Land Snail Genus Research Articles

Diversification over deep and shallow temporal scales in the Holarctic genus Perpolita (Gastropoda: Gastrodontidae)

Abstract The Holarctic land snail genus Perpolita was used to explore the influence of past and current biogeography on diversification. The number of empirically-supported species was determined using a consensus between mtDNA sequence, nDNA sequence, conchology, and geographic and ecological range with five valid temperate-boreal species (Perpolita binneyana, Perpolita electrina, Perpolita hammonis, Perpolita petronella, and Perpolita radiatella) being recognized. Only P. petronella was unchanged in both nomenclature and diagnostic characteristics with the remainder requiring alterations. Perhaps the most important of these was elevation of P. radiatella to a valid species, with its populations having been previously lumped either under European P. hammonis or North American P. electrina. Divergence times of 18.7–10.0 Mya were suggested through genome-wide SNPs in combination with the fossil record, indicating a pre-Pleistocene origin for all Perpolita species. Using genetically-confirmed diagnostic shell characters, we accumulated > 2000 valid occurrences and used these to estimate appropriate modern and Last Glacial Maximum climate extents for all species. These models suggest that modern intra-specific gene pool diversity may generally reflect Pleistocene palaeoclimatology.

Systematic revision of the eastern Queensland land snail genus Figuladra Köhler and Bouchet, 2020 based on mitochondrial phylogenetics and comparative morpho-anatomy (Eupulmonata, Camaenidae)

ABSTRACT The current study revises the systematic taxonomy of Figuladra, a genus of camaenid land snails endemic to eastern Queensland, based on the investigation of many recently collected ethanol-preserved samples as well as historic museum material, including types. We employed comparative analyses to investigate the variation in morphological features (shell, penial anatomy) and performed phylogenetic analyses of mitochondrial 16S rDNA sequences to test species hypotheses. Phylogenetic analyses recovered three principal mitochondrial clades, one occurring in mid-east Queensland, one in south-east Queensland, and another in the upland areas of south-east Queensland. We recognise altogether 15 accepted species, including four that are newly described herein (i.e., Figuladra finlaysoni sp. nov., F. robertirwini sp. nov., F. bromileyorum sp. nov. and F. vidulus sp. nov.). The status of 11 previously described species has been assessed and revised diagnoses are provided for each of these. Species of the south-east Queensland clade revealed comparatively low levels of genetic and morphological differentiation and may represent examples of more recent, conceivably ongoing, speciation. Figuladra species have allopatric distributions with their ranges being separated by altitudinal or riverine barriers. Particularly the St Lawrence Gap dry corridor has been identified as a major biogeographic barrier separating two principal clades of Figuladra.

Slow and steady saves the race: molecular and morphological analysis of three new cryptic species of Iberus land snails from the Iberian Peninsula

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.

Intercontinental dispersal and niche fidelity drive 50 million years of global diversification in Vertigo land snails

AbstractAimWe aimed to understand how biogeographical processes and moisture niche ecology contributed to the spatio‐temporal diversification dynamics in the land snail genus Vertigo.LocationGlobal (North America, Europe, Asia, Africa).Time PeriodCenozoic era.Major Taxa StudiedMinute terrestrial snails of the genus Vertigo.MethodsWe reconstructed a time‐calibrated phylogeny of 94 Vertigo taxa (~85% of all known extant species) based on mitochondrial and nuclear DNA data. Leveraging this phylogeny with distributional and ecological data from >7000 populations, we performed biogeographic and ecological modelling to investigate evolutionary mechanisms of global Vertigo diversification.ResultsVertigo has diversified since the Early Eocene, ca. 47.6 Ma (95% HPD = 46.0–52.7), with its six subgenera originating from the Late Eocene (30.2–48.7 Ma) to the Early Miocene (13.3–23.0 Ma). Species diversity accumulated linearly, with a slight increase 35–30 and 25–20 Ma, coinciding with the emergence of most subgenera and northern hemisphere cooling, respectively. Biogeographic modelling indicated that most diversification events occurred in sympatry (no range modification), but that rare founder events drove global diversification. Soil moisture conditions, a major variable defining Vertigo niches, displayed significant phylogenetic signal, but varied less among subgenera relative to within. Shifts in biogeographical ranges and moisture niches (or the absence thereof) were significantly associated at macroevolutionary scales, with most niche shifts upon sympatric cladogenesis and hardly any upon founder‐event speciation.Main ConclusionsOur results indicate that ecological shifts in soil moisture niches occasionally drove cladogenesis in sympatry and anagenetic range extensions, but that long‐distance dispersal was mainly successful in the absence of such shifts. A combination of neutral (founder events and drift) and selective mechanisms (adaptive habitat shifts) has determined the macroevolutionary success of Vertigo. Our results imply that species with high niche fidelity or fewer opportunities for long‐distance dispersal will be more vulnerable to future anthropogenic stressors.

