Cardiocondyla paranuda

Cardiocondyla paranuda is apparently well adapted to arid and very hot climate and the only species of the whole genus Cardiocondyla occurring in inner Australia. This is demonstrated by significant differences between C. paranuda and the closely related Cardiocondyla atalanta in the continentality of the sites. The mean distance from sea shore and mean annual rainfall are 23 ± 51 [0,252] km and 1430 ± 716 [500, 4500] mm in 27 sites of C. atalanta and 329 ± 332 [0, 904] km and 588 ± 385 [150, 1250] mm in 27 sites of C. paranuda. These differences are significantly different in both sea shore distance (ANOVA F1,52=22.39, p<0.0005) and annual rainfall (ANOVA F1,52=28.90, p<0.0005). As yet only foragers have been collected and colony structure, male morphology, and behavior are unknown.

Identification
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

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.


 * 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
Australia, only species of the whole genus Cardiocondyla occurring in inner Australia (Seifert et al., 2017).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  paranuda. Cardiocondyla paranuda Seifert, 2003a: 246, fig. 31 (w.) AUSTRALIA.
 * Status as species: Seifert et al., 2017: 346.

Worker
Siefert et al. (2017) - Worker (Tab. 2, Figs. 14–16): Head elongated, CL/CW 1.214. Postocular distance rather large, PoOc/CL 0.463. Eyes relatively small, EYE 0.234. Frontal carinae immediately caudal of the FRS level parallel or very slightly converging. Foveolae on vertex without interspaces, deeply impressed, with 13–19 μm diameter, and with an inner corona (a flat tubercle) of 7–9 μm diameter having the base of a decumbent pubescence hair in its center. This type of sculpture can also be described as a strongly sculptured microreticulum. Longitudinal sculpture on vertex often completely absent (Fig. 15). Weak semicircular rugae are found around the antennal fossae. Lateral mesosoma on whole surface regularly and strongly microreticulate-foveolate; longitudinal sculpture except for 4–6 weak and short carinulae on metapleuron completely absent (Fig. 16); dorsal mesosoma irregularly reticulate-foveolate-shagrinate. Sides of petiole with a deeply sculptured microreticulum, dorsal petiole and postpetiole with a weak and shallowly sculptured microreticulum. Cuticular surface of first gaster tergite rather smooth and shining but on its whole surface with a well-developed microreticulum (Fig. 14). The pubescence hairs on gaster tergites are the shortest within the C. nuda group, PLG/CS is only 5.06%. Metanotal depression very shallow, MGr/CS 1.28%. Propodeal spines short but clearly longer than in the C. mauritanica species complex. Dorsal propodeum sloping down to base of spines under an angle of 20°. Petiole node slightly longer than wide. Postpetiole in dorsal view with only suggestedly angulate sides and straight anterior margin that is slightly shorter than posterior margin; postpetiolar sternite bulging, without any protrusions but on each side with a suggested paramedian, longitudinal carina. Head, mesosoma, waist and appendages often amber-colored, gaster significantly darker—this is the most frequently observed coloration but populations with dark headed specimens or such with concolorous amber specimens do occur. For morphometric data of 52 workers see Tab. 2.

Seifert (2003) - holotype: CS 454, CL/CW 1.224, SL/CS 0.775, PoOc/CL 0.473, EYE 0.220, dFOV 17.0, FRS/CS 0.289, SPBA/CS 0.300, SP/CS 0.114, PEW/CS 0.309, PPW/CS 0.501, PEH/CS 0.343, PPH/CS 0.359, sqrtPDG 4.26, PLG/CS 4.57 %, PigCap 8, PigMes 9, MGrlCS 2.5 %.

