ABSTRACT: The article described and illustrated Myoxanthus ruschii (Orchidaceae), a species from the Santa Lúcia Biological Station in the Atlantic forest of Espírito Santo, Brazil. This species is related to Myoxanthus punctatus, Myoxanthus lonchophyllus and Myoxanthus seidelii, from which it differs by non-clavate petals and the general form of the lip with a subtruncate base with a pair of reflexed lateral lobes on the end.
Key words: Atlantic forest, Brazil, Espírito Santo, Myoxanthus, Orchidaceae.
The eastern Brazilian Atlantic coastal forest, although at present highly fragmented, is one of the places with the highest biodiversity on Earth (Myers et al., 2000). One of these fragments with special interest is the Santa Lúcia Biological Station, a site for biological research and conservation encompassing about 440 ha of Atlantic forest located in the municipality of Santa Teresa, in the state of Espírito Santo. According to recent research on trees, birds, mammals, and butterflies there is an especially high biological richness in this region, even when compared with other Atlantic forest areas (Mendes & Padovan, 2000). As a result of fieldwork at this station, a new orchid species has been found and described and illustrated in the article.
The Neotropical genus Myoxanthus Poeppig & Endlicher, long in the synonymy of Pleurothallis, was reinstated by Luer (1982). Later, Luer (1992, 1997) presented a revision of the genus, consisting of 48 species in 3 subgenera, subg. Satyria Luer, subg. Silenia Luer, and subg. Myoxanthus, with this last subgenus containing section Myoxanthus, section Antennella Luer and section Scandentia Luer. Seven species were cited for Brazil for the autonymic subgenus of Myoxanthus: four endemic to the eastern Atlantic forest, two in the Amazonian region and one with disjunct distributions in eastern Brazil and northwestern South America.
Myoxanthus ruschii Fraga & L. Kollmann NOVON 13: 49–51. 2003. Volume 13, Number 1 TYPE: Brazil. Espírito Santo: Santa Teresa, Valsugana Velha, Santa Lúcia Biological Station, dry trail, ca. 19°57'10''–19º59'00''S, 40º31'3''–40°32'25''W, elev. 750 m, 16 June 2001 (fl), C. N. Fraga 780 (holotype, MBML; isotype, RB). Figure 1.
Species haec Myoxantho punctato, M. lonchophyllo et M. seideli affnis, sed floribus parvis successivis pedunculatis aggregatis, sepalo postico oblongo, sepalis lateralibus oblongis apice obtusis, petalis elliptico-ovatis, label-lis trilobatis, et lobo antico elliptico-ovato, marginibus verrucosis, et lateralibus brevibus retrorsis differt.
Epiphytic, caespitose herb. Roots coarse. Ramicauls 14–21 X 0.15–0.2 cm, ascending to erect, stout and enclosed by 5 to 8 purple-colored, tubular hispidulous and paleaceous sheaths. Leaf 8.5–13 X 2–3 cm, erect, thickly coriaceous, narrowly elliptic to narrowly ovate, acute, base cuneate below into a subpetiole. InfIorescence a fascicle of single, successive flowers, at the apex of the ramicaul, occasionally 2 flowers at anthesis simultaneously, the peduncles purple, 7–9.5 mm long, minutely purple pubescent; floral bracts 3–5 X 2–2.5 mm wide expanded, paleaceous, purple pubescent. Flowers resupinate; pedicels 2–3 mm long; ovary 2–4 mm long; sepals yellow with red spots, glabrous, the dorsal sepal 7–8 X 2.5–3 mm, oblong, narrowly subacute, 5-veined, the lateral sepals 7– 8 X 3–3.5 mm, connate at the base, oblong-ovate, apex rounded, 4(–6)-veined; petals 7–8 X 2–2.5 mm, yellow with red spots, glabrous, narrowly elliptic-ovate, obtuse, with revolute margins at the apex, 3-veined; labellum 5–6 X 2–2.5 mm, red with yellow base, non-deflexed, glabrous, the apical lobe elliptic, obtuse, somewhat verrucose with revolute margins, thick, the lower half with low, erect, rounded margins, the disc with a broad, smooth, slightly concave area, the base subtruncate, with a pair of minute lateral lobes reflexed on the
end, 3-veined; column 1–1.5 X 0.5 mm, yellow, flecked with red, stout incurved, 3 mm long, with rounded wings above the middle, the column-foot stout, 2 mm long, concave, with a pair of thick calli near the apex, the upper margin of the anther fimbriate, 2 pollinia-pairs, yellow, obovoid. Capsule unknown.
Etymology. The name of this species pays homage to Augusto Ruschi, a naturalist involved in the conservation of natural areas in Espírito Santo, especially through the Santa Lúcia Biological Station, which was where he started his botanical studies, particularly with Orchidaceae.
This species is apparently related to Myoxanthus punctatus (Barbosa Rodrigues) Luer, M. lonchophyllus (Barbosa Rodrigues) Luer, and M. seidelii (Pabst) Luer, from which it is distinguished by its elliptic leaves, labellum thick and non-deflexed with revolute margins, and fimbriate anther.
The presence of an elliptical labellum with the terminal lobule having a verrucose margin, also observed in Myoxanthus punctatus and M. seidelii, distinguishes M. ruschii from M. lonchophyllus, which has an ovate labellum, somewhat hispid-papillose apically.
The yellow coloring with red spots, non-clavate petals, and general elliptic form of the labellum with subtruncate base with a pair of lateral lobes reflexed on the end, found in Myoxanthus ruschii, are characters absent in M. punctatus and M. seidelii.
Paratype. BRAZIL. Espírito Santo: Santa Teresa, Valsugana Velha, Santa Lúcia Biological Station, dry trail, ca. 19°57'10''–19°59'00''S, 40°31'30''–40°32'25''W, 700 m, Atlantic forest, 28 Apr. 2000 (fl), L. J. C. Kollmann 2899,C. N. Fraga, V. G. Demuner, E. M. C. Leme & B. R. Silva (MBML).
(Brazilian Orchids & Orchid News)