Myrcia urquiolae Z. Acosta, 2022

Ramos, Zenia Acosta & Hechavarría, José Luis Gómez, 2022, Myrcia urquiolae (Myrtaceae), a new species from eastern Cuba, Phytotaxa 549 (1), pp. 111-111 : 111

Myrcia urquiolae Z. Acosta , sp. nov. ( Figures 1 , 2 and 3 ).

Type:— Cuba, Prov. Holguín, municipio Mayarí, Sierra de Nipe, charrascales de La Caridad cerca del río Naranjo , 13 June 2018, Z. Acosta & J.L. Gómez s.n. (holotype HAJB 1255!; isotypes: B!, FTG!, HAC!, HAJB 1254!, HAJU!, HJBHO!, PAL-Gr 129938!) .

Diagnosis:— Myrcia urquiolae differs by all Cuban congeneric species by its strongly revolute linear leaves.

Description:— Small tree up to 7 m high, branchy; old branches cylindrical, glabrous, olive-green with longitudinal and scaly striations due to the loss of the suber; the young branches quadrangular, bright green, with abundant simple hairs and glands visible as black dots. Leaves opposite; petioles 1–2 mm long, ca. 1 mm wide, cylindrical, glabrous; laminas linear, 2.5–4 × 0.15–0.3 cm, bright green and glabrous on the upper surface, brownish green on the underside and brown tomentose on the midvein, bright brown on the upper surface and light brown on the underside when dry, coriaceous, glandular dotted, apex acute to obtuse, base acute to rounded, margin strongly revolute, entire, middle vein sunken on the upper surface and prominent on the underside, secondary veins not visible on both surfaces. Inflorescences in axillary panicles, with up to 10 flowers, peduncles 2–5 cm long, white-tomentose. Flowers with pedicels 2–3 mm long; bracts filiform, albo-tomentose, 1.5–2 × 0.5–0.8 mm, persistent after anthesis; hypanthium albotomentose, conical. Calyx 4–merous, opening irregularly, white-tomentose, with abundant visible glands, sepals 1.5–2 × 1–1.5 mm, apex acute. Petals 4, yellowish–white, deltoid, glandular-dotted, 2–3.5 × 1.5 mm. Stamens numerous, filaments white, 5–6 × 0.2 mm; staminal ring thickened, 0.4–0.5 mm thick; anthers light brown, rounded to oblong, 0.5–1 × 0.5 mm, two thecae. Ovary white-tomentose, glandular, bilocular with 2 ovules per locule; style 10–12 × 0.4–0.5 mm, stigma truncate, 0.6–07 diameter. Fruits and seeds unknown.

Etymology:—The epithet is dedicated to Dr.Armando Jesús Urquiola Cruz (1949–2009), eminent Cuban botanist, founder of the Botanical Garden of Pinar de Río, who dedicated his life to the study and conservation of the flora of Pinar de Río, the Myrtaceae family and Cuban aquatic plants. Professor Urquiola was the first to recognize this species as new to science, in an expedition with the first author in 2007.

Distribution and habitat:—Local endemic species of Sierra de Nipe. It is only known from the Charrascales de La Caridad, near the Naranjo river (20.474592 N; - 75.740322 W), Mayarí municipality, Holguín province ( Figure 3 ). It grows in xeromorphic sub-thorny thickets over serpentinite rocks, on ferromagnesian red-brownish fersialitic soils, between 300–450 m elev. The shrub strata of the charrascal, where the species lives, varies between 3–4 m in height and its cover on the ground is 70–80%. Species composition include Mazaea shaferi ( Standley 1918: 42) Delprete (1999: 221) , Metopium venosum ( Grisebach 1866: 67) Engler (1883: 367) , Miconia rosmarinifolia ( Grisebach 1866: 93) M. Gómez (1894: 68) , Psychotria rufovaginata Grisebach (1866: 136) , Plumeria nipensis Britton (1915: 505) y Solenandra myrtifolia ( Grisebach 1866: 125) Borhidi (2002: 227) .

Reproductive biology:—Tiny yellowish-white flowers with numerous stamens indicate probable insect pollination. Although the fruits of the new species are unknown, dispersal by birds has been reported for other Myrcia species ( Torezan-Silingardi & Alves 2004).

Conservation status:— Myrcia urquiolae is known from only one locality, which was affected by fire in March 2019. In the only population known to date, 25 adult individuals have been registered in an extent of occurrence and area of occupation of 1 km 2. Although this locality is located within La Mensura-Piloto National Park, a managed protected area of national significance, this site is vulnerable to increased fire frequency. For this reason, a future decrease in the area, extent and quality of habitat and in the number of mature individuals is projected. Therefore, according to IUCN (2019) criteria, the available data support the evaluation of Myrcia urquiolae as Critically Endangered (CR), by criteria: B1ab(ii, iii,v)+2ab(ii, iii,v); C2a(i,ii); D.

Taxonomic remarks:— Myrcia urquiolae belongs to Myrcia sect. Myrcia due to its hairy floral disc and the nonprolonged hypanthium on the summit of the ovary, characters that distinguish it from the other sections of the genus. Additionally, it presents a thickened staminal ring, which comprises more than 50% of the disc (vs. less than 30% in Myrcia sect. Gomidesia (O. Berg 1855 –1856: 5) B. S. Amorim & E. Lucas in Lucas et al. 2018: 9), and anthers with thecae of equal size that open completely in two equal parts (vs. vertically displaced that retain curvature at dehiscence) (see Lucas et al. 2018). The phylogenetic position of M. urquiolae in Myrcia sect. Myrcia was proven by Flickinger et al. (2020, as Myrcia sp. 1 ), where in the phylogeny of the family for the Greater Antilles it nested along with M. apodocarpa Urban (1923: 87) , M. retivenia (C. Wright 1869: 433) Urban (1923: 86) and M. abbottiana (Urban 1925: 341) Alain (1971: 138) . Regarding the other species of the section in Cuba, M. urquiolae differs by its strongly revolute linear leaves.

Figures

FIGURE 1. Holotype of Myrcia urquiolae (HAJB 1255).

FIGURE 2. Myrcia urquiolae. A. Portion of the trunk showing the typical bark of the Myrtaceae family. B. Branch showing linear leaves with strongly revolute margins. C. Branch with flowers. D. Detail of the inflorescence.

FIGURE 3. Geographical location of the Myrcia urquiolae population in Holguín (eastern Cuba), La Mensura-Piloto National Park, near the Naranjo river, in the charrascales of La Caridad.