New flat wasps (Hymenoptera: Bethylidae) from the middle Cretaceous Kachin amber of Myanmar

We report a fossil aphidlion-like larva preserved with its egg case in 100 million year old Kachin amber, Myanmar. It appears to have been enclosed very shortly after hatching, especially when comparing it with extant aphidlions during hatching. Although hatching aphidlion-like larvae are known from amber from other localities, this is the first case from Myanmar amber, despite the comparably high number of lacewing larvae known from the latter.

Five specimens of primary larvae of Ripiphoridae (Insecta: Coleoptera) are reported from one piece of Cretaceous Kachin amber. They represent two morphotypes: one conicocephalate and one belonging to the tribe Ripidiini (represented by four specimens). The conicocephalate morphotype is compared with similar larvae known from Kachin, Taimyr and Manitoba Cretaceous amber, and the larvae of Ripidiini are compared with their Cretaceous, Eocene and extant relatives. Phylogenetic analyses were performed to establish a working hypothesis about possible relationships of both lineages. The results, which conform with a recent molecular phylo­geny, indicate that the larvae described here belong to Ripidiini or are closely related, respectively. To allow taxonomic and systematic work with conicocephalate larvae from Kachin amber, a collective group name †“Ripilarva” nov. is proposed here to accommodate these immature stages. Both species of †“Ripilarva” nov. from Kachin amber are described: †“R.” parabolicasp. nov. and †“R.” kachinensissp. nov. Syninclusion of †“Ripilarva” kachinensissp. nov. and four larvae of a species of Ripidiini indicate that females of both ripiphorids chose the same time and microhabitat for oviposition in the Kachin Cretaceous forest. The results are further verified by the use of UV-photography, as the different larval morphotypes occurred in the same resin flow. The presence of larvae of Ripidiini in clusters contrary to the solitary occurrence of †“Ripilarva” nov. in Cretaceous amber of Russia, Canada, USA, and Myanmar is interpreted as a possible result of different oviposition strategies, with different numbers of eggs deposited at one spot. Graphical abstract

Chilopoda, part of Myriapoda, is a species-rich group of ~3300 formally described species. Yet, the phylogenetic relationship of centipedes is not fully clear, and the scarceness of their fossil record, compared to the closely related Diplopoda, is a major challenge for understanding their evolutionary history. Within Chilopoda, Lithobiomorpha is one of the most problematic concerning its fossil record, so far restricted to the Cenozoic (~40 mya) and with a single lithobiomorphan-like specimen from Kachin amber (~100 mya). Here, we report three new exceptionally well-preserved lithobiomorphan specimens from Myanmar amber (~100 mya). These represent the first report of oldest representatives of Henicopidae from the Cretaceous, and with this the oldest definite record of Lithobiomorpha. Two specimens have ten pairs of walking legs (stage IV), and one has a fully developed trunk. These specimens are similar in many aspects to the extant group of Henicopidae and, more precisely, to Lamyctes Meinert, 1868. The specimens seemingly lack ocelli, exhibit ~14 (stage IV) and 24 antenna articles, have 2+2 coxosternite teeth, and present tooth-like setae on their coxosternite margins (=porodont). The fully developed specimen possesses a tibial spinose projection on each tibia of legs 1–11, a blunt projection on the tibia of leg 12, and undivided tarsi on their legs 1–12. With the finding of these specimens, we expand the fossil record of Lithobiomorpha significantly.

A new whip spider (Arachnida: Amblypygi) in mid-Cretaceous Kachin amber

Two new genera and species of Ripipterygidae Ander, 1939 are described from mid-Cretaceous Kachin amber of Northern Myanmar. Ozymandipteryx campanagen. et sp. nov. is remarkable for its absent or very reduced metatarsus. In modern species of Tridactyloidea, a reduced metatarsus can only be found in the Tridactylidae Brullé, 1835 genera Ellipes Scudder, 1902 and Xya Latreille, 1809, but not in Ripipterygidae. Magnidactylus robustus Xu et al., 2020, type species of the genus, is found to share the character of a fully reduced metatarsus (apical spurs were previously misinterpreted as metatarsus), but M. robustus differs from O. campana in several important characters and hence remains a separate genus. However, a new genus Yakkhapipteryx is erected to include the other two former Magnidactylus species M. mirusGu et al., 2022 (Yakkhapipteryx miruscomb. nov.) and M. gracilisGu et al., 2022 (Yakkhapipteryx graciliscomb. nov.), which both have a metatarsus in normal condition. Another newly described taxon is Ciconipteryx bidactylusgen. et sp. nov. This species is the first fossil Ripipterygidae with only two dactyls on its protibia, a feature it shares with the modern species Mirhipipteryx pulicaria (Saussure, 1896). Ciconipteryx bidactylus stands out due to its long mid- and hindlegs in relation to its body size. This character may have enabled it to perform very efficient jumps. The new species add to the diversity of Ripipterygidae from Kachin amber, expanding our knowledge of this little studied family and raising new possibilities for interpreting their evolutionary history.

