Rhagada revisited: on the taxonomy of species from the Kimberley and Dampierland,Western Australia (Pulmonata,Camaenidae)

The genus Rhagada is the second most diverse camaenid genus in Australia. We examined anatomical and mitochondrial characters of previously unidentified material from the Kimberley that was earmarked to potentially represent new species in recently published molecular phylogenetic studies. Our comparisons revealed that specimens from Gibbings Island (‘R. sp. Gibbings’) were morphologically and genetically most similar to Rhagada cygna from the Dampier Peninsula. Hence, ‘R. sp. Gibbings’ is considered to be identical to R. cygna. In addition, we found that R. cygna as so delimited is not clearly distinguished from the second species on the Dampier Peninsula, Rhagada bulgana. Both species differ rather subtly in anatomical and mitochondrial characters, indicating their close relationships and potentially incomplete evolutionary differentiation. Furthermore, we describe two new species based on comparative morphology and mitochondrial sequences: Rhagada worora n. sp. from the Prince Regent Reserve in the Kimberley and Rhagada karajarri n. sp. from Dampierland. The present study confirms that species in Rhagada are best identified by means of both morphological and molecular data.

http://zoobank.org/urn:lsid:zoobank.org:pub:556E1866-6F9E-4CC0-8ACF-CD56E929501F     

Mitochondrial DNA diversity and taxa delineation in the land snails of the Iberus gualtieranus (Pulmonata,Helicidae) complex

Iberus gualtieranus is a species complex of land snails that is endemic to the Iberian Peninsula. The species taxonomy of the group is based merely on the basis of shell morphology, but validity of the existing taxonomy is uncertain. Using mitochondrial DNA (mtDNA) data (cytochrome oxidase I and 16S rRNA sequences) we were able to validate the observed phylogenetic taxa within the I. gualtieranus s.l. complex by means of the analysis of specimens of the different morphospecies, together with the study of topotypes. Strong incongruences were obtained between morphology and molecular data. The Iberus alonensis morphospecies comprised several genetically divergent but morphologically cryptic lineages. Considering (1) the allopatric distribution of the operational taxonomic units (OTUs), (2) the morphological differentiation, (3) the possible occurrence of hybridization among the different lineages, and (4) the strong differentiation of the mtDNA phylogroups, we suggest the main lineages obtained, for the time being, may be treated as evolutionary species. The robust phylogenetic reconstruction obtained allows us to consider I. alonensis s.s., Iberus campesinus, Iberus carthaginiensis, and Iberus gualtieranus s.s. as valid species. Two additional unnominated taxa of the alonensis shell type have also been identified. Further subdivisions are also considered, including Iberus gualtieranus mariae and Iberus gualtieranus ornatissimus. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 722–737.     

Species limits in molecular phylogenies: a cautionary tale from Australian land snails (Camaenidae: Amplirhagada Iredale, 1933)

By complementing two independent systematic studies published recently on the Western Australian land snail Amplirhagada, we compare levels of morphological variation in shells and genitalia with those in the mitochondrial markers cytochrome c oxidase (COI) and 16S to evaluate the utility of mtDNA markers for delimiting species. We found that penial morphology and mitochondrial divergence are generally highly consistent in delimiting species, while shells have little overall taxonomic utility in these snails. In addition to this qualitative correspondence, there is almost no overlap between intraspecific and interspecific genetic distances in COI, with the highest intraspecific and lowest interspecific distance being 6%. This value is twice the general level suggested as a DNA barcode threshold by some authors and higher than the best average found in stylommatophoran land snails. Although in Amplirhagada land snails DNA barcoding may provide meaningful information as a first‐pass approach towards species delimitation, we argue that this is due only to specific evolutionary circumstances that facilitated a long‐termed separate evolution of mitochondrial lineages along spatial patterns. However, because in general the amounts of morphological and mitochondrial differentiation of species depend on their evolutionary history and age, the mode of speciation, distributional patterns and ecological adaptations, and absence or presence of mechanisms that prevent gene flow across species limits, the applicability of DNA barcoding has to be confirmed by morphological studies for each single group anew. Based on evidence from both molecular and morphological markers, we describe six new species from the Bonaparte Archipelago and revise the taxonomy of a further two. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 337–362.     

