The genus italic Rhytisma /italic Alderslade, 2000 (Octocorallia: Malacalcyonacea: Lemnaliidae), formerly comprising four nominal species (italic R. fulvum /italic, italic R. fuscum /italic, italic R. monticulum /italic, and italic R. rubiginosum /italic), is revised using an integrative approach. We combine morphological and phylogenomic data for newly-collected and historical specimens. A neotype is designated for italic R. fulvum /italic and a lectotype for italic R. fuscum /italic to stabilize the application of these names. Six new species are described from the Indo-Pacific: italic R. acoronatum /italic sp. nov., italic R. calyaceum /italic sp. nov., italic R. oblongum /italic sp. nov., italic R. inaequale /italic sp. nov., italic R. karibu /italic sp. nov., and italic R. sperkolae /italic sp. nov. Species delimitation is supported by discrete combinations of morphological characters—particularly those of the tentacle and polyp sclerites—as well as multi-locus DNA barcoding and phylogenomic analyses of conserved elements (UCE and exon loci). Our findings highlight the diagnostic value of tentacle sclerites and reveal extensive species-level diversity that was previously obscured by insufficient morphological examination. The revised genus currently comprises ten valid species, many of which display restricted geographic distributions, reflecting patterns of regional endemism in Indo-Pacific octocoral assemblages. These results underscore the importance of integrative taxonomy in uncovering hidden biodiversity.
Samimi‐Namin et al. (Tue,) studied this question.