New Trigonioidoidea (Bivalvia; Unionoida) from the Early Cretaceous of Spain

Abstract: Two taxa belonging to the Trigonioidoidea (Order Unionoida) are described from the Early Cretaceous of Spain. Nippononaia (Paranippononaia) camerana subgen. et sp. nov. is described from the Aptian of the Cameros Basin of the north‐west Iberian Range. Subnippononaia fordi Barker et al., 1997 is described from new material from the Calizas de la Huérguina Formation (Late Barremian) from Las Hoyas and Buenache de la Sierra, Cuenca Province, and Subnippononaia is raised to generic status. The stratigraphy and palaeoenvironment of the Cornago G exposure of the Enciso Group where Nippononaia (Paranippononaia) camerana originates is interpreted as a fresh to brackish water system.     

Global diversity of freshwater mussels (Mollusca, Bivalvia) in freshwater

The term freshwater bivalve is very inclusive and not very informative. There are representatives of at least 19 families that have at least one representative living in freshwater. This suggests at least 14 different invasions of freshwater. At least nine families have small to large radiations in the freshwater environment: Corbiculidae, Sphaeriidae, Dreissenidae, and the unioniforme families: Hyriidae, Margaritiferidae, Unionidae, Etheriidae, Iridinidae, and Mycetopodidae. The unioniforme families contain at least 180 genera and about 800 species. This order is characterized by the unique parasitic larval stage on the gills, fins or the body of a particular host fish. This order of freshwater bivalves is suffering a very high rate of extinction, with about 37 species considered presumed extinct in North America alone. The level of endangerment and extinction facing these animals is primarily the result of habitat destruction or modification. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

A surprisingly derived hydrometrid (Hemiptera,Gerromorpha) from the Crato Formation,Early Cretaceous of Brazil

In the present paper, we review the fossil record of the Hydrometridae (Hemiptera, Gerromorpha) and present a new species from the Early Cretaceous Crato Formation of Northeastern Brazil, Christometra paradoxa gen. et sp. nov. This species is based on a new specimen (a female), as well as a previously figured one (a male), providing a rare case of preservation of sexually dimorphic features in the fossil record. This is the third species coming from this deposit, which is Aptian-Albian in age and the oldest deposit to have yielded hydrometrids so far. Only five other Mesozoic species are known, being slightly younger in age (Cenomanian). So far, phylogenetic analyses have recovered Cretaceous hydrometrids as basal relative to Cenozoic genera but, Christometra paradoxa exhibits several advanced characteristics that unite it in a clade together with the extant genera Hydrometra and Bacillometroides, in a more derived position than any previously known fossil hydrometrid.

The present publication is registered in the Official Register of Zoological Nomenclature (Zoobank), under the registration number http://zoobank.org/urn:lsid:zoobank.org:pub:3CFA88AB-3CBC-4CCC-8196-698ECC863947. The registration number for the nomenclatural act of the genus is http://zoobank.org/urn:lsid:zoobank.org:act:84744426-1259-4864-8E3F-E43E0DAB2021, and that of the species is http://zoobank.org/urn:lsid:zoobank.org:act:23700AB2-F7AD-4F50-A5E7-CB28868079B2.     

Biostratigraphy of Lower Cretaceous microfossils from the Araripe basin, northeastern Brazil

A biostratigraphic study was carried out in the Lower Cretaceous Araripe basin, northeastern Brazil, allowing the recognition of several chronostratigraphic units: the Dom João (Jurassic?-Lower Cretaceous?), the Rio da Serra (Neocomian) and the Alagoas (Aptian/Albian) local stages. For the first time a large hiatus between the Rio da Serra and Alagoas local stages is carefully documented. The palynomorphs and the ostracode associations throughout the Jurassic?-Aptian/Albian sequence allow the interpretation of the paleoenvironmental evolution of the Araripe basin which otherwise confirms that a polycyclical sedimentation occurred in the basin, being one of the controlling factors on the distribution of ostracodes and palynomorphes.     

