Comparative genomics and adult-female transcriptomics prioritize physiological candidate pathways in the aquatic...

Freshwater-associated life histories are rare in Lepidoptera, and the physiological systems accompanying them remain poorly resolved. We integrated adult-female whole-body RNA-seq from Paracymoriza distinctalis (n = 3) and three terrestrial crambids (n = 3, 3, and 2) with focused comparative genomics to prioritize testable candidate pathways. Adult-female expression-biased genes were enriched for muscle contraction and myofibril assembly, carbohydrate and nucleotide-related metabolism, response to stimulus, and regulation of signal transduction. Protein-interaction analysis further identified coherent modules associated with RNA processing, carbon metabolism, the citrate cycle, and RAF/MAPK signaling. At the genome level, P. distinctalis retained broad macrosynteny with two crambid relatives, whereas putative lineage-biased genes were enriched for vitelline membrane formation, embryonic development, apoptosis, cytoskeletal organization, and transferase activity. Because the transcriptomes were obtained from whole adult females, these patterns may reflect locomotor, reproductive, metabolic, and tissue-composition differences and should not be interpreted as direct mechanisms of larval aquatic adaptation. Together, the results identify a concise set of adult-stage physiological candidates for stage-resolved, tissue-specific, and functional validation.