Alexander V. Kondakov

Multi-locus fossil-calibrated phylogeny, biogeography and a subgeneric revision of the Margaritiferidae (Mollusca: Bivalvia: Unionoida).

The taxonomy and biogeographic history of the bivalve family Margaritiferidae are controversial because previous molecular studies did not provide a well-resolved phylogenetic framework for these enigmatic freshwater mussels that have extensive but disjunct distribution in North America, Eurasia and North Africa. In this study, we present a new, fossil-calibrated phylogenetic hypothesis based on five molecular markers (∼4kb of total length) for ten species. Our results indicate that all recent margaritiferids are in the single genus, Margaritifera Schumacher, 1816. Additionally, we identified three relatively well-supported phylogenetic clades that are valid subgenera, i.e., Margaritifera s. str. (Holarctic), Margaritanopsis (=Cumberlandia) (southeast North America-southeast Asia disjunct) and Pseudunio (Mediterranean). We suggest that the crown lineage of the Margaritiferidae most likely originated in the Cretaceous (mean age 93Ma, 95% CI 66-126Ma). The combined results of ancestral area reconstructions based on the three different approaches (S-DIVA, DEC and S-DEC) showed that ancient vicariance events could have played an important role in speciation within the family. The rates of mitochondrial evolution of margaritiferids are notably slow, which may be associated with their longevity, long generation time and low metabolic rates. Our findings highlight the complex biogeographic history of the Margaritiferidae as an intermixing of ancient vicariance and dispersal events, which were most likely associated with some inland barriers, continental movements and a sea level dynamic.

Ancient River Inference Explains Exceptional Oriental Freshwater Mussel Radiations

The concept of long-lived (ancient) lakes has had a great influence on the development of evolutionary biogeography. According to this insight, a number of lakes on Earth have existed for several million years (e.g., Baikal and Tanganyika) and represent unique evolutionary hotspots with multiple intra-basin radiations. In contrast, rivers are usually considered to be variable systems, and the possibility of their long-term existence during geological epochs has never been tested. In this study, we reconstruct the history of freshwater basin interactions across continents based on the multi-locus fossil-calibrated phylogeny of freshwater mussels (Unionidae). These mussels most likely originated in Southeast and East Asia in the Jurassic, with the earliest expansions into North America and Africa (since the mid-Cretaceous) following the colonization of Europe and India (since the Paleocene). We discovered two ancient monophyletic mussel radiations (mean age ~51–55 Ma) within the paleo-Mekong catchment (i.e., the Mekong, Siam, and Malacca Straits paleo-river drainage basins). Our findings reveal that the Mekong may be considered a long-lived river that has existed throughout the entire Cenozoic epoch.

Taxonomy and distribution of freshwater pearl mussels (Unionoida: Margaritiferidae) of the Russian Far East.

The freshwater pearl mussel family Margaritiferidae includes 13 extant species, which are all listed by IUCN as endangered or vulnerable taxa. In this study, an extensive spatial sampling of Margaritifera spp. across the Russian Far East (Amur Basin, Kamchatka Peninsula, Kurile Archipelago and Sakhalin Island) was conducted for a revision of their taxonomy and distribution ranges. Based on their DNA sequences, shell and soft tissue morphology, three valid species were identified: Margaritifera dahurica (Middendorff, 1850), M. laevis (Haas, 1910) and M. middendorffi (Rosén, 1926). M. dahurica ranges across the Amur basin and some of the nearest river systems. M. laevis is distributed in Japan, Sakhalin Island and the Kurile Archipelago. M. middendorffi was previously considered an endemic species of the Kamchatka. However, it is widespread in the rivers of Kamchatka, Sakhalin Island, the Kurile Islands (across the Bussol Strait, which is the most significant biogeographical boundary within the archipelago), and, likely, in Japan. The Japanese species M. togakushiensis Kondo & Kobayashi, 2005 seems to be conspecific with M. middendorffi because of similar morphological patterns, small shell size (<100 mm long) and overlapped ranges, but it is in need of a separate revision. Phylogenetic analysis reveals that two NW Pacific margaritiferid species, M. laevis and M. middendorffi, formed a monophyletic 18S rDNA clade together with the North American species M. marrianae and M. falcata. The patterns that were found in these Margaritifera spp. are similar to those of freshwater fishes, indicating multiple colonizations of Eastern Asia by different mitochondrial lineages, including an ancient Beringian exchange between freshwater faunas across the Pacific.