New snakeflies (Insecta: Raphidioptera) from the Lower Cretaceous of the UK,Spain and Brazil

Abstract: Several new taxa of snakeflies (Raphidioptera) are described from the Lower Cretaceous deposits of the Wealden, UK (Barremian), Montsec, Spain (Barremian) and the Crato Formation, Brazil (Aptian). Mesoraphidia ednae sp. nov. and M. hilli sp. nov. are described from the Wealden; Nanoraphidia lithographica sp. nov. and Iberoraphidia dividua gen. et sp. nov. are described from Montsec, and Baissoptera lisae sp. nov. is described from the Crato Formation. The geographical range of Nanoraphidia has potentially been extended.     

First record ofColoborhynchus (Pterosauria) from the Santana Formation (Lower Cretaceous) of the Chapada do Araripe, Brazil

The anterior tips of associated upper and lower jaws of a pterosaur from the Lower Cretaceous of Brazil are described and assigned to the taxonColoborhynchus in the family Ornithocheiridae. It is characterized by the shape and position of the sagittal crest on the upper and lower jaw, the arrangement and length of the teeth and the spoon-like lateral expansion of the anterior parts of the jaws. It closely resemblesColoborhynchus wadleighi from North America andColoborhynchus clavirostris from England. Diagnostic anatomical characteristics permit a revision of the genusTropeognathus, which is shown here to be a junior synonym of other described taxa.Tropeognathus mesembrinus is referred toCriorhynchus andT. robustus toColoboryhnchus. Consistent anatomical features enable the new jaw fragment to be assigned toColoborhynchus robustus.      

Estimating the biomass of freshwater mussels (Bivalvia: Unionidae) from shell dimensions

Packs of autumn-shed maple leaves were placed at coal ash effluent-exposed and reference sites in streams on December 5, 1977 and removed after 27 and 96 days. Leaf surface area (cm²/leaf) and disc weight (ash-free dry wt/15 mm disc) were greater at the effluent-exposed site than at the reference site after 96 days (p < .001). ATP content of leaves from the reference stream quadrupled between 27 and 96 days while ATP content of effluent-exposed leaves remained low. Macroinvertebrates colonized the leaf packs in the reference site but were not found on or in effluent-exposed packs. We concluded that leaf processing beyond the leaching of soluble organics did not occur in the effluent-exposed packs owing to reduced colonization and decomposition by fungi. Since stream invertebrates prefer decomposed leaf material and animals grow faster on leaves colonized by microbes, the ash effuent appears to indirectly affect macroinvertebrates by interfering with leaf decomposition and thus reducing the quality of their food.     

On Late Jurassic and Early Cretaceous oysters (Bivalvia,Ostreidae) from northern Siberia

The morphology and taxonomic value of morphological features of Late Jurassic and Early Cretaceous oysters from northern Siberia are considered. A new species, Deltoideum exoticum Kosenko, sp. nov. is described.     

Reproductive phenology of river and lake populations of freshwater mussels (Unionida: Hyriidae) in the River Murray

Gonadal cycles are described for Alathyria jacksoni and Velesunio ambiguus from the River Murray at Overland Corner (near Lock 3) and for V. ambiguus at Point Sturt, Lake Alexandrina. The study included periods of low flow (1982), minor flooding (1983) and intermediate flow (1986). In males, gametogenesis continued year-round with fertilisation in late winter. Female A. jacksoni brooded embryos in spring and released glochidia during spring and summer, whereas in female V. ambiguus, glochidia were present most of the year, with peak releases in spring and summer. In both species, the proportions of actively reproducing individuals varied. In the Murray, populations were influenced by variations in discharge. At Point Sturt, gonadal cycles in V. ambiguus were irregular, influenced by variable lake levels. Although both species are essentially gonochoristic, there were hermaphrodites in river and lake populations, and a female bias in the population at Point Sturt. Infections by parasitic trematodes at Point Sturt were rare, but occurred in 10% of A. jacksoni and 35% of V. ambiguus at Overland Corner. The river populations were also affected by gill damage due to unionicolid mites. The disparities in infections between river and lake mussels are unexplained, but did affect their reproductive activity.     

