Harpalyce magnibracteata São-Mateus, D.B.O.S.Cardoso & L.P.Queiroz, 2016

São-Mateus, Wallace M. B., Cardoso, Domingos Benício Oliveira Silva, Queiroz, Luciano Paganucci De & Jardim, Jomar Gomes, 2016, A striking new species of Harpalyce (Leguminosae, Brongniartieae) from highland cerrado of Bahia, Brazil, Phytotaxa 246 (2), pp. 120-126 : 122-125

Harpalyce magnibracteata São-Mateus, D.B.O.S.Cardoso & L.P.Queiroz , sp. nov. ( Figs. 1‒3 )

It differs from all other Harpalyce species mainly by its large, 1.2‒2.3 × 1.2‒2.3 cm, leaf-like amplexicaul, suborbicular to widely ovate bracts that are strongly auriculate at the base and with superimposed lobes, and persistent until the fruiting stage (vs. bracts less than 0.7 cm, linear to triangular with truncate base and early deciduous). The new species is vegetatively similar to H. brasiliana Benth. , but differs chiefly by the combination of racemes with ferruginous indumentum (vs. canescent in H. brasiliana ) and slightly smaller, 3.8‒4.8 × 0.8‒0.9 cm fruits (vs. 5‒8 × 1.2‒1.6 cm in H. brasiliana ) with 6‒10 seeds (vs. 12‒15 in H. brasiliana ).

Type: ― BRAZIL. Bahia : Macaúbas, Estrada para o povoado de Santa Cruz em direção a torre de telefonia, cerrado de altitude, 13º18’21.4”S, 42º54’45.1”W, 831 m, 23 January 2015 (fl., fr.) W. M. B. São-Mateus, D. Cardoso & J. M. F. Santos 325 (holotype: HUEFS!, isotypes: ALCB!, CEPEC!, K!, NY!, RB!, UFRN!).

Multi-stemmed shrub, 1‒2.5 m; stems 7‒10 cm dbh, bark exfoliate; branches flexuous, densely tomentose or velutinous with short, soft erect, ferruginous or whitish, ca. 0.5 mm long trichomes. Stipules 1.2‒2 × ca. 1 mm, persistent, triangular, sericeous on both surfaces. Leaves 5‒13.5 cm long, imparipinnately compound; petiole 0.9‒1.4 cm long, slender, sericeous; rachis (2‒) 3‒6.3 cm long, when young with dark red colleters between the base of the pulvinules, ferruginous-tomentose, the interfoliolar segments 8‒16 mm long; leaflets 7‒11, opposite, chartaceous, pinnately veined, midvein prominent on lower surface, secondary veins 4–7(‒8) pairs eucamptodromous, nearly reaching the margin, slightly salient on the lower face, peltate glands on both surfaces, upper surface sparsely to densely pubescent, lower surface velutinous, by ferruginous or whitish hairs, more densely so along the midvein, pulvinules 2‒3 mm long, lateral leaflets 1.4‒2.3 × (0.8‒) 1‒1.6 cm, oblong-elliptic to obovate-oblong, base obtuse to rounded, apex retuse to rounded, distal leaflets 2.0‒2.9(‒3.5) × 1‒1.9 cm, elliptic to obovate-oblong, base obtuse to rounded, apex retuse. Racemes 7.8‒16 cm long, 2‒4-flowered, axillary, pendent, as long or sometimes longer than the subtending leaf; dark red colleters conspicuous in bract axils; bracts 1.2‒2.3 × 1.2‒2.3 cm, persistent, leaflike, suborbicular to widely ovate, amplexicaul, base strongly auriculate with lobes superimposed, apex retuse, upper surface glabrous, glabrescent to sparingly pubescent, lower surface tomentose to lanate; pedicels 1.2‒2.4 cm long, sparsely to densely pubescent; bracteoles 2, persistently attached at the base of the calyx, 4‒5 × 0.2‒0.3 mm, linear, densely brownish-pubescent. Flowers 1.9‒2.4 cm long, asymmetrical, papilionate, resupinate; calyx outer surface densely pubescent and with peltate hairs, inner surface glabrous, strongly bilabiate, the vexillary lip 1.9‒2.3 × 0.7‒0.9 cm, elliptic-lanceolate to oblong-lanceolate, strongly cucullate at apex, carinal lip 2‒2.3 × 0.6‒0.8 cm, elliptic-lanceolate to oblanceolate; petals membranaceous, glabrous; standard petal light-red, 2‒2.3 × 1.9‒2.3 cm, orbicular, base attenuate towards the claw, apex rounded; wing petals light-red, 1.5‒1.8 × 0.6‒0.8 cm, obovate, base auriculate on the upper margin, the auricle obtuse 1 × 1.5 mm, apex rounded; keel petals light-red, 1.8‒2.1 × 0.5‒0.6 cm, laterally contorted, falcate, wider in the middle, connate from the base except in the claw, base auriculate on the upper margin, the auricle triangular, ca. 1.5 × 1.5 mm, apex acute; stamens 10, 1.7‒2.4 cm long, pseudomonadelphous, joined in a single tube, the incurved stamen, 1.2‒1.4 cm long, filaments free at apex for 5‒8 mm, anthers dimorphic, alternately short and long, the largest ones 2‒2.2 × 0.2 mm, oblong, basifixed, the smallest ones ca. 0.3 × 0.3 mm, widely elliptic, dorsifixed; ovary 6‒7.5 × 1‒1.2 mm, sessile, glabrous, oblong along its entire length, laterally compressed, erect, 7‒9-ovulate; style 1.7‒2.1 cm long, glabrescent, curved; stigma capitate. Legume 3.8‒4.8 × 0.8‒0.9 cm, elastically dehiscent, compressed, oblong, base cuneate, apex long-apiculate, glabrous, margins straight; valves coriaceous to slightly woody, brownish and slightly clearer in the seed scars or atropurpureus when ripe. Seeds 6‒10, 6.5‒7 × 2‒3 mm, compressed, oblong to ovateoblong, red-brown; strophiole gristly.

