Data from: Phylogenomics, life history and morphological evolution of ophiocomid brittlestars

Brittlestars in the family Ophiocomidae are large and colourful
inhabitants of tropical shallow water habitats across the globe. Here we
use targeted capture and next-generation sequencing to generate robust
phylogenomic trees for 39 of the 43 species in order to test the monophyly
of existing genera. The large genus Ophiocoma, as currently constituted,
is paraphyletic on our trees and required revision. Four genera are
recognised herein: an expanded Ophiomastix (now including Ophiocoma
wendtii, O. occidentalis, O. endeani, O. macroplaca, and Ophiarthrum spp),
Ophiocomella (now including the non-fissiparous Ophiocoma pumila, aethiops
and valenciae) and Breviturma (now including Ophiocoma pica, O. pusilla,
O. paucigranulata and O. longispina) and a restricted Ophiocoma. The
resulting junior homonym Ophiomastix elegans is renamed O. brocki. The
genus Ophiomastix exhibits relatively high rates of morphological
disparity compared to other lineages. Ophiomastix flaccida and O.
(formerly Ophiarthrum) pictum have divergent mitochondrial genomes,
characterised by gene-order rearrangements, strand recoding, enriched GT
base composition, and a corresponding divergence of nuclear mitochondrial
protein genes. The new phylogeny indicates that larval and developmental
transitions occurred rarely. Larval culture trials show that species with
abbreviated lecithotrophic larval development occur only within
Ophiomastix, although the possible monophyly of these species is obscured
by the rapid early radiation within this genus. Asexual reproduction by
fission is limited to one species-complex within Ophiocomella, also
characterised by elevated levels of allelic heterozygosity, and which has
achieved a relatively rapid global distribution. The crown ages of the new
genera considerably predate the closure of the Tethyan seaway and all four
are distributed in both the Atlantic and Indo-Pacific Oceans. Two species
pairs appear to reflect the closure of the Panama Seaway, although their
fossil-calibrated node ages (12–14 ± 6 my), derived from both concatenated
sequence and multispecies coalescent analyses, considerably predate the
terminal closure event. Ophiocoma erinaceus has crossed the East Pacific
barrier and is recorded from Clipperton Island, SW of Mexico.