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

Silva, Diego Ferreira Da, Honório, Mayk, Silva, Chirley Gonçalves, Teixeira-Silva, Márcia A., Silveira, Marcos & Braga, João Marcelo Alvarenga, 2023, Two new species of Thismia (Thismiaceae) from the Brazilian Amazon Forest, Phytotaxa 587 (3), pp. 269-282 : 274-280

Thismia variabilis D.F.Silva, Honório & J.M.A.Braga , sp. nov. ( Figures 4–6 )

Type:— BRAZIL. Acre: Porto Acre, Reserva Florestal Humaitá , estrada AC 40 , Km 27, Floresta Ombrófila Aberta com bambu e palmeiras, 09º45’04.5”S, 67º40’15.9”W, 177 m a.s.l., 24 February 2022, fl. and fr., D. F. Silva et al. 405 (holotype: RB [dried + in spirit])

Diagnosis:— Thismia variabilis shares many morphological characters with to Thismia janeirensis and Thismia luetzelburgii , but it can be recognized by the presence of a strongly zygomorphic floral tube; annulus 1.5–2.1 mm in diam.; inner tepals with a base 1.2–2.5 × 1–3 mm, triangular, terminated by a flagelliform appendage 16–53 mm long, apex plane; stamens with dilated connectives 4-lobed, 2-lobed at the upper 1–2 × 0.3–0.5 mm, triangular, apex acutefalcate and 2-lobed at the lower 0.3–1.3 × 0.1–0.2 mm, deflexed, filiform, apex acute.

Description:—Herbs 3.2–9 cm tall, terrestrial, mycoheterotrophic, achlorophyllous. Roots 5–7 × 3–4.5 mm, tuberous with fibrous roots, 30–70 × 0.2–0.3 mm, white to orange. Stem 1.5–6 × 0.15–0.2 cm, longitudinally bisulcate, erect, unbranched, glabrous, white. Involucral bracts 4, bracts 2.5–4 × 1.1–3 mm, lanceolate, concave appearance, 1-veined, margin entire, apex obtuse, glabrous, ivory. Flowers 21–65.5 × 7–11 mm, solitary, strongly zygomorphic; floral tube 6–10 × 7–11 mm, gibbous, outer surface smooth, glabrous, ivory, 12-veined darkened, inner surface densely pilose with trichomes ca. 0.3 mm long, concentrated from the base to the middle portion of the tube, white; annulus 1.5–2.1 mm in diam., saffron, surrounded by three rings, outermost ring 6-lobed, each lobe alternating with the tepals, with reflexed apical margin, 0.3–0.5 × 1.5–2 mm, saffron, middle 3-lobed, each lobe placed opposite two lobes of the outermost row, 0.3–0.5 × ca. 3 mm, imbricate, saffron, innermost ring 3-lobed, placed like the lobes of the middle ring and exactly similar, ca. 0.1 × 2 mm, imbricate, saffron. Tepals inserted all at same height in the distal portion of the floral tube (3+3); outer tepals 3–7 × 3–5 mm long, reflexed, ovate, glabrous, base truncate, 1-veined, margin entire to slightly dentate, apex obtuse, saffron; inner tepals, base 1.2–2.5 × 1–3 mm, triangular, terminated by a flagelliform appendage 16–53 mm long, glabrous, 1-veined, margin entire, apex plane, saffron at the base, the rest to the apex white. Interstaminal lobes 0.7–1 × 0.1–0.2 mm, inserted ca. 0.1 mm behind the filaments, linear-triangular, apex obtuse-falcate, Stamens 6, ca. 2.5–3 × 1.5–2 mm, glabrous, pendulous; filaments 1–1.2 mm long, inserted ca. 1 mm below the annulus, translucent white; connective 1.8–2.7 × 1.5–2 mm, dilated 4-lobed, translucent white, 2-lobed at the upper 1–2 × 0.3–0.5 mm, triangular, apex acute-falcate, 2-lobed at the lower 0.3–1.3 × 0.1–0.2, deflexed, filiform, apex acute; anthers 0.5–0.8 × 0.5–0.8 mm, inserted in the medial portion of the dilated connective, ovate, white with hippocrepiform lines. Ovary 2–3 × ca. 3 mm, unilocular, top-shaped, smooth, white, glabrous, multiovulate placentation parietal; style 1–1.3 mm long, glabrous, white; stigma 1–2 × 1–2 mm, puberulous, trilobed, lobes ascendants to patent, margin ciliate, cream. Fruits 4–5 × 4–5 mm, cup-shaped, margin irregular, ciliate, with 6 symmetrical lobes 2–3 × ca. 0.1 mm, rounded, emarginate, fawn, young fruit presents the inner surface with 12-foveas, darkned, forming a prominent ornamentation with 12 star-shaped lobes. Seeds ca. 0.5 × 0.2 mm, ellipsoid, reticulate, cream, seminiferous nucleus, cream, funiculus filiform, persistent, translucent white.

Etymology:— The specific epithet refers the great variation in the tepals size, dilated connective lobes and interstaminal lobes.