Etymology: ―The epithet “ magnibracteata ” refers to the large leaf-like amplexicaul bracts that remains persistent with the development of the inflorescence axis until the fruiting stage.

Distribution and habitat: ― Harpalyce magnibracteata occurs exclusively in savanna (“cerrado”) vegetation on gravelly soils in central-western Bahia state, Brazil (municipalities Bom Jesus da Lapa, Brotas de Macaúbas, Macaúbas, Sento Sé, and Tanque Novo) ( Fig. 3 ), where it is found between 820 and 1035 m elevation. Harpalyce magnibracteata grows sympatrically with Angelonia campestris Nees & Mart. ( Plantaginaceae ), Eugenia vetula DC. ( Myrtaceae ), Lychnophora bishopii H.Rob. ( Asteraceae ), Marsdenia zehntneri Fontella ( Apocynaceae ), Polygala harleyi Marques ( Polygalaceae ), Tetrapterys cardiophylla Nied. ( Malpighiaceae ), and the legumes Chamaecrista zygophylloides (Taub.) H.S.Irwin & Barneby , Mimosa irrigua Barneby , and Vatairea macrocarpa (Benth.) Ducke , all of which are typical species in savannas.

Phenology: ―The species was found in flowering from January to February, but also in April. Fruiting specimens were seen in January, April, and July.

Conservation status: ― Harpalyce magnibracteata grows as narrowly distributed populations among the highly fragmented savanna areas in central-western Bahia , where each small populations are separated by 10‒400 km. Furthermore, such patches of savannas are often threatened by fire and agricultural activities. Therefore, according to IUCN Red List Criteria ( IUCN 2012), the conservation status of H. magnibracteata can be considered endangered (EN) following the criteria B2a, B2b(ii, iv) as estimated through software GeoCAT ( Bachman et al. 2011): area of occupancy estimated to be less than 500 km 2 in severely fragmented areas or because the species is known to exist at no more than five localities.

Additional specimens examined (paratypes): ― BRAZIL. Bahia : Bom Jesus da Lapa, Estrada entre São José e Betânia, 13º18’35”S, 42º54’43”W, 820 m, 12 January 2008 (fl), A. Rapini et al. 1490 (HUEFS); Brotas de Macaúbas, cerca de 8 Km SW de Brotas de Macaúbas, Cerradão de altitude, solo arenoso, com Mimosa irrigua , Tachigali paniculata e Plathymenia reticulata , 12º01’44”S, 42º41’60W, 933 m, 30 July 2013 (fr), L.P. Queiroz et al. 15823 (HUEFS); Brotas de Macaúbas, Trilha dos Gerais até o Curralinho, 11º56’10”S, 42º45’22”W, 1035 m, 08 February 2013 (fl), L. Campos & M. Alves 14 (ALCB); Macaúbas, estrada para o povoado de Santa Cruz em direção a torre de telefonia, cerrado de altitude, 13º18’21.4”S, 42º54’45.1”W, 831 m, 23 January 2015 (fl, fr), D. Cardoso et al. 3630 (ALCB, CEPEC, HUEFS, K, NY, RB); Sento Sé, vegetação: savana arbórea aberta, 10º28’S, 41º23’W, 29 April 1981 (fl, fr), R.P. Orlandi 404 (HUEFS); Tanque Novo, Caldeiras, 20 January 1997 (fl), G. Hatschbach et al. 66012 (ALCB, K, MBM, SPSF).