New taxa of freshwater mussels (Unionidae) from a species-rich but overlooked evolutionary hotspot in Southeast Asia

Southeast Asia harbors a unique and diverse freshwater fauna of Mesozoic origin, which is under severe threat of extinction because of rapid economic development and urbanization. The largest freshwater basins of the region are certainly the primary evolutionary hotspots and they attract the most attention as key biodiversity areas for conservation. In contrast, medium-sized rivers are considered low-importance areas with secondary biodiversity, whose faunas originated via founder events from larger basins during the Pleistocene, although such a scenario has never been tested by using a phylogenetic approach. In this investigation, we used freshwater mussels (Unionidae) as a model to estimate the levels of endemism within the Sittaung, a little-known remote basin in Myanmar, compared with the surrounding larger rivers (Irrawaddy, Salween and Mekong). We discovered that the Sittaung represents an exceptional evolutionary hotspot with numerous endemic taxa of freshwater mussels. On the basis of our extensive dataset, we describe two new tribes, two genera, seven species and a subspecies of Unionidae. Our results highlight that medium-sized basins may represent separate evolutionary hotspots that harbor a number of endemic lineages. These basins should therefore be a focus of special conservation efforts alongside the largest Southeast Asian rivers.

Ecology and conservation of the endangered Indochinese freshwater pearl mussel, Margaritifera laosensis (Lea, 1863) in the Nam Pe and Nam Long rivers, Northern Laos

In this paper we present the first ecological data of Indochinese freshwater pearl mussel, Margaritifera laosensis populations. We also provide a comparative study of the ecology of this tropical species with populations of other Margaritiferidae. We conducted surveys in ten tributaries of the River Nam Ou (Middle Mekong Drainage, Northern Laos). Reproductively viable populations were found only in the Nam Long and Nam Pe rivers, which are two of the only three known viable populations of this species in the world. The habitats of M. laosensis include mountainous oligotrophic rivers with circumneutral pH. Optimal mesohabitats are riffles and runs with a median depth of 0.2 m and median current velocity of 0.3 ms−1. Pearl mussels were more common in gravel and fine gravel riverbed substrates. Surveys revealed 252 specimens, but only 78 (31.0%) were alive. The largest mussels observed were 110 mm in length and only 11–12 years of age. The presence of smaller-sized mussels indicates recent recruitment in both populations. The most significant threats to M. laosensis populations are harvest by local people and land development in the River Nam Ou Basin.

A taxonomic revision of two local endemic Radix spp. (Gastropoda: Lymnaeidae) from Khodutka geothermal area, Kamchatka, Russian Far East.

Khodutka geothermal area is located near Khodutka and Priemysh volcanoes and is one of the largest geothermal areas of the Kamchatka Peninsula. Vakin (2003) described geological, geochemical and geothermic conditions of this geothermal area in detail. The main thermal water sources have temperatures up to 87°C and a discharge of approximately 150 l×sec. -1 are flows out into the warm lake with dimensions of ca. 250 m length and 80 m width. This warm river is ca. 20 m in width beginning from the lake and flows to the Bolshaya Khodutka River basin. Two local endemic Radix species were described from this geothermal area, especially Lymnaea ( Radix ) hadutkae Kruglov & Starobogatov, 1989 and L. ( R. ) thermokamtschatica Kruglov & Starobogatov, 1989 (Kruglov & Starobogatov 1989, 1993; Kruglov 2005). These species were separated using proportions of shell and reproductive system (Kruglov & Starobogatov 1989, 1993; Starobogatov et al. 2004). According to the diagnosis, L. ( R. ) hadutkae differs in the ear-shape shell, a form of the provaginal duct with cylindrical distal part and conical proximal part, and larger value of the index of the copulatory apparatus (ICA: proportion of the preputium to phallotheca is 1.27) from other species within the section Thermoradix Kruglov & Starobogatov, 1989. The last whorl is large, 0.86–0.89 of the shell height; an excess of the last whorl over upper margin of the aperture is 0.15–0.16 of the aperture height. L. ( R. ) thermokamtschatica has the cylindrical provaginal duct, relatively short bursa duct (1.5X longer than the bursa copulatrix diameter) and very long phallotheca (ICA is 0.77). The last whorl is large, 0.85–0.87 of the shell height; an excess of the last whorl over upper margin of the aperture is 0.2–0.25 of the aperture height. In accordance with an identification key (Starobogatov et al. 2004), the main diagnostic feature is an excess of the last whorl over the shell aperture, which has ≤0.78 and ≥0.80 of the penultimate whorl width in the first and second species, respectively. In the present paper, we revised these taxa using newly collected topotypes and additional Radix spp. specimens from other areas of the Russian Far East.

Radix dolgini: The integrative taxonomic approach supports the species status of a Siberian endemic snail (Mollusca, Gastropoda, Lymnaeidae).

