A new species of Eoperipatus (Onychophora) from Vietnam reveals novel morphological characters for the South-East Asian Peripatidae

Abstract

Although representatives of Peripatidae are widely distributed in South-East Asia, only three valid species of Eoperipatus and one species of Typhloperipatus have been described from this region. According to previous reports, the three species of Eoperipatus show little morphological variation and are difficult to distinguish from each other. In this study, we describe a new species of Eoperipatus from Vietnam, E. totorosp. nov., using morphological (light and scanning electron microscopy) and molecular data (mitochondrial COI and 12S rRNA sequences). A comparison with specimens of an undescribed species of Eoperipatus from Thailand revealed novel species-specific characters, including the characteristics of male crural complexes, distinct types of scales on the ventral body surface, the inner structure of the circular pits on the male genital pad, and the position and size of the anal gland pads in males. The results of our molecular analyses correspond with those of morphological studies. In contrast to previous assumptions, our findings suggest a high diversity of the South-East Asian Peripatidae, which requires further exploration.