement systems. The diagnose presented here uses numerous morphological characters to achieve an acceptable identification error rate.

Meeting the following definition:


 * Discriminant 176.328×PPH - 49.049×CW + 51.521×SP - 59.844×PPW + 6.61 > 0
 * Discriminant 60.625×SL - 80.384×SP - 61.223×PPW + 356.511×PLG - 12.585 > 0
 * Discriminant 538.753×PLG - 72.321×CL + 174.434×MpGr + 46.778×SL + 4.27 < 0
 * Petiole not very narrow, discriminant 124.351×PEW - 1.129×CW - 13.561 > 0

where:


 * CL: Maximum cephalic length in median line; the head must be carefully tilted to the position yielding the true maximum; excavations of hind vertex and/or clypeus reduce CL.


 * CW: Maximum cephalic width; the maximum is found usually across and including the eyes, exceptionally posterior of the eyes.


 * MpGr: Depth of metanotal groove or depression, measured from the tangent connecting the dorsalmost points of promesonotum and propodeum.


 * PEW: Maximum width of petiole.


 * PLG: Mean length of pubescence hairs on dorsum of first gaster tergite as arithmetic mean of at least 7 measurements measured at magnifications of 320x.


 * PPH: Maximum postpetiole height; the lateral suture of dorsal and ventral sclerites is the reference line perpendicular to which the maximum height of postpetiole is measured.


 * PPW: Maximum width of postpetiole.


 * SL: Maximum straight line length of scape excluding the articular condyle given as the arithmetic mean of both scapes.


 * SP: Maximum length of propodeal spines; measured in dorsofrontal view along the long axis of the spine, from spine tip to a line that orthogonal to the long axis and touches the bottom of the interspinal meniscus (Fig. 3). Left and right SP are averaged. This mode of measuring is less ambiguous than other methods but yields higher spine length values in species with reduced spines. This is the case in the dentiform spines found in the C. nuda group where it is difficult to correctly define the long axis. In such cases, the deviation of the assumed spine axes from longitudinal mesosomal axis should not exceed 30°.

Distribution
C. atalanta is known from all of Australia except its inner desert territories, from Papua New Guinea and Lord Howe Island and Norfolk Island.

Distribution based on Regional Taxon Lists
Australasian Region: Australia, Lord Howe Island, Norfolk Island. Indo-Australian Region: New Guinea.

Nomenclature

 *  atalanta. Cardiocondyla nuda var. atalanta Forel, 1915b: 75 (w.) AUSTRALIA.
 * Junior synonym of nuda: Taylor, 1991b: 601.
 * Revived from synonymy and raised to species: Seifert, 2003a: 247.
 * Status as species: Seifert, 2008: 44; Seifert et al., 2017: 350.

Taxonomic Notes
C. atalanta was synonymised with C. nuda by Taylor (1991 ). Seifert (2003 ) removed C. atalanta from synonymy and considered it to be represented by types only, the remaining Australian material belonging to C. nuda. Seifert (2008 ) then modified his concept of C. atalanta to include essentially all Australian material and found only a few specimens which belonged to C. nuda. Unfortunately he could not find any readily observable characters to separate these two taxa with recognition being based on statistical differences in the length of pilosity hairs on the first gastral tergite. He states that "gastral pubescence length, scape length and postocular distance are significantly smaller in C. atalanta while gastral pubescence density is larger than in C. nuda. However, character overlap is considerable." Thus separation of these cryptic species is not possible using a simple morphology-based key such as this and identification will require more advanced morphometric procedures such as detailed by Seifert (2008 ). More recently, Seifert et al. (2017) restricted C. atalanta to coastal specimens of Cardiocondyla within Australia, transferred more xeric specimens to C. nuda. This was based on subtle morphometric differences identified using complex statistical methodologies.