Endemic Lacustrine Research Articles

Lake Poso's shrimp fauna revisited: the description of five new species of the genus Caridina (Crustacea, Decapoda, Atyidae) more than doubles the number of endemic lacustrine species.

Lake Poso, an ancient lake system on the Indonesian island Sulawesi, harbours an endemic species flock of six, four lacustrine and two riverine species of the freshwater shrimp genus Caridina. In this study, five new lacustrine species are described, bringing the total to eleven species altogether. The number of lacustrine species is more than doubled to nine species compared to the last taxonomic revision in 2009. One of them, Caridina mayamareenae Klotz, Wowor & von Rintelen, sp. nov., even represents the first case of an atyid shrimp associated with freshwater snails which is morphologically adapted to living in shells. An integrative approach was used by providing a combination of morphological, ecological, and molecular data. Based on standard morphological characters, distribution, substrate preferences, and colouration of living specimens in the field, five distinct undescribed species could be distinguished. To support our species-hypothesis based on the mitochondrial genes 16S and COI, a molecular phylogeny was used for all eleven species from Lake Poso. All species form a well-supported monophyletic group, but only four morphospecies consistently correspond to mtDNA clades – a possible reason could be introgressive hybridisation, incomplete lineage sorting, or not yet fixed species boundaries. These results are discussed further in the context of adaptive radiation, which turned out to be more diverse than previously described. Finally, yet importantly, subjecting all new species to similar threats and to the same IUCN category and criterion than the previously described species from the lake is recommended.

Peculiarities of Early Ontogenesis of Nose Char (N1-form), Endemic Lacustrine and Riverine Form of Salvelinus malma Complex (Salmonidae), of the Lake Kronotskoe (Eastern Kamchatka, Russia)

The growth, order of anlage, and features of transitive stages of skeletal elements (cranial bones and serial structures: teeth, gill rakers, fin rays, pterigyophores, vertebrae muscles, predorsalia, and scales) in were studied in pre-larvae, larvae, and fingerlings of the nose char (N1-form), endemic lakustrine-riverine form of the Dolly varden Salvelinus malma complex of the Lake Kronotskoe, reared in the laboratory at a constant temperature. A comparative analysis of the early ontogenesis of sympatric species of nose char and white char of the Lake Kronotskoe evidences on a high similarity in the growth rate and development of the two forms, differing by the body length of free embryos and the larvae coloration.

Special Traits in Early Ontogenesis of the Endemic Lacustrine Form of the Salvelinus malma Сomplex (Salmonidae), Small-Mouth Form, from Lake Kronotskoe (Eastern Kamchatka)

Growth, sequences of anlage, and special traits of transient states are investigated in skeletal elements (skull bones and serial structures—teeth, gill rakers, fin rays and pterygiophores, vertebral centra, predorsalia, scales) in prolarvae, larvae, and fry of endemic lacustrine form Dolly varden Salvelinus malma сomplex from Lake Kronotskoe in small-mouth char grown in a laboratory at constant temperature. A high individual variation of growth rate, osteogenesis, and head profile of small-month char larvae is observed demonstrating a recent, in relation to other endemic Kronotskoe Lake forms, formation of this deep-water lacustrine morphotype. Comparative analysis in early development of sympatric small-mouth and white char indicated the origin of the more warm-water, small-mouth char from the cold-water white char.

Structure of "species flocks" in fishes: Channels of the splanchnocranium divergence in endemic lacustrine benthivorous charrs (Salvelinus, Salmonidae, Teleostei) in Lake Kronotskoye, Kamchatka.

The structure of splanchnocranium bones has been studied in four endemic benthivorous charrs (the genus Salvelinus) from Lake Kronotskoe (Kamchatka). It has been found that, according to the whole set of characters of the splanchnocranium structure, the most expressed differences are observed between specialized forms, nosed and largemouth charrs, inhabiting different biotopes of the lake. Differences between small-mouth and white charrs are less pronounced, and the species are characterized by generalized features of the structure of jaws. It can be suggested that, in addition to diverse feeding preferences within a feeding niche, an extremely high diversity of charrs in Lake Kronotskoe is due to a complex geomorphological structure of the water system. Thus, the "species flock" comprising a complex set of diverse benthivorous morphotypes has been formed and exists in Lake Kronotskoe. Charrs from Lake Kronotskoe are a representative example of sympatric speciation by way of formation of new forms differing from each other in morphological, ecological, and trophic features.

