New combinations in Odontostemma (Caryophyllaceae)

Abstract Sixty-three new combinations in Odontostemma (Alsineae, Caryophyllaceae) are made to accommodate placement of all currently recognized taxa of Arenaria subg. Odontostemma within the genus Odontostemma.


Introduction
In their study of relationships in Arenaria L. and major lineages within the Alsinoideae using nuclear and plastid DNA, Harbaugh et al. (2010) found that three members of A. subg. Odontostemma (Benth. ex G. Don) F.N. Williams clustered in a clade with Pseudostellaria Pax and Lepyrodiclis Fenzl, distinct from most of Arenaria s.s., instead clustering more closely with Stellaria L. and Cerastium L. Th is alignment was also seen in the broad study of family relationships by Greenberg and Donoghue (2011). Sadeghian et al. (2015) completed the most recent and more comprehensive analyses of Arenaria in the broad sense. Th ey confi rmed the results of Harbaugh et al. (2010) and Greenberg and Donoghue (2011), showing that Arenaria s.s. and Eremogone Fenzl are in diff erent clades and are each monophyletic and that Arenaria subg. Odontostemma is in a third clade separate from those including Arenaria s.s. and Eremogone; Odontostemma is also monophyletic. In addition, Arenaria subg. Solitaria McNeill is sister to Odontostemma and subg. Dolophragma (Fenzl) McNeill appears distantly related to any Arenaria species; both of these subgenera should also be excluded from Arenaria and treated as distinct genera.
With only seven names currently available in Odontostemma (six provided by Sadeghian et al. (2015) for species they sampled), nearly all members of Arenaria subg. Odontostemma require new combinations in Odontostemma. With active fl ora projects in India (Flora of India Checklist, in prep.) and China (Flora of China, e.g. Wu et al. 2001) bringing more information to light about these areas, we feel that it is time to supply the 63 combinations necessary for recognizing remaining taxa as members of the genus Odontostemma.

Methods
Th e information about type specimens of the basionyms of the new combinations that we have included is based on examining protologues and searching major indices (Tropicos -http://www.tropicos.org/; JSTOR Global Plants -https://plants. jstor for extant specimens. We also examined images of specimens at A which had not been included in JSTOR and at KUN for twenty-one taxa where information in the CVH appeared to be incomplete. Herbarium abbreviations follow Index Herbariorum (Th iers 2016, continuously updated, http://sweetgum.nybg.org/science/ih/). We have examined a digital image from one (or more) of these sources for any specimen for which we cite a barcode in the type citations. In cases where specimen deposition is not clearly stated in a protologue, we have added "?" after the abbreviation where, based on information about the location of the herbarium where the author worked and/or deposited their herbaria (see Index of Botanists -http://kiki.huh.harvard.edu/databases/ botanist_index.html), we expect, but cannot confi rm, a type specimen should have been deposited.
In the cases where syntypes are cited, we have refrained from designating lectotypes. It is not a requirement for the names to be validly and eff ectively published and we consider those decisions should be made during the course of a taxon-level revision where a serious study of all specimens would lead to the best selections.

Discussion
Odontostemma Benth. ex G. Don was originally described by Bentham to segregate O. glandulosum Benth. ex G. Don from Arenaria (Don 1831). Most subsequent authors have included Odontostemma in Arenaria, most recently as a subgenus (McNeill 1962, Wu et al. 2001). Arenaria subg. Odontostemma includes about 65 species (Wu et al. 2001), all native to eastern Asia with 57 species endemic to China (Wu et al. 2001). Wu et al. (2001) noted that species have sometimes been grouped into fi ve sections (two of which have not been validly published); Sadeghian et al. (2015) suggested it is premature to suggest subdividing the genus pending additional taxon sampling.
Odontostemma taxa can be recognized by a combination of characters. Most members have two, or seldom three (or more in one species), styles, sepals that curve outward distally and are saccate proximally with truncate or acute apices, and seeds with an infl ated testa that lacks reticulate striations. If one were to apply the generic segregations reported in Sadeghian et al. (2015) to the Wu et al. (2001) treatment of Arenaria in China, the 102 species would be distributed among fi ve genera, with Arenaria comprising just six species.
A key to these genera, based in part on McNeill (1962) and Wu et al. (2001), follows: Key to Arenaria and segregate genera

Excluded taxa
Arenaria longistyla var. eugonophylla Although appearing in Wu et al. (2001) and attributed to Fernald as published in Rhodora 21: 5. 1919, this name does not appear on that page and we have not been able to locate a place of publication.
Th is taxon is likely related to O. bomiense (Wu et al. 2001). It was described in Chinese, thus was invalidly published, and was mentioned, but not validly published, by Wu et al. (2001).