A Revised Diagnosis of Palaeodysagrion cretacicus Zheng et al., 2016 (Insecta: Odonata) from mid-Cretaceous Burmese Amber, with erection of a new genus of fossil damselflies.

The diagnosis of Palaeodysagrion cretacicus Zheng et al., 2016 is revised based on the description of a new specimen from mid-Cretaceous Burmese amber. Previously, only a fragmentary wing base was known from the holotype. The new specimen shows the complete wing venation of fore- and hind wings as well as large parts of the body anatomy. The new information proves that Palaeodysagrion youlini Zheng et al., 2017 has a very different venation and does not belong to the same genus. Therefore, a new genus Pseudopalaeodysagrion gen. nov. is erected for this species. Concurring with the results of Archibald et al. (2021), the "dysagrionine" taxa from Burmese amber are transferred from Dysagrionidae to Burmadysagrionidae stat. nov.

On the waiting time until coordinated mutations get fixed in regulatory sequences.

In this paper we consider the time evolution of a population of size N with overlapping generations, in the vicinity of m genes. We assume that this population is subject to point mutations, genetic drift, and selection. More specifically, we analyze the statistical distribution of the waiting time Tm until the expression of these genes have changed for all individuals, when transcription factors recognize and attach to short DNA-sequences (binding sites) within regulatory sequences in the neighborhoods of the m genes. The evolutionary dynamics is described by a multitype Moran process, where each individual is assigned a m×L regulatory array that consists of regulatory sequences with L nucleotides for all m genes. We study how the waiting time distribution depends on the number of genes, the mutation rate, the length of the binding sites, the length of the regulatory sequences, and the way in which the targeted binding sites are coordinated for different genes in terms of selection coefficients. These selection coefficients depend on how many binding sites have appeared so far, and possibly on their order of appearance. We also allow for back mutations, whereby some acquired binding sites may be lost over time. It is further assumed that the mutation rate is small enough to warrant a fixed state population, so that all individuals have the same regulatory array, at any given time point, until the next successful mutation arrives in some individual and spreads to the rest of the population. We further incorporate stochastic tunneling, whereby successful mutations get mutated before their fixation. A crucial part of our approach is to divide the huge state space of regulatory arrays into a small number of components, assuming that the array component varies as a Markov process over time. This implies that Tm is the time until this Markov process hits an absorbing state, with a phase-type distribution. A number of interesting results can be derived from our general setup, for instance that the expected waiting time increases exponentially with m, for a selectively neutral model, when back-mutations are possible.

A new genus of hawker dragonfly (Odonata: Anisoptera: Aeshnidae) from the Early Eocene Fur Formation of Denmark.

A new genus and species of fossil hawker dragonfly, Parabaissaeshna ejerslevense gen. et sp. nov. (Aeshninae: Allopetaliini), is described from the Early Eocene Fur Formation (Mo-clay) of the island of Mors, northern Denmark. Its position among traditional "gomphaeschnine" dragonflies is discussed, and it is attributed to the tribe Allopetaliini as close relative to the Cretaceous genus Baissaeshna, documenting the survival of this lineage through the K-Pg mass extinction. The Recent genus Boyeria and the Eocene genus Anglogomphaeschna are also transferred to Allopetaliini.

First record and a new species of the fossil dragonfly genus Proinogomphus (Odonata: Liassogomphidae) from the Early Jurassic of Bascharage in the Grand Duchy of Luxembourg.

A new species of fossil dragonfly, Proinogomphus kreuzerorum sp. nov. (Liassogomphidae), is described from the Early Jurassic black shale of Bascharage in the Grand Duchy of Luxembourg, based on a very well-preserved isolated female hind wing. This genus was previously only known from the Liassic of Braunschweig region in Germany, and is here recorded for the first time for this fossil locality. The classification of the family Liassogomphidae Tillyard, 1935 and the genus Proinogomphus Cowley, 1942 is briefly discussed and the diagnosis of the latter is emended.

A new stem-coenagrionoid genus of damselflies (Odonata: Zygoptera) from mid-Cretaceous Burmese amber.

A new genus and species of damselfly, Burmagrion marjanmatoki, gen. et sp. nov., is described from Early Cretaceous Burmese amber. It is attributed to the basal stem group of Coenagrionoidea. The inclusion of five wings from the same species suggests that the amber piece contains the remains of a mating pair of damselflies.