Pilsbrylia, a dextral-shelled door snail from South America (Gastropoda, Clausiliidae)

The land snail genus Pilsbrylia Hylton Scott, 1952 has been recently shown to not belong to the superfamily to which it was originally assigned (i.e., the Orthalicoidea), instead pointing out a relationship with the Clausilioidea. In this study, we included the type species of the genus in a multi-marker molecular phylogenetic framework to reassess its family-level classification. Our results show that Pilsbrylia belongs to family Clausiliidae (known as ‘door snails’) and more specifically, to subfamily Peruiniinae. This family is unique among stylommatophorans for consisting almost exclusively of animals with sinistral (left-handed) shells, whilst Pilsbrylia has a “typical” dextral shell.

Phylogenetic evidence suggests the non-validity of the Iberian land snail genus Tartessiberus and confirms its synonymy with Iberus (Helicidae).

The monospecific genus Tartessiberus was described in the year 2021 including a single species (T.cilbanus). However, its description relied solely on morphological and anatomical data. In the present work, we use a fraction of the mitochondrial DNA cytochrome oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA) and the nuclear large ribosomal subunit (LSU) to clarify its validity through phylogenetic positioning. Knowledge of the distribution of this species is also improved by citing new locations and expanding the geographical range to approximately 200 km2. Additionally, a morphometric analysis of 259 shells is presented for comparisons with shells of the Iberusmarmoratus complex and testing the power of conchological features as a tool for specimen identification. The relatively high conchological variability found for T.cilbanus, together with the discovery of populations with intermediate conchological features between T.cilbanus and other closely related taxa, suggest that the determination of this species should be based on genetic criteria. Our molecular analyses demonstrate that T.cilbanus belongs to the Iberus genus, and thus, we proceed to update its taxonomic status to Iberuscilbanuscomb. nov., and, thus, to consider Tartessiberus from now on as a junior synonym of Iberus.

The Caucasus is neither a cradle nor a museum of diversity of the land snail genus Helix (Gastropoda, Stylommatophora, Helicidae), while Crimea is home to an ancient lineage

The Caucasus and the adjacent Pontic Mountains in north-eastern Anatolia are home to numerous endemic land snail genera and species. The diversity of the region is the result of both intra-regional speciation and the persistence of relict lineages. The same seemed to be true for the genus Helix, which has been present in the Greater Caucasus since the Miocene. In the Caucasus region, there are three Helix species. Helix buchii (Pontic Mountains and Georgia) and Helix albescens (southern Ukraine to northern Lesser Caucasus) are both separated by deep splits from the major Helix clades in the mitochondrial phylogeny. In contrast, Helix lucorum belongs to the Anatolian radiation of Helix. At least part of its intraspecific diversification may have occurred in north-eastern Anatolia and the adjacent parts of the Caucasus. Here, we report new evidence suggesting that the Caucasus and the Pontus regions were less important as a refugium of ancient Helix lineages or as a diversification centre than previously hypothesised. Helix lucorum probably diversified more westwards, while H. buchii is a less ancient lineage than previously thought. Helix albescens had its long-term refugium on the Crimean Peninsula in southern Ukraine, not in the Caucasus. The Caucasus is close to the eastern limit of the distribution range of the genus and, although the fossil record shows that Helix was present there as early as the Miocene, the current diversity of the genus there is the result of much later colonisation.

