Dunkleosteus terrelli, an arthrodire placoderm, is one of the most widely recognized fossil vertebrates due to its large size and status as one of the earliest vertebrate apex predators. However, the exact size of this taxon is unclear due to its head and thoracic armor being the only elements of its body regularly preserved in the fossil record. Lengths of 5–10 m are commonly cited, but these estimates are not based on rigorous statistical analysis. Here, I estimate the body size of D. terrelli using a new metric, orbit-opercular length, and a large dataset of arthrodires and extant fishes (3169 observations, 972 species). Orbit-opercular length strongly correlates with total length in fishes (r² = 0.947, PE_cf = 17.55%), and accurately predicts body size in arthrodires known from complete remains. Applying this method to Dunkleosteus terrelli results in much smaller sizes than previous studies: 3.4 m for typical adults (CMNH 5768) with the largest known individuals (CMNH 5936) reaching ~4.1 m. Arthrodires have a short, deep, and cylindrical body plan, distinctly different from either actinopterygians or elasmobranchs. Large arthrodires (Dunkleosteus, Titanichthys) were much smaller than previously thought and vertebrates likely did not reach sizes of 5 m or greater until the Carboniferous. Full article

The diversity of biota in different parts of the planet has demonstrated dramatic changes within the last several decades due to the extinction of native taxa and the appearance of invasive taxa. The correct taxonomic identification of non-native species is important for understanding their dispersal abilities, especially when potential invaders may be of closely related species. Information on the species identity of ricefish (Oryzias spp.), which have formed self-sustainable populations in some parts of Eurasia, is contradictory. In this paper, we studied samples from non-native populations of Oryzias from several Eurasian regions. The results of our mtDNA COI partial sequence study confirm that the individuals we studied belong to the species Chinese ricefish, O. sinensis. Analyses of the literature and our own data suggest that all known alien populations of Oryzias in continental Eurasia belong to the same species, O. sinensis. A recent finding of O. sinensis in the Don delta suggests that one of the species’ secondary dispersal pathways could run from the Kuban region through the lower part of the Don basin to the Cis-Azov area. Full article

Ocean acidification and warming are current global challenges that marine diazotrophs must cope with. Little is known about the effects of pH and temperature changes at elevated CO₂ levels in combination with different nutrient regimes on N₂ fixers, especially on heterotrophic bacteria. Here, we selected four culturable diazotrophs, i.e., cyanobacteria and heterotrophic bacteria, found in association with the endemic Mediterranean seagrass Posidonia oceanica. We tested different pH (from pH 4 to 8) and temperature levels (from 12 to 30 °C), under different nutrient concentrations of both phosphorus, P (0.1 µM and 1.5 mM), and iron, Fe (2 nM and 1 µM). We also tested different CO₂ concentrations (410 and 1000 particles per million (ppm)) under different P/Fe and temperature values (12, 18, and 24 °C). Heterotrophic bacteria were more sensitive to changes in pH, temperature, and CO₂ than the cyanobacterial species. Cyanobacteria were resistant to very low pH levels, while cold temperatures stimulated the growth in heterotrophic bacteria but only under nutrient-limited conditions. High CO₂ levels (1000 ppm) reduced heterotrophic growth only when cultures were nutrient-limited, regardless of temperature. In contrast, cyanobacteria were insensitive to elevated CO₂ levels, independently of the nutrient and temperature levels. Changes in N₂ fixation were mainly controlled by changes in growth. In addition, we suggest that alkaline phosphatase activity (APA) and reactive oxidative species (ROS) can be used as biomarkers to assess the plasticity of these communities to climate change factors. Unlike other studies, the novelty of this work lies in the fact that we compared the responses of cyanobacteria vs. heterotrophic bacteria, studying which changes occur at the cell plasticity level. Our results suggest that the responses of diazotrophs to climate change may depend on their P and Fe status and lifestyle, i.e., cyanobacteria or heterotrophic bacteria. Full article

