Eugenia nordestina L.R.V.Santos & I.R.Costa, 2022

Lima, Igor G., Santos, Lainy R. V., Costa, Itayguara R. & Bünger, Mariana, 2022, Eugenia nordestina (Myrteae, Myrtaceae), a new endemic species from the Septentrional Northeast of Brazil, Phytotaxa 545 (1), pp. 115-120 : 116-118

Eugenia nordestina L.R.V.Santos & I.R.Costa , sp. nov.

Type:— BRAZIL. Ceará: Croatá, São Roque , 1 February 2013, A.S.F. Castro 2625 (holotype EAC!, isotype BHCB!) . Figures 1 , 2 .

Diagnosis:— Eugenia nordestina is morphologically related with Eugenia dysenterica (Martius [in Martius & Spix 1828: 571]) de Candolle (1828: 268), but differs in the following characters: bark longitudinally cleft with a stiff narrowly exfoliating periderm (versus bark cleft in both orientations, with a very thick and non-exfoliating periderm in E. dysenterica ), bracteoles 4.5–6 mm long (vs. 0.9–3.2 mm), flowers with calyx lobes 5–6.5 mm long (vs. 3.1–4.3 mm long), glabrous (vs. pubescent, at least in the apex), petals without glandular dots (vs. with sparse glandular dots) and fruits with 1.3–2.3 × 1–2 cm (vs. 1.8–3 × 2.5–3.5 cm). It also resembles Eugenia megaflora Govaerts (2008: 152) , though differing by its leaves with 2–7 cm long (vs. 6.4–17.3 cm long in E. megaflora ), petioles 2.5–4 mm long (vs. 5.4–7.9 mm long), pedicels 5.5–22.5 mm long (vs. 29.3–62.4 mm long), calyx lobes ovate, elliptic or deltate (vs. orbicular), glabrous (vs. densely pubescent) and fruits glabrous (vs. puberulous-tomentose).

Description:—Shrub, treelet or tree 3–5 m, bark longitudinally cleft, with a stiff and narrowly exfoliating periderm, greyish; hyaline, light-brown or ferruginous simple erect trichomes; colleters linear, 0.7–1.3 mm long, associated with cataphylls, bracteoles, hypanthium and gems, often deciduous. Young twigs cylindrical to slightly flattened, moderately longitudinally striate, covered with simple erect trichomes which occasionally almost conceals the surface, glabrescent with age; cataphylls 4–8 pairs, the proximal ones widely ovate, 0.4–2 mm long, the distal ones ovate, 3–4 mm long, minutely ciliate, imbricated when young, supporting one to three developing twigs; internodes 1–5.4 cm long. Leaves with petioles 2.5–4.8 mm long, frequently pubescent when young, terete; blades elliptic to oblanceolate, 2–7 × 1–3.7 cm, frequently discolorous when dry, lighter abaxially, frequently ciliate, the adaxial side glabrous to scarcely pubescent except for the midvein, the abaxial side glabrous to sparsely pubescent, often with visible glandular dots; base acute to attenuate, rare obtuse or rounded, a little decurrent along the petiole, apex acute to acuminate; midvein adaxially plane to sulcate in base and plane to slightly prominent distally, abaxially prominent, often pubescent in both sides; secondary veins 6–10 pairs, leaving the midvein at angles of 40–75°, adaxially impressed or slightly prominent proximally, abaxially prominent, mostly pubescent abaxially; marginal vein absent. Inflorescences terminal or in axillary portions of younger branches, originated in bracteate shoots, auxotelic, the flowers 1–4 arising from the first internode of the developing auxotelic twig, rachis up to 3 mm long, often pubescent; bracts not observed; pedicels 5.5– 22.5 × 0.5–1 mm, glabrous; bracteoles linear, 4.5–6 × 0.5–1 mm, glabrous, deciduous at anthesis; hypanthium sparsely glandular, glabrous; calyx lobes in two slightly unequal pairs, free in the bud, the external ones elliptic to deltate, 5–6 × 2.8–3 mm, concave, the internal ones ovate to elliptic 5.5–6.5 × 2.5–3 mm, slightly concave, both glabrous, ciliate, glandular dots absent; petals four, elliptic, 10–11 × 4.5–5.5 mm, glabrous, without glandular dots; staminal ring 2.5–4 mm in diameter, densely pubescent, glandular dots absent; stamens 68–96, filaments 6–9 mm long, anthers oblong; style 8–9 mm long, glabrous; stigma subcapitate, slightly papillose; ovary externally pubescent, 2-locular, the locules internally glabrous with 2–3 ovules per locule. Fruits globose to slightly oblate, 1.3–2.3 × 1–2 cm, yellowish when ripe, glandular, glabrous, crowned by the persistent calyx lobes; seed one, ellipsoid, ca. 11 × 9 mm, testa smooth, embryo with cotyledons fused and visible hypocotyl.

