Myoxanthus cereus (Ames) Luer ex Rojas-Alvarado & Karremans (2017: 210)

Rojas-Alvarado, Gustavo, Blanco, Mario A. & Karremans, Adam P., 2021, A taxonomic synopsis and morphological characterization of Myoxanthus (Orchidaceae: Pleurothallidinae), Phytotaxa 507 (3), pp. 211-258 : 231-232

6. Myoxanthus cereus (Ames) Luer ex Rojas-Alvarado & Karremans (2017: 210) . (Fig. 12F)

Basionym: Pleurothallis cerea Ames (1923a: 19–20) .

TYPE:— COSTA RICA. Cartago: Agua Caliente, Lankester 358 (holotype: K, photo of type, illustration of type, AMES!).

Distribution:— Costa Rica and Panama.

Notes:— Pleurothallis cerea has been commonly placed under the synonymy of M. octomeriae or M. congestus . However, Luer noted differences between the two species, and in 1991 annotated a specimen collected by Endrés from Costa Rica as “ M. cereus (Ames) Luer ”, a combination that he never published. When Soto (2008) revised the taxonomy of the Mexican Myoxanthus , he reduced M. octomeriae , with all its synonyms, to the synonymy of the older M. congestus , a name based on material from Mexico. However, he also noted the odd features of P. cerea , especially in leaf size and shape and lip structure. After studying material of Pleurothallis cerea from Costa Rica, Rojas-Alvarado & Karremans (2017) formally recognized it as a species and transferred it to Myoxanthus . This Central American species is easily distinguished from the closely related M. octomerioides ( Mexico) , M. congestus ( Mexico to Colombia-Venezuela) and M. pulvinatus ( Peru and Brazil) by its broad, elliptic to ovate petiolate leaves, and oblong, conspicuously adaxially verrucose, frequently apiculate lip vs. narrow elliptic, sessile leaves and lip not apiculate of the other species ( Rojas-Alvarado & Karremans 2017).

FIGURE 12. Myoxanthus species. A –C. M. affinis . D. M. antennifer . E. M. ceratothallis . F. M. cereus . G. M. chloe . H–I. M. cimex . J–K. M. colothrix . L. M. conceicionensis . Photographs by: L. Grobler (A). L.E. Yupanqui (B). G. Rojas-Alvarado (C, J, K). A. Karremans (F, G). Ecuagenera (D). R. Parsons (E, L). S. Vieira-Uribe (H). H. R. Ellis (I).