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Lateral view of head of: a, Squalius janae , paratype, PZC 453, 157.6 mm SL; b, Squalius squalus, PZC 287, 155.4 mm SL, Italy: Po.
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Squalius janae, sp. nov., is described from the upper Dragonja River system in the Adriatic Sea basin in Slovenia. The new species is distinguished from other members of the S. cephalus species group by a combination of the following characters: a long head, head length, 29−32% SL, always markedly exceeding body depth; a pointed conical snout; a sl...
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... The leuciscid genera exhibit a non-uniform distribution in this region, and chubs of the genus Squalius are the only ones inhabiting all four major Mediterranean peninsulas (Kottelat and Freyhof, 2007). Approximately 50 Squalius species are currently recognized (Kottelat and Freyhof, 2007;Turan et al., 2009;Bogutskaya and Zupančič, 2010;Zupančič et al., 2010;Ö zulug and Freyhof, 2011;Buj et al., 2020), representing two major phylogenetic clades (Sanjur et al., 2003;Perea et al., 2010). The phylogeny and phylogeography of Squalius have been studied intensively over the last three decades, and according to the molecular timing, the evolution of Squalius started in the early Miocene, and gradually still continues today (e.g., Imsiridou et al., 1998;Durand et al., 1999;Perea et al., 2010Perea et al., ,2016aPerea et al., ,2016bPerea et al., ,2021Buj et al., 2020). ...
Host-parasite coevolution is one of the fundamentals of evolutionary biology. Due to the intertwined evolutionary history of two interacting species and reciprocal coadaptation processes of hosts and parasites, we can expect that studying parasites will shed more light onto the evolutionary processes of their hosts. Monogenea (ectoparasitic Platyhelminthes) and their cyprinoid fish hosts represent one of the best models for studying host-parasite evolutionary relationships using a cophylogenetic approach. These parasites have developed remarkably high host specificity, where each host species often serves as a potential host for its own host-specific monogenean species. Here, the cophylogenetic relationships in the Dactylogyrus-Squalius system was investigated, as Squalius is one of several cyprinoid genera with puzzling phylogeography and inhabits all four major peri-Mediterranean peninsulas. Of 29 endemic Squalius species examined for the presence of Dactylogyrus parasites, a total of 13 Dactylogyrus species were collected from the gills of 20 Squalius species across a wide range of distribution. Phylogenetic reconstruction revealed a polyphyletic origin for Dactylogyrus species parasitizing congeneric Squalius, with four major clades being recognized. On the basis of the delimitation of host specificity, strict specialists parasitizing single host species, geographic specialists parasitizing congeners in a limited geographical region, and true generalists parasitizing congeners in various geographical regions were recognized in Dactylogyrus species parasitizing Squalius. The phylogenetic reconstruction of Squalius hosts revealed two major clades, the first encompassing only peri-Mediterranean species and the second including species from other Euro-Asian regions. Distance-based cophylogenetic methods did not reveal a statistically significant global cophylogenetic structure in the studied system; however, several host-parasite links among Iberian endemic species contributed significantly to the overall structure. The widest host range and associated genetic variability were recorded for D. folkmanovae, parasitizing nine Squalius species, and D. vistulae, parasitizing 13 Squalius species. Two different dispersion mechanisms and morphological adaptations to Squalius hosts were clearly reflected in the contrasting cophylogenetic patterns for these two species with different levels of host specificity. While host-parasite cospeciation plays an important role in diversification within D. folkmanovae, diversification within D. vistulae is driven mainly by host switching.
... Thus, the latter might have reduced dispersal abilities, and the genetic structure reflects hydrological conditions in the area before the beginning of karstification. A similar genetic pattern (albeit with reduced sampling) consistent with the Adriatic-Black Sea basin divide has been observed in chub (Squalius sp.; Bogutskaya & Zupančič, 2010) and Telestes (Ketmaier et al., 2004). In Phoxinus, there is possibly some interchange between the north-east and south-west LRS sampling sites, as haplotype sharing has been identified between 'border' sampling sites CERK, MALI, RAKO and IZIC + TOJN. ...