Molecular phylogeny and morphological evolution of the Chinese land snail Cathaica Möllendorff, 1884 (Eupulmonata: Camaenidae) in Shandong Province, China

Abstract Cathaica is a genus of bradybaenid land snails occurring in China and is widespread in Shandong Province. Here we re-describe three species, C. pyrrhozona, C. fasciola and C. leei, and describe two new species, Cathaica fohuiensis Zhang sp. nov. and Cathaica multicostata Zhang sp. nov.. Geometric morphometric analyses demonstrate that C. pyrrhozona, C. fasciola, C. leei and C. fohuiensis are conchologically similar. Based on differences in their genitalia and molecular data, we consider C. pyrrhozona and C. fasciola to be distinct species. This re-establishes C. pyrrhozona as the type species of Cathaica. Cathaica leei can be distinguished based on its plate spiral whorl and wide umbilicus. The new species C. fohuiensis, with a conical shell and expanded vaginal base, can be distinguished from other Cathaica species based on morphological criteria and is robustly supported in the phylogenetic tree. The other new species, C. multicostata, possesses a strongly ribbed discoid shell and exhibits mucous glands that cluster tightly with the vagina. It is robustly supported in the phylogenetic tree and is the sister taxon to the other Cathaica species. Based on morphological characters and our molecular tree, Pliocathaica, represented here by P. buvigneri, P. pulveratricula and P. gansuica, is not monophyletic.

A new species of Metafruticicola (Gastropoda, Hygromiidae) from the Aegean Archipelago and new anatomical and distributional data on some congeneric species

Metafruticicola is a diverse land snail genus inhabiting the north-eastern Mediterranean region from S Albania to Israel. In this study, we describe Metafruticicola kavafis sp. nov., a new species for science from Kasos Island. We also focus on the reproductive system of steno-endemic species and subspecies of the genus from small islands of the Aegean Archipelago, whose anatomy was previously completely unknown. These species are M. crassicosta, M. pieperi, M. coartata gemina and M. nicosiana conciliatrix. For the latter subspecies, only the outlines of the genitalia were previously given. Additionally, we investigated in detail for the first time the genital anatomy of M. nicosiana nicosiana from Cyprus. Hitherto, information on the genital apparatus of this subspecies was based on sparse data derived from sexually immature specimens. These new anatomical data contribute to a plethora of controversies concerning the subgeneric division of Metafruticicola, which was based solely on conchological features and especially the microsculpture of the teleoconch. We suggest that the current subgeneric division of the genus should be abandoned.

First record and description of three new species in the land snail genus Diplommatina Benson, 1849 (Caenogastropoda, Diplommatinidae) from Satun Province, Thailand

The micro land snail genus Diplommatina (family Diplommatinidae) is widely distributed in Southeast Asia and includes many endemic species. Three new species of Diplommatina are described from Satun Province in southern Thailand. Diplommatina bulonensissp. nov., D. laemsonensissp. nov. and D. prakaiphetensissp. nov. are distinguished from other species in the genus by their shell size and shape, the number of radial ribs on the penultimate whorl, the number of whorls, and features of the peristome. The agreement between phylogenetic tree based on analyses of COI and 16S sequences and comparative morphology support the delineation of these new species which, when compared to related species, belong to well-differentiated clades. The K2P distance between any of the three new species and other Diplommatina species included in the molecular phylogenetic analysis was at least 5.5% in COI and 3.9% in 16S. Two of the three new species (D. prakaiphetensissp. nov. and D. bulonensissp. nov.) are apparently endemic to Prakaiphet Hill and Bulon Pai Island, respectively. Additionally, we documented a new regional record for D. naiyanetri in Satun Province. These new species and records contribute to the knowledge of Thailand’s land snail biodiversity and highlight the need of conservation protections for regional karst habitats.

