Hyptidendron pulcherrimum Antar & Harley, 2021

Antar, Guilherme Medeiros, Harley, Raymond Mervyn, Pastore, José Floriano Barêa, Gonella, Paulo Minatel & Sano, Paulo Takeo, 2021, Hyptidendron pulcherrimum Antar & Harley, sp. nov. (Hyptidinae, Lamiaceae), a new narrowly endemic species from Minas Gerais, Brazil, Adansonia (3) 43 (1), pp. 1-8 : 3-6

Hyptidendron pulcherrimum Antar & Harley , sp. nov.

( Figs 1-3 )

The new species is unique in the genus by the combination of flowers arranged in dichasial cymes, branch indumentum pubescent composed of rigid, broad-based and curved eglandular hairs, leaves petiolate, glabrescent and bullate, corolla tomentose, curved, long exserted from calyx, with the tube 7.5-10 mm long and one slightly winged nutlet per fruiting calyx. The new species shares with Hyptidendron vauthieri (Briq.) Harley a similar inflorescence, habitat preference and habit, but differs as it has leaves glabrescent and deeply bullate (vs leaves pubescent to pilose and not deeply bullate), calyx lobes at fruit 0.9-1.4 mm long (vs calyx lobes at fruit 1.9-3.6 mm long), corolla curved with the tube 7.5-10 mm long (vs corolla straight with the tube 4.1-5.0 mm long), and nutlets slightly winged (vs nutlets not winged).

TYPUS. — Brazil. Minas Gerais, Conselheiro Pena, Pico do Padre Ângelo , subida ao pico, 19°18’45.6”S, 41°34’34.7”W, alt. 1260 m, 16.XII.2016, Lopes et al. 453 (holo-, SPF [ SPF227258 ]; iso-, HUEFS, K, RB) .

PARATYPES. — Brazil. Minas Gerais, Conselheiro Pena, Pico do Padre Ângelo , subindo pela crista sul da montanha, 19°19’46.14”S, 41°34’26.43”W, alt. 1025 m, 27.XI.2013, Gonella & Rivadavia 642 ( SPF); Pico do Padre Ângelo , no topo do pico, 19°19’14.2”S, 41°34’43.7”W, alt. 1530 m, 11. VI.2017, Gonella et al. 800 ( SPF with duplicates to be sent to CEN, P, US); Serra do Padre Ângelo, Pico do Padre Ângelo , subindo pela trilha que leva ao topo, 19°18’36.7”S, 41°34’32.8”W, alt. 1165 m, 4.XII.2018, Gonella et al. 966 ( MBML); Serra do Padre Ângelo, Pico do Padre Ângelo , platô do topo do pico, 19°19’13.6”S, 41°34’44.2”W, alt. 1500 m, 8. VI.2020, Gonella et al. 1232 ( SPF) .

ETYMOLOGY. — The specific epithet refers to the beauty of the new species, which presents remarkable conspicuous flowers and shining leaves, making it a potential species for ornamental use.

DISTRIBUTION, HABITAT AND ECOLOGY. — Endemic to the Pico do Padre Ângelo, in the Serra do Padre Ângelo in Conselheiro Pena municipality, eastern Minas Gerais ( Fig. 1 ). It grows at elevations from 1000 to 1530 m, in campos rupestres vegetation among quartzitic rock outcrops, in sandy soils covered by a litter layer. The species is especially abundant in the higher areas of the Pico do Padre Ângelo, above 1400 m, where it is usually associated with the rock outcrops. The Serra do Padre Ângelo region is subjected to a marked seasonality, with rainy summers and dry winters, but water condensation in the form of fog is present year-round at higher elevations.