Karst landscapes are characterized by intermittent and sinking streams. The most common method used to study underground hydrological connections in karst is tracing tests. However, a more biologically oriented approach has been suggested: analysis of the genetic structure of aquatic organisms. Biological tracers can be sought among trogloxenes, i.e. surface species that occasionally enter caves and groundwater. One such example is the fish genus Phoxinus, which exhibits high genetic diversity and complex phylogeography in the Balkan Peninsula. In the northwestern Dinaric Karst, the complex hydrological network was digitalized in 2020. Contemporaneously, P. lumaireul populations in the Slovenian Dinaric Karst were intensively sampled and analyzed for fragments of two mitochondrial genes and one nuclear gene. The derived phylogeographic structure and data on hydrological connections were compared to evaluate support for three alternative scenarios: the genetic structure (1) is a consequence of the ongoing geneflow through underground connections, (2) reflects a previous hydrological network, or (3) is an outcome of anthropogenic translocations. The results suggest that the first two scenarios seem to have played a major role, while the third has not had profound effects on the genetic composition. Comparison between the genetic structure of Slovenian Dinaric Karst sampling sites and that of hydrologically isolated reference sampling sites, indicated a greater genetic connectivity in the former. Moreover, the range of Adriatic (1a) and Black Sea (1c) haplotypes does not correspond to the Adriatic–Black Sea basin divide but is shifted northwards.
... Leuciscus cephalus was also reported from Istrian rivers (Povž & Sket, 1990;Leiner et al., 1995). In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). ...
... In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). However, taxonomic conclusions of previous authors were challenged in light of the results and some taxonomic amendments were made. ...
... That study groups the chubs of the Adriatic basin into two phylogenetic groups within the genus Squalius, i.e. the Mediterranean group including S. illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and the group named 'S. cephalus' [concordant with Squalius cephalus auctorum of Bogutskaya & Zupančič (2010)] containing S. squalus (Bonaparte, 1837) and other non-Adriatic species. All the remaining studies of Squalius species in the Adriatic basin were based only on morphological traits. ...
Fish of the genus Squalius inhabit various freshwater habitats across Europe and Asia, with a particularly high diversity in the Mediterranean area, but the taxonomic status of many populations is still a matter of debate. This study aims to resolve the taxonomic uncertainties of chubs distributed in the Adriatic basin of Croatia and Bosnia and Herzegovina. Phylogenetic reconstruction based on the mitochondrial gene for cytochrome b and two nuclear genes, the recombination activating gene 1 and the rhodopsin gene, reveal high diversity of chubs in the investigated area. Two evolutionary independent groups are revealed: the first comprising the species Squalius illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and a second group corresponding with S. squalus. Genetic distinctiveness of species belonging to different groups is high due to their divergence that began in the Middle Miocene. In addition to allopatric speciation as the main force of divergence of Adriatic Squalius species, several instances of natural hybridizations were detected, contributing to the observed diversity. A comparison of phylogenetic scenarios using Bayesian factors corroborated the molecular basis for recognition of six Squalius species in the Adriatic basin, while Squalius janae is confirmed to be a junior synonym of S. squalus.
... Leuciscus cephalus was also reported from Istrian rivers (Povž & Sket, 1990;Leiner et al., 1995). In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). ...
... In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). However, taxonomic conclusions of previous authors were challenged in light of the results and some taxonomic amendments were made. ...
... That study groups the chubs of the Adriatic basin into two phylogenetic groups within the genus Squalius, i.e. the Mediterranean group including S. illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and the group named 'S. cephalus' [concordant with Squalius cephalus auctorum of Bogutskaya & Zupančič (2010)] containing S. squalus (Bonaparte, 1837) and other non-Adriatic species. All the remaining studies of Squalius species in the Adriatic basin were based only on morphological traits. ...
