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Molecular and morphological differentiation between two Miocene-divergent lineages of Amazonian shrimps, with the description of a new species (Decapoda, Palaemonidae, Palaemon).

Carvalho FL, Magalhães C, Mantelatto FL - Zookeys (2014)

Bottom Line: The divergence time between these lineages was estimated as approximately 10 million years ago.In addition, a new species, Palaemonyuna sp. n., closely related to Palaemonivonicus, is described.Our findings indicate that these species can be differentiated using the projection of the anterolateral margin and anterolateral spine of the first antennular segment, shape of the rostrum, and relative size of the appendix masculina.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Bioecology and Crustacean Systematics (LBSC), Postgraduate Program in Comparative Biology. Department of Biology, Faculty of Philosophy, Sciences and Letters at Ribeirão Preto (FFCLRP), University of São Paulo (USP), São Paulo, Brazil.

ABSTRACT
Palaemoncarteri (Gordon, 1935) and Palaemonivonicus (Holthuis, 1950) are morphologically similar species of South American freshwater shrimps. Past studies have questioned the taxonomic status of both species, which are supposed to have partially sympatric geographic distributions in the Amazon basin. We analyzed a 550 bp fragment of the mitochondrial 16S rRNA gene from these Amazonian Palaemon species as well as from 11 palaemonids as the outgroup. Additionally, we checked diagnostic characters of the genus and family as well as other morphological characters that have been little explored before. Palaemoncarteri and Palaemonivonicus are allocated in two sister lineages, with wide genetic divergence and little morphological differentiation. The divergence time between these lineages was estimated as approximately 10 million years ago. Both molecular and morphological data support the taxonomic validity of both Palaemoncarteri and Palaemonivonicus, refuting the hypothesis of synonymy. In addition, a new species, Palaemonyuna sp. n., closely related to Palaemonivonicus, is described. Our findings indicate that these species can be differentiated using the projection of the anterolateral margin and anterolateral spine of the first antennular segment, shape of the rostrum, and relative size of the appendix masculina.

No MeSH data available.


Putative current distribution of the “carteri” and “ivonicus/yuna” lineages. [Pebas system during the Late Miocene (~11.8 to 10 Ma) according to Lundberg et al. 1998.]
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Figure 11: Putative current distribution of the “carteri” and “ivonicus/yuna” lineages. [Pebas system during the Late Miocene (~11.8 to 10 Ma) according to Lundberg et al. 1998.]

Mentions: The wide genetic dissimilarity between the “carteri” and “ivonicus/yuna” lineages shows that they have no recent divergence, as one could expect based only on their morphological similarity. The approximately 10 million years of divergence estimated for these lineages, based on the 16S rRNA gene, may be associated with marine incursion as well as colonization of different environments in western Amazonia during the Middle Miocene (~16 to 11.6 Ma) and Late Miocene (~11.6 to 5.3 Ma) (Fig. 10). From the Early Miocene until the early Late Miocene (~23 to 9 Ma), the western Amazonia region was mostly submerged and transformed into a continually shifting mosaic of lakes, wetlands and river belts (Wesselingh 2006), which are similar to the environments where specimens of the “ivonicus/yuna” lineage are currently found. This continually shifting mosaic, the Pebas system, had contact with the Caribbean Sea and underwent several marine incursions during the Middle and Late Miocene (Hoorn 1993, Wesselingh 2006). Particularly in the period between 11.8 and 10 Ma, close to our estimate for the time of divergence between the “carteri” and “ivonicus/yuna” lineages, there is evidence of an extensive marine transgression into the low-lying basins of South America (Lundberg et al. 1998). These marine incursions, which established brackish-water conditions in the late Middle Miocene and early Late Miocene (Hoorn 1993, Lundberg et al. 1998), might have isolated freshwater lineages of the Pebas system from others distributed in northern South America outside this wetland system, where the “carteri” lineage is currently found (Fig. 11). Similar biogeographical patterns and speciation events associated with the Pebas system and marine incursions in the Middle and Late Miocene have been reported for several groups in the Amazon region (Hoorn 1993, Lovejoy et al. 1998, 2006, Lundberg et al. 1998, Wesselingh 2006, Santos et al. 2009, Cooke et al. 2012a,b). Therefore, the proposed current parapatric distribution of the “carteri” and “ivonicus/yuna” lineages probably developed after the establishment of the modern west-to-east course of the Amazon River, which may have initiated approximately 8 Ma (Lundberg et al. 1998).


