Temnothorax, Radchenko & Perkovsky, 2021

Radchenko, A. G. & Perkovsky, E. E., 2021, Wheeler’s dilemma revisited: first Oecophylla-Lasius syninclusion and other ants syninclusions in the Bitterfeld amber (late Eocene), Invertebrate Zoology 18 (1), pp. 47-65 : 53-55

Y. geinitzi with Temnothorax gracilis ( Mayr, 1868) , Y. geinitzi with Temnothorax sp. nov.,

Oecophylla brischkei Mayr, 1868 with L. schiefferdeckeri ( Fig. 1 ), and Bradoponera meyeri Mayr, 1868 with F. flori . Two contain only Holarctic species: a F. flori with L. schiefferdeckeri and Myrmica sp.n. with Plagiolepis kuenowi Mayr, 1868 . One contains only tropical ants: Gnamptogenys europea ( Mayr, 1868) with N. pygmaea .

As in the syninclusions with Ctenobethylus reported by Wheeler (1915) (see above), four pieces of amber contain C. goepperti with Holarctic species: three with L. schiefferdeckeri and one with F. flori , but three include C. goepperti with the tropical species N. pygmaea ,

Tetraponera simplex ( Mayr, 1868) and Dolichoderus passaloma Wheeler, 1915 . Two syninclusions with Monomorium pilipes Mayr, 1868 contain tropical genera: Tapinoma electrinum Dlussky, 2002 and Y. geinitzi , and one of M. mayrianum Wheeler, 1915 is with F. flori and another one is with C. goepperti .

Thus, regardless of whether Ctenobethylus and Monomorium are considered Holarctic or tropical, they occur in syninclusions with species of both groups, which not only emphasizes the mixed nature of the amber fauna, giving strong support for the cooccurrence of tropical and Holarctic species at the same time and place, and these syninclusions are no less important than those containing definitely Holarctic and tropical species.

The ratio of Holarctic and tropical taxa is important for a better understanding the climatic conditions in amber forests and the age of amber biota as a whole.

After adding Aphaenogaster , Temnothorax , C. mengei , Eocenomyrma and N. pygmaea the ratio of Holarctic to tropical s.l. elements for representative collections is 2.8–3.5 for Baltic amber, 1.6 for Danish amber and 2.1 for both Bitterfeld and Rovno ambers ( Table 2). It is interesting that at least for two amber faunas with the same (Danish, 1.6) or very similar (Rovno, 1.9) ratios were calculated for biting midges ( Ceratopogonidae ): predominance of Holarctic biting midges in the representative collections from other ambers is even higher than for Holarctic ants ( Perkovsky, 2017).

In the early Eocene at Messel and middle Eocene at Eckfeld, tropical taxa absolutely dominate, nearly as much as in tropical climate Oligocene Sicilian amber ( Emery, 1891; Wappler, 2003; Dlussky et al., 2008, 2009; Archibald et al., 2011; Dlussky, 2012; Dlussky, Wedmann, 2012). The prevalence of Holarctic species in all representative amber ant collections is associated with decreasing of temperature in the late Eocene (see below). The ratio of Holarctic and tropical specimens in the former private amber ant collection of M. Kutscher from Bitterfeld amber (now in the collection of Geowissenschaftlicher Zentrum der Georg-August-Universität Göttingen) is only 0.98, but it is highly biased, containing mainly rare and ‘exotic’ ants ( Dlussky, Rasnitsyn, 2009).

Figures

Fig. 1. Photo of syninclusion of Oecophylla brischkei and Lasius schiefferdeckeri; a — general appearance (photo by E.V. Martynova), b — detail, L. schiefferdeckeri, biting leg of Oecophylla (photo by A.P. Rasnitsyn); Bitterfeld amber, No. GZG.BST.27.063a. Рис. 1. Фото сининклюЗа Oecophylla brischkei и Lasius schiefferdeckeri; a — обЩий вид (фото Е.В.Мартыновой), b — деталь, L. schiefferdeckeri, кусаюЩий Oecophylla За ногу (фото А.П. Расницы- на); саксонский Янтарь, No. GZG.BST.27.063a.