Triolena rojasae Michelang. & R.Goldenb., 2018

Michelangeli, Fabián A. & Goldenberg, Renato, 2018, New and noteworthy Melastomataceae from the Yanachaga-Chemillén National Park and surrounding areas in Oxapampa, Pasco, Peru, Phytotaxa 374 (3), pp. 185-210 : 199-202

5. Triolena rojasae Michelang. & R.Goldenb. sp. nov. ( Figures 9–10 )

Diagnosis:—Differs from Triolena obliqua (Triana 1871: 81) Wurdack (1977: 243) by the presence of subisophyllous to anisophyllous leaves, and when anisophyllous then the smaller leaves petiolate and linear-lanceolate to elliptic-lanceolate or linear-oblong (vs. always anisophyllous in T. obliqua , and the small leaf in each pair subsessile, rounded to reniform). Also differs by the sepals internal laminae with entire margins (vs. lacerate-ciliolate), and the antesepalous stamens lacking a dorsal connective spur (vs. present in T. obliqua ).

Type:— PERU. Pasco: Province of Oxapampa, Dist. Palcazú, Parque Nacional Yanachaga-Chemillén, Sector Paujil , Quebrada Tunel , 429 m, 10°20’42”S 75°15’48”W, 17 March 2008 (fl, fr), R. Vásquez, A. Monteagudo, I. Huamantupa, A. Peña 34034 (Holotype: USM!; Isotypes: AMAZ, HOXA!, HUT, MO, MOL, NY!) .

Rhizomatose herbs 10–30 cm tall. Stems terete, moderately to densely covered with 0.4–1.2 mm long, unbranched trichomes, these simple or gland-tipped, appressed or erect and slightly curved, and also with tufts of 0.7–3 mm long, flattened, paleaceous, sometimes gland-tipped trichomes on the nodes, but sometimes isolated along the internodes and petioles. Leaves opposite, subisophyllous to anisophyllous, when anisophyllous the larger leaf in each pair with petioles 6–16 mm long, blade 5.5–7 × 1.5–2.4 cm, the small leaf in each pair with petioles 0.4–0.6 mm long, blade 2.5– 3 × 0.6–0.9 cm (when subisophyllous similar to the big ones described above); all leaves linear-lanceolate to elliptic-lanceolate or linear-oblong, the apex acute to acuminate, base cordulate or seldom rounded, usually asymmetric, margins crenulate-ciliolate, the cilia slender, 0.5–1 mm long, acrodomous nerves 3, suprabasal (the inner pair of secondaries joining the midvein 1–2.5 mm above the base, often slightly asymetrically), midvein, secondaries, and tertiary veins impressed and located in depressions that make the actual adaxial surface somewhat raised, and slightly prominent on the abaxial surface, reticulation barely visible on both surfaces, adaxial surface with sparse, 0.3–0.6 mm long, unbranched, lacking gland heads, appressed trichomes, plus similar, but denser and larger, 0.5–2.3 mm long trichomes on the nerves, abaxial surface moderately to densely covered with trichomes only on the nerves, 0.4–1.5 mm long, unbranched, gland-tipped or not, erect and curved or appressed. Uniparous cymes 4–5 cm long, 5–7-flowered, apical, the axis reddish, covered with the same indument as the branches; bracteoles lacking. Flowers on short pedicels ca. 1 mm long, 5-merous. Hypanthium 2–2.3 × 2.5–2.6 mm, campanulate, light-green, outside densely covered with trichomes similar to the ones on young stems and inflorescences, inside glabrous; torus glabrous. Calyx tube 0.2–0.3 mm long, light-green, glabrous; sepals internal laminae 0.4–0.6 mm long, widely triangular, the apex broadly acute to obtuse, margins entire; sepals external projections 0.7–0.9 mm long (setula included), longer than the laminae, triangular, the apex acute and tipped with a setula 0.2–0.4 mm long. Petals 4–4.3 × 2.3–2.8 mm, elliptic, apex acute to broadly acuminate, margin entire to slightly crenulate, glabrous, white. Stamens dimorphic, yellow; antesepalous stamens with filaments ca. 2 mm long, glabrous, anthers ca. 1 mm long, oblong, the minute pore ca. 0.15 mm diam., apical, connective barely prolonged below the thecae, ventraly projected into two very long appendages, 1.6–2 mm long, erect (but slightly bending backwards), filiform, apex rounded, glabrous; antepetalous stamens with filaments ca. 2 mm long, glabrous, anthers ca. 0.8 mm long, widely oblong, the minute pore ca. 0.15 mm diam, apical, connective barely prolonged below the thecae, ventrally projected into two short appendages, 0.2–0.3 mm long, erect, narrowly triangular, acute, glabrous, or occasionally with one short appendage and one long appendage (as in the antesepalous stamens). Ovary 3-locular, ½–completely inferior, the apex with a collar around the base of the style 0.7–1 mm tall, glabrous; style 5.5–5.9 mm long, straight but slightly curved at the apex, glabrous, stigma rouded and long-papillose. Fruits capsular, triquetrous, 5–5.5 × 4.3–5.2 mm.

