The structure of a gilled stonefly larva from the mid-Cretaceous Kachin amber.

Perlidae stands as the most diverse family within Plecoptera, with evidence suggesting possible adaptation to warmer aquatic environments. Tracheal gills are hypothesized to have played a pivotal role in this radiation process. This study presents the description of a fossilized stonefly larva with gills, preserved as a fresh exuvia in mid-Cretaceous Kachin amber from northern Myanmar. The larva was classified within the family Perlidae based on distinctive morphological traits, including toothed lacinia and sharp-cusped mandibles, slender palps, glossae shorter than rounded paraglossae, and highly branched gills on the sides and ventral surface of thoracic segments. Additionally, the presence of a transverse, sparse, and irregular setal row on the occiput further indicates classification within the subfamily Acroneuriinae. Notably, the fossilized larva displays striking similarities in gill morphology and distribution to certain extant members within Perlidae, suggesting that these gill structures have an advantage in various aquatic habitats.

First fossil species of family Hyidae (Arachnida: Pseudoscorpiones) confirms 99 million years of ecological stasis in a Gondwanan lineage.

Burmese amber preserves a diverse assemblage of Cretaceous arachnids, and among pseudoscorpions (Arachnida: Pseudoscorpiones), ten species in five families have already been named. Here, we describe a new fossil species from Burmese amber in the pseudoscorpion family Hyidae, providing detailed measurements, photographs and 3D-models from synchrotron scanning. Based on morphology, the new fossil, Hya fynni sp. nov. is placed in the genus Hya, and is nearly identical to extant species in the genus, except for the position of trichobothrium est on the pedipalpal chela, thereby indicating extreme morphological stasis in this invertebrate lineage over the last 99 million years. Hya fynni represents the first described fossil species in Hyidae, and the third described Burmese fossil in the superfamily Neobisioidea. It also joins the garypinid, Amblyolpium burmiticum, in representing the oldest fossil records for extant pseudoscorpion genera. Considering proposed divergence dates, the newly described fossil species bolsters a Gondwanan origin for Hyidae, and provides evidence for the "Late Jurassic Rifting" hypothesis for the Burma Terrane, in which this landmass rifted from Gondwana in the Late Jurassic and collided with Eurasia by the Cretaceous/Eocene. Like Hya species today, H. fynni likely inhabited humicolous microhabitats in tropical forests on the Burma Terrane, supporting ecological niche stasis for this family since the Mesozoic.

An enigmatic Cretaceous beetle with possible affinity to Erotylidae (Coleoptera: Cucujiformia).

The morphology of beetles of the recently defined superfamilies Erotyloidea, Nitiduloidea and Cucujoidea is varied. Determining the systematic positions of Mesozoic fossils within these groups can often be challenging. Here we describe and illustrate a puzzling cucujiform beetle, Isocryptophilus exilipunctus Li & Cai gen. & sp. nov., based on an individual from mid-Cretaceous Burmese amber. While we cannot definitively pinpoint the exact phylogenetic position of Isocryptophilus, its possible affinity to Erotylidae is discussed in light of our phylogenetic analyses. A broader-sampled morphological matrix, coupled with a robust molecular phylogeny of these groups, will be promising for clarifying the systematic placement of the fossil.

The Morphological Diversity of Dragon Lacewing Larvae (Nevrorthidae, Neuroptera) Changed More over Geological Time Scales Than Anticipated.

Nevrorthidae, the group of dragon lacewings, has often been considered a relic group. Today, dragon lacewings show a scattered distribution, with some species occurring in southern Europe, Japan, Australia, and one in China. The idea that this distribution is only a remnant of an originally larger distribution is further supported by fossils of the group preserved in ambers from the Baltic region (Eocene, ca. 35-40 MaBP) and Myanmar (Kachin amber, Cretaceous, ca. 100 MaBP). Larvae of the group are slender and elongated and live mostly in water. Yet, larvae are in fact very rare. So far, only slightly more than 30 larval specimens, counting all extant and fossil larvae, have been depicted in the literature. Here, we report numerous additional specimens, including extant larvae, but also fossil ones from Baltic and Kachin amber. Together with the already known ones, this sums up to over 100 specimens. We analysed quantitative aspects of the morphology of these larvae and compared them over time to identify changes in the diversity. Despite the enriched sample size, the data set is still unbalanced, with, for example, newly hatched larvae (several dozen specimens) only known from the Eocene. We expected little change in larval morphology over geological time, as indicated by earlier studies. However, on the contrary, we recognised morphologies present in fossils that are now extinct. This result is similar to those for other groups of lacewings which have a relic distribution today, as these have also suffered a loss in diversity in larval forms.

