Meriania hirsuta Rob. Fern., Paredes-Burneo & Michelang., 2022

Rocío, Robin Fernandez-Hilario, Gonzáles, Pilar Rojas, Villanueva-Espinoza, Rosa, Lajo, Leticia, Wong Sato, Akira A., Paredes-Burneo, Diego, Pillaca-Huacre, Luis, Michelangeli, Fabián A. & Goldenberg, Renato, 2022, Nine new species and a new country record for Meriania (Melastomataceae) from Peru, Willdenowia 52 (1), pp. 39-74 : 56-58

5. Meriania hirsuta Rob. Fern., Paredes-Burneo & Michelang. , sp. nov. – Fig. 6 , 12 .

Holotype: Peru, Piura, Prov. Huancabamba, Dist. El Carmen de la Frontera, Río Samaniego margen izquierda, Zona de Amortiguamiento del Santuario Nacional Tabaconas-Namballe , 05°06'43.1"S, 79°21'25.7"W, 2150 m, 28 Apr 2003 (fl.), S. Baldeón & J. Campos 5373 ( USM accession no. 273379 !) .

Diagnosis — A species differing from other congeners by the combination of branches and leaves with hirsute indumentum (elongate fluted trichomes up to 4 mm long), campanulate, deep red corollas, slightly dimorphic stamens, stamen connectives with one dorsobasal appendage that is almost perpendicular to the thecae and antisepalous stamen connectives with laterally expanded dorsobasal appendages.

Morphological description — Shrub up to 1.5 m tall; young branches and petioles hirsute with elongate fluted trichomes, these up to 4 mm long, moderately to densely on young branches, densely on petioles. Young branches terete or quadrangular, 5–7 mm in diam., lacking wings, nodes without interpetiolar flaps. Leaves opposite, isophyllous. Petioles terete, 5–15 mm long, without projections. Leaf blades subcoriaceous, 3.2–7.8 × 3–6.7 cm, ovate, apex acute, base cordate, margin denticulate, slightly discolorous; venation acrodromous and basal, with three pairs of secondaries (lateral nerves) and an additional pair of faint submarginal veins running up to leaf apex, tertiary (transversal nerves) 14–16 on each side of primary, percurrent, 2–8 mm distant from each other, midvein, secondary and tertiary veins impressed, reticulation visible on adaxial surface, midvein, secondary and tertiary veins prominent and reticulation impressed on abaxial surface; adaxial surface bullate, black when dry, densely hirsute with trichomes similar to ones on petioles; abaxial surface dark brown when dry, moderately hirsute with trichomes similar to ones on petioles, denser on veins. Inflorescences not clear (see discussion). Flowers 5-merous, apparently pendant, with campanulate corollas; on swollen nodes 3–3.5 mm long, moderately hirsute with trichomes similar to ones on petioles. Pedicels 15–18 mm long, colour unknown, glabrous. Hypanthium 4–4.5 × 7–7.5 mm, campanulate, colour unknown, glabrous; torus glabrous. Calyx opening regularly, colour unknown, glabrous; tube 1.5 mm long; lobes repand; with 5 slightly callose dorsal projections, whitish and much lighter than rest of calyx and hypanthium when dry. Petals 12.5–13 × 11.5–12 mm, 4–4.5 mm wide at base, slightly obovate, apex rounded, margin entire, deep red, glabrous. Stamens 10, slightly dimorphic, all bent to one side of flower giving flower a zygomorphic appearance; antipetalous stamens filaments c. 8.5 mm long, colour unknown, flat, glabrous, connectives prolonged below thecae c. 0.3 mm long (not including perpendicular appendage), colour unknown, with one almost perpendicular dorsobasal appendage to thecae, c. 3 mm long, acute and with a rounded projection, c. 0.5 mm long, with an irregular surface, colour unknown, 1 mm from tip of dorsobasal appendage, anthers c. 6.5 mm long, lanceolate, colour unknown, glabrous, straight or with its apex slightly reflexed, opening by one slightly dorsally inclined pore, thecae surface smooth; antisepalous stamens with shape and size similar to antipetalous stamens, only difference being connectives with laterally expanded perpendicular dorsobasal appendages. Ovary 5-locular, superior, c. 4 × 4.5 mm, spheroidal and 5-lobed, colour unknown, c. 0.25 mm exceeding hypanthium length, glabrous; style 12–13 mm long, colour unknown, glabrous, slightly incurved at apex and opposite to anthers at anthesis; stigma punctiform and minutely papillate, c. 1 mm wide, colour unknown. Fruits and seeds not seen.

Phenology — Flowering occurs in April.

