Isididae
A family of octocorals now comprising three genera.
Isididae is a family of octocorals within the order Malacalcyonacea; it was previously placed in the order Calcaxonia. In its current, strict sense, the family contains only three genera: *Isis*, *Hicksonella*, and *Rumphella*. The broader historical grouping, known as Isididae *sensu lato*, is commonly called bamboo coral. For much of the late 20th and early 21st centuries, Isididae *sensu lato* was divided into several subfamilies: Isidinae (containing only *Isis* and *Chelidonisis*), Muricellisidinae (containing only *Muricellisis*, sometimes merged into Isidinae), Keratoisidinae, Mopseinae (from which Peltastisidinae was occasionally split between 1976 and 1996), and Circinisidinae. In 2016, a proposal elevated these subfamilies to family rank, creating Isididae *sensu stricto* (with only *Isis*), Keratoisididae, Mopseidae, and Circinisidae. The genera *Chelidonisis* and *Muricellisis* were excluded from Isididae *sensu stricto*; *Chelidonisis* was left unassigned to any family, and *Muricellisis* was considered *incertae sedis* within Octocorallia. This proposal was partly revised in 2021, resulting in the currently accepted families: Isididae *sensu stricto* (containing only the genus *Isis*), Chelidonisididae (containing only *Chelidonisis*), Keratoisididae (from the former Keratoisidinae), and Mopseidae (from the former Mopseinae and Circinisidinae). The subfamily Muricellisidinae was eliminated because in 2020 the genus *Muricellisis* was found to be invalid—its two species actually belonged to *Anthothela* (family Anthothelidae) and *Melithea* (family Melithaeidae), and were transferred accordingly. In 2022, the genera *Hicksonella* and *Rumphella*, previously placed in the family Gorgoniidae within the former order Holaxonia, were moved into Isididae *sensu stricto*. Thus, the family now comprises only *Isis*, *Hicksonella*, and *Rumphella*. A cladogram based on a 2022 study by McFadden, Ofwegen, and Quattrini, using Ultra-Conserved Elements and exon loci, shows the relationships among these groups, with taxa historically placed within Isididae highlighted in bold.
Quick Facts
- Taxon
- Isididae
Facts from the source article.
Lore & Background
In the late 20th and early 21st century, the family Isididae sensu lato consisted of the subfamilies Isidinae, Muricellisidinae, Keratoisidinae, Mopseinae, and Circinisidinae. In 2016, it was proposed that these subfamilies be elevated to families: Isididae sensu stricto (only Isis), Keratoisididae, Mopseidae, and Circinisidae. The genera Chelidonisis and Murcellisis were deliberately not included in Isididae sensu stricto, with Chelidonisis left unassigned and Murcellisis considered incertae sedis within Octocorallia. In 2021, the 2016 proposal was partly modified, yielding the currently accepted families: Isididae sensu stricto (containing only the genus Isis), Chelidonisididae (containing only the genus Chelidonisis), Keratoisididae, and Mopseidae (including former Mopseinae and Circisidinae). The Muricellisidinae were removed because in 2020 the genus Mucellisis was found not to exist; its two species were moved to Anthothela and Melitheae. In 2022, the genera Hicksonella and Rumphella, previously in Gorgoniidae, were moved to Isididae sensu stricto, giving the family its current composition.
Reader's Guide
The significance of Isididae lies in its complex taxonomic history, which reflects broader shifts in octocoral classification. The family was once a large grouping (Isididae sensu lato) known as bamboo coral, encompassing multiple subfamilies. Revisions in 2016 and 2021 split these into separate families, and the 2020 discovery that the genus Murcellisis did not exist further refined the group. The 2022 addition of Hicksonella and Rumphella from Gorgoniidae expanded Isididae sensu stricto to three genera. This history illustrates how molecular phylogenetics (using Ultra-Conserved Elements and Exon loci) has reshaped understanding of octocoral relationships, resolving some uncertainties while leaving others, such as the placement of Chelidonisis, unresolved. The family's legacy is as a case study in taxonomic revision, where vernacular names like 'bamboo coral' persist even as scientific boundaries shift.
Did You Know?
- The family Isididae currently contains only the genera Isis, Hicksonella, and Rumphella.
- The vernacular name 'bamboo coral' applies to the historical broader grouping Isididae sensu lato.
- In 2020, the genus Murcellisis was found not to exist; its two species were reassigned to other genera.
- The genera Hicksonella and Rumphella were moved to Isididae from Gorgoniidae in 2022.
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