Morphology and affinities of an Early Cretaceous Ephedra (Ephedraceae) from China

Detailed investigations on Lower Cretaceous Ephedra L. fossils (Gnetopsida) reveal morphological characters similar to those of extant Ephedra rhytidosperma Pachomova, including articulate branches with many fine longitudinal striations, a dichasial branching pattern, uni- or bi-ovulate cones with paired bracts, cones terminal on branchlets, and seeds with a short, straight micropylar tubes, covered by numerous regular and prominent transverse laminar protuberances. Fossils are similar to extant E. rhytidosperma reproductive organs but differ in some vegetative structures and are described and discussed here as Ephedra archaeorhytidosperma Y. Yang et al. Because E. rhytidosperma is currently considered one of the most specialized members in Ephedra L. section Pseudobaccatae Stapf, the occurrence of E. archaeorhytidosperma in the Yixian Formation suggests that Ephedra L. was perhaps a more diverse genus in the Lower Cretaceous. Perhaps the evolution and diversity of Ephedra L. was already in place by the Lower Cretaceous and certainly before the end of the Mesozoic.     

The effect of cryopreservation on mitochondrial function in freshwater mussel tissue samples (Bivalvia: Unionida)

In non-thermoregulating and sessile organisms, such as the imperiled freshwater mussels (Bivalvia: Unionida), thermal sensitivity of mitochondria is a key factor for survival to global warming. Given the protected status of many unionids, non-destructive biopsies and subsequent cryopreservation are advisable procedures for further investigation of their mitochondrial function. To address whether long-term cryopreservation affects mitochondria in freshwater mussels, the mitochondrial respiration in permeabilized somatic cells of Elliptio complanata has been fully characterized through high-resolution respirometry. Our results indicate that cryopreservation does affect the absolute rate of respiration, which significantly decrease compared to fresh tissues, independently of substrates combination, respiratory state and normalizing factor. However, the negative impact is not reflected at the level of flux control ratios, suggesting that, even in front of a sharp decline in the aerobic capacity, cryopreserved tissues preserve the mitochondrial organization and could be thus employed for the qualitative analysis of mitochondrial function.     

On the placement of the Cretaceous orthopteran Brauckmannia groeningae from Brazil, with notes on the relationships of Schizodactylidae (Orthoptera, Ensifera)

The fossil orthopteran Brauckmannia groeningae Martins-Neto (Orthoptera, Ensifera) from the Early Cretaceous Crato Formation of Brazil, currently misplaced at both the genus and family level, is transferred to the family Schizodactylidae and assigned to the extant genus Schizodactylus Brullé; ergo, Brauckmannia enters synonymy under Schizodactylus and Brauckmanniidae enters synonymy under Schizodactylidae. Schizodactylus groeningae (Martins-Neto), comb. n. agrees in size and general habitus with extant members of the genus, but can be readily separated by the robust, subovoid form of the metatibiae and the distinctive morphology of the lateral metabasitarsal processes. This species represents the first fossil occurrence of Schizodactylidae and the only New World record of this ancient lineage. Phylogenetic relationships of the schizodactylids are reviewed and a sister-group relationship with Grylloidea advocated based on a reappraisal of morphological and molecular evidence.     

Mitochondrial DNA phylogenetic structuring suggests similarity between two morphologically plastic genera of Australian freshwater mussels (Unionoida: Hyriidae)

