Evaluating the genus Cespitularia MilneEdwards & Haime, 1850 with descriptions of new genera of the family Xeniidae (Octocorallia, Alcyonacea)

Abstract

Several species of the family Xeniidae, previously assigned to the genus Cespitularia Milne Edwards & Haime, 1850 are revised. Based on the problematical identity and status of the type of this genus, it became apparent that the literature has introduced misperceptions concerning its diagnosis. A consequent examination of the type colonies of Cespitularia coerulea May, 1898 has led to the establishment of the new genus Conglomeratusclera gen. n. and similarly to the assignment of Cespitularia simplex Thomson & Dean, 1931 to the new genus, Caementabunda gen. n. Both new genera are described and depicted and both feature unique sclerite morphology, further highlighting the importance of sclerite microstructure for generic position among Xeniidae. Freshly collected material was subjected to molecular phylogenetic analysis, whose results substantiated the taxonomic assignment of the new genera, as well as the synonymies of several others.

Molecular operational taxonomic units reveal restricted geographic ranges and regional endemism in the Indo‐Pacific octocoral family Xeniidae

“…Both maximum likelihood (Figure ; Figure S1 in Appendix S2) and neighbor‐joining (Figure S2 in Appendix S2) phylogenetic analyses of MOTUs (0.3% threshold) revealed five well‐supported and reciprocally monophyletic clades, all of which have been identified in previous studies (Benayahu, van Ofwegen, & McFadden, ; McFadden, Reynolds, et al., ). Within these clades morphologically‐defined genera were both paraphyletic and polyphyletic (McFadden, Reynolds, et al., ).…”

“…is facilitating our ability to revisit historical species identifications and to revise the biogeographical information that arises from them (e.g. Benayahu, van Ofwegen, & McFadden, ). For groups such as xeniid octocorals for which it is challenging to assign Latin binomials reliably to most species, obtaining DNA sequence data from existing types and other historical material will facilitate the association of morphospecies names with MOTUs.…”

“…Study of the biogeography and ecology of xeniids is impeded, however, by the challenges of identifying species—sometimes even genera—with the result that studies that have reported their impacts on reef communities often identify them to the wrong genera or only to family (Tilot et al., ; Wood & Dipper, ). These challenges arise in part because much of the early literature on the group is poorly illustrated and species descriptions may not correctly describe the type specimens on which they are based, making it difficult to put names on morphospecies without direct comparison to the original type material (Benayahu, van Ofwegen, & McFadden, ; Halàsz, ; Halàsz, McFadden, Aharonovich, Toonen, & Benayahu, ). In addition, recent taxonomic studies have suggested that morphological features of polyps and sclerites that have traditionally been used to diagnose and distinguish species of xeniids from one another are often unreliable and incongruent with genetically determined species boundaries (Benayahu, van Ofwegen, & McFadden, ; Halàsz, Reynolds, McFadden, Toonen, & Benayahu, ; Halàsz et al., ; McFadden, Brown, et al., ; McFadden et al., ).…”

“…Although scanning electron microscopy has identified new morphological characters (e.g. the crystalline microstructure of skeletal elements; Alderslade, ; Aharanovich & Benayahu, ) that help to discriminate genera reliably (Benayahu, van Ofwegen, & McFadden, ), identification of new morphological characters to discriminate species—especially ones that can be observed in the field—is an ongoing challenge (Halàsz et al., ; McFadden et al., ).…”

New approaches to species delimitation and population structure of anthozoans: Two case studies of octocorals using ultraconserved elements and exons

“…At the species level, however, morphological differences can be subtle, and both phenotypic variation and plasticity of growth form often confound assessment of species boundaries (e.g., Forsman, Barshis, Hunter, & Toonen, 2009; Marti‐Puig et al., 2014; McFadden et al., 2017; Paz‐García, Hellberg, García‐de‐León, & Balart, 2015). The advent of integrated taxonomic approaches that utilize molecular characters to inform taxonomy has greatly improved our understanding of species boundaries in numerous coral taxa, and led to the recognition of homoplasy in many morphological characters previously considered to be diagnostic of species and higher taxa (Arrigoni et al., 2014; Benayahu, Ofwegen, & McFadden, 2018; Budd & Stolarski, 2009; McFadden et al., 2017). The relative invariance of mitochondrial genes in corals and most other anthozoans (e.g., sea anemones) has, however, hindered the application of integrated approaches to species delimitation in this ecologically important group (Huang, Meier, Todd, & Chou, 2008; McFadden et al., 2011).…”