Lessonia septentrionalis, ZuccareLLo & School, 2024

Lessonia septentrionalis sp. nov. Zuccarello & D’Archino ( Fig. 3 d View Fig )

Description: Attached by variable to massive rigid/robust haptera and multiple stipes; stipes often flattened, especially in young plants; with blades emanating from the intercalary meristem. Blades split ontogenetically. Blades parallel; various widths, often with widely spaced teeth; distinguished from L. variegata by blades occasionally with striated variegation (stripes of dark and light tissue)( Fig. 6 e, f, g View Fig ); Reproduction as in L. variegata in sori on blades. Distinguished from other species by the genetic regions: Mitochondrial: (1) the spacer between the tRNA’s for tryptophan and isoleucine (trnW-spacer), a partial sequence of the gene coding for nicotinamide adenine dinucleotide (NADH) dehydrogenase subunit 6 (nad6); (2) partial cytochrome oxidase subunit I and 3) the spacer region between adenosine tri-phosphate dehydrogenase subunit 8 and tRNA serine (atp8-Sp); the chloroplast regions: (1) the spacer between the large and small subunit of the ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbc -spacer); (2) ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbc L); the nuclear region covering the internal transcribed spacers (1 and 2) between the small and large ribosomal RNA subunits, and including the 5.8S ribosomal RNA (ITS) ( Martin & Zuccarello 2012, Zuccarello & Martin 2016).

Etymology: Named for its northern geographical distribution on the North Island.

Holotype: WELT A035572 About WELT GoogleMaps

Phycobank registration: http://phycobank.org/104242

Type locality: Motuotau, Bay of Plenty, North Island , New Zealand (37.628735 oS, 176.193603 oE).

Holotype sequence data: rbc L: OR978110; COI: OR978116 About COI ; trn W-L spacer: OR978126.

Morphological identification of species of Lessonia is difficult, both due to the scarcity of characters but also due to the plasticity of these characters, making diagnostic characters difficult to determine. This was recognized by J. Agardh (1878: 6, in Latin) “The species of Lessonia are not easily separated by characters, so the synonymy is as complicated as possible”, despite which he designated L. variegata as a new species. The advent of molecular-assisted taxonomy has helped separate intraspecific variation from interspecific variation. A Lessonia species recognised ( Searles 1978) as L. nigrescens Bory was found along the Chilean coast from 17 oS to 41°S. Molecular studies revealed that two species existed, neither being L. nigrescens , occupying almost completely non-overlapping distributions [ L. berteroana Montagne and L. spicata (Suhr) Santelices ; González & al. 2012; Tellier & al. 2011a; 2011b]. The authors also stressed the importance of recognizing the separate species correctly as wild harvesting needs separate management approaches to conserve these two species resources appropriately ( Tellier & al. 2011c). The species confused under the name L. nigrescens were distinguishable anatomically by the number and diameter of cortical cells and density of medullary filaments ( González & al. 2012). In our experiences, such differences were not obvious in the Lessonia species from New Zealand.

The geographical distribution of the species of Lessonia from mainland New Zealand appears to be non-overlapping (485 samples from 39 populations, Zuccarello & Martin 2016), so species assignments can be made fairly confidently based on location. The species L. berteroana and L. spicata also appeared to be non-overlapping in Chile, but overlapping populations and sympatric populations were found. This overlap was limited to a very small area and did not seem to spread ( Tellier & al. 2011c; Tellier & al. 2011b). Whether these are mixed species populations and whether the distributions of the species in New Zealand have changed since the 2010’s collections needs further study ( Martin, 2011), but these new names will give researchers a taxonomic basis for their research activities.

The species of Lessonia differ subtly from each other. While L. variegata seems to consistently have a spotty variegation on blades ( Fig. 7 View Fig ), this has not been seen in Lessonia media ( Fig. 4 View Fig ), nor has it been observed in L. meridionalis ( Fig. 5 View Fig ). This type of variegation has been rarely seen in L. septentrionalis , but more often a striped (long parallel colour variation), or no variegation, is seen ( Fig. 6 View Fig ). The blades of L. meridionalis are often distinct in having a lighter coloured edge ( Fig. 5 View Fig ). Lessonia septentrionalis also had stipes that were often flattened. Whether any of these characters, or a new set of characters, are completely consistent within the species cannot be determined for certain at this time, but variation in these morphologies has been noted in most of the species based on site and presumed age. Anatomical variation has been studied (e.g. size and abundance of mucus ducts lacunae) but not widely enough to make definitive conclusion of diagnostic anatomical characters ( Martin 2011).

While Lessonia is a commercially utilized crop around the world and experimental cultivation is in its early stages ( Gouraguine & al. 2021; Nardelli & al. 2023) potentially including in New Zealand, a correct nomenclature of the targeted species both for future research and for any management consideration is needed. We hope that this publication with the recognition of three new species in New Zealand provides that.