Pena V. auteur aut IRD Le Gall L. auteur aut IRD Rosler A. auteur aut IRD Payri Claude auteur aut IRD Braga J. C. auteur aut IRD text journalArticle eng text/pdf born digital access Adeylithon gen. nov. with one species, A. bosencei sp. nov., belonging to the subfamily Hydrolithoideae is described from Pacific coral reefs based on psbA sequences and morpho-anatomy. In contrast with Hydrolithon, A. bosencei showed layers of large polygonal "cells," which resulted from extensive lateral fusions of perithallial cells, interspersed among layers of vegetative cells. This anatomical feature is shared with the fossil Aethesolithon, but lacking DNA sequences from the fossils and the fragmentary nature of Aethesolithon type material, we cannot ascertain if Adeylithon and Aethesolithon are congeneric. Morpho-anatomical features of A. bosencei were generally congruent with diagnostic features of the subfamily Hydrolithoideae: (i) outline of cell filaments entirely lost in large portions due to pervasive and extensive cell fusions, (ii) trichocytes not arranged in tightly packed horizontal fields, (iii) basal layer without palisade cells, and (iv) cells lining the canal pore oriented more or less perpendicular to roof surface and not protruding into the canal. However, it showed a predominant monomerous thallus organization and trichocytes were disposed in large pustulate, horizontal fields, although they were not tightly packed and did not become distinctly buried in the thallus. Only mature tetrasporangial conceptacles were observed, therefore the type of conceptacle roof formation remained undetermined. Adeylithon bosencei occurs on shallow coral reefs, in Australia, Papua New Guinea, and South Pacific islands (Fiji, Vanuatu). Fossil Aethesolithon is considered an important component of shallow coral reefs since the Miocene; fossil records showed a broad Indo-Pacific distribution, but a long-term process of range contraction in the last 2.6 million years, resulting in an overlap with the distribution of the extant Adeylithon. While the congeneric nature of extant and fossil taxa remained uncertain, similarities in morpho-anatomy, habitat, and distribution may indicate that both taxa likely shared a common ancestor. specialized coral reefs Corallinaceae distribution fossil coralline algae Hydrolithoideae Pacific paleobiogeography phylogeny systematics taxonomy PACIFIQUE AUSTRALIE LIZARD ILE 034 55 1 134-145 2019 0022-3646 https://www.documentation.ird.fr/hor/fdi:010075249 10.1111/jpy.12799 0022-3646 [F B010075249] https://www.documentation.ird.fr/hor/fdi:010075249 https://www.documentation.ird.fr/intranet/publi/2019/03/010075249.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2019-04-03 2025-02-24 fdi:010075249 fre