Mesozoic tree ferns related to the extant Loxsomopsis, a relict and taxonomically isolated genus endemic to tropical South America, are exceedingly rare, making it difficult to trace its origin and evolution. Here, we describe a mid-Cretaceous fossil attributable to Loxsomopsis, Loxsomopsis minor sp. nov., based on two fertile pinnules preserved in Myanmar amber. The new species is assigned to the extant genus based on a suite of diagnostic features, including pinnate fertile segments with short lobes, marginal paraphysate sori, narrowly cyathiform to urceolate indusia, columnar and exserted receptacles, oblique sporangial annuli, and trilete spores. This discovery extends the fossil record of Loxsomopsis back to the Albian–Cenomanian and provides new evidence that the lineage—now restricted to tropical South America—was once more widespread. The occurrence of Loxsomopsis in the Myanmar amber biota is consistent with a Gondwanan affinity for this mid-Cretaceous forest ecosystem and suggests that the genus may have likely originated prior to the breakup of Pangaea.

This study describes Tubuloreticulaspongia sinensis n. gen. n. sp., a new protospongiid sponge from the Hirnantian (Upper Ordovician) to Rhuddanian (Lower Silurian) of South China. The genus exhibits a tubular body, orthogonal skeletal mesh, and pentactine spicules with elongated vertical rays and short latitudinal rays, distinguishing it from related taxa. Its inward-oriented unpaired rays and delicate structure suggest adaptation to calm, nutrient-poor offshore environments. The discovery extends our knowledge of reticulosan evolution following the Late Ordovician Mass Extinction, and adds a further example of Cambrian-like skeletal traits persisting into the Ordovician-Silurian transition. These findings complement the reticulosan sponge evolution, ecological resilience, an d the role of regional settings in post-extinction recovery. The species is also the first sponge species identified from two distinct faunas in the Ordovician-Silurian transition of South China. (c) 2026 Nanjing Institute of Geology and Palaeontology. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The major animal body plans originated during the Cambrian explosion, yet the phylum Bryozoa has remained a conspicuous exception to this pattern1. The initial discovery of Protomelission gatehousei2 provided compelling evidence for a Cambrian origin for the Bryozoa, together with other major metazoan phyla and compatible with independent molecular clock estimates3-7. Nevertheless, the scarcity of definitive soft-tissue anatomy and diagnostic skeletal microstructure has left its phylogenetic affinities ambiguous and debated8,9. Here we report exquisite fossils of P. gatehousei and a new taxon, Dayingomelission hexaclitia gen. et sp. nov., from the early Cambrian Xiannüdong Formation of China. These specimens preserve in situ phosphatized soft tissues in modular skeletons, revealing critical anatomical structures, including styles, annular muscles, membranous sacs and ring septa. This suite of traits provides definitive evidence that these taxa belong to the Bryozoa. Phylogenetic analysis incorporating these new features identifies them as crown group stenolaemates. These results confirm a Cambrian origin for the phylum and reveal an unexpected early disparity in colonial architecture, demonstrating that bryozoan diversification was an integral component of the Cambrian radiation. Moreover, the early appearance of a differentiated stenolaemate crown group indicates a still deeper origin for the bryozoan stem lineage than was first apparent.

Among living hexactinellids (glass sponges), the Rossellidae are one of the most distinctive species-rich families because of their unique macroscopic characters and, due to the resulting fossil record, are among the most useful for tracing the origins of hexactinellid diversification. Recent discoveries have extended the origin of the total group back to the Ordovician, but these fossils have, so far, all been identified either as stem-group representatives or as sponges with uncertain interpretation. New material described here from the Hirnantian (latest Ordovician) Anji Biota of Zhejiang, China includes demonstrable crown-group representatives of the family, which also appear morphologically similar to living genera and may be closely related to them. The new taxa are described as Crateromorpha? (Neopsacas?) macrospicula sp. nov., Pseudanoxycalyx verrucosus gen. et sp. nov., Eorosselloides antiquus gen. et sp. nov. and Archaeaphorme conica gen. et sp. nov. The similarity to modern forms implies extraordinary evolutionary stasis of at least some members of the modern deep-sea hexactinellid fauna since that time, and suggests that they had an even earlier origin and initial diversification. Possible examples of late Precambrian stem-group hexactinellids remain ambiguous, potentially implying very rapid evolutionary appearance and divergence of the class during the Cambrian or earlier Ordovician. A possible driver of this evolutionary rate change is the remarkable longevity of modern hexactinellids as an adaptation to cold-water environments; this potentially offers an explanation for discordances with molecular clock results, which have previously indicated a much later (late Palaeozoic) origin for total-group Rossellidae.

