Pachymeniopsis lanceolata

D’Archino, Roberta & Zuccarello, Giuseppe C., 2021, Two red macroalgae newly introduced into New Zealand: Pachymeniopsis lanceolata (K. Okamura) Y. Yamada ex S. Kawabata and Fushitsunagia catenata Filloramo et G. W. Saunders, Botanica Marina (Warsaw, Poland) 64 (2), pp. 129-138 : 133-135

4.1 Pachymeniopsis lanceolata

Although Pachymeniopsis lanceolata can be easily confused with Grateloupia turuturu , which was previously established

in Lyttelton Harbour/Whakaraupō, as well as with the native Grateloupia urvilleana (Montagne) P. G. Parkinson , its thalli are thicker and firmer in texture and not silky, as are G. turuturu and G. urvilleana (although older plants of these latter species can be tougher). In addition, P. lanceolata thalli had a strong chlorine smell that the other two lack.

The genus Pachymeniopsis was originally described by Kawabata in 1954 based on Aeodes lanceolata Okamura (1934) from material collected in Japan. Pachymeniopsis was later merged with Grateloupia ( Kawaguchi 1997) but was reinstated ( Gargiulo et al. 2013) based on reproductive features and molecular data. The genus Pachymeniopsis currently includes four species native in northeast Asia ( Guiry and Guiry 2021): P. lanceolata , P. gargiuloi S. Y. Kim, Manghisi, Morabito et S. M. Boo , P. pseudoellittica S. Kawabata and Pachymeniopsis volvita M. Y. Yang et M. S. Kim. Only P. lanceolata and P. gargiuloi have been reported outside their native range. Pachymeniopsis lanceolata has been introduced to Thau Lagoon, Mediterranean France,

probably with Asiatic oysters in the 1970s or later ( Verlaque 2001; Verlaque et al. 2005). In 2003, it was discovered at Santa Catalina Island and in southern California in 2008 ( Miller et al. 2009). It has been recorded from the Canary Islands ( García-Jiménez et al. 2008) and has been found in Sydney harbour (https://www.nationaltribune.com.au/nonnative-marine-algae-detected-in-botany-bay/). Pachymeniopsis gargiuloi so far has been introduced only to Italy ( Kim et al. 2014) and northern Spain ( Montes et al. 2016).

The genetic diversity of New Zealand samples of P. lanceolata , assessed by cox 3 sequence data, revealed a haplotype ( C 9) of P. lanceolata found in Korea and the USA ( Kim et al. 2014). While it is more likely that this species came from Asia rather than California, this alternative route cannot be eliminated based on our data. If from Asia, it is interesting that the same haplotype has established in two non-native environments, which could be just a coincidence or an indication of some particular physiological property of haplotype C 9. It is known that within species different genetic variants can have different physiological properties (see Zuccarello et al. 2001). The North Island sample is of a novel haplotype ( C 17) not found before in New Zealand or in any samples from its native range ( Kim et al. 2014). This could represent either a novel introduction from its native range of a haplotype not sampled, or a range expansion from a single previous introduction that went undetected. Increased sampling is needed both in New Zealand and overseas, especially within its native range, to determine if these two populations are derived from one or separate introductions.

In France’ s Thau Lagoon, P. lanceolata has successfully established and developed reproductive populations without becoming invasive ( Verlaque et al. 2005). Its possible expansion in New Zealand should continue to be monitored and its phenology studied. Miller et al. (2009) warned that monitoring of this species was needed as it has been reported to act as a ‘weed’ having ‘ample reproduction, tenacious recruitment and broad physiological tolerances’ ( Nyberg and Wallentinus 2005). From our observations it seems that P. lanceolata can form large populations that could spread easily. In winter 2019, few plants were encountered at Te Ana Marina, whereas in summer and winter of 2020 it was one of the dominant species, in conjunction with F. catenata and G. turuturu . Both gametophytic and tetrasporangial thalli were growing on artificial substrata and mussels and were reproductive (both carposporophytes and tetrasporophytes present).