Molecular and morphological differentiation between two Miocene-divergent lineages of Amazonian shrimps, with the description of a new species (Decapoda, Palaemonidae, Palaemon).

Carvalho FL, Magalhães C, Mantelatto FL - Zookeys (2014)

Putative current distribution of the “carteri” and “ivonicus/yuna” lineages. [Pebas system during the Late Miocene (~11.8 to 10 Ma) according to Lundberg et al. 1998.]
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4283366&req=5

Figure 11: Putative current distribution of the “carteri” and “ivonicus/yuna” lineages. [Pebas system during the Late Miocene (~11.8 to 10 Ma) according to Lundberg et al. 1998.]
Mentions: The wide genetic dissimilarity between the “carteri” and “ivonicus/yuna” lineages shows that they have no recent divergence, as one could expect based only on their morphological similarity. The approximately 10 million years of divergence estimated for these lineages, based on the 16S rRNA gene, may be associated with marine incursion as well as colonization of different environments in western Amazonia during the Middle Miocene (~16 to 11.6 Ma) and Late Miocene (~11.6 to 5.3 Ma) (Fig. 10). From the Early Miocene until the early Late Miocene (~23 to 9 Ma), the western Amazonia region was mostly submerged and transformed into a continually shifting mosaic of lakes, wetlands and river belts (Wesselingh 2006), which are similar to the environments where specimens of the “ivonicus/yuna” lineage are currently found. This continually shifting mosaic, the Pebas system, had contact with the Caribbean Sea and underwent several marine incursions during the Middle and Late Miocene (Hoorn 1993, Wesselingh 2006). Particularly in the period between 11.8 and 10 Ma, close to our estimate for the time of divergence between the “carteri” and “ivonicus/yuna” lineages, there is evidence of an extensive marine transgression into the low-lying basins of South America (Lundberg et al. 1998). These marine incursions, which established brackish-water conditions in the late Middle Miocene and early Late Miocene (Hoorn 1993, Lundberg et al. 1998), might have isolated freshwater lineages of the Pebas system from others distributed in northern South America outside this wetland system, where the “carteri” lineage is currently found (Fig. 11). Similar biogeographical patterns and speciation events associated with the Pebas system and marine incursions in the Middle and Late Miocene have been reported for several groups in the Amazon region (Hoorn 1993, Lovejoy et al. 1998, 2006, Lundberg et al. 1998, Wesselingh 2006, Santos et al. 2009, Cooke et al. 2012a,b). Therefore, the proposed current parapatric distribution of the “carteri” and “ivonicus/yuna” lineages probably developed after the establishment of the modern west-to-east course of the Amazon River, which may have initiated approximately 8 Ma (Lundberg et al. 1998).

Bottom Line: The divergence time between these lineages was estimated as approximately 10 million years ago.In addition, a new species, Palaemonyuna sp. n., closely related to Palaemonivonicus, is described.Our findings indicate that these species can be differentiated using the projection of the anterolateral margin and anterolateral spine of the first antennular segment, shape of the rostrum, and relative size of the appendix masculina.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Bioecology and Crustacean Systematics (LBSC), Postgraduate Program in Comparative Biology. Department of Biology, Faculty of Philosophy, Sciences and Letters at Ribeirão Preto (FFCLRP), University of São Paulo (USP), São Paulo, Brazil.

ABSTRACT
Palaemoncarteri (Gordon, 1935) and Palaemonivonicus (Holthuis, 1950) are morphologically similar species of South American freshwater shrimps. Past studies have questioned the taxonomic status of both species, which are supposed to have partially sympatric geographic distributions in the Amazon basin. We analyzed a 550 bp fragment of the mitochondrial 16S rRNA gene from these Amazonian Palaemon species as well as from 11 palaemonids as the outgroup. Additionally, we checked diagnostic characters of the genus and family as well as other morphological characters that have been little explored before. Palaemoncarteri and Palaemonivonicus are allocated in two sister lineages, with wide genetic divergence and little morphological differentiation. The divergence time between these lineages was estimated as approximately 10 million years ago. Both molecular and morphological data support the taxonomic validity of both Palaemoncarteri and Palaemonivonicus, refuting the hypothesis of synonymy. In addition, a new species, Palaemonyuna sp. n., closely related to Palaemonivonicus, is described. Our findings indicate that these species can be differentiated using the projection of the anterolateral margin and anterolateral spine of the first antennular segment, shape of the rostrum, and relative size of the appendix masculina.

No MeSH data available.