Hydrolithon braganum sp. nov., the first known exclusively fossil semi-endophytic species of Corallinaceae (Corallinales, Corallinophycidae, Rhodophyta), is based on material from IODP Expedition 310 cores of Last deglacial age (c. 20,000 – 10,000 years BP) from reef terraces around Tahiti, French Polynesia. A detailed morphological-anatomical account is provided, and the taxonomic position of the new species at generic and subfamily levels is considered in relation to recent molecular studies and consequent proposals for changes to the concepts of the subfamily Mastophoroideae and the genus Hydrolithon. Evidence is presented to show that the morphological-anatomical criteria proposed in recent molecular-based studies are untenable for circumscribing the subfamily Mastophoroideae and for separating genera called Hydrolithon and Porolithon. Both the Mastophoroideae and Hydrolithon are best recognized as polyphyletic at present. It is not essential to superimpose a morphological-anatomical based classification system on a set of lineages inferred from analyses of molecular sequence data sets that are based only on genes not known to control any of the morphological-anatomical characters currently used to delimit subfamilies or genera, especially when this results in proposals that do not account for all included taxa and are, to varying extents, not in accord with the International Code of Botanical Nomenclature. An alternative strategy is to direct molecular systematic research more towards discovering which genes are responsible for morphological-anatomical characters used to delimit taxa of coralline red algae and then to use data from those genes along with SSU, LSU, psbA, and COI data in analyses aimed at elucidating monophyletic lineages and producing classification systems in which all included taxa are accounted for, and given valid taxonomic names, and assigned to valid taxonomic ranks that are in accord with the ICBN.
Hydrolithon braganum sp. nov. (Corallinaceae, Rhodophyta), the first known exclusively fossil semi-endophytic coralline red alga
BASSI, Davide;
2012
Abstract
Hydrolithon braganum sp. nov., the first known exclusively fossil semi-endophytic species of Corallinaceae (Corallinales, Corallinophycidae, Rhodophyta), is based on material from IODP Expedition 310 cores of Last deglacial age (c. 20,000 – 10,000 years BP) from reef terraces around Tahiti, French Polynesia. A detailed morphological-anatomical account is provided, and the taxonomic position of the new species at generic and subfamily levels is considered in relation to recent molecular studies and consequent proposals for changes to the concepts of the subfamily Mastophoroideae and the genus Hydrolithon. Evidence is presented to show that the morphological-anatomical criteria proposed in recent molecular-based studies are untenable for circumscribing the subfamily Mastophoroideae and for separating genera called Hydrolithon and Porolithon. Both the Mastophoroideae and Hydrolithon are best recognized as polyphyletic at present. It is not essential to superimpose a morphological-anatomical based classification system on a set of lineages inferred from analyses of molecular sequence data sets that are based only on genes not known to control any of the morphological-anatomical characters currently used to delimit subfamilies or genera, especially when this results in proposals that do not account for all included taxa and are, to varying extents, not in accord with the International Code of Botanical Nomenclature. An alternative strategy is to direct molecular systematic research more towards discovering which genes are responsible for morphological-anatomical characters used to delimit taxa of coralline red algae and then to use data from those genes along with SSU, LSU, psbA, and COI data in analyses aimed at elucidating monophyletic lineages and producing classification systems in which all included taxa are accounted for, and given valid taxonomic names, and assigned to valid taxonomic ranks that are in accord with the ICBN.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