CONSERVATION STATUS. — The estimated Area of Occupancy is low, being just 12 km ², and the estimated Extent of Occurrence is 0.449 km ², both being likely to decline further. All of the collections were found on a single mountain: the Pico do Padre Ângelo, the second highest peak in the Serra do Padre Ângelo, which is an unprotected area that is subjected to invasion by alien grass species and uncontrolled anthropic fires. Furthermore, these mountaintop areas are highly threatened by climate change, which threatens to reduce significantly the suitable areas for the occurrence of campos rupestres vegetation in the next decades, threatening many of its endemic species with extinction ( Barbosa & Fernandes 2016). Propelled by the flagship species Drosera magnifica Rivadavia & Gonella ( Gonella et al. 2015) , there is an attempt among conservationists to make the locality a Protected Area (Mello-Silva 2018). Nearby areas, most remarkably the Pico do Sossego (1550 m alt.), also in the Serra do Padre Ângelo, and the Sete Salões State Park, are currently unexplored and may also contain populations of Hyptidendron pulcherrimum . Although the species could be regarded as still data deficient concerning its distribution, we consider that, due to the precarious state of conservation of its suitable habitats, it should be assessed as Critically Endangered according to criteria CR B1ab(i,ii,iii)+2ab(i,ii,iii) ( IUCN 2012).

DESCRIPTION

Shrub or treelet 1.5-2 m high, erect or somewhat decumbent, supported by nearby rocks or other plants, aromatic, branches sometimes horizontal; stems woody, 3-5 mm in diameter, younger stems quadrangular, canaliculate, pubescent with rigid, broad-based, curved eglandular hairs, small stipitate glandular hairs, and sessile glands, older stems terete and less hairy. Cauline leaves simple, opposite, decussate, not imbricate, petiolate, longer than internodes, rarely equal or shorter, diminishing in size towards stem apex; lamina 2.0-5.8 × 1.4-4.2 cm, chartaceous, discolorous, with the abaxial surface paler, elliptic, ovate or broadly elliptic, base cuneate to rounded, apex obtuse to rotund, rarely cuspidate to mucronate, margin crenulate or rarely serrulate, with the exception of the base which is entire (approximately 1/4 to 1/8 of the leaf), 20-36 teeth on each side of leaf, the tooth apex swollen, acute, glabrous, adaxial surface bullate, shiny, glabrous to glabrescent, with the exception of the main vein which is densely covered with non-glandular curved hairs (mostly near the base), which can be on the secondary veins as well but less densely, also some rare curved hairs can be present, margins with some curved hairs mostly near the base, the venation plane or sometimes slightly impressed, midrib and primary veins visible, other veins obscure, abaxial surface glabrous or glabrescent with rare sessile glands and rarely some indumentum on the main nerve, composed of curved hairs and sessile glands or clustered long uniseriate hairs, venation reticulate, conspicuous, midrib and secondary veins prominent; petiole 5-13 mm long, 1-2 mm wide, terete, canaliculate, pubescent with rigid, curved, eglandular hairs, sessile glands and rare glandular stipitate hairs, the indumentum is denser in the intervenous lacunae. Inflorescence a terminal or axillary cymose panicle with dichotomous or less commonly unilateral cymes subtended by foliaceous bracts, which are conspicuous, similar to the leaves, slightly smaller; bracts elliptic, ovate, rotund or orbicular, 1.4-2.6(-3.9) × 1.1-2.1 cm, petiolate, mostly shorter than the cymes; bracteoles 1.0- 1.4 mm long, with the same indumentum as the pedicels; mature cymes 7-19 flowered, not or only partially obscured by the leaves, borne on peduncles 4-10 mm long, with the same indumentum as the petioles. Flowers on pedicels 3.5-11.7 mm long, pubescent with rigid, broad-based, curved eglandular hairs, stipitate glandular hairs and sessile glands, subtended by linear bracteoles; calyx at anthesis (3.5-) 4.2-6.1 mm long, cylindrical to slightly infundibuliform; tube 3.4-4.7 mm long, straight, ribbed, externally pubescent with small uniseriate hairs mostly on the ribs, and with glandular stipitate hairs and sessile glands, in the margins of the lobes the hairs are longer and uniseriate, with glandular stipitate uniseriate hairs at the apex of the calyx tube, internally glabrous with the exception of sessile glands at the apex; lobes subequal, 1.1-1.6 mm long, narrowly triangular to subulate, externally with the same indumentum as the tube, internally with sessile glands and usually with some small non-glandular hairs, the margins ciliate with small eglandular hairs; fruiting calyx 7.5-8.0 mm long, less hairy, tube accrescent, 6.2-6.9 mm long, ± cylindrical, ribbed, fruiting calyx lobes 0.9-1.4 mm long, subequal, straight; corolla purple to lilac, 11-13 mm long; tube 7.5-10.0 mm long, straight, cylindrical, 2.0- 2.6 mm wide, externally tomentose with simple uniseriate non-glandular hairs, less dense near the corolla base, internally glabrous with the exception of tufts of long uniseriate non-glandular hairs close to the insertion of the posterior pair of stamens in the corolla; lobes spreading, externally tomentose with simple non-glandular uniseriate hairs and sessile glands, internally glabrous; anterior lobe large, boat-shaped; stamens with posterior filaments 4.5-5.8 mm long, villous with long uniseriate entangled eglandular hairs anterior filaments 2.5-3.2 mm long, similar indumentum as the posterior pair but less hairy; anthers ca. 1 mm long; gynoecium with style 7-11 mm long, jointed and basally with a well-developed stylopodium protruding above ovary, 0.9- 1.4 mm long, and apically with two unequal, short, slender stigmatic lobes. Nutlets 2.2-3.0 × 1.6-2.0 mm, 1 per fruiting calyx, ellipsoid, oblong to widely oblong, castaneous, rugulose and shining, glabrous, slightly winged, with deep abscission scars, not mucilaginous when wetted.

