Multigene phylogeny and taxonomic revision of American shrimps of the genus Cryphiops Dana, 1852 (Decapoda, Palaemonidae) implies a proposal for reversal of precedence with Macrobrachium Spence Bate, 1868

Abstract

The freshwater shrimp genus Cryphiops Dana, 1852 has a disjunct distribution in North (Mexico) and South (Brazil, Chile) America, and is composed of only six species. The current classification of genera in the Palaemonidae is controversial, based on variable morphological characters, and still far from a clear definition. Cryphiops differs from the speciose genus Macrobrachium Spence Bate, 1868 only by the absence of the hepatic spines on the carapace. Previous studies with a limited dataset suggested the necessity to link morphology and phylogeny to create an internal rearrangement in the genus to resolve the paraphyletic status. Through a molecular phylogenetic approach, the evolutionary relationships are inferred based on four (mitochondrial and nuclear) genes, among all recognized species of Cryphiops and, in combination with a taxonomic revision, a rearrangement in the systematics of the genus is suggested. The absence of hepatic spines on the carapace, the only character used to separate the genus Cryphiops, is subjective and should be considered as a homoplasy. This implies that Cryphiops and Macrobrachium are subjective synonyms and, because the latter genus is much more diverse and widely known, with several economically important species, to avoid confusion and disturbance in nomenclatural stability and keep universality, a proposal for the priority of the older synonym (Cryphiops) to be partially suppressed in favor of maintaining the prevailing use of the younger synonym (Macrobrachium) is presented. As the species of Cryphiops should be accommodated in the genus Macrobrachium, new names to replace three preoccupied specific names that, by this action, resulted to be secondary homonyms are offered.

Filling gaps in the biology of the endemic and threatened freshwater shrimp Macrobrachium candango (Caridea: Palaemonidae) through basic morphometric and reproductive approaches

“…Some characteristics of M. candango categorize it as a species at risk of decreasing its already low natural abundance: endemic, occurring in environments with anthropogenic pressures and low fecundity. Thus, the biological aspects studied herein are important and reinforce the previous recommendation regarding the unrestricted protection of the species (Mantelatto et al, 2016;2021), including future projects focused on monitoring populations throughout the area of occurrence.…”

“…Some species of freshwater shrimps exhibit this characteristic, in which low fecundity along with large eggs is correlated to the type of larval development, as recorded, for instance, for M. brasiliense, M. iheringi, Macrobrachium nattereri (Heller, 1862), and Macrobrachium totonacum Mejía, Alves and Hartnoll, 2003(Pantaleão et al, 2011Bueno and Rodrigues, 1995;Magalhães, 1989;Mejía-Ortíz et al, 2010, respectively). Molecular analyzes (using mitochondrial 16S and COI genes) indicate that these species are phylogenetically close and are part of the same clade with abbreviated larval development (Pileggi and Mantelatto, 2010;Mantelatto et al, 2021). Thus, the reproductive and phylogenetic aspects found lead us to infer that M. candango presents abbreviated larval development, a condition that should be investigated in the future with the larval description of the species.…”

“…In Brazil, the family Palaemonidae is widely diverse, with species occupying different environments from the coastal region to inland waters in different watersheds (Coelho and Ramos-Porto, 1984;Pileggi and Mantelatto, 2010;Mantelatto et al, 2016). Among the genera of this diverse family, the Brazilian species of Macrobrachium Spence Bate, 1868 received special attention during the last decade with regard to updated taxonomy (Pileggi and Mantelatto, 2012;Dos Santos et al, 2013;Mantelatto et al, 2016;Rossi et al, 2020), and most recently a taxonomic revision proposed a new nomenclatural and phylogenetic rearrangement in which all the six American species of the genus Cryphiops Dana, 1852 were accommodated in the genus Macrobrachium (see Mantelatto et al, 2021). Regarding this latter group, the only known species from Brazilian territory is Macrobrachium candango Mantelatto, Pileggi, Pantaleão, Magalhães, Villalobos andÁlvarez, 2021 (originally described as Cryphiops brasiliensis Gomes Corrêa, 1973), which is endemic to the Paranoá Lake hydrographic basin in Brasília, Federal District (Gomes Corrêa, 1973;Mantelatto et al, 2021).…”

“…Reports from local collections and observations indicate that the abundance of M. candango is naturally low, with a high degree of endemism (Mantelatto et al, 2016), causing the species to be categorized as threatened according to IUCN criteria. Additionally, their habitats have been affected by anthropogenic actions such as pollution and deforestation (Mantelatto et al, 2016;2021). Shrimps have an important ecological role within aquatic ecosystems (March et al, 2002), and in the case of M. candango, which is an endemic species in a region of Brazil, its disappearance from the environment can cause irreversible problems to these ecosystems, influencing the local food chain (March et al, 2002;De Souza and Moulton, 2005).…”

Taxonomy and molecular phylogeny analysis of the genus Diogenes “Edwardsii group” (Decapoda: Anomora: Diogenidae) based on mitochondrial DNA sequences

“…DNA barcoding is a useful tool for the taxonomic classification and identification of species by sequencing a very short, standardized DNA sequence in a well-defined gene (Purty and Chatterjee 2016;Madduppa et al 2017;Landschoff and Gouws 2018). The mitochondrial DNA is widely used in identifying a species from Indonesia marine invertebrates (Aprilia et al 2014;Kurniasari et al 2014;Sahriyani et al 2014;Toha et al 2015;Saleky et al 2016;Madduppa et al 2016;Dailami et al 2018;Pranata et al 2020;Hikam et al 2021), discover new species in a wide range of taxa (Wang et al 2017), and used for phylogenetic studies (Galan et al 2018;Sultana et al 2018;Mantelatto et al 2021). DNA barcoding has advantages in precision and accuracy in the safe identification of species compared with the morphological observations (Madduppa et al 2017;Fuentes-López et al 2020).…”