Thismia (sect. Ophiomeris) Maas & Maas 1986

Key to the species of Thismia sect. Ophiomeris (adapted from Maas et al. 1986)

1. Tepals equal in shape and size, all triangular to ovate, without appendages....................................................... T. espirito-santensis

- Tepals unequal, one outer whorl of shorter triangular to lanceolate tepals and one inner whorl of longer tepals with the proximal portion triangular to lanceolate, gradually tapering into a filiform distal portion or appendage......................................................2.

2. Annulus continuous...........................................................................................................................................................................3.

- Annulus segmented, with segments alternating with outer tepals.....................................................................................................5.

3. Floral tube zygomorphic; annulus without papillose zone, ornamented with three rings of ridges.............................. T. macahensis

- Floral tube actinomorphic; annulus with papillose zone, ornamented with a ring of 6 V-shaped ribs or pitted by 6 depressions...4.

4. Floral tube campanulate; outer surface of floral tube with 12 swellings at base; stigma capitate...................................... T.glaziovii

- Floral tube urceolate; outer surface of floral tube smooth with 6 double longitudinal lamellae; stigma trilobed.......... T. prataensis

5. Inner tepals appendaged, appendage inserted just below the apex of the laminar portion.............................................. T. saulensis

- Inner tepals without appendage, with the laminar portion tapering into the filiform portion...........................................................6.

6. Inner tepals with thickened apex of filiform portion.................................................................................................... T. luetzelburgii

- Inner tepals with slender apex of filiform portion.............................................................................................................................7.

7. Floral tube slightly zygomorphic, tubular to slightly urceolate at apex; connective not projecting beyond thecae (supraconnective absent)............................................................................................................................................................................. T. janeirensis

- Floral tube strongly zygomorphic, urceolate; supraconnective present............................................................................................8.

8. Connective and supraconnective glabrous; sagittate lobes at base of connective ca. 1.3 mm long; stigma obovoid, fully and evenly covered by simple, multicellular uniseriate trichomes..................................................................................................... T. andicola

- Connective and supraconnective pubescent o glabrous; sagittate lobes at base of connective ca. 0.5 mm long; stigma cylindric, proximally papillose and distally with tufts of simple, multicellular uniseriate trichomes........................................... T. panamensis