A new species, Pseudocodium mucronatum, is described from the Chesterfield platform off the west coast of New Caledonia. The species differs from its congeners in having mucronate utricules. A phylogenetic analysis of rbcL and tufA sequences showed that P. mucronatum is most closely associated with P. natalense De Clerck, Coppejans et Verbruggen and P. devriesii Weber Bosse, with which it shares compressed axes, depressed apices, and plastids in the utricles and the medullar siphons. We studied the evolution of climatic and ecological preferences in the genus using an interdisciplinary approach consisting of relaxed molecular clock analysis, extraction of macroecological data from satellite imagery in a geographic information system (GIS) framework, andancestral character state estimation. It was shown that the genus originated in tropical waters during the Early Mesozoic. Whereas the P. floridanum-okinawense lineage remained tropical, the lineage including P. natalense, P. devriesii, and P. mucronatum gradually invaded more temperate waters during Cenozoic times. Except for P. devriesii, which occurs in shallow and intertidal habitats, all Pseudocodium species grow in deep-water habitats, and this ecological preference appears to be ancestral. |
