Convergent evolution of defensive appendages – a lithobiomorph-like centipede with a scolopendromorph-type ultimate leg from about 100 million-year-old amber

Abstract

Centipedes are predatory representatives of the group Myriapoda and important components of the soil and leaf-litter fauna. The first pair of trunk appendages is modified into venom-injecting maxillipeds in all centipedes. The number of trunk appendage pairs varies between the different groups of centipedes, from 15 pairs as apparently ancestral (plesiomorphic) condition, up to 191 pairs. The last pair of trunk legs can be used for different tasks in centipedes, e.g. mechano-sensation, defense, or stridulation. Many morphological details are also known from fossil centipedes, but especially the oldest fossils are often fragmentary and the fossil record in general is rather scarce. Especially the late appearance of lithobiomorphans in Cenozoic ambers is notable, though some not formally described lithobiomorph-like specimens from Cretaceous amber from Myanmar have been published. We present here a new specimen from Cretaceous Kachin amber, Myanmar with a lithobiomorph-type of morphology, Lithopendra anjafliessae gen. et sp. nov. The very large ultimate leg appears to have been used for defence and is, in relative proportions, larger than in any known lithobiomorphan, only comparable to that in scolopendromorphans. With this, the specimen presents a mixture of characters, which are in the modern fauna only known from two different centipede groups. We discuss the implications of this new fossil, also concerning events of convergence in this lineage.