Taxonomy and nomenclature of four unresolved names published by Udo Dammer in the genus Chamaedorea (Arecaceae)

Abstract Dowe, J.L. & D.R. Hodel (2021). Taxonomy and nomenclature of four unresolved names published by Udo Dammer in the genus Chamaedorea (Arecaceae). Candollea 76: 93–98. In English, English abstract. In 1905, Udo Dammer published an account of Chamaedorea Willd. based on the unpublished manuscripts of his friend and mentor Hermann Wendland who had died in 1903. Dammer introduced numerous novel names, most of which were nomenclaturally valid. However, a few names have remained unresolved. We investigated the nomenclatural status of four names – Chamaedorea exorrhiza H. Wendl. ex Dammer, Chamaedorea galeottiana H. Wendl. ex Dammer, Chamaedorea homomalla H. Wendl. ex Dammer and Chamaedorea inaequilateralis H. Wendl. ex Dammer. We determined that they are validly published but are synonyms of earlier described species. Three new synonyms are proposed and we designate four lectotypes from specimens at GOET. Received: September 10, 2020; Accepted: February 8, 2021; First published online: March 22, 2021


Introduction
With about 107 currently accepted species, Chamaedorea Willd. is one of the largest and most variable palm genera in the Americas (Hodel, 1992a(Hodel, , 1992b(Hodel, , 1995(Hodel, , 1996(Hodel, , 1997Hodel et al., 1995Hodel et al., , 1997Henderson et al., 1995;Bernal et al., 2004;Dransfield et al., 2008). Nomenclature for the genus is extensive with about 260 names found in IPNI (2021). Since Willdenow (1806) established the genus, taxonomic progression has been clustered around the productive periods of a number of taxonomists, the most prominent being Wendland, Dammer, Burret, Standley & Steyermark and Hodel. Notwithstanding the large number of names associated with Chamaedorea, nomenclatural stability is relatively settled in comparison to some other large palm genera (Govaerts et al., 2021).
During research about the great German palm botanist Hermann Wendland (1825Wendland ( -1903 of Royal Gardens at Herrenhausen near Hannover, co-author Dowe uncovered an obscure article that fellow German botanist and horticulturist Udo Dammer (1860Dammer ( -1920, a close associate of Wendland, had written about Chamaedorea (Dammer, 1905 (Hodel, 1992a) or any subsequent publications. It also included another name, C. exorrhiza H. Wendl. ex Dammer, that has been placed by Hodel et al. (1992a) and other authors as a synonym of C. tepejilote Liebm., although there are questions about valid publication that are addressed here.
Our work examines these so far four unresolved names, the objective being to clarify their nomenclatural status and establish them within a taxonomic context.

Material and methods
We searched the taxonomic and horticultural literature to determine if the four names had been used formally or informally. The resources included widely used taxonomic databases such as Govaerts et al. (2021), IPNI (2021), The Plant List (2021) and Tropicos (2021). Other broad-scale searches were made of online published texts in BHL (2021) and Hathi Trust (2021). An examination of Wendland's palm herbarium, formerly at Herrenhausen but incorporated in GOET in 1969, located specimens that Wendland had personally annotated and could be directly associated with the names published by Dammer [as "Morenia (Stephanostachya) exorrhiza", "Ch. galeottiana sp. nov.", "Ch. homomalla" and "Morenia (Chamaedorea) inaequilatera"]. The Shenzhen Code (Turland et al., 2018) was consulted to determine and clarify what constitutes valid publication and typification of the names.

