Comparative genomics suggests extensive antithrombotic gene expansion in Haemadipsa yanyuanensis

Haemadipsa yanyuanensis Liu & Song, 1977, is a terrestrial blood-feeding leech whose antithrombotic repertoire remains insufficiently characterized. We present its first chromosome-level genome assembly (165.32 Mb across nine chromosomes; BUSCO: 97.6%) using Nanopore long reads, Hi-C scaffolding, and RNA-seq data. We identified 193 putative antithrombotic genes in 15 putative families, representing a 2.2- to 2.7-fold increase in gene number but reduced family diversity compared with aquatic medicinal leeches, including Hirudo nipponia Whitman, 1886, Hirudinaria manillensis Lesson, 1842, and Hirudo medicinalis Linnaeus, 1758. Notably, the putative bdellin, LDTI, and LCI gene families exhibited marked lineage-specific expansions, ranging from 8.7- to 25-fold relative to those of aquatic leeches. In addition, the putative progranulin gene displayed a distinctive structural organization characterized by 122 cysteine residues and nine tandem repeats. Transcriptomic profiling revealed elevated expression of four expanded putative families, suggesting potential roles in terrestrial blood-feeding adaptation. This chromosome-scale genome provides a valuable resource for investigating anticoagulation mechanisms and may inform the development of next-generation antithrombotic therapeutics.