Molecular Systematics of Threadfin Breams and Relatives (Teleostei: Nemipteridae)
Date Issued
2016
Date
2016
Author(s)
Hung, Kuo-Wei
Abstract
The family Nemipteridae (threadfin breams and relatives) contains five genera including Nemipterus, Pentapodus, Scolopsis, Parascolopsis and Scaevius with 69 currently recognized species that are all confined to the tropical and subtropical Indo-West Pacific. The congeneric species of the family are similar to each other in morphology, especially in the genus Nemipterus. While the precise identification with these species relies notably on coloration of fresh specimens, the results of identification based on the preserved specimens may be problematic. Recently developed molecule-based approaches exploiting DNA sequence variation among species are useful to improve the accuracy of species identification in such the circumstance and to study the evolutionary relationships of taxa. By taking this approach, in this study, multiple-gene analyses for the Nemipteridae were conducted to (1) reconstruct a comprehensive phylogeny of the Nemipteridae; (2) examine the validity of species and explore the cryptic diversity of the family; (3) to test the previous phylogenetic hypotheses, especially those ones infering to intra-generic relationships based on morphology. Two datasets were herein built, for the above objectives: the combined dataset with two nuclear genes (RAG1 and RH) and one mitochondrial gene (COI) that was used for the analyses to infer the higher-level phylogeny; and the dataset with only COI gene sequences (329 newly obtained and 328 from Genebank/BOLD databases) that was primarily used to test species validity by using the species delimitation programs, ABGD and GMYC. The results show that all the genera were monophyletic. The genus Scaevius is the sister-group of Pentapodus and they are sister to Nemipterus. The former three genera together appear to be the sister-group of the clade comprising Parascolopsis and Scolopsis. The validity of most of the examined species is confirmed except some cases. Parascolopsis inermis, Scolopsis affinis, Scolopsis vosmeri and Scolopsis torquata, Nemipterus balinensoides, Nemipterus balinensis, Nemipterus mesoprion and Nemipterus randalli, are non-monophyletic. In addition, several species are found to contain cryptic Evolutionarily Significant Units (or delaminated species); some cannot be unambiguously assigned to any known nemipterid species based on morphology should be considered as new species for further description. Finally, problematic sequences deposited in public databases (Genbank and BOLD) (probably due to misidentification) are also revised in this study.
Subjects
Nemipteridae
molecular systematic
Automatic Barcoding Gap Discovery
General Mixed Yule-coalescent
cryptic species
Type
thesis
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