The systematics and evolution of the Sri Lankan rainforest land snail Corilla: New insights from RADseq-based phylogenetics

The stylommatophoran land-snail genus Corilla is endemic to Sri Lanka and India’s Western Ghats. On the basis of habitat distribution and shell morphology, the 10 extant Sri Lankan species fall into two distinct groups, lowland and montane. Here, we use phylogenetic analyses of restriction-site-associated DNA sequencing (RADseq) data and ancestral-state reconstructions of habitat association and shell morphology to clarify the systematics and evolution of Sri Lankan Corilla. Our dataset consists of 9 species of Corilla. Phylogenetic analyses were based on 88 assemblies (9,604–4,132,850 bp) generated by the RADseq assembler ipyrad, using four parameter combinations and different levels of missing data. Trees were inferred using a maximum likelihood (ML) approach. Ancestral states were reconstructed using maximum parsimony (MP) and ML approaches, with 1 binary state character analysed for habitat association (lowland vs montane) and 6 binary state characters analysed for shell morphology (shape, colour, lip width, length of upper palatal folds, orientation of upper palatal folds and collabral sculpture). Over a wide range of missing data (40–87 % missing individuals per locus) and assembly sizes (62,279–4,132,850 bp), nearly all trees conformed to one of two topologies (A and B), most relationships were strongly supported and total branch support approached the maximal value. Apart from the position of Corilla odontophora ‘south’, topologies A and B showed similar, well-resolved relationships at and above the species level. Our study agrees with the shell-based taxonomy of C. adamsi, C. beddomeae, C. carabinata, C. colletti and C. humberti (all maximally supported as monophyletic species). It shows that C. erronea and C. fryae constitute a single relatively widespread species (for which the valid name is C. erronea) and that the names C. gudei and C. odontophora each apply to at least two distinct, yet conchologically-cryptic species. The MP and ML ancestral-state reconstructions yielded broadly similar results and provide firm evidence that diversification in Sri Lankan Corilla has involved evolutionary convergence in the shell morphology of lowland lineages, with a pale shell and wide lip having evolved on at least two separate occasions (in C. carabinata and C. colletti) from montane ancestors having a dark, narrow-lipped shell.

Molecular investigation on diversity of the land snail genus Aegista (Gastropoda, Camaenidae) in South Korea.

Aegista Albers, 1850 is a large genus of the land snail family Camaenidae Pilsbry, 1895 and distributed in south, southeast and east Asian countries (from India and Nepal to Korea and Japan). Fourteen species and subspecies of Aegista are known from South Korea. They were described, based only on shell morphology during 1887-1943 and our knowledge on diversity of Korean Aegista has seldom been updated since then. In this study, we provide the report on the first molecular investigation of diversity of Aegista in South Korea, which unmasked some of overlooked diversity of this group.

Within‐island diversification in the land snail genus Formosana (Gastropoda, Clausiliidae) in Taiwan

AbstractThe morphology‐based species delimitation of the land snail genus Formosana (Clausiliidae) was questioned, due to the high intraspecific variability and interspecific similarity of morphological characters. The systematics of Formosana from Taiwan are revised using molecular, morphological, and anatomical data. Phylogenies were constructed based on four mitochondrial and nuclear markers, by means of maximum likelihood and Bayesian inference analyses. Twelve valid and endemic species and subspecies were recognised from Taiwan, six of which are newly described herein: Formosana nanaoensis sp. n., Formosana hsuehshanensis sp. n., Formosana lilongshanensis sp. n., Formosana katipulensis sp. n., Formosana kaluluanensis sp. n., and Formosana tianchihensis sp. n. In addition, three nominal species are maintained as synonyms of earlier described species. A congener from China is transferred to the genus Formosanella as a new combination, Formosanella friniana com. n. The variability in morphological characteristics, and resulting difficulties for their taxonomic implication are critically discussed. Divergence time estimation and ancestral range reconstructions indicate that the Taiwanese Formosana most likely colonised in eastern Taiwan, approximately 4.7 million years ago in the Early Pliocene, and then differentiated into four major clades. The speciation events mainly occurred during the Late Pliocene and the Early Pleistocene. The biogeography and diversification of Formosana in Taiwan are discussed, in light of the concept of palaeoislands.