Fish of the genus Squalius inhabit various freshwater habitats across Europe and Asia, with a particularly high diversity in the Mediterranean area, but the taxonomic status of many populations is still a matter of debate. This study aims to resolve the taxonomic uncertainties of chubs distributed in the Adriatic basin of Croatia and Bosnia and Herzegovina. Phylogenetic reconstruction based on the mitochondrial gene for cytochrome b and two nuclear genes, the recombination activating gene 1 and the rhodopsin gene, reveal high diversity of chubs in the investigated area. Two evolutionary independent groups are revealed: the first comprising the species Squalius illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and a second group corresponding with S. squalus. Genetic distinctiveness of species belonging to different groups is high due to their divergence that began in the Middle Miocene. In addition to allopatric speciation as the main force of divergence of Adriatic Squalius species, several instances of natural hybridizations were detected, contributing to the observed diversity. A comparison of phylogenetic scenarios using Bayesian factors corroborated the molecular basis for recognition of six Squalius species in the Adriatic basin, while Squalius janae is confirmed to be a junior synonym of S. squalus.
... The genus Squalius Banaparte is widely distributed throughout Europe and the Middle East, and shows an especially high diversity in the Mediterranean basin. Approximately 50 species are currently recognised in the genus (Kottelat and Freyhof 2007;Turan et al. 2009;Bogutskaya and Zupančič 2010;Zupančič et al. 2010;Özuluğ and Freyhof 2011), and sixteen species are known to occur in Europe (Özuluğ and Freyhof 2011). ...
Squalius microlepis was examined from recent and historical collections within the known range of the species with special emphasis on intraspecific variability and variations, and compared to its closest relative species S. tenellus (in total, 193 specimens; 33 absolute and 52 proportional measurements and ratios, and 12 counts including vertebrae). Squalius tenellus was perfectly differentiated in all statistical analyses and can be diagnosed by 76–95 (vs. 64–80) scales in lateral series, 68–83 (vs. 58–77) lateral-line scales, (17)18–20 (vs. 13–16(17)) scales above lateral line, and (7)8–10 (vs. 4–7) scales below lateral line. Squalius microlepis was morphologically heterogeneous, with two phenotypes readily distinguishable (phenotype 1 corresponding to S. microlepis s. str. as defined by its lectotype) by a combination of many characters; those contributing most to the discrimination were number of gill rakers, length of lower jaw (% interorbital width), and head length (% SL). Only phenotype 1 was found in the Ričina-Prološko Blato-Vrljika karst system; most of the specimens from the lower Matica and the Tihaljina-Trebižat karst system were identified as phenotype 2; the sample from karstic poljes near Vrgorac contained both phenotype 1 and 2, and individuals of intermediate morphology. As very limited molecular data exist on the two phenotypes of S. microlepis , we refrain from any taxonomic conclusions until new molecular approaches (and new markers) are used. We also report on a dramatic reduction of the area of distribution and abundance of S. microlepis in recent years.
... Leuciscus cephalus was also reported from Istrian rivers (Povž & Sket, 1990;Leiner et al., 1995). In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). ...
... In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). However, taxonomic conclusions of previous authors were challenged in light of the results and some taxonomic amendments were made. ...
... That study groups the chubs of the Adriatic basin into two phylogenetic groups within the genus Squalius, i.e. the Mediterranean group including S. illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and the group named 'S. cephalus' [concordant with Squalius cephalus auctorum of Bogutskaya & Zupančič (2010)] containing S. squalus (Bonaparte, 1837) and other non-Adriatic species. All the remaining studies of Squalius species in the Adriatic basin were based only on morphological traits. ...
Fish of the genus Squalius inhabit various freshwater habitats across Europe and Asia, with a particularly high
diversity in the Mediterranean area, but the taxonomic status of many populations is still a matter of debate. This
study aims to resolve the taxonomic uncertainties of chubs distributed in the Adriatic basin of Croatia and Bosnia and
Herzegovina. Phylogenetic reconstruction based on the mitochondrial gene for cytochrome b and two nuclear genes,
the recombination activating gene 1 and the rhodopsin gene, reveal high diversity of chubs in the investigated area.
