Re-appraisal of lacewing mimicry of liverworts from the mid-Cretaceous Kachin amber, Myanmar with a description of Selaginella cretacea sp. nov. (Selaginellales, Selaginellaceae)

Abstract

A unique case of liverwort mimesis in lacewing larvae of Phyllochrysa huangi has been reported from the mid-Cretaceous Kachin amber, Myanmar. However, we caution to take this interpretation for granted because of the still incomplete assessment of the plant diversity preserved in the Kachin amber inclusions. Our re-examination of the plant fossils regarded as models for Phyllochrysa huangi received evidence for a new species of the lycophyte genus Selaginella, namely S. cretacea sp. nov., and two indeterminate species of Selaginella, besides four species of the leafy liverwort family Frullaniaceae, including Frullania baerlocheri, F. kachinensis, F. partita, and Protofrullania cornigera. Careful morphological comparison recovered that the flat larvae of Phyllochrysa huangi closely match the dorsiventrally complanate strobili of Selaginella subgenus Stachygynandrum (lycophytes) represented by S. cretacea sp. nov. In turn, the larval morphology did not show obvious similarities with the shoots of the leafy liverworts. In the context of the improved taxonomic survey of the plant inclusions, it is evident that the so-called liverwort mimesis in Cretaceous lacewing larvae was actually lycophyte mimesis. The larvae of Phyllochrysa huangi provided the earliest evidence of a putative extinct Phyllochrysa-Selaginella mimetic system.