Kekveus brevisulcatus sp. nov., a new featherwing beetle from mid-Cretaceous amber of northern Myanmar (Coleoptera: Ptiliidae).

Ptiliidae (featherwing beetles) is a group of minute staphylinoid beetles with a scarce fossil record. Here a second member of the Mesozoic genus Kekveus Yamamoto et al. is reported from mid-Cretaceous Burmese amber, with detailed morphology obtained through confocal microscopy. Kekveus brevisulcatus Li, Yamamoto, Newton & Cai sp. nov. shares with K. jason Yamamoto et al. the unpaired medial pronotal fovea and narrowly separated transverse metacoxae, but can be separated from the latter based on its less elongate body, shorter pronotal foveae, and much weaker transverse depression on the head. Our phylogenetic analyses support the discheramocephalin affinity of Kekveus, although its relationship with other members of Discheramocephalini cannot be confidently resolved.

Araeoanasillus leptosomus gen. et sp. nov., (Hemiptera, Cercopoidea, Sinoalidae?), a New Froghopper from Mid-Cretaceous Burmese Amber with Evidence of Its Possible Host Plant.

A new genus and species of froghopper, Araeoanasillus leptosomus gen. et sp. nov. (Hemiptera: Cercopoidea, Sinoalidae?), is described from mid-Cretaceous Burmese amber. The new genus possesses the following diagnostic characteristics: slender, medium size body (length, 7.0 mm) with head longer than wide, round eyes; antennae slender with eight antennomeres; pedicel very short, shorter than scape; pronotum with a length/width ratio of 2.4; metatibia with three spines, including one short spine near base and two adjacent, long, thick spines near apex; a single series of 16 thick apical teeth (comb) at metatibial apex; tegmen narrow with a length/width ratio of 3.2; tegmen with coastal area and stigmal cell punctate; CuP meeting base of CuA2; and MP branching at middle of wing. In hind wing, Cu vein forked once. A series of plant trichomes adjacent and attached to the specimen suggests that the froghopper's host plant was a fern.

An Expanded View on the Morphological Diversity of Long-Nosed Antlion Larvae Further Supports a Decline of Silky Lacewings in the Past 100 Million Years.

Lacewings have been suggested to be a relict group. This means that the group of lacewings, Neuroptera, should have been more diverse in the past, which also applies to many ingroups of Neuroptera. Psychopsidae, the group of silky lacewings, is one of the ingroups of Neuroptera which is relatively species-poor in the modern fauna. Larvae of the group Psychopsidae, long-nosed antlions, can be easily identified as such in being larvae of antlion-like lacewings without teeth in their stylets (=compound structure of mandible and maxilla), with empodia (=attachment structures on legs) and with a prominent forward-protruding labrum. Therefore, such larvae can also be recognised in the fossil record. An earlier study demonstrated a decline in the morphological diversity of long-nosed antlion larvae over the past 100 million years. Here, we report several dozen new long-nosed antlion larvae and expand the earlier quantitative study. Our results further corroborate the decline of silky lacewings. Yet, a lack of an indication of saturation indicates that we have still not approached the original diversity of long-nosed antlions in the Cretaceous.

A New Genus and Species of the Suborder Trogiomorpha (Insecta, Psocodea) from Mid-Cretaceous Amber of Myanmar.

We established a new genus with a new species Brachyantennum spinosum Liang et Liu, gen. et sp. nov. from mid-Cretaceous Burmese Kachin amber. It is tentatively placed into the suborder Trogiomorpha, based on the strong external valve, the reduced dorsal and ventral valve, and the short subgenital plate covering the basal part of the external valve. This new genus is apparently close to the family Cormopsocidae, based on the well-developed and very long hindwing Sc vein. However, its familial placement is ambiguous and it can be excluded from the established families of Trogiomorpha by the presence of the tarsal ctenidiobothria on the mid- and hindleg.

