Introduction

Syzygium Gaertn. is the largest genus in Myrtaceae, comprising approximately 1,200 species distributed in the tropics and subtropics of the Old World (Biffin et al, 2010; WCSP, 2015). In the past Syzygium was treated as a section of Eugenia L. by many authors, including Bentham & Hooker (1865), Henderson (1949) and, for Madagascar, Perrier de la Bâthie (1952, 1953), all of whom adopted a broad concept of Eugenia. Subsequent anatomical work by Schmid (1972) demonstrated that Eugenia and Syzygium are independent lineages, and molecular surveys by various authors have confirmed their placement in different tribes of the Myrtaceae (e.g. Wilson et al., 2001, 2005; Biffin et al., 2010). In accordance with this changed generic circumscription, Labat & Schatz (2002) established new name combinations for species from Madagascar formerly included in Eugenia, and together with an addition combination established by Govaerts et al. (2008) and two new species described by Snow (2010), Syzygium is currently represented in Madagascar by 19 species (Madagascar Catalogue, 2015).

In the course of the work undertaken by one of us (JWB) towards a better understanding of global patterns of diversity in Syzygium (Byng, 2014), it became apparent that a better understanding of the Malagasy Syzygium would be a vital element. Furthermore, botanical inventory in Madagascar has moved ahead considerably since the revisionary work of Perrier de la Bâthie (1952, 1953), and much of the newly available material cannot be adequately identified and we have noted that approximately half of the herbarium specimens at Paris (P) and Kew (K) were not identified to species or were identified incorrectly. It has become clear that the Malagasy Syzygium are in need of complete revision, and this work is now underway. Apart from reviewing and revising species delimitations, and the description of additional new species, three nomenclatural issues have arisen that do not need to wait until the full revision can be completed. We address these in this article, which will enable us to provide updated content for the Vascular Plants of Madagascar project (Madagascar Catalogue, 2015), and will be useful for other workers involved with the Malagasy flora. Scans of the specimens cited in this article can be viewed on the online databases of the relevant institutions.

A new combination and status for Eugenia condensata var. thouvenotii Danguy

The taxon was first described as a variety of Eugenia condensata by Danguy but was reduced to synonymy under E. emirnensis by Perrier de la Bâthie (1952). Syzygium thouvenotii (Danguy) Byng is clearly a distinct species from both of these species with its small oh ovate leaves, conspicuous revolute margins, prominent secondary and tertiary venation, and small flowers. These characters contrast to the larger leaves and flowers, often acute or cuspidate apices, and more or less

Transfer of Eugenia cuneifoiia Baker to Syzygium

In his treatment of the Malagasy Myrtaceae, Perrier de la Bâthie (1952, 1953) reduced Eugenia cuneifoiia Baker to a taxonomic form of the typical variety of E. emirnense Baker. Labat & Schatz (2002) followed Perrier's species concept, including E. cuneifoiia within their Syzygium emirnense (Baker) Labat & G. E. Schatz, but did not consider Perrier's taxonomic forms or varieties worthy of further recognition. We believe that S. cuneifolium is quite distinct from S. emirnense and that it merits recognition at species level and we therefore establish the necessary new combination here. Syzygium cuneifolium can be clearly distinguished from S. emirnensis on the basis of its obovate leaves, cuspidate apices, and conspicuous rigid venation on both surfaces.

The identity of Eugenia tanalensis Baker

Eugenia tanalensis and E. condensata Baker were described by Baker (1882) to accommodate two closely-related species, differing mainly in the shape of the leaves and inflorescences, with both species being noted as “a near ally” or “near neighbour” of the Mauritian E. glomerata Lam. Eugenia tanalensis was typified by Baron 295 from “Forests of Tanala” and was reported as “Gathered before in Central Madagascar by Bojer”. Eugenia condensata was typified by Baron 237 from “Central Madagascar”, and following its description, Baron stated “We have four allied species from Madagascar already, gathered by Bojer, Meller, and Gerrard”. It is not entirely clear which four species Baker was referring to, and confusingly he wrote a year later under E. phillyreaefolia Baker that “This and the five other species here described are all near neighbours of the Mauritian E. glomerata” (Baker, 1883). Among these five species was E. cuneifolia (see our treatment above), which was collected by Meller, but we have not found any specific mention of Gerrard as the collector of any of Baker's species of Eugenia from Madagascar. Baker (1883, 1887) later added two more Malagasy species one of which, E. aggregata Baker, was noted as “Near E. tanalensis”.

Perrier de la Bâthie (1953) omitted E. tanalensis from his formal treatment of species, regarding it as incompletely known (“espèce incomplètement connue”), mysteriously he cited the collection Baron 1477 as the type, noting that its flowers were parasitised and therefore inadequately known. He went on to state that it may represent the same species as his newly described E. onivensis H. Perrier. Labat & Schatz (2002) also treated the species as of “Uncertain Systematic Position”, noting that the type, Baron 295 was missing at Kew. Following a thorough search at Kew by JWB, several specimens annotated “Eugenia (Syzygium) tanalensis Baker” presumably in Baker's hand were found. One of these is a sheet of Baron 1477 [K000312797] mentioned above, which bears no indication of being regarded as a type by Baker, it was examined by Jean-Noël Labat in 1999 and identified as Syzygium onivensis (H. Perrier) Labat & G. E. Schatz. A second sheet appears to be a mixed gathering that we believe includes the lost type specimen [K000771833].The specimen on the right bears a label written by hand “295 Eugenia Tanala: forest, Central Madagascar Coll. Barson reed 2/81” and in addition, after “Eugenia (Syzygium) tanalensis Baker” is the mark “!” suggesting that the sheet was seen by Baker for the description of the species (see Fig. 1). There is no record of a collector by the name of Barson listed by Dorr (1997) as active in Madagascar. A search for the collector Barson in the Kew Herbarium Catalogue (2015) produced two specimens databased and scanned under this collector name, both from Madagascar and both bearing handwritten labels similar to the specimen described above and numbered 276 and 324. The latter is annotated as the type of Dombeya modesta Baker, which is cited as Baron 324 in its protologue. We have also searched for specimens at Kew databased under the collector Baron in the number range of these specimens and found that all the specimens with scanned images available on-line have “Barson” labels when an original printed label is not present. It appears that the error was made when handwritten labels were produced for the Baron specimens received at Kew in February 1881. The other material on the left of the same sheet is labelled “Eucalyptus sp. Bojer” in Baker's hand, and we suspect this is the material referred to by Baker when he wrote in the protologue “Gathered before in Central Madagascar by Bojer”. A third sheet at Kew bearing “Eugenia (Syzygium) tanalensis Baker” [K000312796] consists of two gatherings, with the lower element labelled “Herb, ex Blackburn” with the invalid name Eugenia cuspidata in Bojer's hand.

Baker (1882) noted that E. tanalensis has ovate leaves with cuspidate apices and generally open inflorescences. In contrast, E. condensata has oblong-lanceolate leaves with acute apices and dense inflorescences. However, the holotypes of both species are similar, and specimens of the species as a whole form a broadly coherent group with a gradient between acute to distinctly cuspidate leaf apices and open to dense inflorescences. We here place E. tanalensis as a synonym of Syzygium condensatum.

Fig. 1.

Sheet bearing the holotype (specimen on the right) of Eugenia tanalensis Baker at K [K000771833], with the handwritten label “295 Eugenia Tanala: forest, Central Madagascar Coll. Barson reed 2/81” visible in the lower right.

[© Royal Botanic Gardens, Kew]