Eric Coppejans

Systematics and biogeography of the genus Pseudocodium (Bryopsidales, Chlorophyta), including the description of P. natalense sp. nov. from South Africa

O. De Clerck, H. Verbruggen, J.M. Huisman, E.J. Faye, F. Leliaert, T. Schils and E. Coppejans. 2008. Systematics and biogeography of the genus Pseudocodium (Bryopsidales, Chlorophyta), including the description of P. natalense sp. nov. from South Africa. Phycologia 47: 225–235. DOI: 10.2216/07-79.1 This study examines the diversity of Pseudocodium, a small green algal genus assigned to its own family in the order Bryopsidales. The included species are characterized by uncalcified thalli with a medulla composed of a limited number of interwoven siphons that form a cortex of distinctive utricles toward the periphery. Detailed morphological descriptions are provided for all known species. A combination of characters relating to general habit, morphology of the axes, apices and utricles distinguishes all species easily. Re-examination of Indonesian and Papua New Guinean specimens, previously reported as Pseudocodium floridanum, reveals that they belong to the recently described Pseudocodium okinawense. South African specimens formerly attributed to P. floridanum are described as a new species, Pseudocodium. natalense. Pseudocodium australasicum, a species endemic to southern Australia, does not fit the generic concept of Pseudocodium in that it does not possess a cortex composed of utricles. Putative reproductive structures have thus far only been reported for P. floridanum. Observations on Pseudocodium devriesii and P. natalense reveal very similar spherical to irregular structures formed laterally on medullary siphons in the axils of peripheral utricles. Interestingly, and confirming the earlier observations of Dawes & Mathieson, no basal cross wall is formed at the base of the reproductive structures. Instead, a translucent plug at the base of the reproductive structures prevents the cytoplasm from leaking. This suggests that Pseudocodium is not holocarpic, unlike most Halimedineae. DNA sequences of rbcL and tufA are presented for all species and the resulting phylogenies are used as a framework to study the evolution of morphological features as well as the biogeography of the genus, both at the global scale and within the Indian Ocean.

Morphological re-assessment of the Boodlea composita-Phyllodictyon anastomosans species complex (Siphonocladales: Chlorophyta)

Boodlea composita (Harvey) F. Brand and Phyllodictyon anastomosans (Harvey) Kraft & M.J. Wynne, two widespread tropical siphonocladalean green algae, have had a long and confusing history because of the vague taxonomic boundaries between the two species. Molecular phylogenetic studies on the basis of nuclear-encoded rDNA sequences have resolved these indistinct species boundaries and suggest these taxa are part of a species complex. Detailed morphological investigations in combination with field and culture observations show that the concept of traditionally recognised taxa in this species complex is clouded by an ecologically induced phenotypic plasticity and developmental variability. Examination of a large number of specimens of B. composita, P. anastomosans and morphologically allied taxa including Boodlea siamensis Reinbold, Boodlea montagnei (Harvey ex J.E. Gray) Egerod, Nereodictyon imitans Gerloff and Struveopsis siamensis (Egerod) P. C. Silva, worldwide, including types, shows a wide morphological variety. We recognise seven more or less distinct morphological entities based on differences in thallus architectures, branching systems, cell dimensions and tenacular cell types. Awaiting the recovery of the true nature of the defined entities in this species complex (different species or growth forms of the same species), they are referred to as morphotypes, i.e. making no assumptions as to which taxonomic level they best apply.

Rhipidosiphon lewmanomontiae sp. nov. (Bryopsidales, Chlorophyta), a calcified udoteacean alga from the central Indo-Pacific based on morphological and molecular investigations

Coppejans E., Leliaert F., Verbruggen H., Prathep A. and De Clerck O. 2011. Rhipidosiphon lewmanomontiae sp. nov., a new calcified udoteacean species from the central Indo-Pacific on the basis of morphological and molecular investigations (Bryopsidales, Chlorophyta). Phycologia 50: 403–412. DOI: 10.2216/10-90.1 A new species of the green algal genus Rhipidosiphon, Rhipidosiphon lewmanomontiae sp. nov., is described after material from the Mu Ko Tha Lae Tai area (SE Thailand) and Okinawa (Japan) on the basis of morphology and molecular analyses. The new species grows epilithically, just under the low water mark and is occasionally exposed at spring low tide. It differs mainly from the other known species, the Indo-Pacific Rhipidosiphon javensis and the western Atlantic Rhipidosiphon floridensis, by the presence of a rhizoidal pseudocortex surrounding the monosiphonous stipe and the presence of intercalary siphon constrictions. A similar pseudocortex has been described in juvenile stages of some Udotea species, but in this genus, the stipe is polysiphonous and possesses a cortex of lateral appendages in the adult phase.