Cardiocondyla tibetana Seifert 2003

Seifert, Bernhard, 2023, A revision of the Palaearctic species of the ant genus Cardiocondyla Emery 1869 (Hymenoptera: Formicidae), Zootaxa 5274 (1), pp. 1-64 : 53-62

Cardiocondyla tibetana Seifert 2003 [types investigated]

This taxon has been described from the southern margin of Taklamakan Desert. Investigated were the holotype worker (the specimen with CW=510) and 2 paratype workers labelled “ CHINA: Xinjang, Tarim Basin, Ceele Station , leg. H. Heatwole, 1966.08.26 “, SMN Goerlitz ; 2 paratype workers pierced on minute pins in the same block of Sambucus pith and labelled “ Tibet coll. G.Mayr ”, NHM Wien .

All material examined. NUMOBAT data were recorded in 4 samples with 11 worker specimens. For details see supplementary information SI1, SI2. All material originated from China .

Geographic range.Three findings with precise site records are at the southern and northern margin of the Taklamakan desert (37.015°N, 80.729°E, 1366 m; 41.175°N, 84.232°N, 920 m). The precise locality of Gustav Mayr’s sample is unclear but probably at the margin of the Tarim Basin with the Tibetan Plain.

Diagnosis: --Worker ( Tab. 4 , Figs. 101–104 ; images ANTWEB1041252 and CASENT0919737 in www.antweb. org key): Rather small, CS 540 µm. Head short, CL/CW 1.159. Postocular index smaller than in other members of the stambuloffii group, PoOc/CL 0.424. Hind margin of head with a suggested concavity in the median third. Scape longer than in other members of the stambuloffii group, SL/CS 0.838. Eye larger than in other members of the stambuloffii group, EYE/CS 0.248. Frons narrower than in other members of the stambuloffii group (FRS/ CS 0.280), frontal carinae weakly converging immediately caudal of FRS level (FL/FR 1.047). Dorsal profile of promesonotum convex, metanotal depression rather shallow (MGr/CS 3.14 %), dorsal profile of propodeum slightly convex. Propodeal spines reduced to obtuse angled corners, SP/CS 0.044), the distance of their bases much smaller than in other members of the stambuloffii group (SPBA/CS 0.219). Petiole more than half as wide as postpetiole and distinctly higher than wide (PeW/CS 0.271, PeH/CS 0.310), in profile with a moderately short peduncle and the anterior slope of the node much less inclined than the posterior slope (58° vs. 71° relative to ventral petiole profile)—as result the node profile is strongly asymmetric. Petiole node in dorsal view wider than long. Postpetiole much narrower and lower than in other members of the stambuloffii group and less than twice as wide as high (PpW/ CS 0.510, PpH/CS 0.265), in dorsal aspect with a rather straight anterior margin, postpetiolar sternite completely flat. Clypeus, frontal laminae, and anterior 70% of median and paramedian vertex very densely longitudinally carinulate-rugulose; distance between carinulae on central vertex only 4–5 µm. Carinulae on lateral vertex interrupted and with much larger, more or less shining interspaces. Poorly visible hair base punctures of only 5–7 µm diameter are scattered in the interspaces; many of the hair bases without surrounding micropunctures ( Fig. 104 ). Posterior third of head almost glabrous, only scattered hair base punctures present. Foveolae of any size and type on whole head completely absent. Pronotum glabrous. Dorsal parts of mesonotum and propodeum mainly smooth and shining, longitudinal carinulae may be present. Lateral mesonotum with interrupted, meso- and metapleurae with stronger, more continuous longitudinal rugulosity. Petiole and postpetiole smooth and shiny. Pubescence on gaster tergites moderately long and dense, PLG/CS 6.39 %, sqPDG 3.54. Whole body rather concolorous medium to blackish brown, appendages and sometimes clypeus lighter with yellowish tinge.

Taxonomic comments and clustering results. The character combination of Cardiocondyla tibetana is unique and enables a safe distinction from any known Palaearctic species both by morphometry, body shape, and microstructures. The minute or absent hair base punctures and full absence of any foveolae on vertex, as well as spine and postpetiolar shape were the reasons for placing tibetana in the stambuloffii group. However, the larger eye size, the narrower frons, and the lower petiole height and postpetiole width also indicate affinities to the elegans or ulianini groups.

Biology. Two nests were found by Roland Schultz in a semidesert zone in an area with clay or loamy soil occasionally flooded by the river Tarim and covered by light tamarisk stands.

Figures

FIGURES101–104.Cardiocondylatibetana, paratype;Fig.101:headin dorsalview; Fig.102:lateral view (flippedhorizontally); Fig. 103: dorsal view; Fig. 104: head surface between inner eye margin and paramedian vertex (flipped horizontally). China: Tarim: Ceele Station, 1966.08.26