REMARKS

Hyptidendron pulcherrimum Antar & Harley , sp. nov. is similar to other species of the former Hyptidendron sect. Umbellaria , to which it seems to belong. The most similar species is Hyptidendron vauthieri (Briq.) Harley (see diagnosis), a species that occurs in the campos rupestres of the Serra do Cipó, in the southern portion of the Espinhaço Range ( Fig. 1 ). It is also superficially similar to other species endemic to the campos rupestres of the Espinhaço Range, such as Hyptidendron vepretorum (Benth.) Harley , from which it differs by the longer peduncle size (0.5-2 mm long in H. vepretorum vs 4-10 mm long) and the longer corolla tube (4.8-7.0 mm long in H. vepretorum vs 7.5-10 mm); and Hyptidendron unilaterale (Epling) Harley , from which it differs by the longer corolla tube (3.5-5.0 mm long in H. unilaterale vs 7.5-10 mm long) and the cyme structure (unilateral or rarely dichasial in H. unilaterale vs dichasial or rarely unilateral).

Figures

FIG. 1. — Distribution of Hyptidendron pulcherrimum Antar & Harley, sp. nov. (white squares) and Hyptidendron vauthieri (Briq.) Harley (white circles). In the small map, the pink shape shows the extension of the Cerrado domain and the green shape shows the extension of the Mata Atlântica domain.

FIG. 2. — Hyptidendron pulcherrimum Antar & Harley, sp. nov.: A, branch bearing leaves and inflorescences; B, leaf margin, adaxial surface with indumentum detail; C, leaf margin, abaxial surface with indumentum detail; D, immature cyme; E, part of an inflorescence showing calyx and bracteoles; F, flower, side view; G, corolla, side view; H, gynoecium and style, showing stylopodium; I, ovary; J, mature calyx; K, nutlet. Illustration by Carla Teixeira de Lima based on Lopes et al. 453 (SPF). Scale bars: A, 3 cm; B, C, not to scale; D, 6 mm; E, 7 mm; F, 14 mm; G, 12 mm; H, I, 2.5 mm; J, 7.5 mm; k, 2 mm.

FIG. 3. — Hyptidendron pulcherrimum Antar & Harley, sp. nov.: A, habit and habitat; B, flowering branch, highlighting a flower, side view; C, branch; D, flower and inflorescence; E, flowering branch. Photo credits: A-C by P.M. Gonella; D, E by J.C. Lopes.