Myrcia garuvana F.C.S.Vieira & Sobral, 2022

Vieira, Fábio C. S., Sobral, Marcos, Mazine, Fiorella F. & Longen, Fábio, 2022, Myrcia garuvana (Myrtaceae) a new species from Santa Catarina, Brazil, Phytotaxa 560 (2), pp. 254-258 : 254-256

Myrcia garuvana F.C.S.Vieira & Sobral , sp. nov.

TYPE:— BRAZIL. Santa Catarina: Garuva, Rio do Cristo , 26º05’22”S, 48º53’23”W, 14 December 2004, F.C.S. Vieira 680 (holotype JOI! , isotypes HUFSJ!, UFPE!) .

Figures 1 , 2 .

Diagnosis:—This species is morphologically related to Myrcia neocaudata A.R.Lourenço & E.Lucas (in Lima et al. 2020: 251; type image BM 000953737—for description see Lourenço et al. 2020: 40), from which it differs by its leaves with petioles 5–6 mm (versus petioles to 2 mm in M. neocaudata ), blades 28–53 × 10–25 mm, 1.5–2.8 times longer than wide (versus blades 24–35 × 8–10 mm, 3–4 times longer than wide in M. neocaudata ), with acumen 10–15% of the blade’s length (vs. acumen 30–50% of the blade’s length), inflorescences mostly triflorous, rarely uniflorous (vs. predominantly uniflorous) and flowers with petals absent (vs. petals present). It may also resemble Myrcia neolucida A.R.Lourenço & E.Lucas (in Lourenço et al. 2018: 79; type image M 0137175; for description see Lourenço et al. 2020: 41), but differs by the blades 28–53 × 10–25 mm (versus blades to 40–110 × 18–45 mm in M. neolucida ), inflorescences 15–18 mm, with 1 to 3 flowers (vs. inflorescences 45–60 mm, with more than 10 flowers), and ripe fruits dark-blue or black when ripe (vs. fruits yellow or red when ripe).

Description:—Trees to 6 m high, the trunk to 20 cm of diameter at body heigth. Plants glabrous or with very scarce dibrachiate trichomes to 0.1 mm scattered along the petioles and abaxial side of blades. Twigs grey when dry, frequently dichotomously branched, terete or more or less applanate, 20–25 × 0.8–1 mm in diameter (keels not included), with two evident longitudinal keels 0.2–0.5 mm wide. Leaves with petioles 5–6 × 0.7–1 mm, adaxially sulcate; blades elliptic or occasionally obovate, 28–53 × 10–25 mm, 2–2.8 times longer than wide, the surface undulate and discolorous, dull green adaxially and light green abaxially when dry; glandular dots to 0.1 mm in diameter and 10–20/mm², slightly excavated adaxially, darker than the surface and slightly raised abaxially; base cuneate, slightly decurrent along the petiole; apex acuminate in 3–7 mm, 10–15% of the blade’s length; midvein impressed adaxially and prominent abaxially; lateral veins 20–25 at each side, scarcely visible on both surfaces, sometimes finely raised abaxially; intramarginal vein 0.4–0.8 mm from the margin, the margin itself somewhat revolute. Inflorescences 1–3-flowered, the flowers crowded at the apex of a peduncle 15–18 × 0.3–0.4 mm; bracts not seen; pedicels absent; bracteoles not seen, probably decidous before anthesis; flower buds globose to ovate, 2–3 × 1.2–1.6 mm, with calyx lobes completely fused and opening through a calyptra 1–2 mm, deciduous after anthesis, the apex of the calyptra with an apiculum 0.4–1 mm; petals absent in the flowers examined; stamens with filaments to 2 mm, the anthers to 0.3 × 0.4 mm, eglandular; staminal ring 1.5–1.6 mm in diameter; calyx tube to 1 mm deep; style to 3 mm, the stigma punctiform; ovary bilocular with two ovules per locule. Fruits dark-blue or black when ripe, globose, ellipsoid or slightly oblate, 7–8 × 8–10 mm, 1–2-seeded, crowned by the calyx tube; seeds globose to hemispheric, 6–7 × 5 mm and 2–3 mm thick, protected by an easily detachable, membranous, light-brown testa; embryo to 5 × 4 mm and 2 mm thick, with two folded cotyledons surrounded by an evident hypocotyl.

Distribution, habitat and phenology:— Myrcia garuvana is presently known from the coastal rainforests of the municipalities of Garuva and Joinville, in the northeastern portion of Santa Catarina. It is a small tree growing in the interior of the forest along water stream ridges. Flowers were collected from June to December and ripe fruits in April.

Conservation:—This species is presently known from two locations in the municipalities of Garuva and Joinville, with just one individual being registered and recollected in each location, although a total of 5 individuals were observed in both areas (FCSV, personal observation). Garuva has an area of 503 km ² and Joinville of 1,127 km ² ( IBGE 2021), summing up 1,630 km ², and respectively 5,200 and 8,650 plants were collected in these municipalities (SpeciesLink 2022), resulting in the high sampling index of 8.4 collections/km². In light of this, the scarcity of collections of Myrcia garuvana may be an indicative of its rareness. Additionally, 1) it is possible to establish the Extent of Occurrence (EOO, see IUCN 2012: 11) of this species as smaller than 5,000 km ², since the area of the two municipalities where it was collected sums 1,630 km ²; 2) the species is presently known to occur at only two localities, and 3) due to the possibility of extreme meteorological events like explosive cyclones ( Gobato & Heidari 2020), the known populations are prone to extreme fluctuations. These three items fulfill conservation criteria B1, B1a and B1c according to IUCN (2012: 19), allowing to score this species as Endangered (EN).

Affinities:— Myrcia garuvana is morphologically related to M. neocaudata , a species from montane forests from the southeastern Brazilian state of Rio de Janeiro and the more widespread South American M. neolucida , from which it is distinguished in the diagnosis. According to the sectional classification proposed by Lucas et al. (2018), M. garuvana must be assigned to Myrcia sect. Calyptranthes (Sw.) A.R.Lourenço & E.Lucas (in Lucas et al. 2018: 1; basionym: Calyptranthes Swartz, 1788: 79), due to the calyptrate flowers.

Etymology:—The epithet is derived from the locality of the type specimen, the municipality of Garuva.

Paratypes:— BRAZIL. Santa Catarina: Garuva, Rio do Cristo , 15 April 2005, F.C.S. Vieira 959 ( HUFSJ!, JOI!) ; ibidem, 31 July 2005, F.C.S.Vieira 1180 ( JOI!) ; ibidem, 19 December 2005, F.C.S.Vieira 1437 ( JOI!) ; ibidem, 20 April 2006, F.C.S.Vieira 1774 ( JOI!) ; ibidem, 15 June 2006, F.C.S.Vieira 1804 ( JOI!) . Joinville, Piraí, 16 December 2017, F. Longen 04 ( JOI!) .

Figures

FIGURE 1. Myrcia garuvana - holotype. Insert: detail of inflorescence, showing apetalous flower (from isotype at HUFSJ; insert scale: 5 mm).

FIGURE 2. Myrcia garuvana. Branch with fruits (from Vieira 959, at HUFSJ; scale: 10 mm).