One hundred million years of stasis: Siphonophora hui sp. nov., the first Mesozoic sucking millipede (Diplopoda: Siphonophorida) from mid-Cretaceous Burmese amber

Abstract

Fossil records of the ancient and less studied millipede order Siphonophorida are rare and only known from Oligocene-Miocene Dominican amber to date. Here, we describe a Mesozoic species of this order, Siphonophora hui sp. nov., based on two well-preserved specimens from mid-Cretaceous Burmese amber. The new species can be placed in the family Siphonophoridae by having mouthparts strongly modified into a long beak, straight antennae, the separation of tergites, pleurites and sternites, leg-like gonopods derived from 9th and 10th leg pairs, and absence of ommatidia. This discovery pushes back the fossil record of Siphonophorida by more than 60 Ma. It also demonstrates that the details of the siphonophorid body plan have remained virtually unchanged for nearly 100 million years. An enigmatic structure on the antennae of the paratype may represent either the ancestral form of the circular sensory pits, or more unlikely, the earliest occurrence of a fungus parasitic or commensal on an arthropod.