Organisms Diversity & Evolution最新文献

Four species of marine tardigrades were found in deep sea sediment samples of the Newfoundland Basin in the Northwest Atlantic Ocean. Samples were collected during expedition SO286 at more than 3000 m depth in an abyssal area that belongs to the intended new marine protected area “North Atlantic Current and Evlanov Seamount” (NACES). The genus Coronarctus was represented by two specimens of C. dissimilis. The genus Angursa was represented by four specimens of A. capsula, five specimens of A. abyssalis, and one specimen of A. lanceolata. In order to investigate the morphology and morphometry, we primarily used light microscopy with differential interference contrast. However, some specimens were additionally investigated with confocal laser scanning and scanning electron microscopy. The morphological and morphometric details and the new geographic records of the four identified species increase our knowledge of the taxonomy and biogeography of marine tardigrades. For C. dissimilis and A. lanceolata, the new records could indicate a pan-Atlantic distribution for both species, which were so far only known from the South Atlantic Ocean. The new record of A. capsula is even more remarkable since that species was so far only known from its type locality in the East Pacific deep sea.

Abstract

Corsica and Sardinia are amongst the largest islands of the Western Mediterranean. Their complex geological history included belonging to the European–Iberian continental margin (close to current-day Catalonia and Provence) and varying degrees of isolation for the last 30 million years, leading to peculiar, highly endemic faunas and floras. This is especially true for their earthworm faunas, which include endemic species of several Lumbricoidea genera and the endemic family (or subfamily) Diporodrilidae. Only three species have been described for the morphologically unique Diporodrilus, but there exists evidence for wide morphological variability within them and the existence of several species-level genetic lineages within Corsica. This work aimed to investigate the genetic diversity and phylogenetic relationships between the genetic lineages of Diporodrilus from Corsica and Sardinia (based on the sequences of 5 mito-nuclear markers), to perform an integrative systematics revision combining species delimitation techniques and morphological data, and to obtain a time-calibrated phylogeny of Diporodrilus and other Corso-Sardinian Lumbricoidea. Within 15 populations of the morphospecies Diporodrilus omodeoi and Diporodrilus pilosus across Corsica and Sardinia, 10 species-level genetic lineages were detected. Phylogenetic independence, high genetic divergence and morphological differences provided the support for the description of five new pseudocryptic species: Diporodrilus rotundus sp. nov., Di. jorgei sp. nov., Di. minor sp. nov., Di. meridionalis sp. nov. and Di. telti sp. nov. Time-calibrated phylogenetic inference estimated the age for genus Diporodrilus at 65.9 Mya; even if other Corso-Sardinian genera were significantly younger, all of them presented deep divergences predating the break-off of the microplate from the continent. The almost threefold increase in the known diversity of Diporodrilus stresses the need for comprehensive earthworm diversity inventories in both Sardinia and Corsica, and for studies on their ecological role and conservation status. The close correspondence between some geological and cladogenetic events suggest that the distribution of Corso-Sardinian earthworms could be used to inform standing geological controversies.

The Iberian Peninsula constitutes a diversity hotspot with a high number of endemisms, where the land snail genus Iberus is likely the best example. Despite this, its species diversity is still debated as it holds several cryptic species. In the present paper, we use molecular evidence (mitochondrial DNA cytochrome oxidase subunit I) to clarify the position of I. ortizi and three new cryptic species that are described herein: I. giennensis, I. axarciensis and I. antikarianus spp. nov. For this, we sampled 281 sampling points to delimitate a comprehensive geographic mapping of these species. Moreover, we carried out a comprehensive morphometric analysis based on 3205 shells. Our findings show that, morphologically, the three described species overlap in the form of their shells, their morphologies being very similar to other close species with nearby distributions (I. ortizi, I. angustatus and I. marmoratus loxanus). Still, all these species are well-defined by genetic distances, but display allopatric distributions, suggesting that they evolved by allopatric speciation as a consequence of biogeographic isolation. Hence, our findings show insights into the evolution of land snails in southeastern Spain, with implications for their conservation, given that our exhaustive sampling shows that the three species described here have very limited distribution ranges, especially I. antikarianus sp. nov. Our study, moreover, implies an integrated approach to the study of the evolution of land snails, including the sampling of the complete geographic area occupied by the genus, genetic analysis to delimit the actual species range, as well as morphometric analyses to understand the phenotypic differentiation and adaptations of the three new species.

