Characterization of the Complete Mitochondrial Genome of the Red Alga Ahnfeltiopsis flabelliformis (Rhodophyta, Gigartinales, Phyllophoraceae) and Its Phylogenetic Analysis

Red algae are recognized for their health-promoting bioactive substances and dietary fibers, making them important as functional food. In order to identify species and determine phylogenetic relationships, mitochondrial genes serve as important markers. Thus, this study sequenced the complete mitochondrial genome of Ahnfeltiopsis flabelliformis, compared with Phyllophoraceae species, and performs phylogenetic analysis to reveal its evolutionary position. The genome is 25,992 bp long, has 71.3% of biased AT content, and comprises 24 protein-coding genes (PCGs), 22 tRNA, and three rRNA genes. The overall base composition of its mitochondrial genome was 37.4% for A, 33.9% for T, 14.7% for G, 14.0% for C and 28.7% for GC. The gene content, annotation, and genetic makeup are identical to those of Phyllophoraceae species. Phylogenetic study based on the complete mitochondrial genome and shared mitochondrial genes revealed that the six Phyllophoraceae species form a well-supported clade. Within this clade, A. flabelliformis groups with Gymnogongrus griffithsiae, and together they form a distinct subclade including four species of the Mastocarpus. The results indicate that A. flabelliformis shares a closer evolutionary relationship with G. griffithsiae than with Mastocarpus species. Future research on Ahnfeltiopsis is necessary to comprehend the evolutionary history and phylogenetic relationships among species in this genus.