Microchilus longicornu (Cogniaux) Smidt et al. (2021: 341)

Engels, Mathias E. & Smidt, Eric C., 2022, Taxonomic and nomenclatural notes in Microchilus longicornu (Goodyerinae Orchidaceae), Phytotaxa 568 (3), pp. 296-300 : 297

Microchilus longicornu (Cogniaux) Smidt et al. (2021: 341) .

≡ Physurus longicornu Cogniaux (1906: 298) . ≡ Erythrodes longicornu (Cogniaux) Ames (1915: 28) . ≡ Aspidogyne longicornu (Cogniaux) Garay (1977: 202) . ( Figures 1 and 2D–F )

Type :— BRAZIL: sine locu acurato, fl., June 1821, Riedel 77 [First step lectotypification by Christenson (1995) as “ isotypes ”: LE00001368 photograph! and LE00001367 photograph!; second-step lectotypification, lectotype designated here: LE00001368 photograph!; isolectotypes: LE00001367 photograph!; AMES10480 photograph!] .

Taxonomic Discussion:— Botanist Alfred Cogniaux examined several samples of Orchidaceae at the Saint Petersburg Herbarium (LE), Russia, to describe Brazilian species and elaborate the monograph of Orchidaceae of Flora Brasiliensis ( Christenson 1995) . Among the samples of several collectors, Cogniaux examined and described Physurus longicornu Cogniaux (1906: 298) based on sample Riedel 77. This collection is divided into three duplicates (Syntypes according to Art. 9.6, Turland et al. 2018). Two are in the LE herbarium, and the third corresponds to a single individual who was probably removed from the LE samples and added to the “Herbier Alfred Cogniaux” and is currently deposited in the Oakes Ames Orchid Herbarium (AMES).

Analysing the LE collection, Christenson (1995) published a list of the types of Orchidaceae found in this herbarium and presented two duplicates of Riedel 77 as “types” of Physurus longicornu , indicating them as “Isotypes”.According to the art. 7.11 of the code ( Turland et al. 2018), when presenting the term type or similar before 1 January 2001, it is the realised “inadvertent typification” of this name, in this case, a lectotypification. Nonetheless, this lectotypification implies a mistake due to the absence of an indication of a single sample to serve as the main type (art. 9.10, Turland et al. 2018). After seeing the three syntypes, we selected and designated LE00001368 as the lectotype (second step lectotypification, art. 9.17, Turland et al. 2018) because this exsiccate has the original label of Riedel, the signature of Cogniaux when describing the name, the authority of the new species, and an excellent conservation status with a good constitution and aesthetic.

The recognition of M. longicornu is controversial, being considered as an autonomous species (e.g., Hoehne 1945, Pabst & Dungs 1975, Christenson 1996, Engels et al. 2016, Smidt et al. 2016, 2021) but also as a synonym of M. foliosus ( Poeppig & Endlicher 1837: 17) Dietrich (1852: 166) by the recent Brazilian Flora ( Meneguzzo 2020), in addition to exsiccates of M. longicornu in herbaria being identified as M. foliosus [e.g., Dusen 10277 (S 17-12141, photo!) in Kraenzlin (1911) and Ormerod (2009)].

Analysing the types of M. longicornu (presented above) and M. foliosus [E.F. Poeppig s.n. (holotype W48620! and flower illustration W0048621!)], in conjunction with the examination of fresh material of both species (e.g., Figure 2 ), it was possible to consider them distinct taxa. Microchilus longicornu is similar to M. foliosus due to the habit, the pale-green flowers with white labellum, and the shape of the labellum with oval and entire epichile. However, M. longicornu can be differentiated from M. foliosus due to the hypochile length (ca. 20 mm length, considerably longer than the ovary + pedicel vs. ca. 7 mm length, almost the same length or slightly shorter than the ovary + pedicel) and by the larger size of the epichile (ca. 2.5 × 4 mm vs. ca. 1 × 1.5 mm).

Microchilus longicornu occurs in French Guiana, Guyana, Suriname and Brazil, and M. foliosus has a wide distribution, occurring in French Guiana, Guyana, Suriname, Venezuela, Bolivia, Colombia, Ecuador, Peru, and Brazil ( Govaerts 2022).

Figures

FIGURE 1. Lectotype of Microchilus longicornu (Riedel 77 at LE [barcode LE00001368]). Courtesy of the Herbarium LE curators.

FIGURE 2. A–C. Microchilus foliosus (M.E.Engels 8218 at MBM). A. Habit in the natural environment. B. Inflorescence. C. Detail of flowers in an inflorescence. D–F. Microchilus longicornu (M.E.Engels 6618 et al. at MBM). D. Habit. E. Inflorescence, arrow indicates the long hypochile. F. Detail of flowers in an inflorescence. Photos by M.E.Engels.