Molecular phylogeny, taxonomy and evolution of the land snail genus Iberus (Pulmonata: Helicidae)

Partial DNA sequences of two mitochondrial genes [cytochrome oxidase subunit I (COI) and 16S rRNA] from 59 specimens of Iberus were used to test the validity of the described morphospecies of this genus, and examine genetic divergences within and between main phylogenetic groups. Both gene fragments showed phylogenetic concordance. The COI gene was found to be faster evolving than the 16S gene and was fully protein-coding with no insertions or deletions. 16S rRNA was more informative than COI for resolving basal nodes. Both individual and combined analyses of the two gene fragments revealed five main phylogroups. These five groups are genetically unique lineages that are allopatrically distributed and considered to have full species status. Further subdivisions were also considered. Shell morphology was suitable for delimiting species boundaries, but several incongruences between morphology and mtDNA phylogeny were observed. These incongruences were considered consequence of hybridization between Iberus cobosi and Iberus marmoratus , and the result of shell shape polymorphism in Iberus rositai . According to spatial patterns of sequence divergence, life habits and shell morphology may be concluded that the keeled-flat shelled snails independently originated several times within Iberus and they could represent cases of similar shell adaptation to a karstic arid environment.     

The evolutionary history of the Chydoridae (Crustacea: Cladocera)

Although much is known about the evolutionary history of the pelagic 'cladocerans', there is little information on benthic families such as the Chydoridae. In this study, we examine the phylogenetic history of 37 chydorid species using sequence variation in two mitochondrial genes, COI and 16S rDNA, and one nuclear gene, 18S rDNA. The four recognized subfamilies of chydorids (Eurycercinae, Saycinae, Aloninae and Chydorinae) were well supported, being separated by large sequence divergences of 14.3–16.4%. By contrast, the existing taxonomic system appears to be less clear at a generic level, since many genera (e.g. Alona , Chydorus , Pleuroxus ) consist of an amalgam of distantly related species. However, among those genera which are monophyletic, levels of divergence are very high, suggesting that they originated somewhere in the mid-Palaeozoic. The factors involved in promoting diversification in this group are discussed.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79, 629–643.     

A new family of diminutive zooxanthellate zoanthids (Hexacorallia: Zoantharia)

A new family, genus, and species of zooxanthellate macrocnemic zoanthid is described from Okinawa, Japan. The diminutive zoanthid N anozoanthus harenaceus sp. nov. occurs in sandy ‘pools’ upon hard substrates in coral reefs. The results of molecular phylogenetic analyses of mitochondrial 16S ribosomal DNA and cytochrome c oxidase subunit I suggests that Nanozoanthidae fam. nov. is genetically close to family Microzoanthidae and Isozoanthus sulcatus at the intrafamily–suborder level. The Nanozoanthidae fam. nov. –Microzoanthidae clade is clearly highly divergent from all other known zoanthid families and from the order Actiniaria at the suborder level or higher. These results demonstrate that much high‐level (e.g. above genus) diversity remains to be described within the order Zoantharia, and until such work is complete it will be difficult to completely understand their biodiversity. © 2013 The Linnean Society of London     

Salenthydrobia gen. nov. (Rissooidea: Hydrobiidae): a potential relict of the Messinian salinity crisis

The Messinian salinity crisis (MSC) occurred synchronously throughout the Mediterranean basin about 5.96 ± 0.02 Mya and represents one of the most dramatic oceanic changes since the early Miocene. It is thought that the concomitant environmental changes brought about isolation of faunas and the development of endemism. As part of the search for possible speciation events triggered by the MSC, the author studied 38 populations of hydrobiine snails from the Mediterranean and Black Sea, including three populations from the Salentina Peninsula, Italy. Partial sequences (COI, 16S) and anatomical data were used to test the taxonomic and phylogenetic status of the peninsular populations. A maximum likelihood analysis of 11 hydrobiine taxa revealed five clades and lineages, four of which corresponded to previously recognized genera: Adriohydrobia , Hydrobia , Peringia , Ventrosia . The fifth clade was formed by haplotypes of the peninsular populations, which are characterized by distinct male and female reproductive systems. Based on molecular and anatomical data, these populations are considered to represent a new species, Salenthydrobia ferrerii , belonging to a new genus, Salenthydrobia . Ecological and biogeographical data for S. ferrerii strongly support a correlation between its origin and the MSC. Based on an island age of 5.33 Myr and a population divergence of 0.0973 ± 0.0114, the COI molecular clock rate for the Salenthydrobia and Peringia clades would be 1.83 ± 0.21% population divergence per Myr. The genetic diversity of S. ferrerii , its phylogenetic relationships, and the validity of the proposed local molecular clock rate are discussed.     