Upper Miocene endemic lacustrine gastropod fauna of the Turiec Basin: addressing taxonomic, paleobiogeographic and stratigraphic issues

Abstract The present work displays the first detailed taxonomic study on the freshwater gastropod fauna of the Upper Miocene Lake Turiec. Apart from several mentions of species and genus names in the literature, the mollusc fauna has been poorly studied up to now. Some of the cited genera implied peculiar paleobiogeographic relationships, urging a taxonomic investigation to either prove or revise such arising claims. Variable degrees of preservation, however, limited the possibility to identify all the fossils at species level. The fauna includes at least ten species, of which five turned out to be new to science. Four of those were sufficiently well preserved to be described as new species, namely Viviparus pipiki Neubauer & Harzhauser nov. sp., Melanopsis glaubrechti Neubauer & Harzhauser nov. sp., Tournouerina turiecensis Neubauer & Harzhauser nov. sp., and Radix kovaci Neubauer & Harzhauser nov. sp. Additionally, the new genus Popovicia Neubauer & Harzhauser nov. gen. is introduced for the primary homonym Metohia Popović, 1964 non Absolon, 1927. Most importantly, this taxonomic study revises many of the names cited in the literature and proves most of the alleged paleobiogeographic relationships wrong. The only biogeographic and stratigraphic surprise is the record of Popovicia cf. compressa, a species described from lower Pliocene deposits of the Metohia Basin in Kosovo. The majority of the fauna, however, has only been documented for the Turiec Basin, once more confirming the high degree of its endemicity. The faunal relationships indicate a latest Middle to early Late Pannonian (Middle to Late Tortonian) age, which is in agreement with available age models.

Lacustrine mollusc radiations in the Lake Malawi Basin: experiments in a natural laboratory for evolution

Abstract. In terminal Pliocene–early Pleistocene times, part of the Malawi Basin was occupied by paleo-lake Chiwondo. Molluscan biostratigraphy situates this freshwater lake either in the East African wet phase between 2.7–2.4 Ma or that of 2.0–1.8 Ma. In-lake divergent evolution remained restricted to a few molluscan taxa and was very modest. The lacustrine Chiwondo fauna went extinct at the beginning of the Pleistocene. The modern Lake Malawi malacofauna is depauperate and descends from ubiquistic southeast African taxa and some Malawi basin endemics that invaded the present lake after the Late Pleistocene mega-droughts. The Pleistocene aridity crises caused dramatic changes, affecting the malacofauna of all East African lakes. All lacustrine endemic faunas that had evolved in the Pliocene rift lakes, such as paleo-lake Chiwondo, became extinct. In Lake Tanganyika, the freshwater ecosystem did not crash as in other lakes, but the environmental changes were sufficiently important to trigger a vast radiation. All African endemic lacustrine molluscan clades that are the result of in-lake divergence are hence geologically young, including the vast Lavigeria clade in Lake Tanganyika (ca. 43 species).

Evolutionary relationships and biogeography of Biomphalaria (Gastropoda: Planorbidae) with implications regarding its role as host of the human bloodfluke, Schistosoma mansoni.

The wide geographic distribution of Schistosoma mansoni, a digenetic trematode and parasite of humans, is determined by the occurrence of its intermediate hosts, freshwater snails of the genus Biomphalaria (Preston 1910). We present phylogenetic analyses of 23 species of Biomphalaria, 16 Neotropical and seven African, including the most important schistosome hosts, using partial mitochondrial ribosomal 16S and complete nuclear ribosomal ITS1 and ITS2 nucleotide sequences. A dramatically better resolution was obtained by combining the data sets as opposed to analyzing each separately, indicating that there is additive congruent signal in each data set. Neotropical species are basal, and all African species are derived, suggesting an American origin for the genus. We confirm that a proto-Biomphalaria glabrata gave rise to all African species through a trans-Atlantic colonization of Africa. In addition, genetic distances among African species are smaller compared with those among Neotropical species, indicating a more recent origin. There are two species-rich clades, one African with B. glabrata as its base, and the other Neotropical. Within the African clade, a wide-ranging tropical savannah species, B. pfeifferi, and a Nilotic species complex, have both colonized Rift Valley lakes and produced endemic lacustrine forms. Within the Neotropical clade, two newly acquired natural hosts for S. mansoni (B. straminea and B. tenagophila) are not the closest relatives of each other, suggesting two separate acquisition events. Basal to these two species-rich clades are several Neotropical lineages with large genetic distances between them, indicating multiple lineages within the genus. Interesting patterns occur regarding schistosome susceptibility: (1) the most susceptible hosts belong to a single clade, comprising B. glabrata and the African species, (2) several susceptible Neotropical species are sister groups to apparently refractory species, and (3) some basal lineages are susceptible. These patterns suggest the existence of both inherent susceptibility and resistance, but also underscore the ability of S. mansoni to adapt to and acquire previously unsusceptible species as hosts. Biomphalaria schrammi appears to be distantly related to other Biomphalaria as well as to Helisoma, and may represent a separate or intermediate lineage.

Lacustrine fishes and the trophic efficiency of lakes: Prelude to the problem

The regression between the yield of fish (Y) and the mean annual temperature of air (TEMP) both for geologically old lakes with endemic lacustrine fish fauna and those of the relatively recent origin inhabited by riverine species is the same. In contrast, the dependence of Y on the morphoedaphic index (MEI) in lakes with endemic lacustrine fish species differs strongly from that for lakes with riverine fish communities giving the predicted Y about three times higher for the former in comparison with that of the latter. The higher trophic efficiency of ancient lakes with endemic fish faunas is a consequence of the presence of pelagic species. Contrary to this, recent lakes are inhabited with riverine species dwelling along the shores leaving pelagic niche unoccupied.