Strongylognathus dao

Two colonies of S. dao were collected in a typical Inner Mongolian steppe ecosystem dominated by various bunch of grasses (e.g., Wu & Loucks 1992). Other ants occurring in the area were Temnothorax nassonovi Ruzsky, Proformica mongolica Emery, Lasius cf. alienus, and several undetermined species of Formica and Myrmica.

Identification
Strongylognathus dao belongs to the huberi species-group and therefore differs notably from the other species described from China, Strongylognathus potanini Radchenko and Strongylognathus tylonus Wei, Xu et He, which are members of the testaceus-group.

Workers of S. dao resemble Strongylognathus koreanus Pisarski, but differ from the latter by the presence of standing hairs on the temples and genae, while such hairs are restricted to the occipital margin and occipital corners in S. koreanus. Additionally, the latter species is much lighter, orange-yellow or ochreous, and its postpetiole is relatively somewhat longer, lower and narrower (means PPL/PPH 0.81 and PPL/PPW 0.73 vs. 0.67 and 0.62 in S. dao). Workers of S. dao differ from those of Strongylognathus christophi Emery by the longer head (mean HL/HW 1.15 vs.1.10), and by the much more developed longitudinal rugosity on the sides of mesosoma. Queens (gynes) of S. dao are much smaller than those of S. christophi: HL < 0.85, HW < 0.70, ML < 1.25 vs. HL > 1.2, HW > 0.90, ML > 1.60 mm. S. christophi is distributed from southern Ukraine to Kyrgyzstan (Ruzsky, 1905; Pisarski, 1966; Radchenko, 1985, 1991, 2016) and we cannot exclude the possibility of finding this species in north-western China.

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Biology
The first colony was found during a general study on ant biodiversity. The second colony was noticed because of a large number of Tetramorium and Strongylognathus fighting close to two adjacent nest entrances A and B on July 31, 2017 around 10:00 in the morning in full sun after a rainy afternoon and evening. The area was full of dead or dying ants and it appeared that Tetramorium workers tried to block the nest entrances. At 11:05, a raiding column of dozens of S. dao workers left entrance A and rapidly entered a third nest entrance C about 50cm away. Within minutes, the entrances A and C were connected by ants travelling in both directions, and at 11:20, a S. dao worker was seen leaving entrance C and carrying a prepupa towards entrance A. Two more brood items were transported by S. dao in the same way, but presumably because of increasing soil temperatures the activity ceased rapidly and only a few fighting and dying ants were still observed between 12 and 14:00.

Nomenclature

 *  dao. Strongylognathus dao Radchenko, Zhang & Heinze, 2017: 3, figs. 1-4 (w.q.m.) CHINA.

Type Material


Paratypes: ca. 40 workers, 3 gynes and 17 males from the nest of holotype; 8 workers, collected on July 31, 2016 from a second nest in soil during a raid approximately 300 m away from the other nest (SIZK, National Zoological Museum of China, University of Regensburg, Germany). Unique specimen identifiers are: holotype worker – CASENT0916954, paratype gyne – CASENT0916955, paratype male – CASENT0916956 (all these are preserved in SIZK).