The post-impact fauna of the Dalby Limestone of Tvären Bay has been extensively examined, with the exception of the Palaeostomate bryozoan taxa present. Here, we report three palaeostomate bryozoans found in limestone boulders recovered from glacial deposits on Ringsö Island derived from Tvären Bay, Sweden. The bryozoan fauna includes Pachydictya bifurcata, Hallopora sp., and Trematoporid sp. indet. Pachydictya bifurcata has bifoliate zoaria with two layers of zooecia oriented in opposite directions along the mesotheca. Hallopora sp. is characterized by the presence of mesozooecia, tubular autozooecia with rounded apertures, thin walls, and possessing diaphragms. The zoaria of Trematoporid sp. indet are loosely arranged and slightly ambiguous, but lack further identifying features. The report of Pachydictya bifurcata herein represents an extension of its stratigraphic range within the late Ordovician. These findings enhance our understanding of the bryozoan diversity in the region, providing the first detailed report of the presence of these taxa in this geological context.

Mitochondrial introns have a patchy distribution in sponge lineages. Here, we report on the finding of a group-II-intron in Eunapius rarus (Demospongiae, Spongillidae), which constitutes the first report of a mitochondrial intron in freshwater sponges. Group-II-introns are self-splicing ribozymes, and are particularly rare among sponge mitochondrial genomes. The intron contains complete open reading frames (ORFs), including typical intron-encoded proteins (IEPs). Phylogenetic analysis reveals that the intron is more closely related to those found in brown algae, and distant from other sponge group-II-introns, indicating an acquisition of this intron independent from other sponges. Remarkably, the congeneric E. fragilis does not possess this intron in their mitochondrial genome. However, we found pseudogenic copies of the E. rarus group-II-intron in the nuclear genome of E. fragilis, which indicates patterns of group-II-intron presence and their pseudogene transposition into the nuclear genomes in sponges for the first time. Our results show that a group-II-intron must have been present in the last common ancestor of both Eunapius mt genomes, and subsequently lost in E. fragilis, rather than independent acquisition. Consequently, our findings provide an explanation for the patchy distribution of introns in sponges as a result of frequent losses, besides multiple acquisitions.

The mid-Cretaceous Burmese amber was extensively colonized by marine epibiont communities, including pholadids, corals, oysters, and serpulids. In this study, we report a diverse array of marine organisms that adhered to the amber, forming epibiont communities. Notably, cheilostome bryozoans are documented for the first time as an additional group of colonizing organisms on Burmese amber. These bryozoans formed extensive sheets and proliferated on the amber surface, often encrusting other epilithic taxa such as serpulids and oysters. The encrusting organisms exhibited significant marginal competitive interactions, including overgrowth and stand-off behaviours, as they competed for space. These hard substrate communities display trends similar to those observed in extensive soft substrate communities, resembling many counterparts in both modern and geological records. This discovery provides valuable insights into the composition of epibionts, the sequence of their colonization, and their ecological interactions on Burmese amber. Furthermore, this study indicates that the establishment of epibiont communities on Burmese amber occurred later than the entrapment of bioinclusions but earlier than the deposition of nearshore gravel strata.

