Abstract

Taxonomic validation of a well-known odontoglossum (orchidaceae: oncidiinae) "ghost"

Stig Dalström

*^{Dirección para correspondencia:}

Abstract. The plant that was first called “Odontoglossum wyattianum” by Gurney Wilson was exhibited at a meeting of the Royal Horticultural Society on January 3, 1928. No official description was ever published and no type specimen was ever designated, or has surfaced, hence making this distinct species a taxonomic ‘ghost’. The taxonomic validation of Odontoglossum wyattianum is made here through the designation of a holotype, together with a diagnosis, a brief taxonomic history and comparison with similar and closely related species.

Key words: Odontoglossum, Oncidiinae, Cymbidieae, Epidendroideae, Peru, taxonomic validation

The plant that was first called Odontoglossum wyattianum by Gurney Wilson was exhibited by Frederick Sander at a meeting of the Royal Horticultural Society on January 3, 1928. Later the same day, the plant received a Botanical Certificate from the R.H.S. Scientific Committee. The plant had been obtained by Sander from Reverend Paul Wyatt, Bedford, England, who in turn had received it from a friend in Peru (Wilson 1928). Since then this ‘species’ has become a taxonomic ‘ghost’. No official description was ever made and no type specimen was ever designated, or has ever surfaced. It also vanished from cultivation shortly after its introduction together with Odm. harryanum Rchb.f., which appears to be its closest relative.

Due to the earlier rarity of Odontoglossum wyattianum in cultivation, in addition to its close visual resemblance to primarily Odm. harryanum, these species have been mixed-up in both literature and horticulture. Charles Schweinfurth included a collection of Odm. wyattianum by the Polish collector Felix Woytkowski (Woytkowski 35352, UC-Berkeley = holotype), from the Tarma area in Junín, central Peru, as “Odontoglossum harryanum” in Orchids of Peru (Schweinfurth 1961). This was probably the reason why plants of Odm. wyattianum subsequently and for years were imported from Peru under the name of “Odm. harryanum”. An attempt to clarify the situation was made by Jack Fowlie, who explained that the imports were made prior to the re-discovery of the long lost

Odm. harryanum in Colombia (Fowlie 1973). Another reason for the continuation of this confusion was the treatment of the Ecuadorean form of Odm. harryanum, as “Odm. wyattianum” by Leonore Bockemühl (1989). Mark Chase added to this by treating Odm. wyattianum as a variety of Odm. harryanum in The Pictorial Encyclopedia of Oncidium (Chase in Zelenko 1997). When placing flowers of Odm. wyattianum next to the other species in the ‘Odm. harryanum complex' (Fig. 1), however, it is easy to recognize the morphological differences in the column shape, which displays a more distinct curve, and with much larger and serrated wings, versus straighter columns with forward projecting minute wings for other and closely related species, such as Odm. deburghgraeveanum Dalström & G.Merino, Odm. harryanum and Odm. helgae Königer.

Fig. 1

Species of Odontoglossum have been transferred to Oncidium by some authors. A justification for rejecting this treatment is explained in more detail elsewhere (Dalström 2012, 2014).

Taxonomic Treatment

Odontoglossum wyattianum A.G.Wilson ex Dalström, spec. nov.

Type: Peru. Junín, Tarma, Utcuyaco, 1900 m, upon a rotten tree trunk in low forest, 20 Feb. 1948, F. Woytkowski 35352 (holotype and isotype: UC-Berkeley). Fig. ²–³.

Diagnosis: Odontoglossum wyattianum differs from the closely related and morphologically similar Odm. deburghgraeveanum, Odm. harryanum and Odm. helgae in that Odm. wyattianum has a more distinctly curved column carrying much larger, triangular, serrate wings, and frequently with a serrate column hood, versus straighter columns with insignificant and acute winglets for the other species.

Epiphytic herb. Pseudobulbs caespitose, oblong-ovoid to pyriform and apically variably truncate, ancipitous and slightly compressed, bifoliate, 6–8 × 2.5–3.0 cm, subtended basally by 7 to 9 distichous sheaths, the uppermost foliaceous. Leaves subpetiolate, conduplicate, elongate obovate, obtuse-acuminate, to ca. 44 × 2.5–4.0 cm. Inflorescence axillary from the base of the uppermost sheath, erect and arching, to ca. 1 m long, almost straight to loosely flexuous to ca. 10-flowered raceme; bracts appressed, scale-like, ca. 1.0–1.5 cm long. Flower campanulate, showy and fragrant; dorsal sepal light to dark brown with a white transverse bar or markings near the base, and a yellow apex, elliptic-oblong to elliptic, acute to acuminate, 4.5 × 1.3–2.5 cm; lateral sepals similar and slightly oblique; petals similar to the sepals but slightly smaller and slightly oblique; lip white to pale purplish heavily marked with purple near base, fading towards the middle of the lamina and often white near the apex, rigidly attached to the base of the column by a short, fleshy keel, then diverging away from the column in a 90° angle, with basal erect, rounded lobes, then unguiculate and broadly laminate, pandurate to trilobate with rounded, slightly concave lateral lobes, and a wavy, bilobed to retuse, slightly convolute, apiculate front lobe, ca. 3.5 × 2.5 cm; callus white, spotted with purple, emerging from the base as longitudinal, low and fleshy ridges, ending in more or less developed erect digitate denticles or tendrils near the base of the expanded lamina; column basally white then yellow with variable reddish brown markings, clavate, erect, and straight for ca. 2/3^rd of the length, then strongly curved towards the lip, ventrally canaliculate with low angles, or lobes below the stigma, and with a large, triangular and slightly falcate wing on each side, 1.2–1.7 cm long; anther cap white to pale yellow, campanulate and rounded rostrate, dorsally weakly lobulate; pollinarium of two cleft/folded pyriform pollinia on an oblong-rectangular, ca. 3 mm long stipe, on a slightly hooked, pulvinate viscidium.

Additional Material Seen: Peru. Huanuco, Leoncio Prado, Cuevas de Las Pavas, “950 m” [probably 1950 m], collected by E. Jara Mar. 1989, ex D. E. Bennett 4532 (MO). Junín, Tarma, Agua Dulce near Utcuyaco, collected by F. Woytkowski 27, dried specimen prepared Oct. 1951 by P. C. Hutchison s.n. (UC-Berkeley; accession number 50.1517-1). Same area, San Ramón, Quebrada Carmen, 17 Feb. 1964, collected by D. E. Bennett and flowered in cultivation, ex P. C. Hutchison & J. K. Wright 4127 (UC-Berkeley). Between San Ramón and Tarma, ca. 2000 m, flowered in cultivation, 22 Aug. 1979, W. Gann 27; OIC 3131 (SEL). Cusco, Paucartambo, Pilcopata, Kosñipata, “700” [probably 1700] m, 30 Dec. 1961, C. Vargas 014996 (CUZ). Paucartambo, Pillawata, Yanamayo-Tambo, 2200–1800 m, 3 Nov. 1965, C. Vargas 016736 (CUZ).

Distribution: Odontoglossum wyattianum is only known from the seasonally wet cloud forests of central Peru, at altitudes of ca. 1700–2500 m.

Eponymy: Named in honor of Rev. Paul Wyatt, of Bedford, England, to whom the plant had been forwarded by a friend in Peru, which is assumed to be the plant’s origin.

Acknowledgments. I thank Wesley Higgins for reviewing and commenting on the manuscript, Guido Deburghgraeve for lending his color photographs, and the curators of the UC-Berkeley and SEL herbaria for providing the opportunity to study the type specimen.

Literature cited

References

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