New morphological data from the Jurassic of Inner Mongolia confirms the damselfly aspect of Protomyrmeleontidae (Insecta: Odonatoptera)

Abstract

Abstract. Protomyrmeleon daohugouensis sp. n. and Protomyrmeleon lini sp. n., two new species of Protomyrmeleontidae from the Middle Jurassic of Jiulongshan Formation are the first Chinese representatives of this Mesozoic odonatopteran family. The type specimen of P. lini is exceptionally well preserved, showing several particular wing and body structures that were unknown, viz. unique shape of tarsal claws, extreme thoracic skewness, presence of three pairs of long spurs on all femora and tibiae. The type "A" (sensu Nel et al., 2005) of wing venation (i.e. with a very long bridge between IR2 and RP3/4) corresponds to that of the protomyrmeleontid fore wing. The nearly complete absence of the meso-metathoracic interpleural suture, newly discovered in the Protomyrmeleontidae, can be considered as a synapomorphy of the clade Protozygoptera + Odonata.

Systematics and evolution of Paleozoic and Mesozoic damselfly-like Odonatoptera of the ‘protozygopteran’ grade

“…The presence of a complete meso-metathoracic interpleural suture in the specimen PIN 1700/477 ( Fig. 7.1, 7.2) suggests that the (more or less important) reduction of this structure in modern Odonata and Protomyrmeleontidae (Huang et al, 2010) could be a potential apomorphy of Archizygoptera + Panodonata (but the Zygoptera: Calopterygidae, and at least some Isophlebioidea, have a complete suture as well).…”

“…Another character typical of (at least) the archizygopteran family Protomyrmeleontidae is the absence of the subapical spine on tarsal claws (Huang et al, 2010), but this structure remains unknown in other Archizygoptera. The permagrionid specimen PIN 1700/477 ( Fig.…”

“…The strong obliquity of the pterothorax in Zygoptera could be regarded as a possible apomorphy of the Zygoptera, but it is also (convergently?) present in the Archizygoptera: Protomyrmeleontidae (Huang et al, 2010). Also the presence versus absence of a distinct transverse carina near the middle of the abdominal segments is probably subject to homoplasies, as it is present in this Permagrionidae and the Anisoptera, whereas it is absent in Zygoptera and the Protomyrmeleontidae.…”

“…Additionally, the Odonata have long and thin spines on tibiae (Anisoptera) and on tibiae and femora (Zygoptera). This is a potential apomorphy of Odonata (and maybe also Archizygoptera) because in the Protomyrmeleontidae both femora and tibia bear three pairs of long and sharp spines (Huang et al, 2010).…”

“…Thus this character is probably an apomorphy of the Stigmoptera at least. The empodia are also absent in the Protomyrmeleontidae (Huang et al, 2010). The position of the Tarsophlebiidae as sister group of Odonata is questionable because it is only supported by a single wing venation character state (discoidal cell basally open in both pairs of wings) and male secondary genitalia characters (ligula orimentary; vesicula spermalis still very short and flat with a very wide porus), which are very delicate and difficult to observe in fossils.…”