Myoxanthus Poepp. & Endl. (1835: 50)

Rojas-Alvarado, Gustavo & Karremans, Adam P., 2020, Revision of the Costa Rican species of Myoxanthus (Pleurothallidinae: Orchidaceae), Phytotaxa 448 (1), pp. 1-70 : 8

Myoxanthus Poepp. & Endl. (1835: 50) .

TYPE: — Myoxanthus monophyllus Poepp. & Endl. (1835: 50) . Heterotypic synonyms: Pleurothallis poeppigii Lindl. (1836: 354) . Humboldtia poeppigii Kuntze (1891: 668) . Pleurothallis myoxanthus Schltr. (1921: 121) nom. superfl.

Generic synonyms:

Duboisia Karsten (1847: 394) , nom. illeg., non R.Br. 1810.

TYPE:— Duboisia reymondii Karsten (1847: 394) .

Chaetocephala Barbosa Rodrigues (1882: 37) .

TYPE: Chaetocephala punctata Barbosa Rodrigues (1882: 38) .

Pleurolhallis sect. Chaetocephala (Barbosa Rodrigues) Cogniaux (1896: 589) .

TYPE:— Pleurothallis chaetocephala Cogniaux (1896: 590) .

Epiphytic, lithophytic, or occasionally nearly terrestrial herbs, caespitose to repent, frequently with prolific ramicauls. Roots velamentous, flexuous, cylindrical, generally branching. Rhizome covered by hispidulous sheaths, generally of one or two reduced internodes, infrequently elongate with three internodes. Ramicauls erect or spreading, sometimes pendulous, stout to flexible, generally longer than the leaf, with several nodes bearing papery sheaths covered by discontinuous lines of trichomes, basal nodes shorter and sometimes thicker. Sheaths tubular, usually imbricating, generally acute, papery, brownish to whitish, the apical sheath generally covering the base of the leaf; when young usually purple, with age frequently disintegrating into fibers or small fragments. Trichomes arranged in discontinuous lines perpendicular to the ramicaul axis, often deciduous, frequently leaving dark scars; trichomes of younger sheaths generally purple, becoming papery with age. Leaves conduplicate, generally erect, coriaceous, rarely chartaceous, sessile or cuneate into a short petiole, ovate or elliptic, sometimes linear, apex acute to obtuse and generally minutely tridentate. Inflorescence emerging apically on the ramicaul from a small papery spathe, with an obsolete peduncle and extremely abbreviated axis with congested small papery bracts, producing one or several single-flowered branches thus appearing as a fascicle, up to 35 flowers opening simultaneously. Pseudopeduncle (structure traditionally misinterpreted as the peduncle) 1‒15 mm, sometimes covered by minute trichomes and subtended by a small papery bract usually covered by trichomes. Floral bract tubular to infundibular, acute, generally equal in length to the pedicel and frequently covered by minute trichomes. Pedicels glabrous or with minute trichomes with the remainder of the axis adnate and emerging at the end in a form of a filament. Ovary cylindrical to subclavate, glabrous or with minute trichomes, slightly sulcate. Sepals variously coloured, generally ovate, smooth to pubescent abaxially, the apex generally acute and five-veined. Lateral sepals connate to varying degrees, forming a synsepal, sometimes suborbicular. Petals variously coloured, the base frequently ovate then contracted, frequently irregular in the tapering margin, triveined. Lip generally trilobate, sometimes reflexed, base frequently truncate, with a pair of small auricles; lateral lobes erect and irregular; the disc frequently with a longitudinal pair of carinae of lamellae or verrucose, triveined, hinged to column foot by a stalk, apex acute to obtuse, sometimes irregular. Column equal to or shorter than the lip, frequently curved and winged, apex with acute teeth, sometimes with broad wings and not toothed, clinandrium sometimes irregular, column foot concave, sometimes with a pair of calli in the middle. Anther cap sometimes papillose verrucose to ciliate on the upper edge. Pollinia two, yellow, obovoid, with a pair of flat white caudicles. Fruits spherical to ellipsoidal, trivalvate, with the perianth generally persistent.