In the Lake Eyre Basin, the Australian hyriid genus Velesunio is represented by three undescribed species, each of which are highly divergent genetically, but morphologically similar to Velesunio wilsonii (Lea 1859). A fourth species, Velesunio ambiguus (Philippi 1847), occurs not only in the Lake Eyre Basin but throughout much of eastern Australia, including the Murray-Darling Basin. In this study, we show that another hyriid, Alathyria jacksoni (Iredale 1934), which is sympatric with V. ambiguus, is genetically deeply nested within the Velesunio species complex, such that the genus Velesunio is paraphyletic with respect to A. jacksoni. Moreover, our mitochondrial phylogenetic reconstructions indicate that A. jacksoni is closely allied to one of the cryptic Velesunio species occurring in the Lake Eyre Basin, but distinct from V. ambiguus and the two other Velesunio species. These data suggest that the genera Alathyria and Velesunio are in need of revision. The shells of A. jacksoni and Velesunio spp. vary with local conditions and sometimes are difficult to distinguish. Our analyses also show that shell characters of these taxa do not closely match the phylogenetic data, and it appears that the traditional taxonomic emphasis on these plastic characters has obscured evolutionary relationships between these, and possibly other, Hyriidae.     

Pearl mussels (Bivalvia, Margaritiferidae, Dahurinaia) from the Amur River basin

Four species of pearl mussels inhabit the Amur River basin: Dahurinaia prozarovae Bog. et Star. in: Bog et al., 2003; D. dahurica (Midd, 1850); D. ussuriensis Bog., Proz. et Star., 2003; and D. tiunovae Bog. et Star., 1988. The name of Dahurinaia transbaicalica Klishko, 2008 is shown to be a synonym for D. ussuriensis. The finding of D. sujfunensis Moskv., 1973 in the Upper Amur basin turned out to be questionable.     

A new Chanidae (Ostariophysii: Gonorynchiformes) from the Cretaceous of Brazil with affinities to Laurasian gonorynchiforms from Spain

Based on specimens originally referred to as "Dastilbe minor", a nomem-nudum, we describe a new genus of Chanidae ?Nanaichthys longipinnus nov. gen. and sp. which exhibits several diagnostic characters such as the absence of orbitosphenoid and basisphenoid, anteriorly displaced quadrate-mandibular articulation, laterally expanded supraneurals, an acute angle between the preopercular limbs, expansion at the angle between the preopercular limbs, and a curved maxillary articular process. Its occurrence and supposed relationship within the Chanidae reinforce the influence of the Mediterranean Tethys over the Gondwanan main rift system prior to the Aptian/Albian highstands.     

Evolution of bilaterally asymmetrical larvae in freshwater mussels (Bivalvia: Unionoida: Unionidae)

Bilaterally asymmetrical glochidia (i.e. bivalved parasitic larvae bearing a large marginal appendage on a single valve) have been reported from five Asian freshwater mussel genera belonging to two separate subfamilies, the Gonideinae (i.e. Pseudodon, Solenaia, and Physunio) and Rectidentinae (i.e. Contradens and Trapezoideus). This classification requires that the bilaterally asymmetrical glochidium‐bearing mussels are not monophyletic, and suggests that this atypical larval morphology evolved twice in the same geographic region. Although homoplastic glochidium characters are known (e.g. marginal appendages and size), we hypothesized that bilaterally asymmetrical glochidia represent a novel morphological synapomorphy. We tested the monophyly of the mussels bearing bilaterally asymmetrical glochidia using a molecular matrix consisting of representatives from all six freshwater mussel families and three molecular markers (28S, 16S, and COI). Bayesian inference, maximum likelihood, and ancestral state reconstruction were employed to estimate the phylogeny and larval trait transformations. The reconstructed phylogeny rejects the monophyly of the asymmetrical glochidium‐bearing mussels and resolves two putative origins of asymmetrical glochidia; however, ancestral state reconstruction supports asymmetrical glochidia as a synapomorphy of only one supraspecific taxon of the Rectidentinae. In the Gonideinae, asymmetrical glochidia were autapomorphic of Pseudodon cambodjensis (Petit, 1865). That is, no other taxa resolved among the Gonideinae had bilaterally asymmetrical glochidia, including other Pseudodon species. We describe how the alleged intrageneric glochidial variation in Pseudodon, and in the other genera of the Gonideinae reported to have asymmetrical glochidia (i.e. Solenaia and Physunio), challenge the resolved convergence of asymmetrical glochidia. Our results are discussed in the context of freshwater mussel larval evolution, patterns in life‐history traits, and the classification of freshwater mussels generally. © 2015 The Linnean Society of London     