Stromatoporoid sponges were important reef-builders during the middle Paleozoic, yet their early history and integration into reef ecosystems remain poorly understood. Here, we report Lophiostroma leizunia Jeon sp. nov., the oldest known stromatoporoid from upper Tremadocian to lower Floian (~480 My-old) strata of South China. L. leizunia formed complex reef structures, playing crucial roles in framework construction and binding other components, including calcimicrobes, lithistid sponges, stalked echinoderms, and Calathium. This discovery pushes back the fossil record of stromatoporoids and the reefs that they formed by approximately 20 My, advancing the onset of the Great Ordovician Biodiversification Event in reef evolution. L. leizunia unusually constructed its skeleton using fluorapatite-a feature previously unknown in sponges. This establishes Porifera as the first metazoan phylum known to have utilized all three principal biominerals: silica, calcium carbonate, and calcium phosphate. The presence of phosphatic skeletons in this early stromatoporoid expands our understanding of biomineralization capabilities in early animals and suggests that the genetic toolkit for diverse biomineralization strategies may have been present in early sponges. The unique combination of the earliest known reef-building stromatoporoids and their phosphatic skeletal composition provides insights into the evolutionary dynamics of biomineralization and the rise of metazoan-dominated reef ecosystems during a critical period of Earth's history.

Body size evolution is a focus of palaeobiological interest, but few studies have examined long-term changes in the size of the modular zooids of colonial animals. Here we investigate changes in zooid size from the Late Triassic to the present-day among encrusting cyclostome bryozoans of a common morphotype attributed informally to 'Berenicea'. We begin with the na & iuml;ve hypothesis that cyclostome bryozoans should demonstrate size evolution similar to cheilostome bryozoans, which have maintained a constant mean zooid size. Unexpectedly, a striking pattern of decreasing zooid size through time was found in 'Berenicea'. We then hypothesized that decreasing levels of oxygen could make smaller zooid sizes more optimal because of their greater surface area/volume; cyclostome zooid size might be tracking a changing adaptive landscape over 200 million years. Despite some evidence for a statistical correlation between 'Berenicea' zooid size and oxygen, there is no hint of any causal relationship between them when formal timeseries analysis tools, based on linear stochastic differential equations, are applied. Furthermore, neither origination rates of cheilostomes, known to be superior spatial competitors, nor assemblage-level increases in cheilostome representation, are associated with 'Berenicea' zooid size changes. However, there is some support for a switch in the tempo of cyclostome zooid size change at c. 165 to 160 Ma and then again at c. 78 Ma.

The only known fossil of Cystodium (Cystodiaceae) is C. sorbifolioides from mid-Cretaceous Myanmar amber. Here we describe a new fossil species of Cystodium, C. parasorbifolium, also from amber collected in Myanmar. This new species belongs to Cystodium based on pinnate fertile lamina segments, terminal sori protected by a reflexed lobe of the lamina (outer or false indusium), free veins, vertical annuli interrupted at the stalk, trilete spores, and striate perines. It differs from C. sorbifolioides by reflexed ovate-conical indusia and spores with clear striate perines. This new fossil species suggests that Cystodium was more diverse in the forests of Myanmar during the Cretaceous.

Parnassius butterflies have significantly advanced our understanding of biogeography, insect–plant interactions, and other fields of ecology and evolutionary biology. However, to date, little is known about the gene expression patterns related to the high-altitude adaptation of Parnassius species. In this study, we obtained high-throughput RNA-seq data of 48 adult Parnassius individuals covering 10 species from 12 localities in China, and deciphered their interspecific and intraspecific expression patterns based on comparative transcriptomic analyses. Though divergent transcriptional patterns among species and populations at different altitudes were found, a series of pathways related to genetic information processing (i.e., recombination, repair, transcription, RNA processing, and ribosome biogenesis), energy metabolism (i.e., oxidative phosphorylation, thermogenesis, and the citrate cycle), and cellular homeostasis were commonly enriched, reflecting similar strategies to cope with the high-altitude environments by activating energy metabolism, enhancing immune defense, and concurrently inhibiting cell growth and development. These findings deepen our understanding about the molecular mechanisms of adaptative evolution to extreme environments, and provide us with some theoretical criteria for the biodiversity conservation of alpine insects.