In this study, the influence of geographic isolation on the levels of morphological and genetic differentiation among populations of the karst forest-adapted Pilea pteridophylla (Urticaceae) was evaluated. Based on our results, there is a strong morphological differentiation among the only two know populations of Pilea pteridophylla. Both populations can be clearly differentiated based on vegetative and reproductive characters, and the observed variation is geographically structured. Moreover, our genetic data from the chloroplast genome show strong levels of population differentiation and no shared haplotypes were observed between populations. Also, our estimation of divergence times supports a long-term isolation hypothesis between populations. Based on our results, dispersal seed limitation, long-term forest isolation and topographic heterogeneity (local adaptation) are related to high levels of endemism and species turnover in the mountain karst forests of Mexico.

The widespread Tantilla melanocephala is a South American snake, which has a convoluted taxonomic history and a poorly addressed systematics. The taxonomic identity and the phylogenetic affinities of their populations are unclear, suggesting the existence of a complex of undescribed species. Here, we preliminarily address the morphological diversity and genetic structure of the T. melanocephala complex through comparative morphological approaches and phylogenetic analyses using maximum likelihood. Our results confirm the presence of hidden diversity within the T. melanocephala complex and strongly indicate that the populations of T. melanocephala from southern South America represent a distinct lineage, which is morphologically diagnosable under a unique combination of character states. Therefore, we formally describe these populations as a new species and present a comparison among all other South American species of Tantilla. We also estimate the divergence times of the main clades within the complex through Bayesian analysis, suggesting a biogeographical scenario of lineage diversification. Finally, our study clarifies aspects of the intricate taxonomy of the T. melanocephala complex, providing a framework for future studies to avoid the description of synonyms.

To determine the intraspecific variability of microscopic organisms such as dinophytes is challenging, but can be achieved using cultured material. Unusual morphologies of Peridinium tuberosum assigned to the Peridinium cinctum species group have been described as bulges on the posterior end of the cell a hundred years ago and more, but its taxonomic significance is unclear at present. We collected field material in Germany and Poland in order to establish strains to study cell morphology using light and scanning electron microscopy. For the cultured material, DNA sequence data from the rRNA operon was gained as well and included in molecular phylogenetics (including 22 new partial rRNA sequences). Two new, closely related ribotypes were detected, and all strains showed the principle morphology of P. cinctum having an asymmetric epitheca, a large first apical plate and a sulcus extending onto the epitheca. In the single-strain GeoM*979 assigned to one of the two new ribotypes, cells with bulges appeared rarely but consistently, mostly on the hypotheca, but other variations also occurred. Overall, cells of this strain display traits not observed before while studying cultured P. cinctum, and this distinction is further supported by molecular data and additional details of epithecal opening. However, there does not remain enough information to determine strain GeoM*979 as a separate species (namely P. tuberosum) and therefore, it is identified as Peridinium aff. cinctum until further notice.

