Mygalomorph spiders in mid-Cretaceous Kachin amber (Araneae: Mygalomorphae), northern Myanmar: A new genus and species of the family Macrothelidae

Although Kachin amber harbors a remarkably diverse and abundant spider fauna, species of Mygalo-morphae have been conspicuously scant. Here we report the extant family Macrothelidae (Opisthothe-lae: Mygalomorphae) from these deposits, representing the first fossil occurrence for the family. It is represented by a new genus and species, established as Promacrothele polyacantha Tang, Engel, & Yang gen. et sp. nov., and based on a well-preserved adult female. The specimen nicely preserves the key diagnostic features for the family and is distinguished from the two extant macrothelid genera, Mac-rothele Ausserer and Vacrothele Tang et al. The new fossil discovery not only provides a first fossil occurrence of Macrothelidae, but refines existing calibration points for phylogenetic work on mygalo-morph diversification as well as advances our understanding of the Cretaceous diversity of spiders in southern Asia.

Automated summary

Although there is a diverse spider fauna in Kachin amber, species of the family Macrothelidae have been scarce. This study reports the first fossil occurrence of Macrothelidae, represented by a well-preserved adult female specimen of a new genus and species. The discovery refines existing calibration points for phylogenetic work on mygalomorph diversification and contributes to our understanding of Cretaceous spider diversity in southern Asia.