A molecular contribution to the controversial taxonomical status of some freshwater snails (Caenogastropoda: Rissooidea, Cochliopidae) from the Central Andes desert to Patagonia
Abstract:ABSTRACT. For over 40 years malacologists have been discussing the taxonomical status of Heleobia species, an enigmatic genus from Cochliopidae family (Caenogastropoda: Rissooidea). As with other rissooidean families, the considerable character convergence and the paucity of anatomical synapomorphies has proved to be a problem in resolving cochliopid phylogenetic relations and establishing the validity of several nominal cochliopid species. Here we present a molecular contribution to solve the taxonomical stat… Show more
“…In Chile, the presence of the mudsnail was first reported in 2014 and later in 2016 but the species was introduced earlier since it was confused with native species of the genus Heleobia in 2011 18,25,26 . Accurate identification of freshwater snails in the Southern Cone of South America becomes even more difficult considering that native species of Potamolithus have been confused with Heleobia 18,22,36–38 , for example “ Heleobia ” hatcheri (Pilsbry, 1911) and “ Heleobia ” santiagensis .…”
Species delimitation in minute freshwater snails is often difficult to perform using solely shell morphology. The problem intensifies when invasive species spread within the distribution range of morphologically similar native species. In Chile, the Truncatelloidean snails are represented by the native genera
Heleobia
and
Potamolithu
s plus the invasive mudsnail
Potamopyrgus antipodarum
, which can easily be confused. Using an integrative approach, we performed molecular phylogenetic analysis and studied reproductive and morphological features to identify superficially similar forms inhabiting the central area of the country. Truncatelloidean snails were identified in 40 of 51 localities sampled, 10 containing
Potamopyrgus antipodarum
, 23
Heleobia
and 7
Potamolithus
. Based on these results and previously published data, the known distribution of the mudsnail in Chile encompasses 6 hydrological basins, including 18 freshwater ecosystems. The finding of the mudsnails in several type localities of native species/subspecies of “
Heleobia
” that were not find
in situ
suggests species replacement or significant extinction of native fauna, a hypothesis supported by the restudy of type material that shows that endemic forms belong to the genus
Potamolithu
s. This study shows the usefulness of integrative taxonomy not only resolving complex taxa with cryptic morphology but also measuring the extent of an ongoing invasion.
“…In Chile, the presence of the mudsnail was first reported in 2014 and later in 2016 but the species was introduced earlier since it was confused with native species of the genus Heleobia in 2011 18,25,26 . Accurate identification of freshwater snails in the Southern Cone of South America becomes even more difficult considering that native species of Potamolithus have been confused with Heleobia 18,22,36–38 , for example “ Heleobia ” hatcheri (Pilsbry, 1911) and “ Heleobia ” santiagensis .…”
Species delimitation in minute freshwater snails is often difficult to perform using solely shell morphology. The problem intensifies when invasive species spread within the distribution range of morphologically similar native species. In Chile, the Truncatelloidean snails are represented by the native genera
Heleobia
and
Potamolithu
s plus the invasive mudsnail
Potamopyrgus antipodarum
, which can easily be confused. Using an integrative approach, we performed molecular phylogenetic analysis and studied reproductive and morphological features to identify superficially similar forms inhabiting the central area of the country. Truncatelloidean snails were identified in 40 of 51 localities sampled, 10 containing
Potamopyrgus antipodarum
, 23
Heleobia
and 7
Potamolithus
. Based on these results and previously published data, the known distribution of the mudsnail in Chile encompasses 6 hydrological basins, including 18 freshwater ecosystems. The finding of the mudsnails in several type localities of native species/subspecies of “
Heleobia
” that were not find
in situ
suggests species replacement or significant extinction of native fauna, a hypothesis supported by the restudy of type material that shows that endemic forms belong to the genus
Potamolithu
s. This study shows the usefulness of integrative taxonomy not only resolving complex taxa with cryptic morphology but also measuring the extent of an ongoing invasion.
“…and 'Heleobia' hatcheri), already mentioned by Koch et al (2015). 'Heleobia' hatcheri is a parthenogenetic species and has similarities in radular morphology (two or three pairs of basal cusps in the central tooth) as in species of Potamolithus and which are absent in typical species of Heleobia (Cochliopidae) in Argentina (Cazzaniga 2011;Koch et al 2015). 'Heleobia' sp.…”
Section: Discussionmentioning
confidence: 99%
“…Phylogenetic analyses confirm that the South American taxa included are members of the Tateidae, namely the species of Potamolithus and two species attributed to the cochliopid genus Heleobia Stimpson, 1865 ('Heleobia' sp. and 'Heleobia' hatcheri), already mentioned by Koch et al (2015). 'Heleobia' hatcheri is a parthenogenetic species and has similarities in radular morphology (two or three pairs of basal cusps in the central tooth) as in species of Potamolithus and which are absent in typical species of Heleobia (Cochliopidae) in Argentina (Cazzaniga 2011;Koch et al 2015).…”
Section: Discussionmentioning
confidence: 99%
“…comm., 2016). The Cochliopidae family is a well-defined clade being quite distinct from Tateidae (Wilke et al 2013;Koch et al 2015). Reproductive characters (morphology of the penis, prostate gland, as well as female characters) are considered of importance in defining tateid genera, but due to the small size of the samples, and because the specimens were not relaxed prior to fixation, it was not possible to make a more detailed anatomical study of the reproductive system.…”
The genus Potamolithus (Gastropoda: Tateidae) is endemic to South America where it is distributed mainly in the Ribeira, Itajaí-açú and Jacuhy Rivers in southern Brazil and the Uruguay River, part of the Paraná and Río de la Plata drainage systems. An exception to the pattern of distribution is Potamolithus valchetensis Miquel, 1998, which is endemic to the Valcheta Stream, Somuncurá Plateau, Patagonia, Argentina. Here we provide a review of Potamolithus from this plateau based on new samples and review of material deposited in collections. A new species, Potamolithus elenae, is named. The shell, head-foot, penis, pallial organs and radula are described. Differences between the new species and P. valchetensis include details in the shell, radula, body pigmentation and penis. A phylogeny using mitochondrial gene cytochrome c oxidase subunit I is provided which shows that Potamolithus is related to species in New Caledonia (Australasia), suggesting that the Tateidae has a Gondwanan distribution.
“…De las 22 especies presentes en la Argentina, sólo cinco poseen descripciones anatómicas (completas o parciales) que incluyen órganos paleales, rádula, sistema reproductor y caracteres externos de las partes blandas (pigmentación cefalopedal y peneana): P. agapetus Pilsbry, 1911, P. buschii (Frauenfeld, 1865), P. lapidum (d 'Orbigny, 1835), P. rushii Pilsbry, 1896 y P. valchetensis Miquel, 1998 (Pilsbry, 1911;López Armengol, 1985Miquel, 1998). Desde el punto de vista genético solo se posee información para tres especies: P. ribeirensis (genes ribosomales 16S y 18S, y el gen mitocondrial citocromo c oxidasa subunidad I -COI-, Wilke et al, 2013); P. agapetus y P. buschii (COI, Koch et al, 2015).…”
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