SummaryHolometabolan larvae are a major part of the animal biomass and an important food source for many animals. Many larvae evolved anti-predator strategies and some of these can even be recognized in fossils. A Lagerstätte known for well-preserved holometabolan larvae is the approximately 100-million-year-old Kachin amber from Myanmar. Fossils can not only allow to identify structural defensive specializations, but also lifestyle and even behavioral aspects. We review here the different defensive strategies employed by various holometabolan larvae found in Kachin amber, also reporting new cases of a leaf-mining hymenopteran caterpillar and a hangingfly caterpillar with extensive spines. This overview demonstrates that already 100 million years ago many modern strategies had already evolved in multiple lineages, but also reveals some cases of now extinct strategies. The repetitive independent evolution of similar strategies in distantly related lineages indicates that several strategies evolved convergently as a result of similar selective pressures.

Simple SummaryDespite the extant diversity of the rove beetle subfamily Osoriinae, its fossil record remains meagre. The present study reports a new species Priochirus (Eopriochirus) trisclerite subgen. et sp. nov. from Kachin amber (mid-Cretaeous: Cenomanian, ca. 99 Ma). The discovery not only enriches the fossil record of Osoriinae but adds to our understanding of its ancient origin and diversification. With new species described in the present paper, 3 species of osoriines are known from Mesozoic Kachin amber.As one of the largest families of beetles (Coleoptera), the Staphylinidae (rove beetles and their relatives) are rich not only in extant species but also in a comparatively robust fossil record. Despite this preponderance of available fossil material, fossils of the diverse subfamily Osoriinae remain rare. Here, we describe a new ososriine species, Priochirus trisclerite sp. nov., from the mid-Cretaceous amber of Myanmar. The new specimen is similar to the only other definitive fossil of the genus, Priochirus thayerae Yamamoto 2019, and both are placed in the extinct subgenus Eopriochirus subgen. nov. The new species differs noticeably in a number of morphological details in relation to the submentum, gular sutures and protibial crenulae. The new fossil provides further evidence for understanding the radiation of staphylinoid beetles.

A new genus and two new species of the planthopper family Mimarachnidae are described based on two specimens trapped in mid-Cretaceous (early Cenomanian) Kachin amber from northern Myanmar. Morphology maps of the tegmen and hind wing, as well as keys for identification of the new species, are provided. Our new fossils not only increase the diversity of planthoppers from the mid-Cretaceous Kachin amber deposits, but also indicate that the ScP + RA and RP may simplify and the MP terminal branches become more abundant in described mimarachnids. Wenqian Wang* [wangwenqian2@lyu.edu.cn], Yan Zheng [zhengyan536@163.com], Xiaohui Cui [cuixiaohui@lyu.edu.cn] and Jun Chen [rubiscada@sina.com], Institute of Geology and Paleontology, Linyi University, Linyi, 276000, China. De Zhuo [zhuode113@163.com], Beijing Xiachong Amber Museum, 9 Shuanghe Middle Road, Beijing 100023, China. Cihang Luo [chluo@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.

Radula heinrichsii (Radulaceae, Porellales), a leafy liverwort from the mid-Cretaceous of Myanmar

Babinskaiidae is an extinct family of the lacewing superfamily Myrmeleontoidea, currently only recorded from the Cretaceous. The phylogenetic position of this family is elusive, with inconsistent inferences in previous studies. Here we report on three new genera and species of Babinskaiidae from the mid-Cretaceous Kachin amber of Myanmar, namely Calobabinskaia xiai gen. et sp. nov., Stenobabinskaia punctata gen. et sp. nov., and Xiaobabinskaia lepidotricha gen. et sp. nov. These new babinskaiids are featured by having specialized characters, such as the rich number of presectoral crossveins and the presence of scaly setae on forewing costal vein, which have not yet been found in this family. The exquisite preservation of the Kachin amber babinskaiids facilitate a reappraisal of the phylogenetic placement of this family based on adult morphological characters. Our result from the phylogenetic inference combining the data from fossil and extant myrmeleontoids recovered a monophyletic clade composed of Babinskaiidae and another extinct family Cratosmylidae, and further assigned this clade to be sister group to a clade including Nemopteridae, Palaeoleontidae, and Myrmeleontidae. Babinskaiidae appears to be a transitional lineage between Nymphidae and advanced myrmeleontoids, with ancient morphological diversification.