Distribution and habitat:—This species was collected in decidual seasonal forests and more often in stepicsavanna (“Caatinga”), occurring predominantly in “carrasco’’ vegetation, a more dense type of stepic-savanna formation developed under sedimentary formations. Registered for the states of Ceará and Piauí, it is found mainly in caatinga formations associated with the sedimentary basin of Ibiapaba complex.

Phenology:—Flowers were collected in January, February and December, and fruits in February and March.

Conservation:—Due to the extensive geographic distribution of E. nordestina (ca. EOO = 62,674 km ²), it must be placed in the IUCN category of Least Concern (LC). However, it has to be emphasized that the natural habitat of E. nordestina has been considerably altered by human activities ( Moro et al. 2014), such as agribusiness, extractivism and urban expansion, that contributes to loss of diversity and desertification processes and consists in a threat to endemic populations. The species has been registered in one conservation area, in Ceará (Reserva Particular do Patrimônio Natural Serra das Almas).

Etymology:—The specific epithet “ nordestina ” refers to the Brazilian region where the species were collected, northeastern Brazil.

Vernacular names:—There are recorded for this species the following vernacular names (all in Portuguese): “Jacaré” (F.S. Araújo et al. 1291), “Quixaba” (L.W. Lima-Verde et al. 384) and “Guabiraba” (A.S.F. Castro 2265). The first one is most commonly found in collections and its translation means “caiman”, an allusion to the stiff-exfoliating greyish bark.

Paratypes:— BRAZIL. Ceará: Aiuaba, Dist. Barra , 6°43’41”S, 40°19’16”W, 5 February 1997 (fr.), L.W. Lima-Verde 384 (EAC!, HUEFS) ; Crateús, Reserva Natural Serra das Almas , 1 June 2011, A.C.B.P. Pessoa 11 (EAC!, HCDAL) ; ibidem, Serra das Almas , 22 January 2000, L.W. Lima-Verde 1117 (EAC!) ; ibidem, RPPN Serra das Almas , 25 February 2002 (fr.), F.S. Araújo et al. 1291 (EAC!, HUEFS) ; Croatá, São Roque , 1 February 2012 (fl.), A.S.F. Castro 2624 (EAC!) ; Ipueiras, Distrito Nova Fátima, 4°30’45”S, 40°49’07”W, 26 April 2015 (fr.), M.K.N. Tavares s.n. (EAC 58013!) ; Guaraciaba do Norte, Andrade , 27 February 1981, A. Fernandes et al. s.n. ( EAC 9818 !) ; Novo Oriente, Planalto da Ibiapaba , 3 February 1990 (fr.), F.S. Araújo s.n. (EAC 16096!) ; Ubajara, Jaburuna /Sul, 5 January 1995 (fl.), F.S. Araújo 1055 (EAC!) ; ibidem, Planalto da Ibiapaba, 7 November 2011, L.W. Lima-Verde et al. s.n. (EAC 23483!) ; Tianguá, entre Piracuruca e Tianguá, 18 December 1979 (fl.), E. Nunes et al. s.n. ( EAC 7844 !) . Piauí: Pavussu, estrada para Eliseu Martins , 7°57’33”S, 43°17’21”W, 26 February 2010 (fr.), A.S.F. Castro 2265 (EAC!) .

Discussion:— Eugenia nordestina can be placed in Eugenia sect. Pseudeugenia Mazine & Faria (in Mazine et al. 2016), due to the linear and deciduous bracteoles, ovary 2-locular, locules internally glabrous, 2–3 ovules per locule and embryo with cotyledons totally fused. Eugenia nordestina is morphologically close to E. dysenterica , also positioned in Eugenia sect. Pseudeugenia , and E. megaflora , differing by the features cited in the diagnosis.

Besides the morphological features, the geographical distribution of E. nordestina ( Fig. 2 ) indicates that it is limited to a more specific type of habitat, corresponding mostly to the “Carrasco” formations associated with the Ibiapaba complex. According to Moro et al. (2015), “Carrasco” vegetation is a type of stepic-savanna (“Caatinga”) developed on sandy soils with low water retention, characterized by a denser composition of shrubs, treelets and lianas. On the other hand, E. dysenterica is a more widespread species, more commonly found in savanna formations (“Cerrado”), as well as E. megaflora , which is registered only for the states of Goiás and Tocantins ( Faria 2014, Mazine et al. 2021). The three species may be distinguished by the characters cited in the following key.

Figures

FIGURE 1. Eugenia nordestina. A. Holotype (A.S.F. Castro 2625). B. Bark. C. Vegetative branches. D. Branches with flowers. E. Auxotelic inflorescences. F. Branch with immature fruits.G. Mature fruit (scale = 1cm). Herbarium photograph (A) by INCT/SpeciesLink; Field photographs (B-G) by A.S.F. Castro.

FIGURE 2. Distribution map of Eugenia nordestina.