An updated phylogeny of Iphitime (Annelida: Dorvilleidae) revealing multiple host switching, with description of I. nubila sp. nov.

This study provides an updated molecular phylogeny of Iphitime Marenzeller, 1902 (Annelida: Dorvilleidae), a group of symbiotic dorvilleid polychaetes, including a topotypic specimen of the type species, Iphitime doederleini Marenzeller, 1902. Also, a new species, Iphitime nubila sp. nov., was found associated with hermit crab hosts during a faunal survey off Shirahama, Wakayama, Japan, and is described here. Specimens of Iphitime were also found from southern California that were from the gill chambers of two different hosts of brachyuran crabs and are referrable to Iphitime loxorhynchi Hartman, 1952. The study includes morphological descriptions, ecological observations, molecular phylogenetic analyses, and ancestral state reconstruction highlighting at least two independent host switching in Iphitime. Additionally, we present the first mitochondrial genome for Iphitime, comparing its protein-coding gene order with Ophryotrocha Claparède & Mecznikow, 1869 and Veneriserva Rossi, 1984, revealing a conserved gene order within the Iphitime + Veneriserva clade. The conserved order between these two symbiotic genera contrasts with the high variation observed among several dorvilleid species. ZooBank: urn:lsid:zoobank.org:pub:8F472388-4B75-4F6F-A8B9-EE25B69CAFAC