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The taxonomy of the family Mugilidae has historically posed challenges, marked by discrepancies between described and valid species, compounded by cryptic diversity and a similar external appearance. Previous studies left four of six lineages unidentified within Crenimugil, including Crenimugil sp. A and Crenimugil sp. B. The goal of this study is to provide a detailed revision of species assigned to Crenimugil by examining specimens from the Red Sea, which is the type locality of Mugil crenilabis, Mugil seheli and Mugil tade, which were here genetically analyzed. After demonstrating that the genus contains nine monophyletic lineages and Moolgarda pura is a valid nominal species, the mugilid genus Moolgarda is restored. Consequently, Moolgarda has priority over Crenimugil and Valamugil. Additional morphological analyses of specimens from the Red Sea assigned to Moolgarda sp. A and Moolgarda sp. B identified them as representing Moolgarda seheli and Moolgarda crenilabis, respectively. A phylogenetic analysis, including new DNA barcodes, confirmed a wide distribution range of both species in the Indo-West Pacific. The identity of the lineage previously identified as Crenimugil crenilabis remains doubtful, and it is referred to as Moolgarda cf. crenilabis here. A third lineage, previously named Crenimugil buchanani, is re-described as Moolgarda tade, a species originally reported from the Red Sea with a long history of taxonomic confusion. The species is widely distributed in the Indo-West Pacific and distinguished from other congeners by falcate second dorsal and anal fins that are distinctly higher than the first dorsal fin. A detailed description of the Red Sea specimens of M. crenilabis, M. seheli and M. tade is provided, with comments to other unnamed lineages. [ABSTRACT FROM AUTHOR]

Fishes of the Mugilidae family are poorly known from a taxonomic perspective, largely because of their conservative morphology. In this paper, we aim to fill the knowledge gap and data deficiency regarding the genetic diversity of mullets occurring in southern peninsular India. A comprehensive mitochondrial phylogeny based on 238 COI sequences (78 newly generated) and three species delimitation methods (ASAP, RESL, and ABGD) confirmed the presence of 21 species of mullets within eight genera in southern peninsular India. These include one species each under the genera Rhinomugil Gill 1863, Minimugil Durand, Chen, Shen, Fu, and Borsa, 2012, Plicomugil Schultz 1953, and Ellochelon Whitley 1930; seven species of Planiliza Whitley 1945; four species of Crenimugil Schultz 1946; four species of Osteomugil Luther 1982; and two species of the "Mugil cephalus Linnaeus 1758" complex—though with uncertainty regarding the exact geographic origin of one of the two species of the "Mugil cephalus" complex and one species phylogenetically close to Planiliza subviridis (Valenciennes 1836). We provide an overview of the specific geographical regions in southern peninsular India, and "species groups", which require future research using an integrative approach, so as to unravel the true extent of mullet diversity and their distribution in the region. [ABSTRACT FROM AUTHOR]

The Mekong River is one of the largest rivers in the world and hosts the second greatest fish diversity in the world after the Amazon. However, despite the importance of this diversity and its associated biomass for human food security and the economy, different anthropogenic pressures threaten the sustainability of the Mekong River and fish diversity, including the intense damming of the main river. Both the increase in salt-water penetration into the Mekong Delta and the disrupted connectivity of the river may have serious impacts on the numerous freshwater and migratory species. To evaluate the potential of an eDNA approach for monitoring fish diversity, water was sampled at 15 sites along the salinity gradient in the Mekong Delta and along 1500 km of the main stream, from Vietnam to Thailand and Laos. A total of 287 OTUs were recovered, of which 158 were identified to the species level using both reference sequences available in GenBank and references obtained locally. Agglomerative hierarchical clustering and PCA identified up to three main species assemblages in our samples. If the transition from brackish to freshwater conditions represents the main barrier between two of these assemblages, more surprisingly, the two other assemblages were observed in the freshwater Mekong, with a spatial disjunction that did not match any biogeographic ecoregion or the Khone falls, the latter thought to be an important fish dispersion barrier. Between 60% and 95% of the freshwater species were potamodromous. This pioneer eDNA study in the Mekong River at this geographical and ecological scale clearly confirmed the potential of this approach for ecological and diversity monitoring. It also demonstrated the need to rapidly build an exhaustive Mekong fish barcode library to enable more accurate species' assignment. More eDNA surveys can now be expected to better describe the ecological niche of different species, which is crucial for any models aimed at predicting the impact of future damming of the Mekong. [ABSTRACT FROM AUTHOR]

Madagascar is a marine biodiversity hotspot. A recent checklist recorded 1689 marine or transitional water fish species, 2.5% being endemic. To date, studies in this country were mostly focused on adult fishes using morphological-based identification. The early life stages of fishes remain largely understudied. The present work aimed to improve knowledge of fish biodiversity in Madagascar by focusing on post-larval reef fishes and settled juveniles in seagrass meadows of southwest Madagascar by using either species identification keys or DNA barcoding. Up to 119,500 individuals were collected, and 1096 individuals were successfully barcoded. We identified 387 species—85 through their morphology (with 58 unsuccessfully sequenced) and 302 by using CO1 barcoding corresponding to 302 barcode index numbers (BINs). This study added 27 new BINs for the BOLD database, 120 new for Madagascar, but only 159 were assigned a precise species name. By referring to the updated checklist of Madagascar fishes, 10 new species were detected for Madagascar. This number will probably increase when all the barcoded specimens become assigned to precise species names. These preliminary findings stress our poor knowledge of marine fish biodiversity in Madagascar and demonstrate the relevance of DNA barcoding in improving this knowledge. [ABSTRACT FROM AUTHOR]