Dichaea saraca-taquerensis Campacci & Silva (2015: 410)

Krahl, Dayse R. P., Chiron, Guy, Krahl, Amauri H., Da Silva, João Batista F. & Cantuária, Patrick De C., 2024, Notes on taxonomy, distribution and conservation of Dichaea species (Orchidaceae: Zygopetalinae) in Brazilian Amazon, Phytotaxa 638 (3), pp. 277-284 : 278-281

1. Dichaea saraca-taquerensis Campacci & Silva (2015: 410) . ( Figure 1 ).

Type:— BRAZIL. Pará: Oriximiná: Porto Trombetas, FLONA Saracá-Taquera, platô Taquera, 31 March 2009, J.B.F. da Silva 2163 (holotype: MG!).

= Dichaea integrilabia Valsko, Krahl & Chiron (in Krahl et al. 2016: 146), syn. nov.

Type:— BRAZIL. Amazonas: Manaus: “Projeto Dinâmica Biológica de Fragmentos Florestais” (PDBFF), Fazenda Porto Alegre, 2°21’19.19”S; 59°57’31.81”W, 21 September 2012, 9 December 2012, J.J. Valsko 111 (holotype: INPA!).

Description:— Plant epiphytic subpendulous. Stem not swollen into pseudobulb, 6.2–25.5 × 0.2–0.5 cm, compressed or cylindrical, elongated, unbranched, 20–40–leaved. Leaves 2.0–4.1 × 0.3–0.6 cm, oblong-elliptic to oblong-lanceolate, distichous, conduplicate, apex acute. Inflorescence 1.8–2.5 long, lateral, 1-flowered, floral bract double; external bract 0.2–0.3 × 0.2–0.3 cm, ovate, apiculate; internal bract 0.3–0.4 × 0.05 cm, linear, acute. Flower greenish yellow, pedicellate; pedicel + ovary 1.3–2.0 cm long; dorsal sepal 0.6–0.7 × 0.2–0.3 cm, oblong to elliptic, apex obtuse; lateral sepals 0.6–0.7 × 0.2–0.3 cm, oblong to elliptic, asymmetrical, apex obtuse; petals 0.5–0.7 × 0.1–0.3 cm, oblanceolate to elliptic, apex obtuse; lip 0.5–0.6 × 0.3–0.5 cm, entire, obovate, concave, apex obtuse; column 0.3–0.4 cm long; pollinia 4. Fruit not seen.

Distribution and ecology:—The material examined and consulted revealed that D. saraca-taquerensis is restricted to the Brazilian Amazon and occurs in two states ( Figure 2 ). In the state of Amazonas, in the municipalities of Manaus and Presidente Figueiredo, it grows in Dense Ombrophylous Forest in a “terra-firme” vegetation (not flooding environment) in areas de “baixio” (close to streams) and it also occurs near a stream however among in a different vegetation, “campinarana” (on sandy soil). In the Pará state it is also found in Dense Ombrophylous Forest with a “terra-firme” vegetation of the municipalities of Terra Santa and Oriximiná. However, it was also observed in areas of “Platô” (areas higher and usually far from streams).

Conservation status:—The Area of Occupancy (AOO) is estimated at 20 km ². According to the criteria defined in IUCN Guidelines ( IUCN 2022), the threshold for Endangered category (EN) is met (criterion B). Besides the species occurs in five localities (criterion Ba). Three of these localities are within conservation units however the total area of occupancy suffers a continuing decline (criterion Bb) due to deforestation, mostly out of the conservation units but non-only. The total number of mature individuals (criterion D) is estimated to 100. Consequently the taxon may be treated as Endangered (EN category—criteria B2ab[II],D).

Taxonomic notes:—According to the holotype and protologue of Campacci & Silva (2015), D. saraca-taquerensis presents, as an evident distinctive character when compared to other congeneric species, a lip entire and obovate and an infrastigmatic ligule papillose. Based on these features and after analyzing the holotype and protologue of Krahl et al. (2016), we can note that D. integrilabia presents the same morphology. Consequently, we propose here its synonymization. Having been published a year before, the name D. saraca-taquerensis must be retained.

Some differences linked to the descriptive terminology used by Campacci & Silva (2015) and Krahl et al. (2016) can be observed in the descriptions of D. saraca-taquerensis and D. integrilabia respectively. However, they do not directly affect the fact that these taxa have the same morphological circumscription: it is only a matter of points of view. Acceptable differences are observed in the color of some flower segments such as: flower whitish with pale greenish nuances in D. saraca-taquerensis (vs. yellowish cream in D. integrilabia ), column whitish in D. saraca-taquerensis (vs. cream with a slight pinkish to reddish hue near the apex in D. integrilabia ) and an anther cap pinkish in D. saraca-taquerensis (vs. brownish in D. integrilabia ). These differences in the color can be due to different stages of flower ripeness or represent some population variation.

In Campacci & Silva (2015), the leaf of D. saraca-taquerensis is described as oblong-lanceolate whereas Krahl et al. (2016) describe the leaf of D. integrilabia as elliptic. Other differences can be noted in the shape of the flower segments: dorsal sepal elliptic apiculate in D. saraca-taquerensis (vs. lanceolate acute in D. integrilabia ), lateral sepals and petals respectively elliptic-lanceolate and lanceolate and lip respectively sub-orbicular and ovate ( Campacci & Silva 2015, Krahl et al. 2016). However, based on our analyses, both materials can be best described as having oblong-elliptic to oblong-lanceolate leaves, oblong to elliptic sepals and oblanceolate to elliptic petals. The lip must be mainly described as obovate, wider near the apex than near the base (definition according to Gonçalves & Lorenzi 2007).

Additional material examined: — BRAZIL. Amazonas: Manaus: Reserva Florestal Adolpho Ducke, 31 January 2019, D.R.P. Krahl & A.H. Krahl 360 (INPA!); idem, 07 March 2019, A.H. Krahl & D.R.P. Krahl 1131 (INPA!); Presidente Figueiredo: Cachoeira da Iracema, 18April 2020, A.H. Krahl & D.R.P. Krahl 1445 (INPA!); Pará:Oriximiná: Porto Trombetas, FLONA Saracá-Taquera-MRN, Platô SW4, 16 January 2010, J.B.F. da Silva 3334 (MG!); Terra Santa: Abaocu, 14 March 2018, R. Sousa 27 (MG!); idem, R. Sousa 33 (MG!); idem, R. Sousa 34 (MG!); idem, R. Sousa 35 (MG!).

Figures

FIGURE 1. Dichaea saraca-taquerensis. A. Habit. B. Flower. C. External floral bract. D. Internal floral bract. E. Perianth. F. Lip. G–I. Column. J–K. Anther cap. L–M. Pollinarium. Photographs by A.H. Krahl.

FIGURE 2. Geographic distribution map of Dichaea saraca-taquerensis.