Paratypes:— PERU. Pasco: Province of Oxapampa, Dist. Palcazú, Parque Nacional Yanachaga-Chemillén , sector Paujil, sendero en la margen Oeste del Río Iscozacín , camino Colpa Lobo ; rocas en zonas sombreadas a lo largo del río, 380 m, 10.3308°S 75.2541°W, 13 July 2017 (fr) F. A. Michelangeli & R. Goldenberg 2796 ( NY!, USM!) ; Sector San Francisco de Pichanaz ( Puente Albariño ), 500 m, 10°15’S, 75º15’W, 12 February 2005 (fl, fr), R. Rojas et al. 3499 ( HOXA!, MO!) ; Puente Pan de Azúcar, camino a Playa Caliente , 304 m, 10°15’10”S 75°13’28”W, 8 June 2008 (fl, fr), R. Rojas et al. 5693 ( HOXA!, HUT!, MO!, MOL, NY!, USM!) ; Camino del Puente Pan de Azúcar a Playa Caliente , 304 m, 10°15’10”S 75°13’28”W, 22 May 2010 (fl, fr), R. Vásquez et al. 36566 ( HOXA!, HUT!, MO, MOL, NY!, USM!) .

Distribution, ecology, and phenology:— Triolena rojasae is known only from the eastern portion of the Yanachaga-Chemillén National Park where it has been found growing on rocks along rivers and creeks at 300–500 m ( Figure 11 ). It has been collected with flowers and fruits from February to July.

Conservation Status:— Triolena rojasae is known from three localities along the Iscozacín River and has an EOO of 1.78 km 2 and an AOO of 16 km 2. Two of these localities are less than 1 km apart and may be considered the same population. Given the small number of populations, the restricted habitat in shaded and moist areas, we recommend that this species is considered as Endangered (B1ab).

Etymology:—It is an honor to dedicate name of this species after Rocio Rojas, Peruvian botanist who has collected throughout the forests of Peru for the past 20 years, and has made great contributions to the knowledge of the flora of the Yanachaga-Chemillén National Park.

Comments:— Triolena rojasae most closely resembles T. obliqua , a species found from Colombia to the Amazonas region in Northern Peru. Both species share the crenate leaves, and the flattened paleaceous trichomes on the nodes (which are larger in T. rojasae ). However, the stem trichomes are larger in T. obliqua (0.6–1.2 vs. 1.8–2.8). Most notably, T. obliqua seems to be consistently anisophyllous (vs. anisophyllous to sub-isophyllous), with the smaller leaf in each pair suborbicular (vs. lanceolate to elliptic-lanceolate).

Flowers dissected from two different collections of Triolena rojasae show an unusual feature that while the appendages of the antesepalous stamens are always present and of similar size, the appendages of the antepetalous stamens vary in size and may not be present, with some anthers having just one of the appendages fully developed ( Figure 9F ).

Figures

FIGURE 9. Triolena rojasae. A. Plant, with a detail of the leaf margin, adaxial surface. B. Inflorescence. C. Flower bud, lateral view. D. Flower, longitudinal section, petals and five stamens removed. E. Petal, adaxial view. F. Stamens attached to the torus (left) and individual stamens (right), from left to right, antepetalous—lateral view, antesepalous—lateral view, antepetalous—dorsal view, antesepalous— dorsal view. G. Fruit, lateral view (above), apical view (below). A–B, G, Rojas 5693 (NY); C–F. Vásquez 34034 (NY).

FIGURE 10. Photos of Triolena rojasae in the field.A. Plants growing over mossy rocks.B. Large leaves, adaxial surface. C. Inflorescence with flower before anthesis and buds, and leaves, abaxial surface. D. Inflorescence. E. Immature fruits.A–B, E. Michelangeli 2796. C–D. Vasquez 34034.

FIGURE 11. Distribution of Triolena rojasae, Triolena vazquezi and Wurdastom ecuadorense (in Peru).