Phylogenetic patterns of diversification in a clade of Neotropical frogs (Anura: Aromobatidae: Mannophryne)

We used partial sequences of mitochondrial 16S and cytochrome oxidase I genes to perform a phylogenetic study of collared frogs (Anura: Aromobatidae: Mannophryne ), a genus endemic to Venezuela and the islands of Trinidad and Tobago. We analysed 1.2 kb from 13 of the 15 described species of Mannophryne . Maximum parsimony, maximum likelihood and Bayesian analyses support the monophyly of Mannophryne . Mannophryne consists of three deeply differentiated clades that split from each other in a relatively short period of time. The diversification of Mannophryne occurred well before the glacial-interglacial periods of the Quaternary. Our data support the taxonomic validity of M. olmonae , a species endemic to Tobago Island. Mannophryne olmonae is more closely related to the continental species Mannophryne riveroi than to the Trinidad island endemic Mannophryne trinitatis . As in most tropical clades of frogs, molecular evidence indicates that species richness in Mannophryne is largely underestimated and, consequently, current priorities for conservation are inadequate.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 185–199.     

Phylogeography of the freshwater crayfish Cherax destructor Clark (Parastacidae) in inland Australia: historical fragmentation and recent range expansion

The yabby, Cherax destructor Clark, is the most widespread species in the most widespread genus of Australian freshwater crayfish. It has a distribution that spans several distinct drainage basins and biogeographical regions within semiarid and arid inland Australia. Here we report a study designed to investigate patterns of genetic variation within the species and hypotheses put forward to account for its extensive distribution using DNA sequences from the mitochondrial 16S rRNA gene region. Results of phylogenetic analyses contradicted previous allozyme data and revealed relatively deep phylogenetic structure in the form of three geographically correlated clades. The degree of genetic divergences between clades (8–15 bp) contrasted with the relatively limited haplotype diversity within clades (1–3 bp). Network-based analyses confirmed these results and revealed genetic structure on both larger and more restricted geographical scales. Nevertheless some haplotypes and 1-step clades had large distributions, some of which crossed boundaries between river basins and aquatic biogeographical regions. Thus both older and more recent historical processes, including fragmentation on a larger geographical scale and more recent range expansion on a local scale, appear to be responsible for the observed pattern of genetic variation within C. destructor . These results support elements of alternative hypotheses previously put forward to account for the evolutionary history of C. destructor and the origin of its large distribution.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 539–550.     

Molecular phylogenetics of Triculine snails (Gastropoda: Pomatiopsidae) from southern China

Triculine (Gastropoda: Rissooidea: Pomatiopsidae) snails are involved in the transmission of schistosomiasis and paragonimiasis; their distributions are mainly across southeastern Asia and southern China. In the present investigation, partial sequences of COI, 16S, and 28S were examined to infer the phylogenetic relationships among the species rich and poorly understood gastropod. Samples were collected from 12 geographic locations in six provinces of southern China. Several methods such as maximum parsimony, maximum likelihood and distance analysis were used in phylogenetic analyses among these taxa. The resultant phylogenetic trees showed a similar topology irrespective of the phylogenetic methods used. The taxa fell into two clades, with those from Fujian, Guangxi, and Zhejiang Provinces in one clade and those from Hunan, Sichuan and Hubei in the other. Among the taxa in Hubei Province, five formed a monophyletic clade, but Tricula sp. H-SHY fell into a sister clade of Tricula hortensis of Sichuan, whilst Tricula hongshanensis formed a single clade. Sister taxa Tricula pingi and Tricula hsiangi formed well-supported clade within almost all the trees. These results, while preliminary, represent the first attempt to reconstruct a phylogeny for Triculinae across China.     

Small snails in a big place: a radiation in the semi‐arid rangelands in northern Australia (Eupulmonata,Camaenidae, Nanotrachia gen. nov.)

