Ботанический журнал, 2019, T. 104, № 9, стр. 1468-1474

Kelp taxa are among the most studied algae in the flora of the world ocean due to their high ecological and economic importance. For most regional floras, revision of kelp species composition is believed to be completed (Wynne, 1969). However, the validity of some species described in the past centuries is still questionable, and to solve such issues type specimens should be studied in some cases, although they may be difficult to find and access or can even be lost. In other cases, one should thoroughly compare different forms of species morphological variability, and in some cases, karyological, cultural, molecular-phylogenetic or other studies are required.

In the history of kelp study, different morphological forms of a species were described as different species or even different genera. For example, different morphotypes of the far eastern species Hedophyllum bongardianum (Postels & Ruprecht) Yendo were referred to the genera Hedophyllum Setchell (Yendo, 1903) and Streptophyllum Miyabe et Nagai (Nagai, 1940). Petrov and Suchovejeva (1976) described morphologically abnormal samples of Laminaria gurjanovae Zinova as a new species, Laminaria multiplicata Petrov et Suchovejeva (Klochkova et al., 2010). We suspect that haploid parthenosporophytes of the kelp species might have been described as new species at times, since their morphology differs from that in the diploid sporophytes of the same species, as shown in case of Tauya basicrassa Klochkova et Krupnova (Klochkova et al., 2017). In this paper, we investigated the case of incorrect description of the representative of genus Durvillaea Bory as a new species, Laminaria himanthophylla Postels et Ruprecht.

We studied the specimens of Laminaria himanthophylla collected during the round-the-world expedition by F.P. Litke and M.N. Stanyukovich (1826–1829), preserved in the Komarov Botanical Institute (Russia, St. Petersburg, LE) (Figs. 1–3). Also, in order to find any other existing specimens of L. himanthophylla we searched electronic catalogues of the herbaria of Swedish Museum of Natural History (Sweden, Stockholm, S), Muséum National d’Histoire Naturelle (France, Paris, PC) and British Museum of Natural History (UK, London, BM).

The species L. himanthophylla was described in 1840 (Postels, Ruprecht, 1840: 2, pl. 39: fig. 32 ) based on the study of herbarium materials collected by the botanist K.H. Mertens in Chile during the round-the-world expedition by F.P. Litke and M.N. Stanyukovich (1826–1829). Postels and Ruprecht (1840) provided a very brief description of its morphology and a single illustration of the blade cross-section (Fig. 4), indicating large thalli size, an unusual blade shape, presence of a hollow stipe, and ‘sporidia’ developing in the outer cortex layer of the blade as characteristic features of this species.

The absence of the type specimen illustration or records, that would specify which plants were studied by Postels and Ruprecht (1840) to describe L. himanthophylla did not allow to check its status as a species. However, it was taxonomically accepted by phycologists in 19th century. To date, there are few reports on L. himanthophylla in the checklists of kelp species from the world ocean (Endlicher, 1843: 27; Berger, 1846: 174; Le Jolis, 1855: 71; Kuntze, 1891: 914). Usually, all the reports repeated the same information as initially specified by Postels and Ruprecht and referred to their original work. Swedish scientist J. Agard first doubted the status of L. himanthophylla as a separate species, calling it as a doubtful species (species inquirendæ) (Agardh, 1848: 136). Later, De Toni (1895: 351) also attributed this species to the category of doubtful taxa (species maxima dubiæ). In the late 19th century, Setchell (1893) analyzed the distribution of the kelp species in the world ocean. As he noticed, among 28 representatives of the genus Laminaria only 1 species, L. himanthophylla, was described from the South Pacific American coast. He also noticed the lack of new collections of this species from 1827 to 1895, and considered its generic attribution controversial (Setchell, 1893: 363).

In the last decades, the genus Laminaria was repeatedly revised by Russian and foreign phycologists (Shchapova, 1948; Petrov, 1975; Kain, 1979; Bartsch et al., 2008; Bolton, 2010), but none mentioned L. himanthophylla. In modern references on the seaweed checklists and resources from Chile, Laminaria species were not mentioned, and the only kelp species reported from this region were Durvillaea, Macrocystis, and Lessonia (Bolton, 2010; Fraser et al., 2010; Camus et al., 2018). Thus, although L. himanthophylla is recognized as a separate species by AlgaeBase (Guiry, Guiry, 2019), no evidence exists that it is present in the southeastern Pacific Ocean.

