Dichaea integrilabia Valsko, Krahl & Chiron, 2016

Krahl, Amauri Herbert, Valsko, Jefferson José, Holanda, Ana Sofia Sousa De & Chiron, Guy, 2016, A new species of Dichaea (Orchidaceae) from Brazil with special reference to its foliar anatomy, Phytotaxa 265 (2), pp. 145-150 : 146-149

Dichaea integrilabia Valsko, Krahl & Chiron , sp. nov. ( Figs. 1 and 2 )

Type:— BRAZIL. Amazonas: Manaus, “Projeto Dinâmica Biológica de Fragmentos Florestais ( PDBFF), Fazenda Porto Alegre”, 2021 ’19.19” S, 59057 ’31.81” W, 21 September 2012, fl. in cult. 9 December 2012, J. J. Valsko 111 (fl.) (holotype INPA!).

Haec species specie sympatrica Dichaea bragae Valsko, Krahl & Holanda similis sed foliis majoribus, floribus cremeo-luteis (virescentibus cum labello albo in D. bragae ), floris partibus majoribus, labello simplici (unguiculato trilobatoque in D. bragae ) et columna majore differt.

Epiphytic caespitose plant. Roots thick, ca. 2–2.3 mm in diameter, whitish, glabrous. Stem ca. 10–25 × 0.5 cm, terete, sub-erect, covered by sheathing bases of the leaves. Leaf sheaths 14.6 × 4.3 mm, glabrous, deep green. Leaves ca. 36.1 × 6.4 mm, elliptic, apex acute, base rounded, margin entire. Leaf laminae distant, deep green, glabrous, deciduous, articulate with the leaf sheath. Inflorescence ca. 18 mm long, 1-flowered, lateral, growing between the leaf sheaths. Pedicel ca. 13–14 mm long, glabrous, with two tubular bracts at the base. Bracts ca. 2.5–3 mm long, acute, glabrous, cream to whitish, with entire margins. Floral bracts similar, ca. 3 mm long, the internal one slightly shorter. Ovary ca. 2 × 1 mm, terete, glabrous. Flowers yellowish cream, column cream with reddish marks aroud the stigma, anther cap reddish brown. Sepals lanceolate, with a truncate base and an acute apex, glabrous, the dorsal one ca. 5.5 × 2.5 mm, the lateral ones ca. 6 × 2.3 mm, slightly curved, asymmetric, with entire margins. Petals similar, 5.4 × 2 mm, concaves. Lip ca. 5.4 × 3.8 mm, entire, oval, acute, with entire margin. Gynostemium ca 4 × 2 mm, fully glabrous, with a very small and linear ligule below the sub-orbicular stigmatic cavity; anther cap ca 2.3 × 2 mm, orbicular; pollinia 4 in two sub-equal pairs, ca 0.45 mm diameter, orbicular, yellow, with a triangular stipe and an elliptic viscidium. Fruit not seen.

Etymology: —the specific epithet refers to the entire lip, an uncommon feature within the genus.

Distribution and habitat: — Dichaea integrilabia is up to now known only from the type locality. It grows in a continuous area of dense ombrophilous forest, at 90–100 m ( Fig. 3 ). In the rainy season, this area is frequently flooded for short periods of time, resulting in the formation of small lakes. Around these lakes the vegetation is composed of smaller trees that host larger quantities of epiphytes. The specimens were growing on small branches at 4–8 m above the ground.

Phenology: —In cultivation the species flowers during the months with heavy rains, i.e. from December to May.

Anatomy: —The epiderm is uniseriate and covered by a rather thin cuticle which goes with the wall of the epidermal cells. On both faces the epidermal cells are rounded, the cells of the adaxial face being larger than the abaxial ones. As for the stomata, the leaf is hypostomatic, in accordance with what was observed in other Dichaea species ( Oliveira & Sajo 1999; Moreira et al. 2009). The stomata are located at the same level as the other epidermal cells and show a large substomatic chamber. The mesophyll is homogenous, without any sclerified cell. Its cells are rounded in accordance with what was observed in the allied species ( Oliveira & Sajo 1999; Moreira et al. 2009). In the central part of the leaf, around the V-shaped fold, larger and elongated cells occur which may show the presence of a thin hypoderm. Around the vascular fascicles the mesophyll cells show a radial arrangement. The vascular fascicles are of the collateral type, are located in the central area of the mesophyll and show various sizes. In the area adjacent to the xylem and mainly near the phloem we can observe about five chambers of sclerified cells.