Continuing the revision of the Camaenidae in the Australian Monsoon Tropics, we employed comparative analyses of morphological features (with a focus on shell and penial anatomy) and genetic markers (with a focus on mitochondrial COI and 16S sequences) to address the systematic relationships of land snails from the Victoria River District, Northern Territory, and adjacent East Kimberley (Western Australia). These analyses revealed that the species under study represented the previously undescribed genus Nanotrachia. This genus differs from all other camaenid genera known from north‐western Australia most conspicuously by its small, flat, and ribbed shell. Six species are identified as members of the new genus, four of them new species ( Nanotrachia costulata sp. nov. , Nanotrachia carinata sp. nov. , Nanotrachia coronata sp. nov. , Nanotrachia levis sp. nov. ). Two further species have already been described previously but assigned to different genera. These species, Ordtrachia intermedia (as the type species of Nanotrachia) and Mouldingia orientalis, are here transferred to Nanotrachia. Like other camaenids from the Australian Monsoon Tropics, species of Nanotrachia are characterized by essentially allopatric distributions, regional endemism, and a patchy distribution across their range. © 2013 The Linnean Society of London     

Molecular phylogenetics and complementary geographical distributions of species of the Western Australian land snail genera Plectorhagada Iredale, 1933 and Strepsitaurus Solem, 1997 (Gastropoda: Camaenidae)

The Western Australian camaenid genera Plectorhagada and Strepsitaurus have morphological similarities and mutually exclusive ranges near Cape Range. Sequences of ctyochrome c oxidase subunit I (COI) and 16S mitochondrial DNA (mtDNA) genes confirmed that the two genera are genetically close sister clades. Targeted sampling showed that Strepsitaurus, which is confined to Cape Range, lies within a hole in the distribution of the more broadly distributed Plectorhagada that occurs on the coastal strip surrounding Cape Range. Species of the two genera meet at the transition between the rocky Cape Range and the sandier coastal areas, providing a rare example of the close replacement of genera. Within each genus, mtDNA sequences confirmed the monophyly and genetic distinctness of species, with few exceptions that show the need for additional work, and with the addition of three new species in the Cape Range area. As is typical of Australian camaenids, distributions of congeneric species are mutually exclusive, but in some cases close proximity is associated with contrasting habitats, such as gorge endemics versus the species on top of Cape Range. In sympatry, Strepsitaurus rugus (Cotton, 1951) and Strepsitaurus williami Solem, 1997 are separated by microhabitat. These local associations with habitat indicate that ecological differences, and not simply allopatric divergence, contribute to the lack of sympatry between closely related Australian camaenids. © 2015 The Linnean Society of London     

Hybridization between genetically and morphologically divergent forms of Rhagada (Gastropoda: Camaenidae) snails at a zone of secondary contact

Congeneric sympatry is rare in Australian camaenid land snails, and the reasons are poorly understood. As the first example of contact between species of the Western Australian genus Rhagada, we examined the parapatric zone between the coastally distributed Rhagada convicta and an undescribed inland species, which differ in size, shape, and banding of their shells and in their reproductive systems. Phylogenetic analysis of sequences of the mitochondrial 16S RNA gene indicated secondary contact between two distinct clades, with an average sequence divergence of 6.5%. Despite these substantial differences, the two forms hybridize in the narrow contact zone, resulting in intermediate phenotypes for shells and reproductive anatomy, and incongruence of the mitochondrial DNA (mtDNA) lineage and morphology. Hybridization appears to be asymmetric, however, as all morphological intermediates possessed the R. convicta mtDNA. Interbreeding between these deeply divergent forms challenges the use of reproductive structures as indicators of reproductive isolation in snail taxonomy. This is the first contact zone detected between mainland species of Rhagada and indicates that the widespread pattern of geographical replacement is not simply a result of allopatric divergence without subsequent contact. Instead, the perspective for understanding the radiation and geographical distributions must include interactions between the species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 348–362.     

A new species of Camaenidae (Gastropoda,Pulmonata) from Nusa Penida and Lombok Islands,Indonesia: novelty in a well-known fauna

A new species of camaenid land snail, Vulnus wallacei Páll-Gergely, Otani & Hosoda n. sp. is described from Nusa Penida and Lombok Islands, Indonesia. The new species is putatively classified into the genus Vulnus, which is only known so far from the Northern Maluku Islands. The genital anatomy, especially the presence of a well-developed penial sheath in V. wallacei, suggests a close relationship with Australian camaenids. However, the molecular phylogeny based on partial cytochrome c oxidase I, and 16S and 28S ribosomal RNA genes shows that the new species falls outside the cluster of all Australian Camaenidae.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:D28554D0-3578-4E95-8849-09EAFB7D30F7     

