Randia muricata R.Borges, J.G.Jardim & R.M.Salas

Borges, Rodrigo Lopes, Roque, Nádia, Jardim, Jomar Gomes & Salas, Roberto Manuel, 2024, Novelties in Randia L. (Gardenieae, Rubiaceae) from Brazil, Phytotaxa 645 (1), pp. 43-54 : 44-47

Randia muricata R.Borges, J.G.Jardim & R.M.Salas , sp. nov. ( Figure 1 )

Type:— BRAZIL. Bahia: Licínio de Almeida, Serra Geral , estrada para Urandi , ca. 7 Km de Licínio de Almeida, 14°44’43¨S, 42°32’02¨W, 750 m, 09 December 2009 (fr.), E. Melo et al. 7366 (holotype ALCB!, isotype HUEFS!) .

Diagnosis:— Randia muricata is restricted to Caatinga and Cerrado domains, being recognized by its muricate fruit, a characteristic uncommon in Randia , and exclusive among South American species. Besides, it is also distinguished by the discolor venation on abaxial surface of leaf blades, covered by a puberulent vestiture, and branches occasionally scandent. During the dry season, this species maintains only the edible fruits, yellow-greenish at maturity.

Description:— Tree or treelets, up to 2 m high. Branches erect or scandent, striate, bark peeling on small pieces on the older portions, lenticellate, spinescent, bearing one to three thorns, frequently two on the base of brachyblasts; brachyblasts opposite, covered by stipules on the distal portion; thorns 3.1–7.4 mm long, striate, brownish, glabrous. Stipule deciduous, triangular, 2.5–2.9 × 1.1–1.7 mm, smooth, margin entire, glabrous outside, strigose inside. Leaves decussate, clustered on distal part of branches, petiolate; petiole 1.2–6.5 mm long, canaliculated, scabrid; leaf blade 31.4–41.5 × 25.1–27.6 mm, elliptic to obovate, apex acute to rounded, base attenuate, puberulent, smooth, discolour, becoming olive-green when dried, chartaceous, 9–11 veins on each side, conspicuous, discolour, puberulent. Male inflorescences with flowers organised in sessile fascicles, up to six flowers; flowers pedicellate, pedicel 4–4.5 mm long, strigose; calyx 5-lobed, lobes triangular, 3.5–4.0 × 1.0– 1.1 mm, white, glabrous on both sides, slightly pilose at the base; corolla tubular, 1.7–1.9 cm long, tube white, expanding on the throat region, 1.0– 1.2 cm long, glabrous externally, tomentose internally, near the mouth, stamens 5, exserted, anthers narrowly elliptic to oblanceolate, 3.0–4.0 × 1.0– 1.1 mm, glabrous; style equal or smaller than the corolla tube, stigmatic region 2-lobed, non-functional, ovary rudimentary. Female inflorescence not observed. Fruit globose, with persistent calyx, 1.6–2.0 × 1.5–1.9 cm, green to yellowish when immature, passing to yellow in maturity, muricate, with projections of 0.5–2 mm long, puberulous. Seeds lenticular, 6.8–7.8 × 6.1–6.5 mm, surrounded by a fleshy mesocarp which turns black when dried, foveolate, brown to reddish, glabrous.

Distribution and Ecology:— Randia muricata is presumably endemic to seasonal forests in Caatinga and Cerrado biomes. Collections are registered to Bahia, Ceará, and northern of Minas Gerais, Brazil ( Figure 2 ).

Phenology:—This species is frequently found in fruits all year, from January to December. We suppose that the female flowers are ephemeral, considering no specimens with functional pistillate flowers have not been collected yet. Possibly this species has a fast development and a short-anthesis period during the rainy season, quickly developing the fruits. Based on herbaria observation is noticeable that R. muricata has deciduous leaves, falling completely during the driest months of the year, however maintaining the berry fruits, edible, possibly, a resource available to birds and small mammals during the driest season (Kulhmann & Ribeiro 2016). On some field labels, the species is described as a climbing plant with scandent branches ( Melo 9025, Melo 6843, Correia 8, all from HUEFS), however most of specimens just mention an erect habit from 1–2 m high.

Etymology:—The species epithet refers to the surface of the fruits in R. muricata , conspicuously covered with short and hard protuberances, defined by Radford et al. (1974) as muricate surface.

