The first complete mitogenome of the bumblebee catfish, Pseudomystus siamensis (Regan, 1913), resolves its phylogenetic position and provides molecular evidence for the monophyly of the genus.

BACKGROUND

The family Bagridae, a diverse catfish group, is known for its taxonomic complexity, wherein evolutionary relationships are often obscured by morphological convergence. The Asian Bumblebee Catfish, Pseudomystus siamensis (Regan, 1913), endemic to the Mekong and Chao Phraya River basins, exemplifies this ambiguity. Its phylogenetic position has remained uncertain due to limited molecular data, hindering taxonomic clarity and conservation planning.

METHODS AND RESULTS

To resolve the phylogenetic placement of P. siamensis, we sequenced its complete mitogenome using Oxford Nanopore Technologies. The circular mitogenome is 16,525 bp long and contains the canonical 37 vertebrate genes. A maximum-likelihood phylogeny built from a concatenated dataset of 13 protein-coding genes across 40 bagrid species robustly placed P. siamensis as a distinct lineage sister to the large, paraphyletic East Asian assemblage comprising Tachysurus, Pseudobagrus, Leiocassis, and Pelteobagrus. To test the monophyly of Pseudomystus, we conducted a second analysis using the cytochrome b gene that included two congeners. This analysis recovered Pseudomystus species as a strongly supported monophyletic group.

CONCLUSION

This study provides the first mitogenomic-scale placement of P. siamensis, definitively refuting earlier hypotheses that allied it with Hemibagrus and Mystus. We also provide the first molecular evidence supporting the monophyly of Pseudomystus. Our findings reinforce the widespread paraphyly of several East Asian bagrid genera, highlighting an urgent need for formal taxonomic revision. The mitogenome presented here is a useful genomic resource for future systematic and conservation studies in Bagridae.