An investigation of the "Ancyloplanorbidae" (Gastropoda, Pulmonata, Hygrophila): preliminary evidence from DNA sequence data

The Planorbidae is the largest family of freshwater pulmonate snails, yet an understanding of their intrafamily phylogenetic relationships is lacking and existing inferences are tentative. Moreover, it has been suggested that the Ancylidae, limpet-like freshwater pulmonates, should be merged with Planorbidae according to analysis of internal organ morphology. The present study explicitly tests this hypothesis by phylogenetic inference from partial DNA sequences of three molecular markers, nuclear ribosomal small subunit 18S and the mitochondrial cytochrome oxidase, and large subunit 16S. A molecular phylogeny was inferred based upon 22 taxa representing 12 ancylid and planorbid genera; additional taxa were included from the authors' database and from available sequences from GenBank, to further explore this basic data set. Taxa from Acroloxidae, Lymnaeidae, and Physidae were used as outgroups. Ancylidae and Planorbidae were found to be paraphyletic, with Planorbidae including some members of Ancylidae. "Ancyloplanorbidae" was also found to be paraphyletic because Acroloxus (Acroloxidae) surprisingly was included. Burnupia was found to be ancestral to "Ancyloplanorbidae" (including Acroloxus). The following clades of Planorbidae were supported: Bulininae and Planorbinae, Biomphalarini (including Helisoma and Planorbarius), and Planorbini and Segmentini.     

Molecular identification and phylogenetic relationships of seven Indian Sciaenids (Pisces: Perciformes,Sciaenidae) based on 16S rRNA and cytochrome c oxidase subunit I mitochondrial genes

The partial sequences of 16S rRNA and cytochrome c oxidase subunit I (COI) mitochondrial genes were analyzed for species identification and phylogenetic relationships among the commercially important Indian sciaenids (Otolithes cuvieri, Otolithes ruber, Johnius dussumieri, Johnius elongatus, Johnieops vogleri, Otolithoides biauritus and Protonibea diacanthus). Sequence analysis of both genes revealed that the seven species fell into three distinct groups, which were genetically distant from each other and exhibited identical phylogenetic resolution. Partial sequences of both the genes provided sufficient phylogenetic information to distinguish the seven sciaenids indicating the usefulness of mtDNA-based approach in species identification.     

A new species of Caracolus (Pulmonata: Camaenidae) from the Oligocene of Nebraska and the biotic history of the American camaenid land snails

A fossil land snail from the Oligocene White River Group of Nebraska is described as Caracolus aquilonaris sp nov. Living members of the genus Caracolus occur in tropical forest on the islands of the Greater Antilles. It is likely that C. aquilonaris occupied a similar habitat and that the present restricted occurrence of the genus Caracolus is a fragment of a previously wider range. The American carnaenid genera Pleurodonte, Polydontes and Zachrysia form a well defined monophyletic group, but there is an unresolved trichotomy involving this group, Labyrinthus and Caracolus . Well characterized fossil camaenids assigned to Pleurodonte (Jamaica, Carriacou) and the related Pleurodontites (Florida) occur in the Miocene. Antecedents to Labyrinthus were isolated in South America and to Caracolus and Pleurodonte in North America, possibly in the late Cretaceous. The latter genera reached the Antilles where Caracolus has persisted relatively unchanged. Ancestral Pleurodonte has diversified producing the distinctive subgenera Eurycratera and Thelidomus on Jamaica and the genus Polydontes on the other Greater Antilles. Drier conditions on Cuba have resulted in the divergence of Zachysia from Polydontes .     

Species diversity of Onchidiidae (Eupulmonata: Heterobranchia) on the mainland of China based on molecular data

The identification of members of the Onchidiidae is based on morphological characters; this is often time-consuming and can be inconclusive. In order to explore the species diversity of onchidiids in China, we provide a phylogeny constructed using partial sequences of two mitochondrial genes (16S rRNA and COI) and one nuclear ribosomal RNA gene (28S rRNA) from 32 samples comprising five genera. The topology, using both Bayesian and Maximum Likelihood inference methods, showed that the taxa clustered in two main groups of six species, one of which included Platevindex mortoni, Platevindex sp. and Onchidium ‘struma’; the other included Paraoncidium reevesii, Onchidella sp. and Peronia verruculata. It is clear that COI will be useful in discriminating onchidiid species-group taxa.