The molecular techniques are the standard tool for the study of the taxonomic position and phylogenetic affinities of the lymnaeid genus Radix Montfort, 1810, and the majority of the European representatives of this taxon have been studied in this respect. However, a plethora of nominal species of Radix described from Northern Asia (Siberia and the Russian Far East) are still characterized only morphologically, raising some doubts concerning their validity. In this paper, we present the triple (morphological, molecular, and zoogeographical) evidence that there is at least one endemic species of Radix, Radix dolgini (Gundrizer and Starobogatov, 1979), widely distributed in Siberia and Western Mongolia. Phylogenetically, it is a sister species to the European R. labiata (Rossmaessler, 1835) [=R. peregra auct.], and their common ancestor most probably lived in the Pliocene, nearly 3.25Myr ago. Our results assume the existence of an extended dispersal barrier for freshwater hydrobionts between Europe and Siberia in the Late Pliocene that may be important for biogeographical explanations. Three other nominal Siberian species of Radix: R. kurejkae (Gundrizer and Starobogatov, 1979), R. gundrizeri (Kruglov and Starobogatov, 1983), and R. ulaganica (Kruglov and Starobogatov, 1983) proved to be the junior synonyms of R. dolgini.

An integrative approach underscores the taxonomic status of Lamellidens exolescens, a freshwater mussel from the Oriental tropics (Bivalvia: Unionidae)

The Oriental Region harbours the second richest fauna of freshwater bivalves in the world, including many endangered endemic taxa. However, the Oriental fauna of the Unionidae have been very poorly studied using an integrative taxonomic approach, which may provide reasonable revisions of complicated (cryptic) taxa based on morphological, molecular, biogeographic and ecological evidence. Here, we present the first example of an integrative taxonomic revision concerning the status of Unio exolescens Gould (1843), a nominal mussel taxon that was accepted as a valid species within the genus Trapezoideus Simpson (1900). Currently, Trapezoideus exolescens is considered the type of the genus as far as the originally designated type species, U. foliaceus Gould (1843), was considered to be a synonym of T. exolescens. Using nucleotide sequences obtained from mitochondrial (COI and 16S rRNA) and nuclear (28S rDNA) genes, we found that the topotypes of Unio exolescens Gould (1843) cluster together with representatives of another mussel genus, Lamellidens Simpson (1900). Based on these results and on morphological data, we transfer Unio exolescens Gould (1843) from Trapezoideus to Lamellidens and propose Lamellidens exolescens (Gould, 1843) comb. nov. In addition, we revisited the status of Unio foliaceus Gould (1843) as a valid species and the type of the genus Trapezoideus based on the morphological study of the type specimen, although a question concerning the true position of this taxon is still open because its molecular sequences are not available. Our findings highlight that an integrative taxonomic approach is an important tool, particularly when dealing with such species-rich Unionidae fauna as those of the Oriental Realm.

Leptocneria vinarskii sp. nov. (Lepidoptera: Erebidae: Lymantriinae), an overlooked Wallacean lineage of the Australian genus

The tussock moth genus Leptocneria Butler, 1886 (Lepidoptera: Erebidae: Lymantriinae) has been considered an entirely Australian taxon that includes two species: L. reducta (Walker, 1855) and L. binotata Butler, 1886. However, we discovered a divergent lineage of Leptocneria inhabiting Flores Island, Lesser Sundas, Indonesia. Here, we describe this lineage as the third species of the genus, L. vinarskii Bolotov, Kondakov et Spitsyn sp. nov. The new species is sister to L. reducta but differs from it by dark gray marking patterns of the forewing that lack orange or dark yellow marks. The mean COI genetic distance between L. vinarskii sp. nov. and L. reducta sensu lato is 2.9%. Our findings confirm that the Wallacean region was a faunal exchange area between Sundaland and Sahul during the Pleistocene but highlight that the vicariance events may have played a crucial role in origin of the endemic faunas on the islands of East Nusa Tenggara. Additionally, we show that both Australian species most likely represent cryptic species complexes, which are in need of further taxonomic revision.

Ladislavella tumrokensis: The first molecular evidence of a Nearctic clade of lymnaeid snails inhabiting Eurasia

In this study, we provide the first molecular evidence for a possible connection between freshwater mollusc faunas across the Bering Strait via the Beringian Land Bridge using data inferred from gastropods of the family Lymnaeidae. The gastropods collected from geothermal springs in the Tumrok Mountains, West Kamchatka, Russia, share the nuclear internal transcribed spacer 2 (ITS2) and the cytochrome oxidase subunit I gene (COI) haplotypes, thus being as sister to those recorded for lymnaeid snails in the Stagnicola elodes group from Canada and the USA. Two lymnaeid species, Lymnaea (Orientogalba) tumrokensis Kruglov and Starobogatov, 1985 and Lymnaea (Polyrhytis) kurenkovi Kruglov and Starobogatov, 1989, were described from the Tumrok geothermal locality, but actually they are morphological variations of a single taxon of subspecies rank re-classified here as Ladislavella catascopium tumrokensis. This subspecies is the first discovered representative in the genus, which formed a dwarf race in a geothermal habitat. Our findings highlight the possible exchange between freshwater faunas in Beringia during the Pleistocene and an important role of geothermal ecosystems as possible cryptic refugia for freshwater hydrobionts.