Hattoria 11: 9–11. 2020

New nomenclatural combinations in for the Hawaiian Islands and Aleutian Islands

John R. SPENCE

California Academy of Science, Department of Botany, 55 Music Concourse Drive, Golden Gate Park, San Francisco, CA 94118-4503, U.S.A. Author for correspondence: John R. SPENCE, [email protected]

Abstract Seven species of the genus Hedw. are transferred to other genera for upcoming treatments of the Bryaceae for the Aleutian Islands and Hawaiian Islands. These are Gemmabryum flavituber (R.Wilczek & Demaret) J.R.Spence, G. mauiense (Broth.) J.R.Spence, Imbribryum baldwinii (Broth.) J.R.Spence, I. megalostegium (Sull.) J.R.Spence, hawaiicum (Hoe) J.R.Spence, P. sibiricum (Lindb. & Arnell) J.R.Spence, and P. vermigerum (Arnell & C.E.O.Jensen) J.R.Spence.

Introduction As part of ongoing studies in the Bryaceae, collections of the family from the Hawaiian Islands and for the upcoming Flora of the Aleutian Islands have been studied. The flora of the Aleutian Islands is relatively rich with 36 documented species, with an unusual mix of East Asian, Arctic and cold-temperate elements. Among these species are several new to the region. The Hawaiian Islands have a relatively rich and incompletely documented bryophyte flora. Due to its isolation, the archipelago appears to have a fairly high level of endemism in the . Staples et al. (2004) reported that the overall endemism among moss families was ca. 15%, although ongoing molecular studies may significantly alter this value (Shevock et al. 2019). Studies on the moss family Bryaceae from the islands have had a long and complicated history, with both misidentifications as well as confusion over species concepts. Several of the endemics in the family have been sunk into widespread Indo-Pacific species. However, recent examination of new collections as well as treatments provides strong support for the older treatment by Bartram (1933) as well as several of the endemic species documented in that study. Currently, 23 species have been reported from the islands, although some of these have not been confirmed, with an estimated endemism rate of ca. 30%. In this study, I transfer seven species from the Aleutian and Hawaiian Islands from the broadly conceived but highly polyphyletic genus Bryum Hedw. to other genera including Gemmabryum J.R.Spence & H.P.Ramsay, Imbribryum N.Pedersen and Ptychostomum

9 Hornsch. Details on collections, distributions and ecology will be included in upcoming floristic treatments for the family from these regions. The seven species include five Hawaiian endemics and two northern hemisphere arctic-alpine species.

Taxonomy 1. Gemmabryum flavituber (R.Wilczek & Demaret) J.R.Spence, comb. nov. Basionym: Bryum flavituber R.Wilczek & Demaret, Bull. Jard. Bot. Natl. Belg. 46: 408. 1976. This species was described from Oahu based on a collection from highly disturbed lowland habitats. It appears to be close to G. tenuisetum (Limpr.) J.R.Spence & H.P.Ramsay. Although possibly introduced, the species has not been reported from elsewhere and remains an enigmatic Hawaiian endemic.

2. Gemmabryum mauiense (Broth.) J.R.Spence, comb. nov. Basionym: Bryum mauiense Broth., Bernice P. Bishop Mus. Bull. 40: 14. 1927. Gemmabryum mauiense is an endemic related to the widespread pantropical G. apiculatum (Schwägr.) J.R.Spence & H.P.Ramsay and was previously considered to be that species. However, it differs in having a very short wide-mouthed capsule and much larger irregularly spherical rhizoidal tubers that are orange-red and with protuberant cell walls.

3. Imbribryum baldwinii (Broth.) J.R.Spence, comb. nov. Basionym: Bryum baldwinii Broth., Bernice P. Bishop Mus. Bull. 40: 15. 1927. A large distinctive endemic species from Maui and Kaua’i that has long evenly foliate stems, rigid leaves, and long narrow incrassate laminal cells, all characteristics of the genus Imbribryum.

4. Imbribryum megalostegium (Sull.) J.R.Spence, comb. nov. Basionym: Bryum megalostegium Sull., U.S. Expl. Exped., Musci 9. 7a. 1859. An endemic species that was originally identified as the Eurasian I. mildeanum (Juratzka) J.R.Spence (Staples et al. 2004), from which it differs by its much narrower and longer laminal cells and serrulate distal leaf margins.

5. Ptychostomum hawaiicum (Hoe) J.R.Spence, comb. nov. Basionym: Bryum hawaiicum Hoe, Lyonia 1: 9. 1974. A highly distinctive endemic species with a strong reddish-purple costa and dark purple rhizoids. Leaf characters ally this species with Ptychostomum subg. Cladodium (Brid.) J.R.Spence, and the are reminiscent of small forms of P. creberrimum (Taylor) J.R.Spence & H.P.Ramsay but differ in being dioicous.

10 6. Ptychostomum sibiricum (Lindb. & Arnell) J.R.Spence, comb. nov. Basionym: Bryum sibiricum Lindb. & Arnell, Kongl. Svenska Vetensk. Acad. Handl., n.s. 23: 37. 1890. An arctic-alpine species related to P. pallens (Swartz) J.R.Spence, with very narrow ovate leaves and a long awn, distributed primarily in south and east Russia (Zolotov 2006).

7. Ptychostomum vermigerum (Arnell & C.E.O.Jensen) J.R.Spence, comb. nov. Basionym: Bryum vermigerum Arnell & C.E.O.Jensen, Bot. Not. 1916: 129. 1916. Although Nyholm (1993) accepted this species, most subsequent workers have not, considering it to be atypical material of other small Bryum species such as B. argentum Hedw. or B. oblongum Lindb. It is a tiny julaceous , with most stems ＜1 mm long. The defining characteristic are the slender filiform gemmae found along the stem. Although they are very small and easily overlooked, they appear to be constantly present on all material I have seen. The only taxa in the family with these gemmae are Ptychostomum and Rosulabryum J.R.Spence. Given its arctic-alpine distribution, its Ptychostomum-type laminal areolation, and similarity to depauperate material of several small Ptychostomum species such as P. nitidulum (Lindb.) J.R.Spence and P. teres (Lindb.) J.R.Spence, it is best placed in this genus.

Acknowledgements Thanks to James Shevock and the staff at CAS for providing Hawaiian Island collections, and to Judy Harpel and Olivia Lee and the staff at UBC for Aleutian Island collections. Norm Trigoboff generously provided several interesting personal collections from Hawaii for study.

References Bartram E. B. 1933. Manual of Hawaiian mosses. Bishop Museum Bulletin 101: 1–275. Nyholm E. 1993. Illustrated Flora of Nordic Mosses. Fasc. 3. Bryaceae–Rhodobryaceae–Mniaceae– Cinlcidiaceae–Plagiomniaceae. Nordic Bryological Society, Copenhagen and Lund. Shevock J. R., Flynn T., Game J. C., Ma W. Z., Williams A., Toren D. R., Tan B. C. & Spence J. R. 2019. New additions, range extensions, and nomenclatural updates for the Hawaiian moss flora, island of Kaua’i, USA. Acta Musei Silesiae, Scientiae Naturales 68: 105–122. Staples G. W., Imada C. T., Hoe W. J. & Smith C. W. 2004. A revised checklist of Hawaiian mosses. Tropical Bryology 25: 35–69. Zolotov V. I. 2006. On systematics and distribution of some species of Bryum (Bryaceae, ) in Russia. Arctoa 15: 155–162. manuscript received April 20, 2020; accepted May 8, 2020

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