Phylogeny and taxonomy of Haloclavidae (Verrill, 1899) with a redescription of the parasitic, burrowing sea anemone, Peachia chilensis Carlgren, 1931

Abstract

Haloclavidae Verrill, 1899 is a family of burrowing sea anemones grouped within the superfamily Actinioidea (Rafinesque, 1815). Currently, it includes 30 species in 10 genera. Characters given for this family in descriptions of its taxa have not been consistent, with numerous exceptions to the expectations of the familial diagnosis. Previous phylogenetic analyses have shown that Haloclavidae is potentially a polyphyletic group, but resolution of relationships of the few representatives of Haloclavidae included in analyses has been problematic. Here we address questions of monophyly and affinity of Haloclavidae using three mitochondrial and two nuclear markers. We assess the monophyly of Haloclavidae in the context of all major lineages of Actiniaria Hertwig, 1882, emphasizing diversity of superfamily Actinioidea. We use parsimony-based character optimization to interpret the distribution of key traits in the superfamily. We find that Haloclavidae is not monophyletic and propose two new families, Peachiidae fam. nov. and Harenactidae fam. nov., while also retaining some species in the family Haloclavidae, so that taxonomy better reflects relationships and diversity of the group. In addition, we redescribe a species within the newly created Peachiidae, Peachia chilensis Carlgren, 1931. We use recent larval samples obtained in Antofagasta, Chile, and the histological slides from the original description to redescribe P. chilensis, to provide a complete account of cnidae, external, and internal morphology. Finally, we compare P. chilensis to other burrowing anemones found in Chile and provide an understanding of the genus Peachia that reflects recent phylogenetic perspective on diversity of anemones previously assigned to family Haloclavidae.

A Cnidarian Phylogenomic Tree Fitted With Hundreds of 18S Leaves

“…2, S2-4). These discordant relationships are well known from previous studies (Barragán et al, 2019;Izumi et al, 2020;Rodríguez et al, 2014;Yap et al, 2014), and the taxonomy of Haloclavidae has recently A Cnidarian Phylogenomic Tree Fitted With Hundreds of 18S Leaves been updated to better reflect the position of H. producta (Hamilton et al, 2022). While multilocus phylogenies are generally preferred to those based on a single marker, taxon sampling in the phylogenomic dataset is almost an order of magnitude lower for Actinioidea and Metridioidea than that of the 18S tree and mesomyarian taxa, which typically branch near the base of the actiniarian tree.…”

Litophellia enoplosa sp. nov., a new species of sea anemone (Actiniaria, Metridioidea) from cold-water coral environments in the North-western Mediterranean Sea

“…Although more common than documented, only a few genera within Actiniaria have a clear octomerous arrangement of mesenteries and tentacles (Barragán et al, 2019). Examples of regular octamerous symmetry in actiniarians are found in Edwardsiidae Andres, 1881 and among Actinostoloidea Carlgren, 1932(Stomphia (Gosse, 1859, Sicyonis Hertwig, 1882), Phymanthidae Andres, 1883 (some species of Phymanthus Milne Edwards & Haime, 1851), Andvakiidae (L. octoradiata Carlgren, 1938), Aiptasiidae Carlgren, 1924a (some species of Bartholomaea Duchassaing de Fombressin & Michelotti, 1864; Aiptasiogeton Schmidt, 1972a), Actiniidae Rafinesque, 1815 (Bunodactis octoradiata (Carlgren, 1898) [authorship date traditionally attributed to 1899 although original description was published in 1898, see Rodríguez et al, 2023] and Peachiidae Hamilton, Daly & Rodríguez, 2022in Hamilton et al, 2022(Metapeachia tropica (Panikkar, 1938]; in addition, there are some species within some genera with octomerous symmetry (e.g., species within Sagartiogeton Carlgren, 1924b) (reviewed in Grebelny, 1982).…”