Results and discussion
Although the aim of the dominant online taxonomic resources is apparently to achieve broad consensus, the comparative results amongst them are considerably variable. Three of the four names, Chamaedorea galeottiana, C. homomalla and C. inaequilateralis are not cited in primary online nomenclatural resources for palms such as Govaerts et al. (2021) and IPNI (2021), but are, in contrast, cited in Tropicos (2021) as tentatively valid names and in The Plant List (2021) as unresolved names. The fourth name, C. exorrhiza, is included in all the online nomenclatural resources but is conflicted or unresolved. Dammer (1904aDammer ( , 1904bDammer ( , 1905 provided a descriptive summary of all the then recognised species of Chamaedorea with his work largely based on unpublished manuscripts that Wendland, at that time the worldwide palm expert, presented to him. Toward the end of his career, Wendland intended to prepare a monograph of Chamaedorea, a genus that had occupied a considerable amount of his taxonomic and horticultural energies (Hodel, 1992a). He had provided an early taxonomic account (Wendland, 1854) and described new species through his career (Dowe, 2019).
Dammer commenced to publish the Chamaedorea articles in 1904, the year after Wendland's death. He chose to publish in the Gardeners' Chronicle, a British horticultural periodical that had international reach and, despite its main focus being horticultural, it also included taxonomic articles on plants that were of horticultural interest. Dammer's articles included proposed names and Latin descriptions of some new species, despite his interest in providing a vegetative key for gardeners who would not otherwise have plants with flowers or fruits. The simple-leaved species were treated in two articles (Dammer, 1904a(Dammer, , 1904b whilst the pinnate-leaved species in a single article (Dammer, 1905). It is in this later article that the unresolved names were used.
Dammer structured his work in the Gardeners' Chronicle in the form of an extended text key largely based on the characteristics (i.e. form and dimension) of leaves and leaf segments. Thus, species with morphologically similar leaves were treated as discreet groups and affinities between them and other groups were proposed. He also provided discussion on the generic limits of Chamaedorea and some nomenclatural rationalisation of the names that could be applied to the genus, in particular under the genera Morenia Ruiz & Pav. and Kunthia Bonpl. Dammer (1905) noted that he also intended to complete a monograph of Chamaedorea but this never happened. However the three articles were in themselves a monograph of sorts, as all the then known species were systematically accounted for and new species formally described. The choice of new names in Dammer's articles can unequivocally be attributed to Wendland as Dammer noted that "for the new species where no authority is mentioned Wendland is always the authority" (Dammer, 1905: 44). Therefore authorship of all new names in Dammer's articles is "H. Wendl. ex Dammer". As Dammer did not cite any specimens in his article, it is appropriate to designate lectotypes from the specimens that Wendland had annotated and provided tentative names. Since Dammer considered Wendland as the author of the names, he makes an implicit reference to the original material used by Wendland (see Turland et al., 2018: Art. 9.4(a)). It is reasonable to conclude that Dammer examined the specimens as part of his investigations and not only saw the specimens before publishing the names, but associated them with the respective taxa. These specimens are all held in GOET. Notes. -Dammer (1905) provided the following description when presenting the first use of the name Chamaedorea exorrhiza: leaves pinnate, segments lanceolate, 10 -20 per side, more than 5 cm wide, 9-nerved. Dammer's publication clearly satisfies the requirements of valid publication of the name. Guillaumin (1922: 542) described the same species based on a plant cultivated in the greenhouse in Paris grown from seeds received from Wendland in 1901 because he believed that Dammer's species was not validly published and noted that: "C'est sans doute la même espèce que celle signalée sans description, sous le nom de C. exorrhiza Wendl par Dammer [It is probably the same species reported without description, under the name of C. exorrhiza Wendl by Dammer]". Guillaumin's name has therefore to be treated as an illegitimate later homonym, and a heterotypic synonym, of Dammer's name. Original material in P is a mixed gathering between the Guillaumin collection and the seeds sent by Wendland in the fragment packet of P00725350. Therefore a lectotype is designated here on the Guillaumin cultivated collection from 1921 -1922.
The lectotype of Chamaedorea exorrhiza H. Wendl. ex Dammer chosen here [GOET025396] consists of a single collection composed of five sheets. One sheet has a complete inflorescence including bracts, an inflorescence without bracts, and a leaf petiole. The remaining four sheets hold a complete leaf divided into four sections. The collection was labelled by Wendland as "Morenia (Stephanostachya) exorrhiza".
Chamaedorea tepejilote (Fig. 1A) is one of the most wideranging species in the genus, occurring from Colombia north into Mexico. One of the largest species of the genus in habit, it is unusually variable across its range and is found as solitary or cespitose individuals and has leaves and inflorescences that vary in size and quantity of subdivisions (pinnae and rachillae). In the northern part of its range, especially in Guatemala and southern Mexico, it has been domesticated and cultivated for thousands of years for its unopened staminate inflorescences consumed as a cooked vegetable called "pacaya". Notes. -Dammer (1905) provided the following description: leaves pinnate, segments regularly arranged, either lanceolate, oblong-lanceolate or elliptical, not decurrent, less than 15 per side, less than 3 cm wide, single nerved. The specimen designated here as lectotype for Chamaedorea galeottiana [Galeotti 4972] was cited in Martens & Galeotti (1843) under the name "Chamaedorea oblongata? Mart." and was noted as growing in the woods and dark damp ravines of the German Colony of Mirador from 2,000 to 5,000 feet with yellow flowers in December. After returning to Europe, Galeotti renumbered his collections more or less into family groups, so specimen numbers cannot provide any information about time or place of his collections (McVaugh, 1973). Henri-Guillaume Galeotti (1814 -1858) was a French-born Belgian botanist and collector in Central America (1835 -1840) and later director of the botanic garden of Bruxelles (1853 -1858) (McVaugh, 1973).