GIGARTINA ALVEATA FROM NEW ZEALAND: AMONG THE OLDEST AND NEWEST MARINE RED ALGAE IN THE SOUTHERN HEMISPHERE Max H. Hommersand & Geoffery L. Leister Department of Biology, University of North Carolina Chapel Hill, NC, USA & Wendy A. Nelson National Institute of Water and Atmospheric Research (NIWA), Kilbirnie, Wellington, New Zealand

Habitat of Gigartina alveata, rocky outcroppings on sandy beaches, North Island, New Zealand

Gigartina alveata, with up to 12 dichotomies, withstands desiccation well

Gigartina alveata: concavo-convex shape of the thallus showing the canaliculae and curved tips

Joseph Banks, 1774 Sir Joseph Banks (Barron) Fucus alveatus Turn. Lectotype: BM, Ex. Herb. Banks Fucus alveatus Turner 1819, pl. 239a (1/2 size) Coast of New Zealand Gigartina alveata (Turn.) J. Ag. Herb. Agardh (LD 23721) (Sent by Harvey from TCD)

North New ZealandMotuarohia Island (‘Motuaro’) Captain Cook Mercury Bay Bay of Islands

Phylogeny of the Gigartinaceae rbcL tree subgenus Eogigartina subgenus Chondracanthus Mastocarpus stellatus Phyllophora crispa D.W. Freshwater (In: Hommersand et al. 1994, 1999)

View from concave side (cystocarps along margin and on convex side) Gigartina alveata - cystocarpic

Tetrasporangia in series derived from primary cortical filaments Tetrasporangial sori (arrows) (Lindauer 1949) Gigartina alveata (tetrasporangia)

Gigartina alveata Tip of a male plant Cross section showing spermatangial clusters (arrows)

Carpogonial branch before Carpogonial branch after fertilization presumed fertilization (= Aux cell?)

Gigartinaceae Cystocarps showing types of internal pericarps Green = secondary filaments

Auxiliary cell Cystocarp envelope (arrows) forming from cortical filaments around the functional auxiliary cell

cortexcortex medullamedulla Auxiliary cell Cortical cells form rosettes of short-celled filaments Medullary cells (arrowheads) undergo intercalary cell divisions

cortexcortex medullamedulla gonimoblasts The auxiliary cell has produced gonimoblasts The modified medullary cells have formed rosettes developing envelope

Gonimoblast filaments (g) elongate and ramify through the medulla g Older stage with a mixture of gonimoblast filaments, medullary cells and carpo- sporangia Carposporangia appear to arise from medullary cells

Young gonimoblasts surrounded by developing envelope with ostiole ostiole gonimoblasts

Mature cystocarp with an auxiliary cell (ac), gonimoblast filaments, medullary cells, carposporangia and a spinose envelope with an ostiole ostiole ac

CONCLUSION 1. Our observations call for establishment of a new genus and combination: Psilophycus alveatus (Turner) W.A. Nelson, Leister & Hommersand. WHAT ELSE WOULD BE IMPORTANT TO KNOW? 2. The behavior of the nuclei in the development of the gonimoblast filaments and the possible role of the modified medullary cells in the formation of the carposporangia should be investigated. 3. The life history needs to be studied: To what extent is the life cycle sexual, apomictic or clonal by vegetative propagation? 4. Etc., etc.