Phylogeny and morphological evolution of the so‐called bougainvilliids (Hydrozoa, Hydroidolina)

Abstract

We present phylogenetic analyses (parsimony, maximum likelihood and Bayesian inference) for 69 lineages of anthoathecate hydroids based on 18 morphological characters (12 proposed for the first time) plus mitochondrial (16S and COI) and nuclear (18S and 28S) molecular markers. This study aims to test the monophyly of the present concept of the family Bougainvilliidae, assessing its phylogenetic position within Hydroidolina. Our working hypothesis is used as a context for inferring the evolution of certain morphological characters, focusing on the exoskeleton. Our results shed light on some phylogenetic uncertainties within Hydroidolina, delimiting eight well‐supported linages, viz. Hydroidolina, Siphonophorae, Leptothecata, Aplanulata, Filifera II, Filifera III, Capitata and Pseudothecata taxon novum, the latter supported by four morphological synapomorphies. The monophyly of several families was not supported, viz. Bougainvilliidae, Cordylophoridae, Oceaniidae, Rathkeidae and Pandeidae. Some of the genera typically considered in Bougainvilliidae, including Bougainvillia, fell into the clade Pseudothecata, which is consistently reconstructed as the sister group of Leptothecata. We formally suggest that Dicoryne be removed from Bougainvilliidae and placed in the resurrected family Dicorynidae. The exoskeleton was a key feature in the diversification of Hydroidolina, especially with the transition from the bare hydranth to one completely enveloped within the exoskeleton. In this context, bougainvilliids exhibit several intermediate states in the development of the exosarc. Although the concatenated analysis unravels some interesting hypotheses, taxon sampling is still deficient and therefore more data are necessary for achieving a more complete understanding of the evolution and ecology of bougainvilliids and their allies.

The state of Medusozoa genomics: current evidence and future challenges

“…All graphs were generated using Python v.3 with ETE Toolkit v.3 [ 34 ], Matplotlib v3.3.1 [ 35 ], and Seaborn v.0.11 [ 36 ] and modified with Inkscape v.0.92 [ 37 ] to improve visualization (e.g., font size and spacing). The tree of Figs 2 and 4 represents a simplified phylogenetic hypothesis obtained by combining phylogenies from previous studies (Scyphozoa [ 38 ], Medusozoa [ 5 ], Hydrozoa [ 39 , 40 ]), taking into account clades with high congruence and support values. Although the different phylogenetic hypotheses were mostly congruent, no single study nor molecular dataset comprised all the terminals discussed here.…”

Skeletons of Calcareous Benthic Hydroids (Medusozoa, Hydrozoa) under Ocean Acidification

“…Phylogenetic analysis supports the independent origins of a calcified skeleton in Hydrozoa [9,28,29], and the distribution of CaCO 3 polymorphs in their skeletons is considered to have been produced by non-environmental causes [22]. However, Figure 1.…”

Biodiversity and biogeography of hydroids across marine ecoregions and provinces of southern South America and Antarctica

“…The taxonomy of all species was standardized following the pertinent literature to their area of occurrence (Oliveira et al 2016 and references therein;Ronowicz et al 2019 and references therein;Schuchert 2021). Species were phylogenetically classified according to Maronna et al (2016), Mendoza-Becerril et al (2018) and Schuchert (2021).…”

“…Along the SSA & A coasts, hydroids-the polyp stage of the cnidarian class Hydrozoa (Cornelius 1992)-are abundant in benthic communities, being usually among the first organisms to settle available space and having the capacity to grow quickly on several natural and artificial substrates (Gili and Hughes 1995;Genzano et al 2009). Recent phylogenetic studies have identified several likely clades corresponding roughly to the suborder or order level in hydrozoan classifications, including Limnomedusae, Leptothecata, Aplanulata, Capitata, and Pseudothecata; the latter three taxa along with a few other groups of "Filifera" are still united under a non-monophyletic "Anthoathecata" (Collins et al 2006;Cartwright et al 2008;Leclère et al 2009;Kayal et al 2015;Maronna et al 2016;Mendoza-Becerril et al 2018).…”