Insects harbor a remarkable diversity of gut microbiomes critical for host survival, health, and fitness, but the mechanism of this structured symbiotic community remains poorly known, especially for the insect group consisting of many closely related species that inhabit the Qinghai-Tibet Plateau. Here, we firstly analyzed population-level 16S rRNA microbial dataset, comprising 11 Parnassius species covering 5 subgenera, from 14 populations mostly sampled in mountainous regions across northwestern-to-southeastern China, and meanwhile clarified the relative importance of multiple factors on gut microbial community structure and evolution. Our findings indicated that both host genetics and larval host plant modulated gut microbial diversity and community structure. Moreover, the effect analysis of host genetics and larval diet on gut microbiomes showed that host genetics played a critical role in governing the gut microbial beta diversity and the symbiotic community structure, while larval host plant remarkably influenced the functional evolution of gut microbiomes. These findings of the intimate insect-microbe-plant interactions jointly provide some new insights into the correlation among the host genetic background, larval host plant, the structure and evolution of gut microbiome, as well as the mechanisms of high-altitude adaptation in closely related species of this alpine butterfly group.

Sarcotragusolides A-D (1-4), four new butenolide sesterterpenes featuring a rare methyl-transferred 6/6/6-tricyclic fused ring system with a butyrolactone moiety, and echinohalimane B (8), an unprecedented monocyclic diterpenoid featuring a 2,7-ring-opened halimane-type skeleton, were isolated from the sponge Sarcotragus sp. A γ-hydroxybutenolide sesterterpene derivative (5), a new scalarane sesterterpene (7), a new subersin-type diterpenoid (10), and two known terpenoids were also isolated and identified. The discovery of sarcotragusolides C and D (3 and 4) with an unprecedented inversion of configuration implied a distinct biosynthetic pathway. The structures of these compounds were elucidated based on their spectroscopic data, single-crystal X-ray diffraction, chemical derivatization, and quantum chemical calculations. Compounds 1a, 1b, and 2 presented modest cytotoxic activities against several human cancer cell lines.

Few bryozoan faunas have been reported globally from the time of the late-Ordovician mass extinction (LOME). A depauperate bryozoan fauna from the Kuanyinchiao Bed of North Guizhou Province, South China are described here as the first record following the first phase of the LOME. This bryozoan fauna includes five species belonging to five genera: Homotrypa ramulosa Bassler, 1903 , Trematopora sp., Radiotrypa gothica Brood, 1978 , Nematopora lineata (Billings, 1866 ), and Phylloporina sp. In generic composition and colony morphology, the bryofauna resembles contemporary examples from Sweden ( Dalmanitina beds = Hirnantian), probably because of the similarities in their palaeoenvironment, including bathymetry, and depositional latitudes.

We present a comprehensive morphological description of Ephydatia fluviatilis collected in Nanjing for the first time in studies of freshwater sponges in China, based on scanning electron micrography of the sponge meshwork, the megascleres, the gemmules, and the delicate gemmuloscleres, in comparison with relevant data reported worldwide. The morphotype revealed in this study shows a peculiar spicular complement of the skeleton composed of two types of megascleres (the normal oxeas and occasional styles) with abundant tiny, centrally distributed microspinoses, gemmules (ca. 440 & mu;m in diameter) bearing two types of spinose decoration on the shaft (i.e., erect long spines and microspinoses). We report the first complete ITS sequences of the morphotype of E. fluviatilis from China, which, combined with homologous sequences of related taxa from GenBank, are used in a phylogenetic analysis in order to understand the species relationship within Ephydatia and neighbouring taxa. Combining the ITS phylogeny and the gemmulosclere morphotypes, we identify three clades in the paraphyletic genus Ephydatia that are distinguished by different birotule gemmulosclere morphotypes for gemmule-bearing species. Multiple losses of gemmules within endemic taxa, as previously proposed, are confirmed in this study in a phylogenetic context obtained herein. Additionally, genetic similarities are found in some morphologically diverse species, likely indicating recent endemism leading to morphological specialization. Considering the diverse fossil record of Ephydatia from Cenozoic sedimentary strata of wide geographic ranges, we hypothesize that Ephydatia might have a deep root in the Paleogene or earlier and experienced a rapid, Quaternary radiation with emergences of specialized endemic species that lost gemmules under glacial-interglacial paleoenvironment.