The study of L. himanthophylla authentic specimens would solve a problem regarding its taxonomic status. The algal specimens collected during the round-the-world expedition by Litke and Stanyukovich (1826–1829) are known to be stored in S, PC, BM, and LE. We searched electronic databases at the official websites of S, PC, BM herbaria and, to the best of our knowledge, none contained specimens of L. himanthophylla. We also worked with the type herbarium collection in LE (St. Petersburg) and found surviving specimens of L. himanthophylla. One of them (specimen LE A0000302) is composed of two fragments of the blade and has no original label. On its modern label, only the species name and country are indicated – Laminaria himanthophylla P. et R., Chili. Currently, it is not possible to state whether this specimen was a part of the original material; however, it was stored with other type specimens, suggesting that it was used by Postel and Ruprecht in describing this species.

The second specimen (LE A0000301) is illustrated in Figs. 1–3. Its original label contains information in Ruprecht’s handwriting: “Laminaria himanthophylla P. et R., Chile, leg D Mertens” (Fig. 3) and this information is consistent with L. himanthophylla protologue. Indeed, K.H. Mertens visited Chilean coast during the round-the-world expedition by Litke and Stanyukovich; therefore, this specimen (LE A0000301) is a part of the original material. Postels and Ruprecht did not specify exact collection site in the protologue, but according to their publication (Postels, Ruprecht, 1840: 2) and the field diary of captain F.P. Litke (1835a), the ship “Senyavin” was at the coast of Chile in the Bay of Concepción on March 16–17, 1827 and in the Bay of Valparaíso on March 27–April 15, 1827.

In his records, Litke mentioned several days-long works of his expedition’s naturalists in the suburb of Almendral, Bay of Valparaíso (Litke, 1835b: 45, 48) and one day-long stay near Tome settlement in the Bay of Concepción (Litke, 1835b: 41). These two bays are located in the center of the Chilean coast, approximately 450 km apart from each other. Based on the available information, it is impossible to identify in which bay L. himanthophylla was collected, but it is certain that samples were collected between 32° and 36° South latitude on the Chilean coast.

The specimens of L. himanthophylla from LE herbarium collection are well-preserved. The specimen illustrated in Fig. 1 has a thallus up to 1 m long, with a cylindrical stipe 7 cm long and 1 cm wide in its basal part, and without organs of attachment. In the blade’s basal part, the stipe is slightly wider. The blade’s basal part is wedge-shaped, leathery, thicker than the upper part (Fig. 2). At the distance of 9–12 cm from its basal part, it splits into 21 straplike blades 7 to 80 cm long and 2–5 cm wide. The straplike blades have smooth edges and are narrower in the basal part than in the upper part. The organs of attachment are missing, so we cannot accurately identify these surviving specimens on the species level, but their genus level is obvious.

Postels and Ruprecht (1840) did not mention organs of attachment in L. himanthophylla, although they clearly described them for other laminarialean algae. Thus, we assume that they studied the plants of L. himanthophylla without the organs of attachment, and the specimen from Fig. 1 was probably the only specimen with an intact blade. It is also confirmed by the identity of size characteristics of the specimen studied by us with the data specified in the protologue of L. himanthophylla. It seems unlikely that a new Laminaria species was described solely based on the specimen LE A0000302, which consists only of two blade fragments. Also, it is not possible to prove that the authors described L. himanthophylla using only specimen LE A0000301. Based on Art. 9.3 of the International Code of Nomenclature for algae, fungi, and plants (Turland et al., 2018) we designate the sample shown in Fig. 1 as the lectotype.

Fig. 1.

The authentic specimen of Laminaria himantophylla collected by K.G. Mertens from the Chilean coast during the expedition by F.P. Litke and M.N. Stanyukovich (1826–1829) and preserved in LE. 1 – general view of the specimen, 2 – blade’s basal part, 3 – original label written in F.I. Ruprecht’s handwriting, 4 – original illustration of the internal structure provided by Postels and Ruprecht (1840). Scale: 1 – 10 cm, 2 – 5 cm.