Head elongated, CL/CW 1.224. Postocular distance very large, PoOc/CL 0.473. Scape short, SL/CW 0.775. Occipital margin straight or slightly concave. Frontal laminae converging immediately caudal of FRS level, FL/FR 1.107. Eyes small, EYE 0.220. Vertex with rather deep, well-demarcated, flat-bottomed foveolae of 16 - 18 mm diameter, showing an inner corona of 7 - 9 mm diameter; foveolae densely packed, interspaces much narrower than foveolar diameter. Clypeus and frontal laminae longitudinally carinulate; remaining dorsal head without longitudinal sculpture. Dorsal area of pronotum with scattered and very shallow foveolae of 15 - 18 mm diameter; interspaces much wider than foveolar diameter, more or less shining, and with very delicate cross-branched or semi-reticulate microsculpture. Mesonotum and propodeum dorsally with irregular foveolate-rugulose microsculpture. Whole area of lateral mesosoma strongly microreticulate, metapleuron with 3 short longitudinal carinulae. Petiole and postpetiole finely microreticulate, on petiole sides stronger. Surface of 1st gaster tergite shining, with very delicate microreticulum, and very short pubescence, PLG/CS 4.57 %. Most of pubescence hairs on first tergite of type specimen torn-off, sqrtPDG calculated from PLG and mean distance of hair base pits as 20.0 mm. Metanotal depression shallow. Spines short, acute, and rather steep, comparable to situation in Tetramorium caespitum. Petiole node rather massive, in dorsal view slightly wider than long, in profile with truncate-rounded dorsum. Petiolar peduncle thicker than in C. nuda. Postpetiole higher than petiole (PEH/PPH 0.954), with bulging sternite; in dorsal view with angulate-convex sides and slightly concave anterior margin. Whole body medium brown with yellowish tinge; waist and appendages lighter, gaster darker.

Type Material


Seifert et al. (2017) - There is a serious problem with the site documentation in the holotype of C. paranuda. The specimen was sent by C.A. Collingwood to the senior author in the 1980s with the labelling "TUNISIA: Medinine-32 km SE Chabania-6 km NW leg. H.Heatwole 1976“. If run as a wild-card in a LDA considering all 16 morphometric characters and collecting all samples of the C. mauritanica species complex in class 1 and all of the C. nuda complex in class 2, the holotype C. paranuda is allocated to the C. nuda complex with p=1.0000. This is problematic because species of the C. nuda species complex are completely absent from the West Palaearctic and North Africa and it appears also most unlikely that ants from Australia should have been anthropogenically introduced to a site in the Sahara desert. Furthermore, NC-clustering places the holotype in a cluster of C. nuda group specimens that are treated as a single species that is restricted to the Australian continent and sister to C. atalanta. A wild-card run in a LDA confirms this allocation with p=0.9916 (see section 4.4). The most probable explanation for this conflicting situation is a confusion of labels. Harold Heatwole collected in North Africa, Tibet and Australia—for instance, the two C. paranuda samples from Queensland: Chilcott Island in 1967 were taken by him. He usually gave his specimens to Collingwood stored in tubes with ethanol. As repeatedly witnessed by the senior author in personal contacts during laboratory work in 1982 and 1990, Collingwood had the dangerous habit of placing similar ethanol-stored ants from different tubes side-by-side under the microscope for better comparison and sometimes he confused from which tube he had taken the specimens. We conclude that the type of C. paranuda has most probably been collected somewhere in Australia.

Taxonomic History
Previous identification:

Seifert (2003) - A member of the Cardiocondyla nuda group. Morphometric and structural similarities suggest a close relation to Pacific Cardiocondyla nuda, from which it differs by extremely small PLG, small EYE, and large PEW/PPW, with all these data outside of the range of variation known for C. nuda. Less obvious differences are the smaller diameter and the less dense arrangement of vertex foveolae and the more massive petiole node (however, specimens with massive petioles that have a truncate-rounded dorsal profile may occur in Pacific C. nuda). The separation from Cardiocondyla mauritanica and C. mauritanica morph B is easily possible by much smaller PEH/PPH, much larger PoOc/CL, much smaller PLG/CS, and more erect spines. Heatwole's sample originally included also an ergatoid male with a morphology similar to the ergatoids of C. mauritanica. This specimen was unfortunately lost by a handling accident.