An integrative approach to the evolution of shrimps of the genus Palaemon (Decapoda, Palaemonidae)

Abstract

Shrimps of the genus Palaemon Weber, 1795 comprise of 86 species with a wide morphological and ecological variability along the tropical and temperate regions. Studies based on molecular data have indicated that despite a recent taxonomic rearrangement, it may remain not monophyletic. On the other hand, cladistic, morphological analyses have suggested the presence of synapomorphies, implying a natural status for the genus. In this work, a broad taxonomic and molecular sampling is applied to verify whether Palaemon is a monophyletic taxon and, based on the recovered phylogeny, identify geographical and morphological patterns related to the lineages. Partial sequences of 16S rRNA, histone H3 and 18S rRNA from 60 species of Palaemon and 15 species from other genera of Palaemonidae were analysed. In addition, previously used characters as well as novel diagnostic characters were scrutinized. The present phylogeny indicates that the species of Palaemon fall into three distinct lineages and that the colonization of America and Europe likely occurred multiple times. Morphological characters allow for the identification of at least four monophyletic groups in Palaemon; two of which are monospecific at the moment. Based on the present results, it may become necessary to establish two new genera (to accommodate Palaemon concinnus and Palaemon mercedae, respectively), as well as re‐erect the genus Alaocaris Holthuis, 1949 for Palaemon antrorum, potentially including a further six American species.

Mitogenome phylogenetics in the genus Palaemon (Crustacea: Decapoda) sheds light on species crypticism in the rockpool shrimp P. elegans

“…The genus Macrobrachium comprises over 200 freshwater prawns globally distributed across tropical and subtropical regions [66]. Carvalho et al [8] already reported that Palaemon species with freshwater phases exhibited a closer relationship with the genus Macrobrachium than to other Palaemon species, and were included in one of the three clades identified within Palaemon, the 'Alaocaris' clade. Consequently, P. capensis may be included in the 'Alaocaris' clade as is an amphidromous shrimp [67].…”

“…Therefore, molecular data could be crucial to elucidate taxonomic ambiguities. Indeed, the family Palaemonidae has been the subject of numerous systematic and evolutionary studies due to its wide geographical distribution, large variety of habitats and the economic importance of some species [8]. Specifically in Palaemon, extensive worldwide phylogenetic analyses have been performed revealing the need for further systematic rearrangements.…”

“…This new genus Palaemon, redefined by De Grave & Ashelby [2], mainly grouped species according to their biogeographical distribution. Nevertheless, the last phylogenetic assessment of the genus indicated that Palaemon clearly remained as a non-monophyletic group [8] where the species were divided into three different clades: one monospecific clade formed by P. concinnus; a second clade referred as 'Alaocaris' and composed by American species; and the larger 'Palaemon' clade that included P. mercedae as the sister species of the remaining species of the genus that would be "Palaemon sensu stricto". Hence, phylogenetic relationships among Palaemon species are still a disputed systematic issue.…”

Comparative cytogenetic analysis of marine Palaemon species reveals a X1X1X2X2/X1X2Y sex chromosome system in Palaemon elegans

“…Recently, phylogenetic and taxonomic revisions changed the status of the genus Palaemon [8–11] as well as the number of its species. The genus Palaemon currently comprises 86 species, two of which have been recently described ( Palaemon minos sp.…”

Understanding the molecular basis of adaptation to freshwater environments by prawns in the genus Macrobrachium

“…Crustaceans in particular, represent an excellent group for investigating this question in a greater detail because they represent one of the most diversified groups (67,000 recognized species), that occur in all types of aquatic habitats (fresh to sea water), with distinctive phenotypic traits apparent between freshwater and saltwater inhabitants (Vogt, 2013;Carvalho et al, 2016). In some instances, even different con-specific populations have been observed to tolerate different ranges of environmental salinity (Moshtaghi et al, 2017).…”