The species was found in an anthropized area of Atlantic forest (a private property called Sítio do Cedro), next to the roads and residences and without undergrowth (Map 1, Fig. 1A-B). The collection was made in 2015 during a fieldwork carried out under a taxonomic revision of Monimiaceae and also the Brazil Flora Online project (Lírio et al. 2020a). In 2018 and 2019 we did new fieldworks to recollect the species and to search for more individuals, however, the only known individual was found dead (Fig. 1C) and no other new individuals have been found. Despite this setback, the present study led us to an update of the species taxonomy and description because some characteristics were unknown in the protologue, which can help in the rediscovery of new individuals. Furthermore, we were able to confirm and better describe the species habitat and to assess its risk of extinction.
Mollinedia myriantha Perkins (1900:655). Type: Brazil, Rio de Janeiro, Nova Friburgo, Alto Macaé, 16 Feb. 1892, Glaziou 19859 (Lectotype P00080080! Here designated; isolectotypes C!, F!, GH!, K!, P!). (Fig. 2)
Tree up to 8 m, 40 cm DAP, bark corky, dioecious, cylindrical branches, young branches white-tomentose, then glabrous as they grow. Leaves opposite, 8.5–10 x 3–4 cm, elliptical, obovate or oblong, apex long acuminate to acute, base cuneate, entire, rigid-chartaceous, discolour, brownish-dark in the adaxial surface and brownish-light in the abaxial surface when dry, glabrous in the adaxial surface and white-strigose in the abaxial surface, except in the veins where the trichomes are dense and longer, five to six secondary veins, barely apparent in the adaxial surface and protunding in the abaxial surface, white-hirtelous, petiole 0.9–1 cm, canaliculate, white-puberulous. Staminate inflorescences in triflorous cymes organized in long thyrses up to 24 flowers, axillary or terminal, trichomes white-tomentose, rachis (0.2–0.4) 2.2–5 cm, peduncle 0.3–0.9 cm, pedicel 0.4–0.6 cm. Staminate flowers greenish-yellow, 3–3.5 x 4–7 mm, bracts 3.5–4 mm, oblong, apex acute, bracteole 1.5–2 mm, ovate, apex acute, receptacle flat, tepals about 3/4 of the length of the flower, ovate, external with rounded apex, internal with truncated apex and denticulate margin, stamen 22–23, ovate, non-confluent locule at the apex. Pistillate flowers and fruits remain unknown.
SPECIMENS EXAMINED. Brazil, Rio de Janeiro, Nova Friburgo, Macaé de Cima, 29 Jan. 2015, E. J. Lírio et al. 1196 (NY!, RB!, P!).
TAXONOMIC COMMENTS. The species resembles Mollinedia gilgiana Perkins (1900: 656) due its staminate flowers with a flat receptacle and leaves shape and length, and resembles Mollinedia triflora (Spreng.) Tulasne (1855: 394) due its staminate flowers with a flat receptacle and corky stem. Mollinedia myriantha can be differentiated from both species by the diameter of its flowers (4–7 mm in M. myriantha vs. 8–10 mm in M. gilgiana and 3–4 mm in M. triflora). The species can be differentiated of M. gilgiana by its corky stems and by the canescent leaves with trichomes densely distributed in the secondary veins (vs. striate stems, leaves glabrous or glabrescent, not canescent in M. gilgiana). Also, it differs from M. triflora by its white-tomentose multiflorous staminate flowers and bracts with 3.5–4 mm long (vs. white-strigose triflorous staminate flowers and bracts with c. 1 mm long in M. triflora).
DISTRIBUTION AND HABITAT. The species is endemic to the Atlantic montane forest, only found in Macaé de Cima, an Environmental Protection Area located in Nova Friburgo municipality, Rio de Janeiro state. The patch where we found the specimen was a disturbed secondary forest at 850 m elevation, without understory and a canopy of about 10 m of sparse trees. We found the individual in the superior left side of the fragment of forest. The site where the individual was collected was bordered to the north by a dirt road, to the south by residences and banana crops, to the east by a second dirt road, and to the west by residences (Map 1B). The region is also impacted by invasive species, small farmlands and leisure residences.
EXTINCTION RISK ASSESSMENT.Mollinedia myriantha is a dioecious species and has a very restricted distribution, known only from the type collection made in 1892 (staminate flowers) and from a recent collection made in 2015 in a private area (also staminate flowers), on the border of a small disturbed secondary forest fragment located within the region of the type locality (Macaé de Cima), at 850m elevation. Its estimated extent of occurrence (EOO) and area of occupancy (AOO) based on records is 4km2, falling within the thresholds of Critically Endangered category under criterion B. There is only one known location for this species and the major threats are the habitat loss and habitat degradation due to edge effects caused by fragmentation, expansion of roads, residential areas related to tourism and recreational activities, agriculture and invasive species. A continuing decline of area of occupancy, number of locations and mature individuals is inferred based on the threats mentioned, and also considering that since the species rediscovery in 2015, the single individual alive recorded was later in 2018 noticed as dead. Therefore, this species is assessed here as Critically Endangered as it meets the criterion B2ab (ii, iii, iv, v), and we suggest that it could be in the future tagged as “Possibly Extinct” (IUCN 2019), after targeted fieldwork to complete the documentation since the findings from the previous fieldworks carried out in 2015, 2018 and 2019, which include the local threats, and the information that the species was last recorded alive in 2015. As the cause of death for this individual is unknown, new surveys must be provided including searches for this species on potential habitats (considering the type of forest and altitudinal range within its native distribution) in different months and seasons. Financial support and resources are strongly needed to provide the targeted searches and according to the IUCN Standards and Petitions Committee (IUCN 2019), once the status of taxa is assigned with a ‘Possibly Extinct’ tag, its status should preferably be reviewed at five-year intervals.
CONSERVATION OF MONIMIACEAE IN BRAZIL. Nowadays, out of the 46 species of Monimiaceae’ family occurring in Brazil, 34 species were evaluated following the IUCN Red List assessment at national or global level (1998–2021) (Suppl. 1). Eleven (23.9%) out of the 34 species assessed are threatened; among these, 4 (8.7%) are considered Critically Endangered (CR), 5 (10.9%) are Endangered (EN) and 2 (4.3%) are Vulnerable (VU) of extinction, besides 4 (8.7%) are Near Threatned (NT) and 1 (2.1%) Data Deficient (DD). The major threats are deforestation, fragmentation and fire in the Atlantic forest (Suppl. 1). Twelve of the 46 species still need a formal assessment, including the assessment for M. myriantha which is here rated as Critically Endangered, and we suggest it to be tagged as Possibly extinct. The results of the assessments are summarized in the Supplementary material (Figure S1).