Stelis glaucus A.Doucette & J.Portilla, 2016

Doucette, Alfonso, Portilla, Jose & Cameron, Kenneth M., 2016, Ten new taxa in the orchid subtribe Pleurothallidinae (Epidendroideae, Epidendreae) from Ecuador, Phytotaxa 257 (3), pp. 230-248 : 240-242

Stelis glaucus A.Doucette & J.Portilla , sp. nov. ( Figs. 8 , 11I )

Type:— ECUADOR. Without specific locality, flowered in cultivation at Ecuagenera Orchid Nursery, 4 September 2015, Doucette 0310 (holotype: HA).

Diagnosis: The species is most similar to Stelis gemma Garay (1969: 77) but differs in its larger size, development of the inflorescence, and colour of the sepals.

Epiphytic, caespitose herbs, roots 1mm in diam. Stems 17.0–20.0 5 1.5–2.0 mm, and enveloped by 2–3 papery sheaths, 10.0–20.0 5 1.5–2.0 mm. Leaves pendent, oval, petiolate, glaucous, 90–98 5 31–39 mm. Inflorescence a raceme; peduncle 30–35 5 1 mm; bracts papery, many, 2–4 5 3–5 mm; pedicel 2 5 1 mm; ovary 4 5 1 mm, dorsal sepal triangular, tan, minutely pubescent, 6 5 5 mm; lateral sepals similar to the dorsal sepal; petals rectangular, concave, dark tan, 0.5 5 1.5 mm; lip semicircular, dark tan, 1 5 1 mm; column bilobed, 1.2 5 1.0 mm.

Etymology:— The name of the Greek sea-god, Glaucus, born mortal and turned immortal upon eating a magical herb, is used as a noun in apposition for the species epithet.

Notes:— Stelis s.s. was discovered to be embedded in a grade formed by species of Condylago , Pleurothallis , and Salpistele . In order to maintain a monophyletic Pleurothallis the circumscription of Stelis was expanded to include these lineages (Pridgeon et al. 2001). The decision was controversial based on the absence of morphological characters that diagnose the clade. We hypothesize that the species described here, Stelis glaucus , belongs to the clade thought to include the type of the genus Stelis based on the shared traits of a racemose inflorescence, transversely bilobed stigma and reduced petals tightly flanking the column.

Stelis glaucus is unusual in the genus given its habit and similar to only one other described species, S. gemma . Luer (2009) noted that Stelis gemma “is unique in the genus with the pendent, overlapping, glaucous green leaves”. The species described here represents a second species in the genus sharing this habit.

Stelis glaucus represents one of over 120 new species attributable to Stelis s.s. described since the treatment of Stelis gemma by Luer (2009). Of the 120+ new species, S. glaucus is only similar to S. pendulata O. Duque (2010: 141) but differs in the leaf width (3.1–3.9 cm vs. 1.8 cm) and leaf (glaucus vs. green) and flower colour (beige vs. purple). Other than S. pendulata , S. glaucus not similar to any of the species listed by International Plant Names Index (2016) published between 2009 and 2015.

Figures

FIGURE 8. Stelis glaucus. A. Habit, drawn to 5 cm scale. B. Flower. C. Dorsal sepal. D. lateral sepals. E. Petal. F. Lip. G. Flower with petals and sepals removed.All drawn to 1 mm scale.

FIGURE 11. A. Masdevallia constricta f. glabra. B. Masdevallia pachyura f. pardinella. C. Masdevallia posadae f. rugosepala. D. Acianthera nikoleana. E. Pleurothallis papillingua. F. Pleurothallis gigiportillae. G. Pleurothallis cardiostola f. magnidraba. H. Zootrophion machaqway. I. Stelis glaucus. J. Trisetella portillae.