Monographs Details: Sigmatostalix
Authority: Bennett, David E. & Christenson, Eric A. 1994. New Species and New Combinations in Peruvian Orchidaceae. Brittonia. 46 (1): 24-53.
Family:Orchidaceae
Scientific Name:Sigmatostalix
Discussion:

Schweinfurth (1961) recorded six species of Sigmatostalix for Peru, two of which have been subsequently reduced to synonymy (S. aurosanguinea Rchb. f. and S. peruviana Rolfe = S. graminea (Poepp. & Endl.) Rchb. f.). With the addition (Bennett & Christenson, 1993) of S. caquetana Schltr. (Chase 87207) and S. putumayensis P. Ortiz (Bennett 5207-1), recognition of species previously placed in synonymy, and new country records, nine species of Sigmatostalix are now known from Peru. To aid in their iden- tification, we provide the following key

1 Labellum abruptly and distinctly clawed.

2 Labellum cordate without basal auricles or lateral lobes.

3 Base of labellum blade with a 2-seriate callus ......................................................... S. bicallosa Garay

3 Base of labellum blade with a single callus ......................... ................................. S. crescentilabia C. Schweinf

2 Labellum quadrangular-pandurate with pronounced basal auricles or lateral lobes.

4 Lateral labellum lobes falcate, forward-projecting .......................................................... S. caquetana Schltr.

4 Lateral labellum lobes not falcate, projecting backwards.

5 Lateral labellum lobes approximately 1 mm long; callus obovate .................................... S. buchtienii Kraenzl.

5 Lateral labellum lobes more than 2 mm long; callus ovate .................................... ...................... S. eliae Rolfe

1 Labellum cuneate or sessile, not abruptly and distinctly clawed.

6 Labellum transverse, sessile; inflorescences few-flowered racemes ........... S. graminea (Poepp. & Endl.) Rchb. f.

6 Labellum longer than broad, cuneate; inflorescences many-flowered racemose panicles.

7 Labellum flabellate, sidelobes completely lacking .. .............................................. S. putumayens

7 Labellum weakly 4-lobulate-to strongly 4-lobed.

8 Labellum weakly 4-lobulate, cuneate towards the base; column straight ................... S. amazonica Schltr.

8 Labellum strongly 4-lobed, not cuneate towards the base; column strongly curved ................................ ......................................... S. huebneri Mansf.