Journal of Applied Phycology 11: 411–419, 1999. © 2000 Kluwer Academic Publishers. Printed in the Netherlands. 411 An evaluation of characters obtained from life history studies for distinguishing New Zealand Porphyra species G.A. Knight & W.A. Nelson ∗ Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington, New Zealand ( ∗ Author for correspondence; e-mail: wendyn@tepapa.govt.nz) Received 8 June 1999; revised 12 June 1999; accepted 12 June 1999 Key words: Bangiales, Porphyra life history, culture, conchocelis, conchosporangia, spores, neutral conchospores morphology, taxonomy Abstract Since 1992, as part of a study to circumscribe the genus Porphyra in New Zealand, an extensive culture programme has been developed at the Museum of New Zealand Te Papa Tongarewa. This collection currently houses more than 800 cultures and 150 strains. We currently recognise at least 20 species in New Zealand, most of which are undescribed. Close observation of reproduction and the development of conchocelis-phase filaments grown in the laboratory, under controlled conditions of temperature, irradiance and photoperiod, has enabled the recognition of characters that can assist in species separation. The comparative taxonomic value of a range of such characters is discussed, including reporting a novel reproductive mode. Introduction The taxonomy of the genus Porphyra is notoriously problematic. Some species exhibit a great deal of phenotypic plasticity in the gametophyte phase whilst in other species complexes it has been difficult to identify genetically distinct but morphologically sim- ilar taxa (e.g. Hannach & Waaland, 1989; Lindstrom & Cole, 1992a; Brodie et al., 1996). Species cir- cumscriptions based on convergent morphologies of the foliose thallus, misapplication of species names, and blurred species boundaries have been some of the problems affecting taxonomic studies in this genus. Uncertainty about the reliability of particular charac- ters for the recognition of species limits is a recurring concern expressed in the literature. In order to clarify species limits, various non-morphological characters have been examined, including sequence data (Stiller & Waaland, 1993, 1996; Oliveira et al., 1995; Brodie et al., 1996, 1998), isozyme composition, using starch gel electrophoresis (Lindstrom & Cole, 1990, 1992a, 1992b, 1992c; Abo and Noda, 1995; Abo et al., 1996), karyology (Lindstrom & Cole, 1992b) and physiology and ecology (Suto, 1972; Mumford, 1975; Waaland et al., 1990; Sidirelli-Wolff, 1992; Lindstrom & Cole, 1993). Diversity within the genus Porphyra in New Zeal- and has been the subject of our research for about ten years. Prior to this work it was generally understood that there was a single epilithic species present around mainland New Zealand (Chapman, 1969; Conway & Wylie, 1972), and that the archipelago exhibited a ‘paucity of forms’ of Porphyra (Conway & Cole, 1973). The discovery of many taxa requiring circum- scription (Nelson & Adams, 1990; Nelson, 1993; Brostoff and Gordon, 1997; Nelson et al., 1998) has challenged us to examine the genus in detail, employ- ing a range of techniques. Apart from morphological, anatomical, ecological and cytological observations, we are including data from life history studies, cell wall carbohydrate chemistry and molecular biology (Nelson & Knight, 1996; Nelson & Broom, 1997; Broom & Nelson, 1998; Nelson et al., 1998). In this paper, we examine whether morphological features of the conchocelis phase, aspects of spore release, and accessory asexual reproductive modes