Research Article |
Corresponding author: Grzegorz J. Wolski ( grzegorz.wolski@biol.uni.lodz.pl ) Academic editor: Matt Renner
© 2020 Grzegorz J. Wolski, Jarosław Proćków.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wolski GJ, Proćków J (2020) A new synonym from Hawaii and lectotypification of Plagiothecium longisetum (Plagiotheciaceae). PhytoKeys 164: 21-31. https://doi.org/10.3897/phytokeys.164.56612
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Plagiothecium mauiense was first described in 1927 by V.F. Brotherus, based on materials from Hawaii. It has, so far been, treated as a separate species. A detailed analysis of the original material housed in the New York Botanical Garden Herbarium (NY01256708) found the specimen to be characterised by a lack of metallic lustre; concave, asymmetrical, lanceolate to lanceolate-ovate leaves, shrunken in their dry condition; a straight, not denticulate, acute to apiculate apex; elongate-hexagonal cells in irregular transverse rows, 101–131 × 15–21 µm at mid-leaf; very lax areolation, with decurrencies composed of three rows of cells. These characteristics indicate that this species is identical to the original material of P. longisetum (e.g. H-SOL 1563 011; PC0132572). Hence, we propose that P. mauiense should be recognised as a new synonym of P. longisetum. In addition, a review of P. longisetum syntypes found one (H-SOL 1563 011) to have the same date of collection as the protologue, and to possess a quite abundant gametophyte turf with well-preserved sporophytes, indicating it to be fertile. Considering the above, we propose that specimen H-SOL 1563 011 be designated the lectotype of P. longisetum.
Codes of Botanical Nomenclature, Orthophyllum section, Plagiothecium, Plagiothecium mauiense, Plagiothecium nemorale, typification
In this paper we demonstrate that all the characteristics of the original material of P. mauiense Broth. are identical to those of the P. longisetum Lindb. type. Hence, we propose P. mauiense as a new synonym of P. longisetum. In addition, among the three syntypes of P. longisetum, we propose the specimen (H-SOL 1563 011) deposited at the Herbarium of the University of Helsinki (Finland) as the lectotype of this name. The aim of the work is to demonstrate that P. mauiense and P. longisetum are synonyms, and to propose a lectotype for the name of the latter.
The study was based on herbarium specimens analysed during research conducted at the NY Herbarium (The New York Botanical Garden, New York, U.S.A.) from November to December 2018 and November to December 2019, as well as at the PC Herbarium (Muséum National d’Histoire Naturelle, Paris, France) in January 2019; and on specimens loaned from the H Herbarium (The University of Helsinki, Helsinki, Finland). However, due to renovation ongoing at the S Herbarium (The Swedish Museum of Natural History, Stockholm, Sweden) and the temporary closure of some herbaria, some less important specimens could not be examined; despite this, they are cited in the manuscript to present the most complete dataset possible. Specimens that were analysed directly were marked with an exclamation mark.
In Hawaiian Mosses, V.F. Brotherus described a new species, Plagiothecium mauiense, based on materials collected by D.D. Baldwin from Hawaii (
During the revision of Plagiothecium nemorale sensu lato, the original materials collected by D.D. Baldwin from Hawaii were found in four herbaria: Harvard University Herbarium (FH00220142), New York Botanical Garden Herbarium (NY01256708), Miami University Herbarium (MU 000000546), and Yale University Herbarium (YU 233890). On the envelopes of two specimens, from the MU and NY Herbaria, notes indicating them to be isotypes of P. mauiense were also found. In 1967, a similar note was added to the specimen from the NY Herbarium (NY01256708) by H.A. Miller, who studied this material (Fig.
However, given the above, and according to Article 9.6 of the Shenzhen Code (
Three years later, on April 3, 1970, following a study by H.A. Miller, Z. Iwatsuki analysed the same material (NY01256708) and attached a note (dated April 4, 1970) to the examined specimen, together with hand-drawn pictures of its gametophyte (Fig.