Two evolutionary independent groups are revealed: the first comprising the species Squalius illyricus, S. microlepis,
S. svallize, S. tenellus and S. zrmanjae, and a second group corresponding with S. squalus. Genetic distinctiveness of
species belonging to different groups is high due to their divergence that began in the Middle Miocene. In addition
to allopatric speciation as the main force of divergence of Adriatic Squalius species, several instances of natural
hybridizations were detected, contributing to the observed diversity. A comparison of phylogenetic scenarios using
Bayesian factors corroborated the molecular basis for recognition of six Squalius species in the Adriatic basin, while
Squalius janae is confirmed to be a junior synonym of S. squalus.
... Second, asymmetric speciation, which took place in the Danube basin but not in the Adriatic basin, opens a new perspective on the protection of freshwater fauna in the region. In Slovenia, the Adriatic drainage basin represents 19% of the total surface, but harbours about one half of all fish species on the Slovenian Red List, including several narrowly endemic species 57,58 . While these data imply that the Adriatic drainage deserves higher conservation attention than Danube drainage basin, our results suggest that the opposite may be true for subterranean and cryptic biodiversity. ...
Molecular taxonomy often uncovers cryptic species, reminding us that taxonomic incompleteness is even more severe than previous thought. The importance of cryptic species for conservation is poorly understood. Although some cryptic species may be seriously threatened or otherwise important, they are rarely included in conservation programs as most of them remain undescribed. We analysed the importance of cryptic species in conservation by scrutinizing the South European cryptic complex of the subterranean amphipod Niphargus stygius sensu lato. Using uni- and multilocus delineation methods we show that it consists of 15 parapatric and sympatric species, which we describe using molecular diagnoses. The new species are not mere “taxonomic inflation” as they originate from several distinct branches within the genus and coexist with no evidence of lineage sharing. They are as evolutionarily distinct as average nominal species of the same genus. Ignoring these cryptic species will underestimate the number of subterranean endemics in Slovenia by 12 and in Croatia by four species, although alpha diversity of single caves remains unchanged. The new taxonomy renders national Red Lists largely obsolete, as they list mostly large-ranged species but omit critically endangered single-site endemics. Formal naming of cryptic species is critical for them to be included in conservation policies and faunal listings.
... Leuciscus cephalus was also reported from Istrian rivers (Povž & Sket, 1990;Leiner et al., 1995). In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). ...
... In 2010, Bogutskaya & Zupančič identified chubs from the Dragonja River as S. janae Bogutskaya & Zupančič, 2010. Taxonomic designation employed in this investigation was based on Kottelat & Freyhof, 2007, with the addition of the newly described S. janae (Bogutskaya & Zupančič, 2010). However, taxonomic conclusions of previous authors were challenged in light of the results and some taxonomic amendments were made. ...
... That study groups the chubs of the Adriatic basin into two phylogenetic groups within the genus Squalius, i.e. the Mediterranean group including S. illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and the group named 'S. cephalus' [concordant with Squalius cephalus auctorum of Bogutskaya & Zupančič (2010)] containing S. squalus (Bonaparte, 1837) and other non-Adriatic species. All the remaining studies of Squalius species in the Adriatic basin were based only on morphological traits. ...
The genus Squalius comprises more than 40 species inhabiting various freshwater habitats. They are distributed in Europe and Asia, with particularly high diversity recorded in the Mediterranean area. The taxonomic status of many populations is still matter of debate. With this investigation we aimed to help in resolving taxonomic uncertainties of the chubs distributed in the Adriatic basin in Croatia and Bosnia and Herzegovina. Phylogenetic reconstruction based on mitochondrial gene for cytochrome b revealed high diversity of chubs in the investigated area. Two evolutionary independent lineages are revealed: the first one comprising species Sq. svallize, Sq. tenellus, Sq. illyricus and Sq. zrmanjae; whereas the second lineage corresponds with Sq. squalus. High intraspecific structuring of Sq. squalus was detected, implying necessity of taxonomic revision of that species. Based on the obtained results, most important aspects of the evolutionary history of the genus Squalius in the Adriatic basin will be discussed and evolutionary significant units identified.