Birmaniaespina robustispina gen. et sp. nov., a new yuripopovinid bug from Cenomanian Kachin amber, Myanmar (Hemiptera, Pentatomomorpha)

Bruchomyiinae is a small subfamily of moth flies (Psychodidae) which includes fewer than 60 species restricted to tropical and subtropical regions (Curler & Jacobson, 2012; Wagner & Stuckenberg, 2016; Wagner, 2017; Skibińska & Santos, 2023). Despite their low species diversity, representatives of this subfamily are relatively common in the fossil record. To date, 28 fossil species across five genera have been identified. All known fossil representatives are preserved as inclusions in various fossil resins, ranging in age from Lower Cretaceous Lebanese amber (Azar et al., 2022) to Lower Miocene Dominican amber (Wagner, 2017). The genus Palaeoglaesum Wagner, 2017 is an extinct taxon known exclusively from Kachin amber, Myanmar. This genus comprises 15 species distributed in two subgenera: Palaeoglaesum (Palaeoglaesum) and Palaeoglaesum (Amplissimum) (Skibińska & Santos, 2023). This genus is the most diverse fossil representative of this subfamily. Diagnostic characters of Palaeoglaesum include a small body size (approximately 2‒2.5 mm), dense setation, a head with a median longitudinal strip of setae, elongate mouthparts with prominent labellum, and an oval wing with a broadly rounded apex. The vein R2+3 is at least twice as long as R2, and the radial fork is positioned distally to the medial fork. Male genitalia exhibit either an elongated, apically bifurcated aedeagus or a short, non-bifurcated form, both surrounded at the base by a sleeve-like parameral sheath (Skibińska et al., 2021; Skibińska & Santos, 2023). The high number of Palaeoglaesum species found in Kachin amber suggests that the tropical, near-coastal climate of the mid-Cretaceous Myanmar amber forest provided favorable conditions for a high diversity of Bruchomyiinae. Their ecology is closely associated with forest habitat, particularly tree hollows, forest litter, and tree trunks, which likely contributed to their frequent preservation in amber. The ongoing discoveries of new fossil taxa suggests that the diversity of Bruchomyiinae during the Cretaceous was likely much greater than it is today (Skibińska et al., 2019, 2023).

Despite the large number of species in the group Coleoptera (beetles), it is usually relatively easy to identify an adult beetle as such due to certain common characteristics. Among beetle larvae, however, there is a larger variability of body organisation. In some lineages, specialised larval morphologies are carried on into the adult phase by heterochrony, more exactly paedomorphosis. Such evolutionary events resulted in larviform females, as they occur in some extant representatives of Lycidae (net-winged beetles) and Lampyridae (fireflies). However, such larviform individuals, larvae or paedomorphic females, have been very rarely described in the fossil record until now and were restricted to Cenozoic ambers. Here, we report fossil larviform representatives, resembling larvae of the groups Lampyridae and Lycidae in certain aspects, from 100-million-year-old Myanmar amber. We furthermore discuss the morphological similarities and differences of the three new specimens in relation to extant larviform representatives of the groups and possible relationships of the new fossils.

Interactions between animals and plants represent an important driver of evolution. Especially the group Insecta has an enormous impact on plants, e.g., by consuming them. Among beetles, the larvae of different groups (Buprestidae, Cerambycidae, partly Eucnemidae) bore into wood and are therefore called wood-borer larvae or borers. While adults of these beetle groups are well known in the fossil record, there are barely any fossils of the corresponding larvae. We report here four new wood-borer larvae from Cretaceous Kachin amber (Myanmar, ca. 99 Ma). To compare these fossils with extant wood-borer larvae, we reconstructed the body outline and performed shape analysis via elliptic Fourier transformation and a subsequent principal component analysis. Two of the new larvae plot closely together and clearly in the same area as modern representatives of Buprestidae. As they furthermore lack legs, they are interpreted as representatives of Buprestidae. The other two new larvae possess legs and plot far apart from each other. They are more difficult to interpret; they may represent larvae of early offshoots of either Cerambycidae or Buprestidae, which still retain longer legs. These findings represent the earliest fossil record of larvae of Buprestidae and possibly of Cerambycidae known to date.

Two new species and new material of the family Evaniidae (Hymenoptera: Evanioidea) from the mid-Cretaceous amber of Northern Myanmar