Unnamed for over 30 years: Gigartina falshawiae sp. nov. (Gigartinaceae, Rhodophyta) and its confusion with Iridaea tuberculosa in New Zealand

Abstract

ABSTRACTGigartina species are very common and abundant on intertidal rocky shores in New Zealand but members of this genus and the family Gigartinaceae are still not fully documented. A well-known species, distributed as No. 164 of the Lindauer Nova-Zelandicae Exsiccatae, were labelled by Lindauer as Gigartina tuberculosa from material collected in Stewart Island. However, Gigartina tuberculosa (as Chondrus tuberculosus) was described based on specimens collected from the New Zealand subantarctic Auckland Island. Later, material from the Strait of Magellan was referred to this species. In 1993, Gigartina tuberculosa was transferred to Iridaea tuberculosa with its distribution considered to be Chile, Cape Horn, Antarctica, Falklands Islands, Tristan da Cunha, Gough Island and the Campbell Plateau. The species distributed by Lindauer is here described as Gigartina falshawiae sp. nov. These species can be differentiated morphologically: G. falshawiae has thalli that are forked, somewhat irregular and form bushy clumps, with proliferations at the margins and on the blades, and with cystocarps surrounded by lobes, whereas thalli of Iridaea tuberculosa are fan-shaped, lack proliferations, and have globose cystocarps. The distributional ranges of these species also differ: G. falshawiae is found on Stewart Island and I. tuberculosa on the New Zealand subantarctic islands (recorded from the Antipodes, Auckland and Campbell Islands), while the species co-occur on the Snares Islands.