Thismia Griffith (1844: 221)

Silva, Diego Ferreira Da, Engels, Mathias Erich & Soares-Lopes, Célia Regina Araújo, 2020, Novelties in Thismia (Thismiaceae) from South Brazilian Amazon with the description of a new species, Phytotaxa 429 (4), pp. 261-273 : 262

Thismia Griffith (1844: 221) .

Mycoheterotrophic herbs. Roots thickened or not, terete. Tuber present or absent; when present irregular and flattened laterally. Stem terete. Leaves reduced or conspicuously developed and laminar, alternated or verticillate, narrowly-triangular, deltoid, widely-elliptical, sub-oblong to lanceolate, base truncate, cuneate, acute or decurrent, margin entire, apex acute or obtuse. Flowers actinomorphic, upward oriented, pedicelated or sessile; pedicel terete when present; ovary wide-obovate, conical, wide-ovate to sub rounded, angular or not; placentation 3-parietal basal; flower tube ellipsoid, obovoid or oblanceoloid, terete, angular or not, inner surface smooth or horizontally striated; tepals with two similar whorls (6) or two distinct whorls, outer and inner (3+3); tepals when equal, lanceolate-ovate, base cuneate and becoming decurrent, margin entire, apex rounded and sub truncate; when in two whorls, with outer tepals inserted at the distal portion of the tube, filiform or laminar, terete to sub cylindrical or sub elliptical to ovate, base truncate to acute, decurrent or not, martin entire, apex rounded to obtuse; inner tepals inserted at distal portion of the tube, curved over the annulus or patent to deflexed, unguiculate or not, sub rounded, sub ovate, ovate, obovate or sub spatulate, base rounded or acute, margin entire, apex rounded or inconspicuously obtuse; free or adnate to each other at distal middle portion forming the mitre; mitre when present hexagonal, foveolate; annulus rounded or sub-hexagonal. Anther 6, obovate, rounded, elliptical or oblanceoloid, auriculate at the base or absent, rimose; connective not dilated; filament reduced or conspicuously developed, filiform or deltoid. Stigma elliptical, pyramidal-capitate or sub pyramidal in general, 3-lobate; lobes ascendant with apex slightly curved to the center, descendant-patent or descendant with apex slightly to strongly curved to the center, papillose. Fruit conical, not estiolated or with pedicel cylindrical estiolated.

All registered species in the present study occur in the Amazonian domain, in Seasonal Evergreen Forest and Ombrophilous Dense Forest, and are sympatric and synchronic. However, there is variation in the ecological environment they occupy, Thismia hyalina , T. melanomitra and T. singeri have been found growing in leaf litter understory, where the soil is drained; and T. ribeiroi sp. nov. has been found growing in leaf litter understory, in humid and clay soil, related to watercourse, and which can periodically be flooded during the rainy season.