Preliminary Conservation Status:— Randia muricata was collected in many localities, being widely distributed in seasonal forests which occur in Caatinga and Cerrado biomes in Bahia, Ceará, and Minas Gerais, Brazil ( Figure 2 ). R. muricata is considered endangered (EN) when analyzed the criteria of Area of Occupancy (AOO 76.000 Km²) and of least concern (LC) according to the Extent of Occurrence (EOO 160,835.448 Km²). As one species that is endemic to seasonal forests, it suffers from the extensive logging of the vegetation to cattle raising and human occupation ( Ribeiro et al. 2015). Considering the distribution of this taxon, and its occurrence near Conservation Units (Lençois Serra da Chapadinha, Chapada Diamantina National Park), R. muricata is classified here as a species of “Least concern”— LC.

Additional specimens examined (paratypes):— BRAZIL. Bahia: Andaraí , APA dos Marimbus, 12°46’00”S, 41°46’38”W, 317 m, 5 April 2011, E. Melo et al. 9025 ( HUEFS) ; Barra do Mendes, Povoado São Bento , 11°49’39’’S, 42°08’11’’W, 730 m, 25 October 2009, E. Melo et al. 6843 ( HUEFS) ; Caetité, Serra Geral de Caetité , ca. 14 km SW of Caetité by road to Morrinhos, and ca. 15 km W along this road from juntion with Caetité-Brejinho das Ametistas road, 950 m, 13 April 1980, R. M. Harley 21348 ( CEPEC, HUEFS, K, SP) ; ibid, beira da estrada, 11 km de Maniaçu em direção a Odebrecht , 13°51’27’’S, 42°18’20’’W, 950–1000, 28 August 1999, D. S. Carneiro-Torres et al. 106 ( HUEFS) ; ibid, coleta arredores da área de Preservação da Industria Nucleares do Brasil , 13°50’27’’S, 42°16’21’’W, 26 September 2009, J. L. Paixão et al. 1533 ( HUEFS, RB, SPF) ; ibid, estrada Caetité para Guanambí , ca. 5 km, 14°03’47’’S, 42°30’53’’W, 22 February 2016, L. Daneu et al. 696 ( CEPEC, UESC) ; Iraquara , 12°19’38”S, 41°30’06”W, 711 m, 12 July 2007, R. M. Santos & F. A. Vieira 1807 ( HUEFS) ; Irecê, Ibipeba , 11°37’06’’S, 42°00’03’’W, 742 m, 26 October 2009, M. L. Guedes et al. 16143 ( ALCB, HUEFS) ; Jequié , 5 ponte, 13°45’S, 40°16’W, 30 May 2000, S. J. Correia 8 ( HUEFS, K) ; Lapão, Morro Pelado, próximo à Torre , 11°24’22’’S, 41°49’21’’W, 790 m, 25 October 2009, E. Melo et al. 6919 ( HUEFS) ; Lençóis, Serra da Chapadinha, cercado, próximo a fazenda do Velho , antes da cancela, 12°26’00’’S, 41°28’00’’W, 520 m, 28 April 1995, PCD 1906 ( CEPEC, HUEFS, HSTM, IBGE, SP) ; ibid, entroncamento e entrada para Lençóis / Itaberaba, BR 242 , km 13, 11 September 1992, L. Coradin 8566 ( CEN) ; Licínio de Almeida, Mata do Xaxá , 21 January 2015, R. L. Borges et al. 250 ( ALCB, CEPEC) ; ibid, Estrada Licínio de Almeida-Jacaraci , 14°44’45’’S, 42°31’3’’W, 9 December 2009, M. L. Guedes et al. 16723 ( ALCB, HUEFS) ; Maracás , ca. 6 km SW da cidade, January 1988, M. Sobral & L. A. Mattos Silva 5893 ( CEPEC, ICN, NY) ; ibid, estrada de terra para Boca do Mato , 13°22’27’’S, 40°25’58’’W, 826 m, 4 November 2011, E. Melo et al. 10619 ( HUEFS) ; ibid, Estrada para Marcionilio Souza , ca. 12,6 km da cidade, 13°17’14’’S, 40°32’42’’W, 517 m, 3 November 2011, E. Melo 10573 ( HUEFS) ; Morro do Chapéu, variante que liga Duas Barras do Morro a Utinga , próximo Fazenda Descoberta, 11°58’S, 41°02’W, 1 April 1986, A. C. Sarmento & H. P Bautista 846 ( HRB, RB) ; Wagner, Chapada Diamantina, Ponto 06, CETEP, 12°17’19’’S, 41°09’39’’W, 488 m, 12 March 2016, M. L. Guedes 24321 ( ALCB, UFRN) ; Tanhaçu, Fazenda Corcovado, Serra do Corcovado (do Sr. Eduardo Brito ), alto da Serra próximo ao paredão da Pedra, seguindo pelo espigão, 13°55’10’’S, 41°10’00’’W, 900–1050 m, 22 December 2013, A. M. Amorim et al. 8539 ( CEPEC, RB). Ceará: Aiuaba, Estação Ecológica de Aiuaba , 06°36’01’’/ 06°44’35’’S, 40°07’15’’/ 40°19’19’’W, 400–600 m, 9 June 2005, J. R. Lemos & P. Matias 317 ( SPF) ; Santa Quitéria, Serra dos Quirino ou dos Pejeú, ca. 8 km SW (em linha reta) de Itatira, 06°33’48.97’’S, 39°41’37.02’’S, 26 April 2012, J. Paula-Souza et al. 11018 ( ESA, RB). Minas Gerais: Montezuma , Vargem de Salinas , carrasco em altiplano em baixa de chapada, 15°17’00’’S, 42°27’05’’W, 924 m, 8 March 2017, A. C. Sevilha et al. 7316 ( CEN) .