Thermal sensitivity of metabolic enzymes in subarctic and temperate freshwater mussels (Bivalvia: Unionoida)

Temperature has a major impact on the physiological processes of freshwater invertebrates. Despite the endangered status of many freshwater mussel species and the potential effect of global warming on North America’s northern aquatic habitats, thermal sensitivity of the metabolic apparatus of freshwater bivalves has received little attention. By examining the thermal sensitivity of 10 key metabolic enzymes and in situ growth rates of latitudinally separated populations (temperate and subarctic) of two closely-related Pyganodon species from northeastern North America, we provide the first insights into thermal sensitivity of key enzymes of energy and reactive oxygen species metabolism in relation to habitat localization and growth performance. The subarctic population of Pyganodon grandis displayed higher in situ growth rates than the temperate population of Pyganodon fragilis. The subarctic population of P. grandis had a lower mitochondrial capacity as expressed by citrate synthase and cytochrome c oxidase but displayed similar electron transport system (ETS) and higher isocitrate dehydrogenase capacities. Our results suggest that higher growth performance of the subarctic population of P. grandis is not associated with higher aerobic capacity. The high thermal sensitivity of mitochondrial enzymes in subarctic population of P. grandis might rather reflect enhanced stenothermy. The higher electron transport system/cytochrome c oxidase ratio for the subarctic P. grandis species than P. fragilis might affect mitochondrial regulation or reactive oxygen species production. Antioxidant enzymes displayed lower Q₁₀s suggesting thermal independence of antioxidant capacity.     

Establishing conservation units to promote recovery of two threatened freshwater mussel species (Bivalvia: Unionida: Potamilus)

Population genomics has significantly increased our ability to make inferences about microevolutionary processes and demographic histories, which have the potential to improve protection and recovery of imperiled species. Freshwater mussels (Bivalvia: Unionida) represent one of the most imperiled groups of organisms globally. Despite systemic decline of mussel abundance and diversity, studies evaluating spatiotemporal changes in distribution, demographic histories, and ecological factors that threaten long‐term persistence of imperiled species remain lacking. In this study, we use genotype‐by‐sequencing (GBS) and mitochondrial sequence data (mtDNA) to define conservation units (CUs) for two highly imperiled freshwater mussel species, Potamilus amphichaenus and Potamilus streckersoni. We then synthesize our molecular findings with details from field collections spanning from 1901 to 2019 to further elucidate distributional trends, contemporary status, and other factors that may be contributing to population declines for our focal species. We collected GBS and mtDNA data for individuals of P. amphichaenus and P. streckersoni from freshwater mussel collections in the Brazos, Neches, Sabine, and Trinity drainages ranging from 2012 to 2019. Molecular analyses resolved disputing number of genetic clusters within P. amphichaenus and P. streckersoni; however, we find defensible support for four CUs, each corresponding to an independent river basin. Evaluations of historical and recent occurrence data illuminated a generally increasing trend of occurrence in each of the four CUs, which were correlated with recent increases in sampling effort. Taken together, these findings suggest that P. amphichaenus and P. streckersoni are likely rare throughout their respective ranges. Because of this, the establishment of CUs will facilitate evidence‐based recovery planning and ensure potential captive propagation and translocation efforts are beneficial. Our synthesis represents a case study for conservation genomic assessments in freshwater mussels and provides a model for future studies aimed at recovery planning for these highly imperiled organisms.     

Freshwater mussels (genus Anodonta) from Anatolia and adjacent areas (Bivalvia,Unionidae)

Abstract

A review is given of the species of Anodontinae in Anatolia and the adjacent areas, based mainly on the author’s collections. Five species (A. anatina, A. cygnae, A. palustris, A. pseudodopsis, A. vescoiana) and several subspecies are recognized. Their distribution and the patterns of subspeciation are discussed.