The species description was accompanied by a drawing (Fig. 4) and explanation of the blade internal structure (Postels, Ruprecht, 1840). As they noted, L. himanthophylla had ‘sporidia’ located in the outer cortex and visible to the naked eye (Postels, Ruprecht, 1840: 5, pl. XXXIX: fig. 32 ). Until early 1900s, the term ‘sporidia’ was used as a synonym for the term ‘spore’, but nowadays this term is outdated and not used regarding the brown algae. Also, asexual and sexual reproduction has not yet been described in the laminarialean algae at the time of publication of ‘Illustrationes algarum’ (Postels, Ruprecht, 1840), thus some inconsistency is found with the modern phycological terminology. However, Postels and Ruprecht clearly indicated that the structures designated by them as ‘sporides’ were associated with reproduction (Postels, Ruprecht, 1840: 7, §10).

Based on ‘sporidia’ location on the thallus, Postels and Ruprecht attributed L. himanthophylla to the same group with Fucus, Cystoseira, and Corallina in the section “Addition to the seaweed anatomy” (Postels, Ruprecht, 1840: 7); however, the location of reproduction organs in these algae differs from the laminarialean algae. It is currently known that in the above-mentioned genera concepticales are the reproductive structures, but they are not found in all kelp species. As to remaining laminarialean algae, Postels and Ruprecht (1840) attributed them to another group based on the type of sporangial sori location. This clearly indicates that the sample, which they described as L. himanthophylla does not belong to the genus Laminaria, although it shows great similarity with its representatives.

In addition, as noted above, only representatives of Macrocystis and Lessonia are found from the laminarialean algae on the coast of Chile. Morphologically, they differ significantly from all species of the genus Laminaria. Their stipes are dichotomously branched, the blades are formed due to splits in the basal part, and each new branch of the stipe carries a separate blade. In addition, Macrocystis pyrifera has pneumatocysts, which are absent in the specimen of L. himanthophylla seen by us. Finally, because Postels and Ruprecht indicated the presence of concepticals in this species, it is obvious that it does not belong to the genus Laminaria, as well as to the order Laminariales.

In the area under discussion, among the brown algae (Phaeophyceae) only the fucalean species are characterized by large thalli and the presence of conceptacles. Representatives of the genus Durvillaea have the greatest morphological similarities with L. himanthophylla. The genus Durvillaea includes 6 species (Hay, 1979; Fraser et al., 2010, 2012; Guiry, Guiry, 2019) and the center of its species diversity is Australia and New Zealand (Fraser et al., 2010). Currently, it is known that in the southeastern Pacific, in particular off the coast of Chile, the only Durvillaea species is D. antharctica. Obviously, it was described by Postels and Ruprecht as L. himanthophylla. We propose to exclude it from the genus Laminaria and consider as heterotypic synonym of D. antarctica.

It is noteworthy that Durvillaea potatorum was recorded from Chile, however, it was based on Bory de Saint-Vincent’s records (1826–1828) and requires confirmation (Kim, 1971; Ramírez, Santelices, 1991). During the last 200 years, there has not been a single documentary evidence of this species being present in South America. In all revisions, D. potatorum was recorded as an Australian endemic species (Hay, 1979; Fraser et al., 2010). Therefore, we exclude the possibility of attributing our specimen to this species (see Fig. 1).

During an investigation of the Chilean marine algal flora, there was a similar example of describing Durvillea species as a new Laminaria taxon. In the early 19th century, Laminaria caepaestipes (Montagne, 1839) was described from the Pacific coast of South America, but it was later transferred to the genus Durvillaea (Skottsberg, 1907).

Herein, we present the following taxonomic information on L. himanthophylla:

Laminaria himanthophylla Postels et Ruprecht

Status of name: heterotypic synonym of Durvillaea antarctica (Chamisso) Hariot.

Description: Postels et Ruprecht 1840: 2, pl. XXXIX: fig. 32 .

Type locality: central part of Chile (Bay of Concepción, Bay of Valparaíso).

Lectotype (here designated): LE A0000301, dried specimen deposited at Herbarium of Komarov Botanical Institute (LE!) (Figs. 1–3).

Collector: K.H. Mertens.