Crusticorallina gen. nov., a nongeniculate genus in the subfamily Corallinoideae (Corallinales, Rhodophyta)

Abstract

Molecular phylogenetic analyses of 18S rDNA (SSU) gene sequences confirm the placement of Crusticorallina gen. nov. in Corallinoideae, the first nongeniculate genus in an otherwise geniculate subfamily. Crusticorallina is distinguished from all other coralline genera by the following suite of morpho-anatomical characters: (i) sunken, uniporate gametangial and bi/tetrasporangial conceptacles, (ii) cells linked by cell fusions, not secondary pit connections, (iii) an epithallus of 1 or 2 cell layers, (iv) a hypothallus that occupies 50% or more of the total thallus thickness, (v) elongate meristematic cells, and (vi) trichocytes absent. Four species are recognized based on rbcL, psbA and COI-5P sequences, C. painei sp. nov., the generitype, C. adhaerens sp. nov., C. nootkana sp. nov. and C. muricata comb. nov., previously known as Pseudolithophyllum muricatum. Type material of Lithophyllum muricatum, basionym of C. muricata, in TRH comprises at least two taxa, and therefore we accept the previously designated lectotype specimen in UC that we sequenced to confirm its identity. Crusticorallina species are very difficult to distinguish using morpho-anatomical and/or habitat characters, although at specific sites, some species may be distinguished by a combination of morpho-anatomy, habitat and biogeography. The Northeast Pacific now boasts six coralline endemic genera, far more than any other region of the world.

Phymatolithon (Melobesioideae, Hapalidiales) in the Boreal–Subarctic Transition Zone of the North Atlantic

“…This agreement is in contrast to nearly all other coralline geniculate (Gabrielson et al, 2011;Hind and Saunders, 2013;Hind et al, 2014aHind et al, ,b, 2015 and non-geniculate genera and species (Basso et al, 2015;Hernandez-Kantun et al, 2014Sissini et al, 2014;van der Merwe et al, 2015;Hind et al, 2016), wherein type specimens have been matched to field-collected material based on DNA sequences. The major reasons for this are fourfold with respect to non-geniculate corallines: (1) most coralline morpho-anatomists have relied on small sample sets stored in museums, and rarely have population analyses supported by statistical analysis been employed; (2) during the past 60 years since scuba has been widely available, few have taken the opportunity to intensively study these organisms in their natural habitat; (3) the gross morphology of a species can vary widely with substrate characteristics, such as local fleshy algal cover, depth, and wave and current action; and (4) specimens often are bulky, especially when collected with their substrate intact, and are often mosaics of crusts of several different species; rarely has enough coralline-covered substrate been returned to museum collections to allow the evaluation of infra-and interspecific variation in relationship to the original environment.…”

“…With the advent of DNA sequencing, genera and species of the more intensively studied non-geniculate corallines, especially in Subarctic and Boreal waters in the North Atlantic, have been supported by DNA sequencing and phylogenetic reconstructions (Adey et al, 2015). This support has not proved true for many coralline genera and species in the rest of the world, where DNA sequencing is revealing a multitude of undescribed taxa (e.g., Basso et al, 2015;Hind et al, 2015Hind et al, , 2016Hernandez-Kantun et al, 2016;Peña et al, 2015a,b;Rosler et al, 2016).…”

Evolutionary reversals in Bossiella (Corallinales, Rhodophyta): first report of a coralline genus with both geniculate and nongeniculate species

“…The amplification and sequencing of COI‐5P (664 bp), psb A (853 bp), and rbc L (1,401 bp) gene fragments followed Hind et al. (). DNA was extracted from historical specimens following the protocol of Hughey et al.…”

“…Bayesian analysis parameters followed Hind et al. (). Morpho‐anatomical assessments of nongeniculate corallines followed methods used for Crusticorallina species in Hind et al.…”

“…Recently, Hind et al. () erected a new genus, Crusticorallina , for P. muricatum and related species. Although Metagoniolithoideae, Lithophylloideae, and Corallinoideae all contain geniculate and nongeniculate species, genera within each subfamily are defined as possessing one or the other morphological character state (Hind et al.…”