A New Genus of Sap Beetles (Coleoptera: Nitidulidae) from Mid-Cretaceous Amber of Northern Myanmar.

Nitidulidae is the most diverse family of the recently recognized superfamily Nitiduliodea, but Mesozoic nitidulids that are critical for understanding their early diversification are sparse. Here, we report a new genus and species of Nitidulidae, Protonitidula neli gen. et sp. nov., that was recovered from mid-Cretaceous amber in northern Myanmar. The new genus is distinguished from all members of the extant nitidulid subfamilies most prominently by the loose antennal club and the absence of subantennal grooves. Protonitidula neli can be excluded from the closely related Kateretidae and classified into Nitidulidae by the broad and apically expanded prosternal process, although it has many pleisiomorphic characters.

A New Subgenus and Species of Priochirus from Mid-Cretaceous Kachin Amber (Coleoptera: Staphylinidae: Osoriinae).

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.

Nothotytthonyx, a new genus of Malthininae (Coleoptera, Cantharidae) from mid-Cretaceous amber of northern Myanmar.

A new fossil genus and species of Cantharidae, Nothotytthonyxserratus Li, Biffi, Kundrata & Cai gen. et sp. nov., is reported from mid-Cretaceous Burmese amber. The new species is tentatively attributed to the extant subfamily Malthininae based on a combination of characters, including the symmetrical apical maxillary palpomeres, shortened elytra, pronotum with arched margins and well-defined borders, tibiae with apical spurs, and tarsal claws simple, although its well-developed gonostyli are atypical in Malthininae. The discovery of Nothotytthonyx also suggests a possible Gondwanan origin for Malthininae.

Review of the Family Thanerocleridae (Coleoptera: Cleroidea) and the Description of Thanerosus gen. nov. from Cretaceous Amber Using Micro-CT Scanning.

The predaceous beetle family Thanerocleridae is one of the smallest families of Cleroidea. It comprises only 36 extant species widespread on all continents. Three more species have been described from Cretaceous ambers of Myanmar and France. The fourth fossil representative of Thanerocleridae is described herein. Thanerosus antiquus gen. and sp. nov. is based on one fossil specimen preserved in an amber piece from Upper Cretaceous Kachin amber. The holotype was imaged using an X-ray micro-CT system to obtain high-quality 3D images. A phylogenetic analysis based on 33 morphological characters supports the placement of the new genus at the basal position in a tree of Thanerocleridae, in the vicinity of extant Zenodosus Wolcott and three extinct Mesozoic genera with which the new fossil shares open procoxal and mesocoxal cavities and transverse procoxae. We offer here a key to all extant and extinct genera in the family together with a complete list of all valid thaneroclerid taxa.

A New Species of Vetubrachypsectra from Mid-Cretaceous Amber of Northern Myanmar (Coleoptera: Brachypsectridae).

A new species, Vetubrachypsectra huchengi Li, Kundrata & Cai sp. nov., is described from mid-Cretaceous Burmese amber on the basis of a single adult female. The species is assigned to genus Vetubrachypsectra Qu & Cai based on its serrate antennae, long maxillary palps, presence of tibial spurs, and elytra without clear striae. Vetubrachypsectra huchengi differs distinctly from V. burmitica Qu & Cai, the only other species in the genus, in having the pedicel apically attached to the scape. Some other differences between the female of V. huchengi and the male of V. burmitica include less serrate antennae, a broader pronotal disc, a broader scutellar shield and smaller tibial spurs. However, at least some of these characters can be considered sexually dimorphic.

A New Genus and Species of Lophocateridae from Mid-Cretaceous Amber of Myanmar (Coleoptera).

