Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Actinella aotearoaia

R.L.Lowe, B.J.F.Biggs & F.Francoeur

Actinella aotearoaia

Type slide

BM slide 100921, The Natural History Museum, Department of Botany, London. Collected from Ariels Tarn, Harman Pass (Arthur's Pass National Park, South Island, New Zealand), surface sediment samples.


Institution holding the type material

Publication

Known distribution

Known from epiphytic and sediment samples from New Zealand's South and Stewart Islands, and probably from the North Island. Also known from Sydney, Australia.

Etymology

After "Aotearoa", a common Maori name for New Zealand.

Description

Cells clavate in girdle view, 9.0-31.2 (20.1 ±6.3) µm long, attached to the substratum via a long mucilaginous stalk. Two elongate, valve-appressed plastids. Valves strongly clavate and slightly semi-arcuate, 2.5-3.5(2.5 ±0.4) µm wide at midpoint; larger specimens distinctly sole-shaped. Headpole 3.3-6.2(4.5 ±0.7) µm wide, rounded, strongly bulged on the dorsal and ventral side, and strongly asymmetrical about the apical plane. Footpole 1.0-2.2(1.4 ±0.3) µm wide, not tumescent. Striae 16-20 (18.3 ±1.4) in 10 µm, parallel to radiate at the headpole. Areolae round, occluded by volate vela. No marginal spines. Sternum indistinct. Raphe short, largely situated on the valve mantle; distal ends bent onto the valve face. Helictoglossae small, but usually clearly visible on the ventral side of the valve. Rimoportula one per valve, lying on the ventral side of the footpole or headpole on the valve face:mantle transition; in a complete frustule, the rimoportulae of the two valves always lie at opposite poles. Cingulum composed of 4 open, strongly curved, porous copulae.

Notes

Images published online with kind permission from the British Museum of Natural History.

Funding from TFBIS (Terrestrial and Freshwater Biodiversity Information System), administered by the New Zealand Department of Conservation, is gratefully acknowledged.

Reference

Sabbe K, Vanhoutte K, Lowe RL, Bergey EA, Biggs BJF, Francoeur S, Hodgson D, Vyverman W 2001. Six new Actinella (Bacillariophyta) species from Papua New Guinea, Australia and New Zealand: further evidence for widespread diatom endemism in the Australasian region. European Journal of Phycology 36: 321-334.