Two patterns are apparent in the altitudinal distribution of Neotropical passalid beetles: (a) species that occur only in lowland forest habitats but have broad geographic distributions, and (b) montane endemic species with relatively limited distributions. The transition zone between these distributions in upper Mesoamerica occurs, on average, at approximately 1500 m above sea level (a.s.l.). We studied the altitudinal stratification of passalid beetle communities living on two volcanoes in Guatemala (Atitlan and Santa Maria), revisiting a study conducted in 1981 by MacVean and Schuster. We collected passalid beetles at the same study sites and compared the community composition along the altitudinal gradient. We collected all but one of the species reported by MacVean and Schuster and found three additional species. We observed two key differences in the passalid communities observed in 1981 versus the present: (a) for the Atitlan site, the species’ turnover line from lowland to montane species shifted from 1600 to 1800 m a.s.l.; and (b) in both volcanoes, we collected passalid beetles well above 2700 m a.s.l., which was the upper limit at which they were found in 1981. Both observations are consistent with a shift of the passalid beetle community to higher elevations, perhaps in response to changes in local climate/habitat conditions, including increased temperatures and changes in forest composition. Full article

Turtle shells frequently exhibit anomalous osseous modifications on their surface which can sometimes compromise the survival of the organism. Nowadays, despite the large number of anomalies identified in both extant and extinct turtle shells, the etiology, as well as the pathogenesis, of the various osseous modifications remains unknown in most documented extinct representatives. In fact, the interpretation of these anomalies in most fossil turtles is often speculative, the great majority of anomalous osseous modifications being attributed to vertebrate feeding traces, without considering other potential causative agents. In this context, we herein re-analyzed the shell anomalies recognized in an individual determined as Neochelys sp. (Pleurodira, Podocnemididae) from the middle Eocene (Lutetian) of the El Tejar fossil site (Corrales del Vino, Zamora, Spain), previously proposed as traumatic injuries resulting from a crocodile attack. The re-evaluation of these osseous alterations through detailed physical examination, comparison through direct observation and from the literature on extant turtles, and the use of the files obtained from a computerized axial tomography scan, allows the proposal of diverse causal agents, none of them supporting the previous interpretation. In addition, information regarding the pathogenesis and stages of the healing of the shell anomalies studied herein is provided. Full article

To better understand the phenotypic plasticity of the highly invasive native weed, Pedicularis kansuensis, we investigated and compared phenotypes (morphology, biomass, and nutrient composition) at different levels of invasion (low: 0 < cover ≤ 30%; medium: 30% < cover ≤ 70%; and high: cover > 70%). With the increase in invasion level, the plasticity of inflorescence length, single-leaf thickness, and specific leaf area increased, while the plasticity of single-leaf area and crown width decreased. During the invasion process, we observed significant density-dependent effects, including changed morphological characteristics, increased total aboveground biomass, and decreased plant height, inflorescence length, root length, crown width, single-leaf area, structure biomass of structures (root, stem, inflorescence), and individual biomass (p < 0.05). During the reproductive period of P. kansuensis, the resource allocation (C, N, and P content, total biomass, biomass allocation) to inflorescence was significantly higher than to root and stem, while the elemental ratios (C:N, C:P, N:P) of inflorescences were significantly lower than those of roots and stems (p < 0.05). When the invasion level increased, the ratio of inflorescence C:N and biomass allocation to roots increased significantly; conversely, inflorescence N and biomass allocation to inflorescences and stems decreased significantly (p < 0.05). This led to a decrease in resource allocation to aboveground parts and more resources allocated to the roots, significantly increasing the root-to-shoot ratio (p < 0.05). Based on the phenotypic differences among different invasion levels, we suggest that P. kansuensis adapted to a competitive environment by regulating morphology, biomass, and nutrient allocation, thereby enhancing the potential of invasion and spread. Full article

Entomopathogenic fungi (EPF) consist of a wide range of fungi that can be used as pest control agents, endophytes, and plant growth promoters. In this study of EPF in suburban soils from Achaia, Greece, we used adult beetles as baits for trapping fungal isolates. According to the macroscopic and microscopic traits of the collected isolates, three species corresponded to Beauveria varroae Vuill. (Hypocreales: Cordycipitaceae); Purpureocillium lavendulum Perdomo, Gené, Cano & Guarro (Hypocreales: Ophiocordycipitaceae); and Cordyceps blackwelliae Mongkolsamrit, Noisripoom, Thanakitpipattana, Spatafora & Luangsaard (Hypocreales: Claviceptaceae). Their taxonomic identity was established by ITS-rDNA sequence amplification and sequencing, molecular database comparisons, and phylogenetic analysis. The application of these new EPF species clearly demonstrated remarkable insecticidal action on Thaumetopoea pityocampa (Lepidoptera, Notodontidae) larvae, which increased with the application dose. Our findings are important based on the enhancement of the application of new EPF species as biocontrol agents within the framework of eco-friendly pest management. Full article

