Cardiocondyla yemeni

The second collection of this species, from Oman, was found in dry leaf litter.

Identification
This is, by far, the smallest of the Arabian Cardiocondyla species.

Seifert (2003) - A member of the Cardiocondyla emeryi group. The morphometric character combination of the C. yemeni worker is unique and provides an easy distinction from any known species. The gynes of C. yemeni have a unique combination of extremely short scape, narrow postpetiole, and elongated head, and can be distinguished from other species with anterolateral postpetiolar sternite comers by a collective index (SL*PPW) / CS*CW/CL of 0.271 ± 0.006 [0.262, 0.275] (n = 4), which is much lower than in Cardiocondyla obscurior (0.322 ± 0.014 [0.296, 0.353] n = 20) or Cardiocondyla wroughtonii (0.305 ± 0.008 [0.296, 0.320] n = 15).

Distribution based on Regional Taxon Lists
Afrotropical Region: Yemen. Palaearctic Region: Oman.

Biology
Collingwood and Agosti (1996) - It is interesting that there were often two or three species of Cardiocondyla in the same locality. In particular Cardiocondyla shuckardi, Cardiocondyla wroughtonii and Cardiocondyla yemeni were all collected at the same site at Wadi Surdud, and at Sana' a two of these species were seen wandering over the ground in close proximity.

Nomenclature

 *  yemeni. Cardiocondyla yemeni Collingwood & Agosti, 1996: 328, fig. 11 (w.) YEMEN. See also: Seifert, 2003a: 281.

Worker
Holotype: TL 2.3; HL 0.48; HW 0.38; SL 0.30; EL 0.12; PW 0.11; PPW 0.17.

This species is characterised by its small size, broad dentate spines, reticulopunctate sculpture over the whole dorsum including the gaster and overall pale yellowish-brown colour. In profile the petiole is broadly rounded and relatively low.

Seifert (2003) - Very small size CS 377. Head long, CL/CW 1.260. Scape extremely short, SL/CS 0.724. Postocular index large, PoOC/CL 0.453. Eyes rather prominent, with large ommatidia of 1 3 mm diameter, minute setae absent, EYE 0.238. Frons narrow, FRS/CS 0.242, frontal carinae slightly converging immediately behind FRS level. Anterior clypeal margin with straight or slightly concave medial portion, occiput weakly excavated. Clypeus and frontal laminae rather smooth, not shining and weakly shaginate-carinulate. A small median stripe on vertex weakly carinulate. In the paratype, paramedian and lateral areas of vertex with moderately deep, bicoronate foveolae, their interspaces moderately shining and with a perifoveolar reticulum; in the topotypical worker foveolae deeper and more densely packed; diameter of foveolae 13 - 16 mm diameter. Whole surface of mesosoma mat; dorsal area of mesosorna rather mat, irregularly foveolate-shagrinate-microreticulate; lateral area of mesosoma more strongly reticulate. Waist segments weakly reticulate. Spines short, their axis in lateral view deviating by 45° from longitudinal mesosomal axis. Metanotal groove in lateral view invisible. Petiole in profile with rather short peduncle and rounded dorsum of node that appears almost globular in dorsal view. Axis of petiolar peduncle in lateral aspect deviating by 40° from longitudinal axis of petiole node. Postpetiole in dorsal view with convex sides that meet with the straight anterior margin without a distinct corner; postpetiolar sternite with strong anteroventral corners, resembling situation in Cardiocondyla wroughtonii. Surface of 1st gaster tergite shining, but weakly microreticulate. All body parts light-yellowish brown.

Queen
Seifert (2003) - Very small, CS 450. Head much elongated, CL/CW 1.222. Postocular index large, PoOc/CL 0.440. Scape extremely short, SL/CS 0.714. Occipital margin slightly concave or almost straight. Anterior clypeal margin with a suggested median concavity. Frontal carinae slightly converging immediately caudal of FRS level, in most caudal portion diverging. With exception of 5 - 6 longitudinal rugae on metapleuron and weak longitudinal rugosity on vertex and median area of clypeus, whole head and mesosoma without any rugosity. Vertex with deep foveolae of 16 - 17 mm diameter in dense honey-comb arrangement and with inner coronae of 8 - 9 mm diameter. Whole surface of mesosoma and waist densely foveolate, foveolae on dorsal area of mesosoma similar to those on vertex, those on lateral area of mesosoma and in particular on waist with slightly lower diameters. Cuticular surface of 1st gaster tergite shining, with delicate, but fully developed microreticulum. Propodeal spines acute, directed caudad (in lateral view diverging from longitudinal axis of mesosoma by only 25 0), and shorter than in C. wroughtonii, SP/CS 0.130. Postpetiole with sharp anteroventral corners, similar to situation in Cardiocondyla wroughtonii. Postpetiole in dorsal view with angulate-convex sides and straight anterior margin not forming distinct anterior comers. Petiolar node in dorsal view globular, about as wide as long. Head, mesosoma, and waist light-yellowish brown, antennal club blackish brown, gaster entirely blackish brown.

Type Material
Holotype: worker, Yemen, Sana'a, 5.III.1993, CA. Collingwood. - Paratypes: Yemen: 2 workers, same series as holotype; 4 workers, Wadi Surdud, 21.III.1991, A. van Harten.

Seifert (2003) - Yemen [type investigated]. 1 paratype worker labelled “YEMEN: Sana' a (sandy path) 05 03 1993 leg. CACollingwood”, “Cardiocondyla yemeni male”, and “Typus”,. 1 topotypical worker, without postpetiole and gaster, labelled “YEMEN Sana'a 17 III 93” (day not clearly legible, other possible reading “27 III 93”) and “Cardiocondyla yemeni sp.n. Collingwood & Agosti 1996”.

References based on Global Ant Biodiversity Informatics

 * Sharaf M. R., B. L. Fisher, H. M. Al Dhafer, A. Polaszek, and A. S. Aldawood. 2018. Additions to the ant fauna (Hymenoptera: Formicidae) of Oman: an updated list, new records and a description of two new species. Asian Myrmecology 10: e010004