... Chubs, small to large fishes of the genus Squalius (Family Cyprinidae), are widely distributed throughout Europe; about 40 species are currently recognized in this genus, showing a particularly high diversity in the Mediterranean area, where some species are extremely localised and endemic to single basins (Kottelat and Freyhof, 2007;Bogutskaya and Zupancic, 2010). As underlined by Kottelat and Freyhof (2007) "the systematics of Squalius is still not resolved. ...
The systematic is still unresolved for the genus Squalius (Cyprinidae, Leuciscinae), a rich group of small to large fishes widely distributed throughout Europe. The distinction of one of the Italian narrowly endemic species, Squalius albus ( Bonaparte, 1838), described for the area surrounding lake Trasimeno, from the more common and widespread Squalius squalus (Bonaparte, 1837) is doubtful. The application of integrative taxonomy, with DNA taxonomy and quantitative morphometric, using both living and preserved individuals collected from lake Trasimeno before Squalius sp. restocking, allowed us to explicitly test for the identity of the two species in the complex. COI barcoding data, used for phylogenetic reconstructions, underlined that two clades may exist in the complex; nevertheless, DNA taxonomy (ABGD and GMYC) and morphometrics show no statistical support for their identity as separate species. Moreover, during our survey of the genetic diversity of the Italian Squalius, we provided further support for the species status of Squalius lucumonis, and found evidence of the occurrence in Southern Italy of another chub species, Squalius vardarensis (Karaman, 1928), previously known only from the Southern part of the Balkan Peninsula.
... 3). Th e Pazinčica and Boljunšćica specimens and the historical sample from Čepić Lake examined in this study are thus identifi ed as S. janae based on the diagnostic characters of the latter (Bogutskaya and Zupančič 2010), seeTable 1 and Figs 2–5. Comparative remarks. ...
... occurs in the Krka River drainage. Th e data presented above on the distribution of Squalius chubs in the northern Adriatic Basin support the assumption by Bogutskaya and Zupančič (2010) that the range of S. janae encompassing most of Istra Peninsula, except for its north-western section, is determined by the geology of two fl ysch basins forming the base of the Istra Peninsula. Th ese basins are the Trieste Flysch Basin and the Pazin Flysch Basin bordered by limestone areas of the Buje and West Istria anticlines in the west and the Čičarja and Učka mountain ranges, which belong to the Dinaric Alps, in the east (Fišer et al. 2006; Babić et al. 2007). ...
A chub of previously ambiguous identity from the Boljunscica and Pazincica rivers (south-eastern Istra Peninsula) was studied and compared with geographically close Squalius squalus, Squalius zrmanja, and Squalius janae recently described from the Dragonja River drainage in the Adriatic Sea basin in Slovenia. It was shown that the chub from the south-eastern Istra Peninsula differs from all know species of Squalius but one: Squalius janae. Three samples examined from Boljunscica and Pazincica rivers and Squalius janae from its type locality, Dragonja River, show the following characters typical for the latter species: a long head (the head length 27–32% SL); a pointed conical snout with a clearly projecting upper jaw; a long straight mouth cleft, the lower jaw length (39–45% HL) exceeding the caudal peduncle depth; a large eye; commonly 9½ branched anal-fin rays; commonly 44 total vertebrae (24+20 or 25+19); bright silvery colouration, scales easily lost; iris, pectoral, pelvic and anal fin pigmentation with yellow shades. The data on the distribution of Squalius chubs in the northern Adriatic basin support the assumption that the range of Squalius janae is determined by the geology of the Trieste Flysch Basin and the Pazin Flysch Basin forming the base of the Istra Peninsula. The distribution pattern of this species does not support a simple model of fish dispersal and a complete connectivity within the whole Palaeo-Po historical drainage. Indeed, it indicates a disrupted surface palaeohydrography that was heavily fragmented by karstification in the whole Dinaric area.