The Late Jurassic elasmobranch Protospinax annectans is often regarded as a key species to our understanding of crown group elasmobranch interrelationships and the evolutionary history of this group. However, since its first description more than 100 years ago, its phylogenetic position within the Elasmobranchii (sharks and rays) has proven controversial, and a closer relationship between Protospinax and each of the posited superorders (Batomorphii, Squalomorphii, and Galeomorphii) has been proposed over the time. Here we revise this controversial taxon based on new holomorphic specimens from the Late Jurassic Konservat-Lagerstätte of the Solnhofen Archipelago in Bavaria (Germany) and review its skeletal morphology, systematics, and phylogenetic interrelationships. A data matrix with 224 morphological characters was compiled and analyzed under a molecular backbone constraint. Our results indicate a close relationship between Protospinax, angel sharks (Squatiniformes), and saw sharks (Pristiophoriformes). However, the revision of our morphological data matrix within a molecular framework highlights the lack of morphological characters defining certain groups, especially sharks of the order Squaliformes, hampering the phylogenetic resolution of Protospinax annectans with certainty. Furthermore, the monophyly of modern sharks retrieved by molecular studies is only weakly supported by morphological data, stressing the need for more characters to align morphological and molecular studies in the future. Full article

Ramalina farinacea is an epiphytic lichen-forming fungus with a broad geographic distribution, especially in the Northern Hemisphere. In the eighties of the last century, it was hypothesized that R. farinacea had originated in the Macaronesian–Mediterranean region, with the Canary Islands as its probable southernmost limit, and thereafter it would have increased its distribution area. In order to explore the phylogeography of this emblematic lichen, we analyzed 120 thalli of R. farinacea collected in 38 localities distributed in temperate and boreal Europe, the Western Mediterranean Basin, and several Macaronesian archipelagos in the Atlantic Ocean. Data from two nuclear markers (nrITS and uid70) of the mycobiont were obtained to calculate genetic diversity indices to infer the phylogenies and haplotype networks and to investigate population structure. In addition, dating analysis was conducted to provide a valuable hypothesis of the timing of the origin and diversification of R. farinacea and its close allies. Our results highlight that phylogenetic species circumscription in the “Ramalina farinacea group” is complex and suggests that incomplete lineage sorting is at the base of conflicting phylogenetic signals. The existence of a high number of haplotypes restricted to the Macaronesian region, together with the diversification of R. farinacea in the Pleistocene, suggests that this species and its closest relatives originated during relatively recent geological times and then expanded its range to higher latitudes. However, our data cannot rule out whether the species originated from the Macaronesian archipelagos exclusively or also from the Mediterranean Basin. In conclusion, the present work provides a valuable biogeographical hypothesis for disentangling the evolution of this epiphytic lichen in space and time. Full article

The western region of Saudi Arabia is a major vegetation diversity hotspot with wide range of habitats and variant climatic and topographical characteristics. The vegetation diversity in this region has not been fully studied to monitor the changes that happen over time in these habitats. This study aims to identify the floristic diversity and vegetation structure of the plant species in invaded habitats of the western region of Saudi Arabia. A total of 58 stands in the different invaded habitats (i.e., mountains, protected areas “ridge mountain habitat”, wadis, farmlands, ruderal areas, and coastal areas) were examined. A total of 146 plant species (94 native and 52 alien species) distributed among 132 genera and 49 families were recorded. Asteraceae, Poaceae, and Fabaceae were the most represented families and accounted for approximately 35% of the identified species. Multivariate analysis of the identified species clustered them into four main vegetation groups: VG I dominated by Opuntia ficus-indica-Juniperus phoenicea, VG II dominated by Reichardia tingitana-Heliotropium aegyptiacum, VG III dominated by Prosopis juliflora-Acacia seyal-Abutilon pannosum, and VG IV dominated by Suaeda monoica. The ecological information represented in this study may help in monitoring the changes in vegetation diversity across the western region of Saudi Arabia and designing the required conservation plans. Full article