Complete Mitochondrial Genome of the Poorly Known Fish Parasinilabeo maculatus (Cypriniformes: Cyprinidae) and Its Phylogenetic Implications

Parasinilabeo maculatus is a rare cyprinid endemic to China whose phylogenetic position and taxonomy are poorly understood. We present its first complete mitogenome to clarify its phylogenetic placement within Semilabeonini. The circular mitogenome is 16,606 bp and shows the typical vertebrate gene arrangement: 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and a control region, with the L-strand replication origin (OL) in the WANCY tRNA cluster. It has a pronounced AT bias (58.7%), with AT-skew (0.094) and GC-skew (−0.250), consistent with other cyprinids. Phylogenetic trees reconstructed using ML and BI methods based on concatenated PCGs show similar topologies: (1) placing P. maculatus within Semilabeonini, where it is only provisionally grouped with P. assimilis and P. longicorpus in the full PCG dataset. This placement receives low gene and site concordance (gCF = 15.38%, sCF = 40.57%) and conflicts with the first + second codon position tree, in which P. maculatus is sister to Hongshuia microstomata rather than to its congeners; (2) supporting the monophyly of Semilabeonini and of several genera (e.g., Ptychidio), whereas the monophyly of Parasinilabeo is tentatively resolved at best and is therefore treated here as tentative (see point 1); (3) preliminarily revealing non-monophyly of some genera (e.g., Sinocrossocheilus) based on the current sampling, suggesting that some relationships may not fully match morphological classifications. However, these inferences rest on mtPCGs and limited taxon sampling and require testing with broader taxonomic and genomic sampling. These mitogenomic data provide a genomic resource for taxonomic and conservation studies of Semilabeonini.