Thismia violacea D.F.Silva & J.M.A.Braga, 2023

Silva, Die- -- Go Fe- -- Rre- -- Ira Da & Braga, João Marce- -- Lo Alvare- -- Nga, 2023, Thismia violacea (Thismiaceae), a new mycoheterotrophic species from the Brazilian Cerrado, Phytotaxa 620 (2), pp. 188-192 : 188-191

Thismia violacea D.F.Silva & J.M.A.Braga , sp. nov. ( Figure 1 )

Type:— BRAZIL. Góias: Jataí, Parque Natural Municipal Mata do Açude, Fragmento de Mata E­­­ stacional Semidecidual e de Galeria, 28 February 2013, fl. and fr., D. C. Gomes & L. R. Souza 283 (holotype: HJ 6768) .

— Thismia panamensis auct. non (Standl. 1927: 163) Jonker (1938: 234): Guilherme et al. (2016).

Diagnosis:— Thismia violacea is similar to Thismia panamensis (Standl.) Jonker , but differs by to floral tube pale purplish (vs. whitish tinged with greenish–brown to colorless or pinkish in Thismia panamensis ); inner tepals erect, base triangular with plane margin (vs. inner tepals reflexed, base triangular with revolute margin); anthers ca. 0.5 × 1.2 mm, inserted at the apex of the connective and with glabrous apex (vs. anthers ca. 1 × 0.8 mm, inserted in the medial part of the connective and with a tuft of trichomes at the apex); and stigma ca. 2.5 mm long, with inconspicuous lobes (vs. stigma ca. 1.5 mm long, with conspicuous lobes).

Description:—Herbs 9.5–12.9 cm tall, terrestrial, mycoheterotrophic. Root-tuber ca. 17 mm long, with filiform roots, white to orange. Stem 3.5–9.5 × 0.2–0.3 cm, longitudinally bisulcate, erect, unbranched, glabrous, white to purplish. Involucral bracts 4, white. Flowers ca. 54 × 14.3 mm, solitary, strongly zygomorphic; floral tube ca. 10 × 14.3 mm, gibbous part of the floral tube with one longitudinal slit, outer surface smooth, glabrous, pale purplish, with 12- veined, magenta, inner surface densely pilose with trichomes 0.6–1 long, white; annulus 2–3 mm in diam., magenta, surrounded by three rings, outermost ring 6-lobed, each lobe alternating with the tepals, with erect to patent apical margin, middle, and inner ring surrounded by 3-lobed each, exactly similar, imbricate, magenta. Tepals inserted all at same height in the distal part of the floral tube (3+3); outer tepals ca. 2 × 2 mm, reflexed, ovate, base truncate, 1- veined, margin entire, apex rounded to obtuse, pale purplish; inner tepals erect, base ca. 1 × 2 mm, broadly triangular, terminated by a flagelliform appendage 36–38 mm long, 1-veined, margin entire, apex plane, glabrous, pale purplish at the base, the rest to the apex magenta. Interstaminal lobes not seen. Stamens 6, ca. 2.5 × 2.5 mm, pendulous; filaments ca. 1 × 1.15 mm, inserted just below the annulus, translucent white; connective ca. 2.5 × 2.5 mm, dilated, 4-lobed, translucent white, 2-lobed at the upper ca. 0.8 × 0.5 mm, triangular to deltoid, 2-lobed at the lower ca. 1.8 × 0.3 mm, filiform; anthers ca. 0.5 × 1.2 mm, hippocrepiform, inserted in the distal part of the dilated connective, widely ovate, white, apex glabrous, thecae ellipsoid, longitudinally dehiscence. Ovary ca. 2 × 3 mm, unilocular, top-shaped, smooth, white, glabrous, multi-ovulate, placentation parietal; style ca. 2 mm long, cylindrical, glabrous, purplish; stigma ca. 2.5 × 3.5 mm, trilobed, inconspicuous lobes 0.3 mm long, ascendants, densely pilose. Fruits 4–6 × 3–5 mm, cup-shaped, margin with 6 symmetrical lobes 3.5–4 mm long., rounded, emarginate, glabrous, white. Seeds 0.5–0.7 × 0.3–0.4, elipsoid, reticulate, tan-colored, seminiferous nucleus brown.

Etymology:— The specific epithet refers to the color of the flower.

Phenology:— Flowering was observed between February to April and fruiting between March to May, with ombrohydrochoric dispersion ( Guilherme et al. 2016; Coelho et al. 2021).

Distribution and habitat:— Thismia violacea is endemic to the semideciduous seasonal forest in the Brazilian Cerrado, and is known only in the “Parque Natural Municipal Mata do Açude, municipality of Jataí”, Goiás, Brazil ( Figure 2 ).

Taxonomic notes: —According to the classification of Mass et al. (1986), Thismia violacea belongs to Thismia subg. Ophiomeris sect. Ophiomeris . This section is characterized by root-tubers, longitudinally bisulcate stem, tepals inserted all at same height in the distal portion of floral tube, outer tepals often smaller and reflexed, inner tepals larger and of different shape and size, most often terminated by a flagelliform appendage (rarely absent), and ovary with parietal placentation, inserted near the base to half way up the ovary ( Maas et al. 1986).

Thismia violacea is morphologically related to Thismia panamensis , when compared to the shape of the strongly zygomorphic floral tube, coloration of the annulus, shape of the outer tepals and androecium, but is distinguished from this species by the characters given in the diagnosis. Additional ilustrations and images this new species can be found in Guilherme et al. (2016), Azevedo (2019), Coelho et al. (2021), ASCOM/UFJ (2021) and FAPE­­­ G (2021).

Figures

FIGURE 1. Holotype of Thismia violacea at HJ (D.C. Gomes & L.R. Souza 283, HJ00006768) Image: speciesLink network (Herbario Jataiense—HJ).

FIGURE 2. Distribution map of Thismia violacea. A. Record of the species in the state of Goiás. B. Distribution in Parque Natural Municipal Mata do Açude, municipality of Jataí, state of Goiás, Brazil (satellite images by Google satellite obtained in 2023).