Morphological affinities: —The new species is closely related to Dichaea bragae Valsko, Krahl & Holanda (2014b: 398) , a sympatric and morphologically similar species. However some differences can be noted. Dichaea integrilabia has longer leaves (36 mm vs. 22 mm), with an acute apex (vs. apiculate), yellowish cream flowers (vs. greenish with a white lip), larger floral segments (dorsal sepal 5.8 × 2.5 mm vs. 3.6 × 1.2 mm, lateral sepals 5.9 × 2.3 mm vs. 4.9 × 1.9 mm, petals 5.4 × 1.9 mm vs. 4.3 × 3.7 mm), a simple lip (vs. 3-lobed) and a larger gynostemium (4 × 2.1 mm vs. 1 × 0.6 mm) ( Valsko et al. 2014b). Both species grow in the reserves belonging to the “Programa Dinâmica Biológica de Fragmentos Florestais (PDBFF)”, however in different places since D. integrilabia occurs in the “Fazenda Porto Alegre” whereas D. bragae occurs in the “Fazenda Dimona” ( Valsko et al. 2014b). Both localities are about 1.6 km far from each other. Both taxa are really separate species and not only variations of the same species: the differences, chiefly in the lip, were observed in all the individuals of these populations.

The entire lip is an uncommon distinctive feature within the genus and very good support to a separate species. However there are at least two other Dichaea species with an entire (however more or less clawed) lip: some populations of Dichaea pendula ( Aublet 1775: 819–820) Cogniaux (1903: 182–183) and in Dichaea tuerckheimii Schlechter (1916: 188–190) (according Pupulin 2007) but both species are very different from D. integrilabia . Dichaea pendula , with its muricate ovary and its non-articulate leaves ( Pupulin 2007), belongs to section Dichaea ; it has a hanging (vs. suberect) 15–100 cm long (vs. 10–25 cm) stem, its leaves are lanceolate (vs. elliptic) and shorter (18–30 mm vs. 36 mm long), its sepals and petals are elliptic (vs. lanceolate) and its lip is only rarely simple, generally 3-lobed. As for D. tuerckheimii , it can be differentiated by its prostrate and scandent, 5–14 cm long stem, its oblong-ovate leaves and its obcuneate shortly clawed lip. Moreover it belongs to section Dichaeastrum (glabrous ovary and articulate leaves).

In the phylogenetic tree published by Neubig et al. (2009), Dichaeopsis is divided into three clades. Based on its delicate stem, its rather thick roots, its anther cap reddish brown and, chiefly, its reduced infrastigmatic ligula, the new species probably belongs to the clade formed by Dichaea panamensis Lindley (1833: 209) and Dichaea ancoraelabia Schweinfurth (1947: 614) . The clade formed by Dichaea glauca ( Swartz 1788: 124) Lindley (1833: 209) occurs in Central America and West Indies and comprises species with multiple simultaneous inflorescences on each stem ( Neubig et al. 2009), which is not observed in D. integrilabia . Finally D. integrilabia is similar to D. trulla Reichenbach (1866: 104) , but has shorter and wider leaves (3.6 × 0.6 cm vs. 5–11 × 0.4–0.6 cm) and suberect (vs. pendulous) stems (Barbosa Rodrigues 1882; Cogniaux 1893 –1896; Pupulin 2007). Besides, D. trulla has an elliptic dorsal sepal and elliptic petals and a purplish, clawed, 3-lobed, hastate and subsagittate to subdeltoid lip (Rodrigues 1882; Cogniaux 1893 –1896; Pupulin 2007). Its flowers are larger ( Pupulin 2007): for example its dorsal sepal is 7–10 mm long and 4–5 mm wide (vs. 5.8 × 2.5 mm). Some features observed in the species of the D. trulla clade do not exist in D. integrilabia , e.g. a large infrastigmatic ligula ( Neubig et al. 2009).

Dichaea integrilabia is also similar to Dichaea australis Cogniaux (1906: 498) , which is allied to D. trulla . However D. integrilabla has shorter (3–4 × 0.6 cm vs. 6–9 × 0.2–0.3 cm long) and wider leaves and very different lip morphology: D. australis has a clawed obovate and deltoid lip, with acute and reduced lateral lobes ( Cogniaux 1893 – 1896). Moreover D. australis is endemic to the Atlantic forest of the States of São Paulo, Paraná and Santa Catarina (Barros et al. 2015).

Additional specimen examined (paratype): — BRAZIL. Amazonas: Manaus, “Projeto Dinâmica Biológica de Fragmentos Florestais (PDBFF), Fazenda Porto Alegre”, 2021 ’19.19”S, 59057 ’31.81”W, 13 Outubro 2012, fl. in cult. 10 Abril 2013, Valsko 118 (fl.) (EAFM).

Figures

FIGURE 1. Dichaea integrilabia. A. Habit. B. Flower. C. Perianth. D. Gynostemium and ovary. E. Pollinia and stipe (J.J. Valsko). Drawing by Ana Sofia S. de Holanda.

FIGURE 2. Dichaea integrilabia. A. Habit. B. Flower. C. Labellum. D. General look of the mesophyll. E. Vascular bundle. FB = Fiber; ME = Mesophyll; PH = Phloem; VB = Vascular bundle; XY = Xylem. Photograph by Jefferson J. Valsko and Amauri H. Krahl.

FIGURE 3. Distribution of Dichaea integrilabia in Brazil (red dot).