Waidelotinae, a new subfamily of Pyrochroidae (Coleoptera: Tenebrionoidea) from Baltic amber of the Sambian peninsula and the interpretation of Sambian amber stratigraphy, age and location

Abstract

Waidelotus hoffeinsorum gen. et sp. nov. is described from Eocene Baltic amber and assigned to Waidelotinae subfam. nov. within family Pyrochroidae (Coleoptera). The new subfamily differs from the other subfamilies by the following combination of features: penultimate tarsomere of all tarsi deeply bilobed, antepenultimate tarsomere of each pro- and mesothoracic tarsus slightly bilobed, antepenultimate tarsomere of metathoracic tarsi slightly widened apically; pronotum laterally margined in basal half; eyes emarginate; pretarsal claws appendiculate; prosternal intercoxal process incompletely separating prothoracic coxae; pronotum with fine posterior submarginal groove; head without distinct constriction behind eyes; posterior pronotal pits absent; and elytral pubescence homogenous. It is the only authentic species of Pyrochroidae (Coleoptera) from Baltic amber, pending final placement of Palaeopyrochroa crowsoni Abdullah, 1965. Additionally, the available data on stratigraphy of amber-bearing strata on the Sambian peninsula, and the age and location of Eocene amberiferous forests are discussed. A middle Eocene (mostly Bartonian) age is interpreted for the extinct Central European resin-producing forests resulting in the Sambian amber deposits.

X-ray micro-computed tomography reveals a unique morphology in a new click-beetle (Coleoptera, Elateridae) from the Eocene Baltic amber

“…Morphological terminology follows partly Calder 41 , Costa et al 42 and Kundrata et al 47 , and the classification of Elateridae follows Kundrata et al 43 . Although there are several hypotheses concerning the age of Baltic amber 36,37,39 , we follow the Middle Eocene (mostly Bartonian, 41.2-37.8 Ma) which was recently proposed for the extinct Central European resin-producing forests according to the stratigraphy of the Sambian amber deposits 40 www.nature.com/scientificreports/ Moscow, Russia (PIN), and collections of Robin Kundrata, Václav Dušánek (both Czech Republic), Andris Bukejs (Latvia), and Christel and Hans Werner Hoffeins (Germany). This included a majority of described species from ambers.…”

“…The age of Baltic amber has also been the subject of much debate, usually due to the repeated re-deposition of the amber, the broad range of the ancient resin-producing forest, and its probable long-term existence 36 . Using various methods such as K-Ar dating, palynological biostratigraphic analysis or comparison of the faunas from different amber sources, most estimates generally range from the middle to upper Eocene (Lutetian to Priabonian, 47.8-37.8 Ma) 28,[36][37][38][39][40] .…”

A new Eocene genus of the subtribe Tylodina (Coleoptera: Curculionidae) and notes concerning local differences of Baltic amber in the Kaliningrad Region

“…The first records are from the early Eocene Oise amber (Legalov et al, 2019), the early Eocene of London Clay (Britton, 1960) and the early-middle Eocene of Green River (Scudder, 1876). One species is described from the middle Eocene of Geisel valley (Haupt, 1950). The rich Cryptorhynchini fauna is known from the Miocene Dominican amber (Poinar and Legalov, 2014).…”

“…Baltic amber from Eocene amber-bearing Blue Earth layers, mostly Bartonian age is interpreted for the extinct central European resin-producing forests according to Bukejs et al (2019).…”

“…At the present time, this amber is found mainly along coastlines of the Baltic on beaches or in different geological Tertiary and Quaternary layers, but the source stratum, the Paleogene Blaue Erde (Blue Earth), is particularly productive in the west of the Samland (Sambia) Peninsula. The ages of succinite-bearing horizons can differ by at least 7 Myr according to stratigraphy (Bukejs et al, 2019). Baltic amber of the Kaliningrad Region is not uniform in regional view and originates from several regionally different localities (with distance of ±100 km), comes from different stratigraphic layers (from the Eocene source stratum and stratum above) and is obtained by the different methods.…”