The Malay Archipelago comprises thousands of islands that house a variety of biomes, from tropical rainforests of Borneo, Sumatra and Celebes to the Lesser Sundas deciduous forests. In this paper, we present an extensive genetic and morphological dataset for the genus Kristenseniscus, demonstrating the presence of the walteri complex that contains several pseudocryptic species. One of them, Kristenseniscus exanthema sp. nov., is described from Ambon and Seram (the Moluccas). First genetic data are released for two potentially pantropical Echiniscus species: E. africanus Murray, 1907 and E. pusae Marcus, 1928. Furthermore, Echiniscus minutus sp. nov. (Sulawesi Tengah), exhibiting trunk spines and contrasting dorsal sculpturing that comprise both pores and epicuticular granules, is found to constitute a separate evolutionary lineage within the Echiniscus spinulosus morphogroup (epicuticular granules are typically absent in the spinulosus group). Based on the phylogenetic reconstructions involving ca. 80 spp. of echiniscids representing the Echiniscus evolutionary line, we hypothesise that the tropical and subtropical regions served as the main radiation zone for this heterotardigrade clade. Finally, Pseudechiniscus (Meridioniscus) celebesiensis sp. nov. (Sulawesi Tengah) is a characteristic species with an apomorphic lack of claw spurs and intricate dorsal cuticular sculpturing. Our findings suggest that the tropical areas of the globe harbour a phylogenetically important but yet mostly uncovered portion of Earth’s tardigrade diversity.

Endoparasitic annelids living inside another annelid host are known, particularly with regard to Oenonidae, but in general are poorly studied. The dorvilleid Veneriserva pygoclava is known from southern California, and its genus name (Latin = Venus’s servant) alludes to the close association with the host aphroditid scaleworm Aphrodita longipalpa. Little is known on fundamental questions on the biology of Veneriserva pygoclava. What is its mode of reproduction? How do they feed? How do they penetrate the host? We have studied multiple parasitized hosts and V. pygoclava specimens, using an integrative approach, combining µCT, histology, and electron microscopy. 3D reconstructions from µCT data of a parasitized Aphrodita show the exact position of the parasites in their natural condition within the host’s coelomic cavity. Ultrastructural investigations of the parasites revealed interesting adaptations to their lifestyle such as the complete reduction of their gut, despite the presence of a functional jaw apparatus and a modified epidermis enabling nutrient uptake from the host’s coelomic fluid. In addition to these, we also investigated spermatogenesis and oogenesis in V. pygoclava. Sperm morphology indicates an external fertilization of eggs within the coelomic cavity of the host. Mature male and female parasites living inside the same mature host and the presence of juvenile V. pygoclava within juveniles of Aphrodita suggest an obligate form of parasitism with a very early penetration of the hosts. In addition to our detailed morphological investigation, we conducted a phylogenetic analysis showing the position of Veneriserva within Dorvilleidae and its position was recovered nested among taxa of the Iphitime. Our phylogenetic analyses also show that the taxation Ophryotrocha puerilis siberti should be given full species rank and referred to as Ophryotrocha siberti. Finally, we publish here the full mitochondrial genome of V. pygoclava and discuss its novel gene order with reference to other annelids.

The invasion of non-native species has been a chronic problem in reservoirs of hydroelectric plants. Among the species recorded in Brazil, the cnidarian Cordylophora caspia is often misidentified as macrophytes or completely overlooked, although reports state that the colonies obstruct structures and pipes in industrial plants, generating high maintenance costs. In addition to modifying the ecological balance of invaded ecosystems, studies indicated that C. caspia can influence the occurrence of other invasive species, such as Limnoperna fortunei. In this study, we reported two new records for C. caspia in Brazil, the first occurrence in Minas Gerais and Goiás. We described the colonies in detail and reviewed the known geographic distribution of the species in Brazilian waters. We provided the first Brazilian genetic sequences of the species, which were phylogenetically placed into a broad evolutionary inference using C. caspia COI sequences available from different regions of the world. Our results indicate that there is no clear pattern of ecophysiological specialization of main clades regarding salinity that would justify the validation of the nominal C. lacustris for freshwater specimens. High levels of genetic differentiation in the lineages support the existence of multiple cryptic species within the genus Cordylophora. Finally, our ancestral state reconstruction analysis suggested a presumed freshwater origin for C. caspia and independent shifts between fresh and brackish waters. Advances in the study of populations from different regions of the world will be important for further understanding species delimitation, possible routes of invasion, economic impacts, and ecological interactions, including with other invasive species.