On the verge of extinction - revision of a highly endangered Swiss alpine snail with description of a new genus, Raeticella gen. nov. (Gastropoda, Eupulmonata, Hygromiidae).

The phylogenetic status of the alpine land snail Fruticicolabiconica has remained questionable since it was described by Eder in 1917. Considered a microendemic species from mountain tops in Central Switzerland, the shell is specially adapted for life under stones. Herein, we show via molecular and anatomical investigations that F.biconica neither belongs to the land snail genus Trochulus, nor to any other genus within Trochulini, but rather warrants placement within the newly established genus Raeticella Kneubühler, Baggenstos & Neubert, 2022. Phylogenetic analyses reveal that R.biconica is clearly separated from Trochulus. These findings are supported by morphological investigations of the shell and genitalia.

The land snail genus Pincerna Preston, 1907 (Gastropoda: Alycaeidae) from Vietnam and Laos, with description of a new species

The land snail genus Pincerna Preston, 1907 (Gastropoda: Alycaeidae) from Vietnam and Laos, with description of a new species

Long-distance dispersal from island to island: colonisation of an oceanic island in the vicinity of the Asian continent by the land snail genus Karaftohelix (Gastropoda: Camaenidae)

ABSTRACT Ullung Island is an oceanic island in the Sea of Japan about 130 km distant from the Korean peninsula. The biota of this oceanic island is thought to be derived from the closest continental region while the importance of long-distance dispersal from other areas for the formation of the Ullung Island biota was considered negligible. In this study, we have examined the origin of the Ullung Island-endemic land snail Karaftohelix adamsi (Kuroda & Hukuda, 1944) using a molecular phylogenetic approach with two mitochondrial (COI and 16S rRNA) and nuclear (ITS regions) DNA sequences. Our results revealed that K. adamsi has originated from the northernmost region of the Japanese archipelago or Sakhalin Island, most likely from Rebun Island of Hokkaido, by long-range dispersal across a distance of 1200 km. This finding reveals that the biota of the oceanic Ullung Island has not exclusively originated from the Asian mainland, but that some elements have originated from the more distant archipelago of Japan and the Far East of Russia.

Multigene phylogeny reveals the ribbed shell morphotypes in the land snail genus Sarika (Eupulmonata: Ariophantidae), with description of two new species from Thailand and Myanmar

Abstract The speciose land snail genus Sarika is widely distributed throughout mainland Southeast Asia. This genus is generally recognized by a smooth and polished shell. However, we recognize four species with a ribbed shell surface (S. siamensis, S. theodori, S. costabilis sp. nov., and S. costata sp. nov.) exhibiting genital characters similar to those of Sarika s.s. and so a rearrangement in the systematics of the genus is suggested. Here, we analysed these four ribbed shell species together with Sarika s.s. by a combined morphological and molecular approach to species delineation, the latter based on both mitochondrial (coi and 16S) and nuclear (28S) markers. Our molecular phylogeny affirms the monophyly of the genus Sarika including both smooth and ribbed shell morphotypes that is statistically well supported. The ribbed shell morphotype in the land snail genus Sarika is also well defined in terms of diagnostic morpho-anatomical characters that can be divided into two species groups. The S. costata species group consists of only one species, S. costata sp. nov., while the S. siamensis species group comprises S. siamensis, S. theodori and S. costabilis sp. nov. These findings provide a solid basis for the systematics of family Ariophantidae.