Phenology:— Flowering and fruiting observed in February to April. A notable phenological characteristic of this species is that the fruit continues to develop even after the seeds are exposed, and may present a significant difference in the size of the lobes and the loss of the foveae present when young (see Figure 6 J and K )

Additional specimens examined (Paratypes): — BRAZIL. Acre: Porto Acre, Reserva Florestal Humaitá, estrada AC 40 , Km 27, Floresta Ombrófila Aberta com bambu e palmeiras, 09º45’19”S, 67º40’18”W, 185 m a.s.l., 28 March 2021, fl., M. H. Oliveira et al. 231 ( UFACPZ [in spirit]); Ibidem, 09º45’19”S, 67º40’18”W, 185 m a.s.l., 16 April 2021, fr., M. H. Oliveira et al. 237 ( UFACPZ [in spirit]); 09º45’24”S, 67º39’33”W, 185 m a.s.l., 25 February 2022, fl., D. F. Silva et al. 406 ( RB [dried + in spirit]) .

Distribution and habitat:— Thismia variabilis is known from three localities, found growing amongst leaf litter, under shade in an isolated fragment of the Brazilian Amazon Forest, located in Reserva Florestal Humaitá (RFH), municipality of Porto Acre, Acre State (see Figure 7 A and C ). The RFH consists of an important forest fragment with about 2000 ha, managed by the Federal University of Acre (UFAC). The local vegetation follows the topographic gradient towards the slope of the Acre River, with a predominance of open rainforest with bamboo ( Guadua weberbaueri Pilg. (1905: 152)) ( Silveira 2001; ACRE 2010). According to the K̂ppen classification, the predominant climate is Am, with an average annual temperature between 22º to 24ºC and annual rainfall between 2.200 –2.500 mm ( Alvares et al. 2013).

Conservation status: — Thismia variabilis is known only from three localities,collected in the southern portion of Acre Amazon Forest. From these set of records, it was possible to estimated the EOO at 0,312 km 2 and AOO estimated at 8 Km 2. Although T. variabilis records were collected in the same gradient of the Open Ombrophylous Forest, were observed recent activities of logging and expansion of pasture areas. Such activities, combined with the low number of individuals and their restricted area of occurrence, can put these populations at risk, given the loss of habitat. Therefore, the preliminary assessment proposed for the new species according to the IUCN Red List categories and criteria ( IUCN 2012, 2022), is for Critically Endangered (CR) by meeting the criteria B2ab(ii,iii).

Morphological affinities: —According to the classification of Mass et al. (1986), T. variabilis belongs to T. subg. Ophiomeris sect. Ophiomeris .

Thismia variabilis is similar to T. luetzelburgii Goebel & Şssenguth (1924: 56), when compared to shape, color, indumentum of the inner floral tube and ornamentation of the annulus, but can be distinguished by having a strongly zygomorphic tube (vs. slightly zygomorphic), annulus 1.5–2.1 mm in diam. (vs. ca. 0.5 mm in diam.), inner tepals terminated by a flagelliform appendage 16–53 mm long, apex plane (vs. inner tepals terminated by a flagelliform appendage 5–7 mm long, apex tumescent), connective dilated, 2-lobed at the upper 1–2 mm long and 2-lobed at the lower 0.3–1.3 mm long (vs. connective dilated, 2-lobed at the upper ca. 0.3–0.8 mm long and 2-lobed at the lower 0.8–1 mm long).

In addition, the new species is similar to Thismia janeirensis Warming (1901: 182) , but can be distinguished by strongly zygomorphic tube with inner surface densely pilose (vs. slightly zygomorphic to actinomorphic with inner surface glabrous in T. janeirensis ), inner tepals with base 1.2–2.5 mm wide, terminated by a flagelliform appendage 16–53 mm long (vs. inner tepals with base 0.3–1 mm wide, terminated by flagelliform appendage 6–12 mm long) and stigma with lobes ascendants to patent, puberulous with margin ciliate (vs. stigma with lobes ascendants, slightly curved to the center, densely pilose). For a detailed comparison of morphological characters among T. variabilis and related species (see Table 1 .)

Figures

FIGURE 4. Thismia variabilis.A–C. Panoramic views of the areas habited by T. variabilis. C. Flowering and fruiting habit. D. Floral bud. E. Flowering habit. F. Flowering and fruiting habit. Photographs by Diego Ferreira da Silva.

FIGURE 5. Thismia variabilis. A. Flowering and fruiting habit. B. Floral bud. C. Top view of the flower, showing the arrangement of the tepals, and annulus surrounded by three rings. D. Detail of de flower, upper view. E. Fruiting habit. F. Fuit, upper view. Photographs by Diego Ferreira da Silva.

FIGURE 6. Thismia variabilis. A. Longitudinal section of floral tube with inner and outer tepals, stamens, interstaminal lobes, and stigma. B. Bract. C–D. Stamen, showing the difference in size of the lower lobes of the connective. E. Interstaminal lobe. F. Detail of trichomes on the inner surface of the floral tube. G. Ovary, bracts and stigma, side view. H. Top view of the stigma. I. Longitudinal section of ovary showing the ovules, style, and stigma. J. Young fruit with seeds. K. Mature fruit without seeds. L. Seeds. Photos A–C and I, are provenient of the material in alcohol, disregard coloration. Photographs by Diego Ferreira da Silva.

FIGURE 7. Distribution map. A. Distribution of T. calcarata and T. variabilis. B. Delimitation of the Parque Estadual Chandless, Manoel Urbano, Acre, Brazil. C. Delimitation of the Reserva Florestal Humaitá, Porto Acre, Acre, Brazil (satellite images by Google sattelite obtained in 2022).