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. NelsonNational 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 thallusshowing the canaliculae and curved tips

Joseph Banks, 1774

Sir Joseph Banks (Barron)

Fucus alveatus Turn.Lectotype: BM,Ex. Herb. Banks

Fucus alveatus Turner1819, 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 Zealand Motuarohia Island (‘Motuaro’)

CaptainCook

Mercury Bay

Mercury Bay

Bay of Islands

Phyllophoraceae

'alveata'

Gigartina / Rhodoglossum

Chondracanthus

OstiophyllumSarcothalia

'skottsbergii'

Iridaea / "Sarcothalia"

Mazzaella

Chondrus

100

76

52

84

100

81

99 100

10076

94

1000 Bootstrap replicates

L = 2146 Cl = 0.341 RI = 0.693

L = 2164 CI = 0.341 RI = 0.693

20 changes

Phylogeny of theGigartinaceae

rbcL tree

subgenus Eogigartina

subgenus Chondracanthus

Mastocarpus stellatusPhyllophora 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 showingtypes of internal

pericarps

Green = secondary filaments

Auxiliary cell

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

cortex

medulla

Auxiliary cell

Cortical cells form rosettes of short-celled filamentsMedullary cells (arrowheads) undergo intercalary cell divisions

cortex

medulla

gonimoblasts

The auxiliary cell has produced gonimoblastsThe modified medullary cells have formed rosettes

developing envelope

Gonimoblastfilaments (g)elongate and ramify through

the medulla

g

Older stage with amixture of gonimoblastfilaments, medullary

cells and carpo-sporangia

Carposporangiaappear to arisefrom 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.