Under rapid radiation, the earliest components of evolutionary divergence are often difficult to resolve, which were always driven by the characteristics of taxa and the limitations of alternative analytical methods. The origin and radiation of the alpine butterfly Parnassius , a high‐altitude mountainous insect group, can be attributed to the uplift of the Qinghai‐Tibet Plateau. Despite detailed phylogenetic analyses of the genus, deep phylogenetic relationships among the major subgenera remain recalcitrant. In this study, 102 individuals from 10 representative Parnassius species were sampled to resolve the phylogenetic relationships among subgenera based on nuclear and mitochondrial genome datasets. Gene‐tree/species‐tree conflicts were detected by concatenation and multispecies coalescent (MSC) approaches. We recovered a well‐supported species tree, despite these conflicts, and detected considerable phylogenetic discordance among genomic regions. The main explanation for the topological discordance among subgenera was extensive incomplete lineage sorting (ILS), whereas introgression events were not prominent. The origin and explosive radiation of Parnassius (i.e., rapid succession of speciation events) in the late Miocene associated with environmental events on the plateau led to short internal branches, thereby increasing ILS and topological conflicts, especially among closely related subgenera. Our results also suggested that MSC approaches (SNP and AFLP Package for Phylogenetic analysis [SNAPP] and SVDquartets) are accurate and superior to the concatenation approach; in particular, SVDquartets can explicitly accommodate gene‐tree/species‐tree conflicts caused by high ILS and demonstrate strong robustness. Finally, we explored the phylogenomic data by testing multiple sources of phylogenomic conflict to clarify the strengths and limitations of different approaches, while considering phylogenetic signal variation in mitochondrial loci. We anticipate that the phylogeny described here will be the backbone of future evolutionary studies of the genus and will provide insight into phylogenetic discordance due to rapid radiation.

Stromatoporoid-type hypercalcified sponges are known to have contributed to the global reef system since the late Middle Ordovician until their major disappearance in the latest Devonian. However, the timing of their appearance and how the earliest stromatoporoids were incorporated into the reef ecosystem remains a mystery. A stromatoporoid taxon was previously reported from the lower Floian of South China, but this example limitedly occurs within the cryptic space of a lithistid-Calathiumreef and has negligible importance in reef construction, unlike the later stromatoporoids that formed the major reef frameworks during the Palaeozoic. In this study, we describe the earliest known definitive stromatoporoids and the reefs constructed by them in the upper Tremadocian to the lower Floian of South China. The reef framework is dominated by various growth forms of stromatoporoids – ranging from laminar, domical, bulbous to digitate morphologies – that alternate with other organisms such as the calcimicrobe Girvanella and stalked echinoderms. Stromatoporoids have played a significant role in frame-building and binding associated with other reef components, contributing to the construction of a complex reef community similar to those found in the late Middle Ordovician and onwards. In South China, late Cambrian microbial-dominant reefs were rapidly substituted by newly-emerging metazoan reef-builders in the Early Ordovician, such as lithistid sponges, quasi-sponge Calathium, bryozoans, echinoderms, the problematic Pulchrilamina and stromatoporoids. This is in contrast to other palaeocontinents where lithistid-microbial reefs dominated throughout the late Cambrian and Early Ordovician, with Calathium being incor­porated in the Early Ordovician. This finding supports the idea that there was regional heterogeneity in reef evolution during this critical time of the Great Ordovician Biodiversification Event.