First record of hawker dragonflies from Eocene Baltic amber (Odonata: Anisoptera: Gomphaeschnidae).

Based on three specimens, the first record of hawker dragonflies from Baltic amber is described in a new genus with two new species: Elektrogomphaeschna peterthieli gen. et sp. nov. and E. annekeae sp. nov.. They belong to the family Gomphaeschnidae and are tentatively attributed to the extinct subfamily Gomphaeschnaoidinae. The latter was previously only known from Cretaceous fossils and is here shown to have survived the K-Pg mass extinction event. This discovery also confirms the still higher diversity of Gomphaeschnidae during the Paleogene compared to the Neogene that was dominated by the more derived Aeshnidae sensu stricto.

First Record of Anisoptera (Insecta: Odonata) from mid-Cretaceous Burmese Amber.

The fossil dragonfly Burmalindenia imperfecta gen. et sp. nov. is described from mid-Cretaceous Burmese amber as the first record of the odonate suborder Anisoptera for this locality and one of the few records from amber in general. The inclusion comprises two fragments of the two hind wings of a dragonfly. The fossil can be attributed to a new genus and species of the family Gomphidae, presumably in the subfamily Lindeniinae, and features a strange teratological phenomenon in its wing venation.

New fossil insect order Permopsocida elucidates major radiation and evolution of suction feeding in hemimetabolous insects (Hexapoda: Acercaria).

With nearly 100,000 species, the Acercaria (lice, plant lices, thrips, bugs) including number of economically important species is one of the most successful insect lineages. However, its phylogeny and evolution of mouthparts among other issues remain debatable. Here new methods of preparation permitted the comprehensive anatomical description of insect inclusions from mid-Cretaceous Burmese amber in astonishing detail. These "missing links" fossils, attributed to a new order Permopsocida, provide crucial evidence for reconstructing the phylogenetic relationships in the Acercaria, supporting its monophyly, and questioning the position of Psocodea as sister group of holometabolans in the most recent phylogenomic study. Permopsocida resolves as sister group of Thripida + Hemiptera and represents an evolutionary link documenting the transition from chewing to piercing mouthparts in relation to suction feeding. Identification of gut contents as angiosperm pollen documents an ecological role of Permopsocida as early pollen feeders with relatively unspecialized mouthparts. This group existed for 185 million years, but has never been diverse and was superseded by new pollenivorous pollinators during the Cretaceous co-evolution of insects and flowers. The key innovation of suction feeding with piercing mouthparts is identified as main event that triggered the huge post-Carboniferous radiation of hemipterans, and facilitated the spreading of pathogenic vectors.

Preservation of three-dimensional anatomy in phosphatized fossil arthropods enriches evolutionary inference.

External and internal morphological characters of extant and fossil organisms are crucial to establishing their systematic position, ecological role and evolutionary trends. The lack of internal characters and soft-tissue preservation in many arthropod fossils, however, impedes comprehensive phylogenetic analyses and species descriptions according to taxonomic standards for Recent organisms. We found well-preserved three-dimensional anatomy in mineralized arthropods from Paleogene fissure fillings and demonstrate the value of these fossils by utilizing digitally reconstructed anatomical structure of a hister beetle. The new anatomical data facilitate a refinement of the species diagnosis and allowed us to reject a previous hypothesis of close phylogenetic relationship to an extant congeneric species. Our findings suggest that mineralized fossils, even those of macroscopically poor preservation, constitute a rich but yet largely unexploited source of anatomical data for fossil arthropods.

A re-description of the fossil damselfly Eolestes syntheticus Cockerell, 1940 (Odonata: Zygoptera: Eolestidae n. fam.) with description of new taxa from the Eocene of North America.

The enigmatic species Eolestes syntheticus Cockerell, 1940, from the Early Eocene of North America, previously attributed to the lestoid family Synlestidae, is re-examined in light of the discovery of new material from the Middle Eocene Kishenehn Formation in northwestern Montana. E. syntheticus and a new species, Eolestes ramosus sp. n., are attributed to a new family Eolestidae fam. n.. In addition, a new genus and species very closely related to Lestidae but assigned to family unknown, Lutetialestes uniformis sp. n., is described from the Kishenehn Formation.