Patterns of diversification of the operculate land snail genus Cyclophorus (Caenogastropoda: Cyclophoridae) on the Ryukyu Islands, Japan

The Ryukyu Islands, an island chain in southwestern Japan, originated from land masses that separated from the Eurasian continent due to the formation of sea barriers about 1.55 million years ago. In this study, we investigated the phylogenetic relationships of the operculate land snail genus Cyclophorus (Caenogastropoda: Cyclophoridae) in the Ryukyu Archipelago and surrounding regions based on DNA sequence data. According to our results, all studied Cyclophorus specimens from Japan form a monophyletic group containing eight subclades. Six of these subclades were found only on the Ryukyu Islands. On most islands of the Ryukyu Archipelago, no more than one Cyclophorus subclade was recorded, which may be due to limited ecological niche space and competition. No subclade was found to occur on both sides of the Watase Line, a regional zoogeographical boundary. Divergence times were estimated based on a time-calibrated phylogeny. We found that multiple splits among the Japanese Cyclophorus subclades predate the emergence of major sea barriers in the Ryukyu Archipelago. Vicariance due to sea barrier formation, as assumed for many other taxa from the region, was thus likely not the main driver for subclade divergence in these snails. Instead, certain geographical features might have shaped the diversification of subclades prior to sea barrier formation. Given that Cyclophorus populations were also present on islands that have never been connected to other land masses, the snails must have colonized them via oversea dispersal. As not all nominal taxa corresponded to monophyletic groups, our molecular phylogenetic approach revealed that a taxonomic revision of the Japanese Cyclophorus fauna is necessary. The eight subclades may be regarded as potential species-level groups based on COI p-distances. A canonical discriminant analysis using shell morphological data revealed slight differences among the subclades.

Five new species of the land snail genus Landouria Godwin-Austen, 1918 (Gastropoda, Camaenidae) from northeastern Thailand, with note on genitalia and radula morphology of Landouria diplogramma (Möllendorff, 1902)

Five new species of the terrestrial snail genus Landouria Godwin-Austen, 1918 (Camaenidae) are described from northeastern Thailand, based on shell features, radular morphology, genital anatomy, and DNA sequence data: Landouria circinata sp. nov., L. tuberculata sp. nov., L. trochomorphoides sp. nov., L. chloritoides sp. nov., and L. elegans sp. nov. These species are phylogenetically well separated from each other by mtDNA phy-logeny and COI sequence divergences of 0.073–0.156. The record of Thaitropis Schileyko, 2004 (currently synonymized with Landouria) in Thailand is re-interpreted as referring to L. diplogramma (Möllendorff, 1902) comb. nov.

Systematic revision of the limestone karst-restricted land snail genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with description of a new species

Thai limestone karsts are known to contain a rich biodiversity of animals, especially terrestrial snails, but still require further intensive exploration to evaluate their biodiversity. To date, only a few studies on the limestone karst-inhabiting land snail genera have been published. The present work focuses on the species diversity and phylogenetic relationships of the limestone karst-restricted land snail genus Aenigmatoconcha from Thailand, based on comparative morphology and molecular evidence. The results yielded three known species (A. clivicola Tumpeesuwan & Tumpeesuwan, 2017, A. sumonthai Tumpeesuwan & Tumpeesuwan, 2018, and A. mitis (Pfeiffer, 1863) comb. nov.), plus a new species (A. eunetis Pholyotha & Panha sp. nov). The phylogenetic analyses of partial fragments of the mitochondrial cytochrome oxidase c subunit I (COI) gene confirmed the monophyly of all recognized species and congruence with the traditional morphology-based species designations. Average uncorrected p-distances of COI sequences between species were 9.7–12.0% and within species were 0.2–4.2%. This study also provides the re-description of penial sculpture, penial sheath, flagellum, penial caecum, and mantle lobe morphology that were neglected from the type species description. The present discovery of a new species increases the known diversity of Thai land snails and will support the conservation planning to protect karst biodiversity.