Distribution and ecology — Meriania hirsuta is known only from two localities, about 5 km away from each other, between 2150 and 3035 m. This plant inhabits the montane forests of the E slopes of the Andes, at the northernmost limit of the Yungas ( Comunidad Andina 2009), in the headwaters of the Samaniego river, which is part of the Chinchipe river basin. So far, this is a species endemic to Peru, found only in the Piura department (even though the paratype label records it for the Ayabaca province, it rather belongs to the Huancabamba province). Also, this species occurs in the core of the Amotape-Huancabamba zone, which is home of many other endemic species of Melastomataceae ( Bussmann & Paniagua 2012; Bussmann & Paniagua 2013; Burke & al. 2017; Paredes-Burneo & al. 2018; Michelangeli & Paredes-Burneo 2019; Fernandez-Hilario & al. 2021 a).

Conservation status — The short range of occurrence of Meriania hirsuta is under the constant pressure of cattle grazing and logging, which might be prevented due to the recent setup of a Private Conservation Area ( MINAM 2016). Therefore, following IUCN (2012, 2019) guidelines and based on an estimated area of occupancy of 8 km 2, we recommend the category Critically Endangered CR B 2ab(iii) for this species.

Etymology — The specific epithet refers to the indumentum of this species.

Discussion — Meriania hirsuta is clearly distinguished from other species within the genus by its hirsute indumentum (trichomes up to 4 mm long) on the branches and leaves. Other species with similar indumentum are M. arizae Humberto Mend. & Fern. Alonso (trichomes up to 4.5 mm long), M. horrida C. Ulloa & Achá (up to 12 mm long) and M. mutisii (Humb. & Bonpl.) Humberto Mend. & Fern. Alonso (up to 4.5 mm long). However, M. arizae and M. mutisii belong to the Meriania “brachycera ” group ( Mendoza-Cifuentes & Fernández-Alonso 2012) characterized by its calyptrate calyces with circumscissile dehiscence and spreading corollas, whereas M. hirsuta has calyces with repand lobes and regular dehiscence and campanulate corollas. On the other hand, M. horrida has dendritic trichomes intermixed with simple trichomes (vs only simple in M. hirsuta ), flowers 6(–7)-merous (vs 5-merous) with spreading, reddish purple corollas (vs campanulate, deep red).

Due to the characteristics of the leaves (bullate, ovate and cordate leaf blades) and flowers (campanulate, deep red corollas and stamen connectives with perpendicular dorsobasal appendages to the thecae), Meriania hirsuta seems to be closely related with species of the M. radula complex, formed by M. almedae Wurdack , M. radula (Benth.) Triana , M. tetragona and M. sanguinea . These species have isomorphic stamens and glabrous, granulose-furfuraceous or setulose abaxial leaf blades with dendritic trichomes up to 1 mm long, whereas M. hirsuta has hirsute indumentum with elongate fluted trichomes up to 4 mm long and slightly dimorphic stamens (antisepalous stamen connectives with laterally expanded appendages). Within M. radula complex, M. hirsuta and M. radula do not have interpetiolar flaps, but the former is distinguished from the latter by its abaxial leaf blades with trichomes only on nerves and reticulation (vs trichomes evenly covering the entire surface) and petals 12.5–13 mm long (vs 17–19 mm). The laterally expanded appendage of antisepalous stamen connective is a character observed in other Peruvian species such as M. amischophylla Wurdack , M. sumatika , M. vargasii Wurdack , M. vilcabambensis Wurdack and M. weberbaueri J. F. Macbr. , but all these have stamen connectives with spreading, reddish purple corollas and stamen connectives with descending dorsobasal appendages (vs perpendicular dorsobasal in M. hirsuta ) and ascending dorsal appendages of the antisepalous stamens (vs absent in M. hirsuta ), except M. amischophylla , which has dorsal appendages as mere humps, and M. weberbaueri , which lacks dorsal appendages.

The location of the inflorescences on the branches in Meriania hirsuta is unclear as the only fertile specimen (Baldeón & Campos 5373) has three short branches with flowers located at the distal nodes. The inflorescences could be interpreted as axillary fascicles (8–10-flowered) or as one terminal panicles (8–18.5 cm long with 3 nodes). The former is a feature not seen within Meriania and the latter is present in all species within the M. radula complex, although in these species the inflorescences longer than 18 cm and with more than (4 or)5 nodes.

Additional specimens examined (paratypes) — PERU: Piura, Prov. Ayabaca [Huancabamba], Dist. El Carmen de la Frontera, Carretera Sapalache-Cerro Chinguelas , 05°08'23.6"S, 79°23'45.4"W, 3035 m, 3 Sep 2016 (sterile), F. A. Michelangeli & al. 2636 ( NY!, USM!) .

Figures

Fig. 6. Distribution map of Meriania bongarana, M. hirsuta, M. juanjil and M. megaphylla.

Fig. 12. Meriania hirsuta – A: terminal fertile branches with inflorescences; B: detail of hirsute internode; C: detail of adaxial leaf surface; D: flower bud, lateral view; E: antisepalous stamen, lateral view, with detail of perpendicular dorsobasal appendage; F: antipetalous stamen, lateral view, with detail of perpendicular dorsobasal appendage; G: longitudinal section of flower with petals and stamens removed. – A–G from S. Baldeón & J. Campos 5373. – Drawing by Leticia Lajo (E, F).