Description, morphometric characterization and distribution pattern of <i>Paradiopatra multibranchiata</i>, a new onuphid (Annelida: Polychaeta) from the tropical eastern Pacific

<p><i>Paradiopatra multibranchiata</i>, an onuphid found commonly in shelf sediments of the tropical eastern Pacific, is described here. It belongs to the group of <i>Paradiopatra</i> species characterized by the presence of branchiae on the most anterior parapodia (chaetigers 2–3), with at least seven filaments when fully developed. The new species closely resembles <i>P. parva</i>, also distributed in the eastern Pacific but in temperate habitats. It can be distinguished from the latter by the presence rather than the absence of eyes, and because it bears the highest number of branchial filaments (up to 37) observed in any <i>Paradiopatra</i> species known so far (14–18 filaments at most). The taxonomic status of the new species is supported by comparative morphometric and multivariate analyses, which also allowed us to verify its differences with <i>P. parva</i>. The branchial development was the most useful character to determine the relationships between the specimens of <i>P. multibranchiata</i> sp. nov., while its separation from <i>P. parva</i> (Wilks’ lambda = 0.060, P < 0.0001) was weighted most heavily by the number of filaments at chaetigers 2 and 10, and the length of the median antenna. An anatomical examination with methylene blue stain and with scanning electron microscopy was carried out to illustrate the ventral glandular pad staining pattern and the features of their cuticular pores.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:194636C6-A032-4B1F-B0B8-1D494C344623" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:194636C6-A032-4B1F-B0B8-1D494C344623</a></p>