Over 40 years later (June 25, 2012), the specimen deposited at the New York Herbarium (NY01256708) was reviewed by J.T. Wynns, who added the note: “Insular form of Plagiothecium nemorale (Mitt.) A. Jaeger”. In addition, in his revision of the genus Plagiothecium, he also added next to P. mauiense that the material did not differ from the type of Stereodon nemoralis Mitt. (being a basionym of P. nemorale) (
Despite the above-presented assumptions indicating that P. mauiense, recorded from Hawaii, is closely related or even identical to S. nemoralis, the two are still treated as separate species (see:
The features given in the diagnosis by
Its light green to yellow green turf colour, leaf asymmetry and narrow cell areolation and irregular arrangement of cells reported by
The above-presented features and a detailed analysis of the specimen deposited at the New York Herbarium (NY01256708) indicated that this material represents P. longisetum. The specimen is large, light green to yellowish green, without metallic lustre; stems up to 2–2.5 cm long, complanate-foliate, rounded in cross-section, 330–380 µm in diameter, a developed central strand, epidermal cells 7–16 × 14–24 µm, parenchyma thin-walled, 22–47 × 19–43 µm; leaves gently concave, asymmetrical, lanceolate to lanceolate-ovate, spreading, shrunken in dry conditions, those from the middle of the stem 2.5–2.7 mm long, and 1.1–1.5 mm in width, measured at the widest point; the apex straight, not denticulate, acute to apiculate; two costae, extending almost to ½ leaf length, reaching 0.50–0.70 mm; elongate-hexagonal cells in irregular transverse rows, areolation very lax; cells reach 85–134 × 15–20 µm at the apex, 101–131 × 15–21 µm at mid-leaf, and 113–170 × 18–25 µm at the lower part of the leaf; decurrencies of three rows of rectangular cells, 32–44 × 15–31 µm (Fig.
Plagiothecium mauiense from the NY Herbarium (D.D. Baldwin 221, NY01256708) A the plain leaf apex B the grey arrow indicates the three rows of decurrencies C the stem cross section D–F the shape and dimensions of cells from individual leaf zones: D from the upper part E from the middle part F from the lower part of the leaf. Scale bars: 50 µm (B); 150 µm (A, D, E); 200 µm (C, F).
As only one syntype was examined (NY01256708), and due to the current inability to examine specimens from the other three herbaria (from FH, MU, YU), lectotypification of P. mauiense will be carried out later, once all original materials collected by D.D. Baldwin from Hawaii have been examined.
Lindberg described Plagiothecium longisetum in Contributio ad Floram Cryptogamam Asiae Boreali-Orientalis based on materials collected by C. Maximovicz from Japan (
At the beginning of the 20th century,
During this revision, the specimens on which
In addition to the description of gametophyte morphology given in the diagnosis of P. longisetum,
The specimen deposited at the herbarium in Helsinki (H-SOL 1563 011) was awarded the same date of collection as in the prologue, and is characterised by a fairly large, well-preserved gametophyte turf with three sporophytes (Fig.
The material deposited in Helsinki (H-SOL 1563 011) is distinguished from other analysed syntypes by the presence of a fairly large gametophyte turf and more importantly, well-preserved sporophytes (Fig.
Plagiothecium longisetum Lindb., Acta Soc. Sci. Fenn. 10: 232 (1875). – Lectotype (designated here): [Japan], ad Nikosan ins. Kiusiu, [fertile], 16 Junii 1863, S.O. Lindberg s.n. (lecto-: H-SOL 1563 011!, isolecto-: PC0132572!, S-B160017) = P. mauiense Broth., Bernice P. Bishop Museum Bulletin 40: 28 (1927), syn. nov. Type: [United States], Hawaii, E Maui, Haleakala, 8000 ft., in damp ravines, fertile, June 1876, D.D. Baldwin 221 (syn-: NY01256708!, FH00220142, MU000000546, YU233890).
We are grateful to Sannamaija Laaka-Lindberg, PhD, the Curator of Collections of the Briological Herbarium at the University of Helsinki (Finland) and Laura Briscoe, MSc, Collections Manager of the Cryptogamic Herbarium NY (New York Botanical Garden, USA) for the loan of type specimens.