Comments:— Randia muricata is the only species in South America in having muricate fruits, green when immature, and yellow/yellowish at maturity. However, among northern hemisphere taxa there are at least eight species with fruit surfaces covered by projections of variable shape: Randia cinerea Fernald (1897: 93) Standley (1919: 201 ; ribbed, and tuberculate), R. coronata Borhidi (2004: 44 ; muricate), R. denticulata Borhidi (2004: 46 ; spinose surface), R. echinocarpa Sessé & Mociño ex De Candolle (1830: 385 ; tuberculate), R. grandifolia (Donnell Smith 1913: 436) Standley (1928: 166 ; ribbed), R. guerrerensis Lorence & Rodríguez Acosta (1986: 195; 8–10-ribbed, rugose, or tuberculate), R. ovalifolia Borhidi (2004: 52 ; 10-ribbed and spinose), and R. pterocarpa Lorence & Dwyer (1987: 43 ; 5–11 ribbed and glabrous). Randia coronata , the only mentioned as having muricate fruits, was compared with the new species. The isotype (MEXU00725323!) has fruits with glabrous surface, not muricate, and microscopically warty (very small projections less than 0.3 mm long), whereas R. muricata has projections 0.5–2 mm long. In Brazil, the morphologically closest species to R. muricata is R. claesii R.M. Salas (2021: 582) , both sharing similar shape of leaf blade and the abaxial vestiture. It differs in having the leaf blades 20–120 × 12–70 mm, adaxially tomentose, hispid or villous abaxially (versus the leaf blade 31.4–41.5 × 25.1–27.6 mm, puberulent in R. muricata ), the calyx lobes variable in shape, even on the same plant, from narrowly ovate, narrowly obovate to linear (vs. calyx lobes triangular, glabrous on both sides); fruit pubescent, frequently with numerous lenticels (vs. fruit with muricate surface, puberulous).

This species was sampled on the phylogeny to the Randia group published by Borges et al. (2021) (M.L. Guedes 24321, ALCB), being placed in the Randia armata subclade with Randia armata ( Swartz 1788: 51) De Candolle (1830: 387) , R. carlosiana K. Krause in Diels (1941: 389), R. calycina Chamisso (1834: 246) , and R. ferox ( Chamisso & Schlechtendal 1829: 198) De Candolle (1830: 387) with high support.

Figures

FIGURE 1. Randia muricata. A. Branch with fruits. B. Detail of the fruit on apex of the branches. C. Brachyblasts with three thorns. D. Stipule, in detail vestiture on internal surface. E. Elliptic leave, in detail puberulent vestiture over the vein. F. Male inflorescence (Fascicles). G. Male flower. H. Fruit, in detail surface of fruits, typically muricate. I. Pilled seeds. J. Seed, lateral view. K. Seed, frontal view. Illustration by Gustavo Surlo, based on Melo et al. 7366 (ALCB, HUEFS) and Borges 250 (ALCB).

FIGURE 2. Map of Distribution to Randia muricata and Randia sulbahiana. Abbreviations: BA—Bahia; CE—Ceará and MG—Minas Gerais.