Discussion: ― Harpalyce magnibracteata has a unique feature that helps us to easily distinguish from all other species of the genus: the leaf-like amplexicaul bracts that are persistently attached along the inflorescence axis until the fruiting stage. Such large, 1.2‒2.3 × 1.2‒2.3 cm bracts are suborbicular to widely ovate and with strongly auriculate base, rendering the superimposed lobes. In contrast, all other Harpalyce species bear early deciduous, less than 0.7 cm long bracts that are linear to triangular and basally truncate. Among neotropical Brongniartieae , morphologically similar conspicuous foliaceous and amplexicaul bracts are only seen in some North American species of Brongniartia Kunth (1824: 465) . We are confident that the herein described new species fits well within Harpalyce since it exhibits all other putative morphological synapomorphies that describe the genus ( Queiroz et al. 2010), for example the peltate glands, strongly bilabiate calyx, and contorted keel, whereas Brongniartia lacks the peltate glands in the plant body and clearly has bilaterally symmetrical papilionate flowers with straight keel and the calyx never bilabiate. Also, our preliminary results from an ongoing molecular phylogeny of the Brongniartieae based on chloroplast (matK, trnL intron) and nuclear (ITS, ETS) sequences strongly support H. magnibracteata nested within a Harpalyce clade.

Vegetatively, specimens of H. magnibracteata have been misidentified as H. brasiliana Bentham (1859: 50‒51) , probably because of their flexuous and tomentose branches and chartaceous leaflets with velutinous abaxial surface. However, in addition to the large bracts, H. magnibracteata differs from H. brasiliana by the combination of smoothed stem without striate bark (vs. sulcate branches that are often longitudinally streaked), racemes with usually ferruginous indumentum (vs. canescent), leaflets absent at base of the inflorescence (vs. one- to three-foliolate leaves subtending the inflorescence), and slightly smaller, 3.8‒4.8 × 0.8‒0.9 cm pods (vs. 5‒8 × 1.2‒1.6 cm) with 6‒10 seeds (vs. 12‒15 seeds).

The new species is also morphologically related to H. minor Bentham (1859: 52) , with which it shares the highly branched shrubby habit, the ferruginous trichomes along the branchlets, leaf rachis, abaxial surface of leaflets, and inflorescence axes. However, H. magnibracteata differs from H. minor by lateral leaflets that are predominantly oblong-elliptic to obovate-oblong (vs. ovate to oblong-ovate), the longer bracts (1.2‒2.3 cm long vs. ca. 0.1 cm long), longer inflorescences (the main axis 7.8‒16 cm long vs. usually ˂ 5 cm long), 1.2‒2.4 cm long pedicel (vs. 0.8‒1 cm long), 1.9‒2.3 cm long standard (vs. 1.2‒1.8 cm long), and the predominantly light-red petals (vs. pale pink petals). In addition, the geographical range for these species does not overlap, with H. minor being restricted to the savannas in the northeastern Minas Gerais.

Figures

FIGURE 1. Harpalyce magnibracteata. A. Flowering and fruiting branch. B. Floral bract. C. Floral bud. D. Bracteole. E. Flower. F–G. Calyx showing the vexillary (F) and carinal lips (G). H. Standard petal. I. Wing petal. J. Keel petal. K. Open staminal tube.L. Gynoecium. M. Seed. Drawn by Natanael Nascimento based on W.M.B. São-Mateus et al. 325 (HUEFS).

FIGURE 2. Harpalyce magnibracteata. A. Habit. B. Stem showing exfoliating bark. C. Leafy branchlet showing the inflorescences. D. Flower in front view. E. Flower, lateral view. F. Inflorescence axis with floral buds and immature fruits. Photos by Domingos Cardoso.

FIGURE 3. Geographical distribution of Harpalyce magnibracteata (circles).