A new genus and species of the cleroid family Lophocateridae are described and illustrated from the mid-Cretaceous amber of northern Myanmar. Gracilenticrus burmiticus Yu, Kolibác & Slipinski gen. et sp. nov. is unique among Lophocateridae in the tiny body size, frontoclypeal suture and antennal grooves absent, symmetrical antennal clubs, protrochantin reduced, tarsal claws small and widened at base. A key to the species of Mesozoic Lophocateridae is also provided. Morphological characters of the newly discovered Gracilenticrus were analyzed together with representatives of 43 extant genera of Cleroidea (broadly defined Trogossitidae) in a matrix of 91 characters. Gracilenticrus burmiticus was resolved as a member of Lophocateridae. The discovery of a diverse fauna of Lophocateridae in the mid-Cretaceous sheds a new light on the early evolution of superfamily Cleroidea.

emEminepygia/em emmyanmarensis/em sp. nov., a new Earwig (Dermaptera) Nymph in Burmese Amber.

A new fossil earwig nymph, Eminepygia myanmarensis gen. et sp. nov. (Pygidicranidae), from the mid-Cretaceous amber of Myanmar, is described and figured. Eminepygia myanmarensis gen. et sp. nov. can be readily distinguished from all other extinct and recent members of Dermaptera by the prominent bulges on the last three terga. Our new finding sheds further light on the diversity and morphological disparity of fossil dermapterans during the Late Mesozoic.

Fossils Shed a New Light on the Diversity and Disparity of the Family Limoniidae (Diptera, Nematocera).

A new subfamily Drinosinae (Diptera, Limoniidae) is established with two fossil genera, Drinosa and Decessia gen. nov. with one new species, Decessia podenasi gen. et sp. nov. from Cretaceous Burmese amber. Additional description of Drinosa prisca is based on new material. A new subfamily shows unique reduction of radial veins combined with complete set of medial veins.

A new species and genus of Alienopteridae (Blattodea) from mid-Cretaceous amber of northern Myanmar.

Eminespina burma gen. et sp. nov., is described and illustrated based on a female embedded in Cretaceous Burmese amber of Cenomanian age. Autapomorphic are three unique spines distributed anterior quarter of pronotum from longer posterior part. The new evidence of Batesian mimicry in the insect fossil record is briefly discussed.

New Genera and Species of the Family Throscidae (Coleoptera: Elateroidea) in Mid-Cretaceous Burmese Amber.

Captopus depressiceps gen. et sp. nov., Electrothroscus yanpingae gen. et sp. nov. and Pseudopactopus robustus gen. et sp. nov. are reported from the mid-Cretaceous Burmese amber. These new findings greatly extend the Mesozoic diversity of Throscidae, which implies a high degree of morphological disparity for this family in the Cretaceous.

Burmese Amber Compared Using Micro-Attenuated Total Reflection Infrared Spectroscopy and Ultraviolet Imaging.

Attenuated Total Reflection (ATR) spectroscopy coupled with a microscope allows for the analysis of specimens without any preparation, spatially correlated with the morphology of the specimen. These characteristics make micro-ATR systems very useful for studying gemstones and in particular amber samples. Indeed, in this report, the micro-ATR technique was used to characterize three Burmite samples, as case studies. Particularly, focusing the ATR crystal spot on the amber surface where a difference in the Ultraviolet (UV) reaction was previously detected, thereby relative differences in the IR spectrum could be analyzed. Here we present a methodology combining the UV imaging technique with the micro-Attenuated total reflection Fourier transform infrared spectroscopy (micro-ATR/FT-IR) analyses, in order to correlate the fluorescence information with the molecular vibrational modes of amber and their relative spatial distribution. Finally, this work is intended as an initial methodology study and part of the amber characterization project, focused on characterizing the Burmese amber collection of the Peretti Museum Foundation from several disciplines (i.e., palaeoentomology, vibrational spectroscopy, neutron tomography, etc.).

A new fossil record of Lymexylidae (Insecta: Coleoptera) from mid-Cretaceous amber of northern Myanmar.

The fossil ship-timber beetle, Adamas hukawngensis gen. et sp.n., is described and defined based on one well preserved specimen in mid-Cretaceous amber from the Hukawng Valley in Northern Myanmar. The new species can be readily distinguished from all other extinct and recent members of the family due to the presence of a lozenge-shaped scutellum with a meso-longitudinal groove. Modifications of lymexylid metathoracic wing venation and palaeobiomigratory significance are briefly discussed.