Spigelia alborubra A.R.Macedo & E.M.Pessoa, 2019

Macedo, Arthur, Pessoa, Edlley & Alves, Marccus, 2019, A new species of Spigelia L. sect. Graciles (Loganiaceae) from northeastern Brazil, Phytotaxa 404 (4), pp. 146-154 : 148-152

Spigelia alborubra A.R.Macedo & E.M.Pessoa , sp. nov.

Type— BRAZIL. Pernambuco: a 3km leste de Trindade, 7°45’00’’ S, 40°15’30’’ W, 500–550 m, 20 March 1982, J. L. S. Lima 374 (fl., fr.) (holotype: UFP!, isotypes: INPA!, HTSA!).

Spigelia alborubra is similar to S. pulchella Mart. (1826: 128) due to the habit, color of the corolla tube and exserted stigma, but it differs by having a shorter corolla (1.1–2 cm vs. 3–3.3 cm long), with a reddish to pale pinkish tube and whitish lobes (vs. reddish to orange tube and yellowish lobes), a constriction at the apex of the tube (vs. tube without constriction), corolla lobes only apically free (vs. entirely free), inserted stamens (vs. exserted) with shorter anthers (2.5–2.8 mm vs. 3–3.2 mm long) and shorter metastilo (2–2.2 mm vs. 6–7 mm long).

Herbs to subshrubs, 0.3–1.5 m tall. Underground stem often developed. Stems quadrangular, glabrous, 1–5 interangular ribs. Leaves opposite, sessile, caducous; stipules inconspicuous; leaf blade 5–13 × 0.8–2.0 mm, linear, glabrous, margins slightly revolute, apex acute, base attenuate, venation hyphodromous. Inflorescences scorpioid cymes, terminal or axillary and terminal; peduncle 0.7–5.8 cm long, rachis 0.8–12.8 cm long. Bracts and bracteoles similar, 1.5–1.8 × 0.3–0.4 mm, lanceolate, glabrous, green to vinaceous. Flowers 8–35, calyx lobes 2.5–2.8 × 0.7–0.9 mm, lanceolate, glabrous, green to vinaceous, glands 2 on the base of the inner side of each lobe; corolla 1.1–2 × 0.13–0.30 cm, tube salverform, constricted at the apex of the tube, reddish to pale pinkish, lobes 1.2–3 × 1.7–3.7 mm, widely ovate, glabrous, whitish, only apically free; stamens 5, inserted, anthers 2.5–2.8 × 0.5–0.7 mm, base sagittate; ovary 1–1.2 × 0.7–0.8 mm, orbicular, glabrous, metastilo 2–2.2 mm long, epistilo 1.13–1.15 cm long, stigma exserted, 1–1.3 mm long, slightly papillose. Capsules 3–4 × 5–5.5 mm, smooth, glabrous; carpoatlas 2.3–2.5 × 3.3–3.5 mm, transversely rhombic, foramen 0.7–0.8 × 1.2–. 14 mm, transversely elliptical, lateral extremities acute. Seeds 1.4–1.6 × 0.8–1 mm, brownish to blackish when dry, dorsal surface slightly rugose, ventral surface strongly rugose.

Some samples analyzed and recognized here as Spigelia alborubra were misidentified by Brandão & Rapini (2018) as three similar species. The collection E. B. Miranda et al. 109 was identified as Spigelia linarioides and L. P. de Queiroz et al. 5523 as S. spartioides , probably by the similar habit. However, Spigelia alborubra differs from both species due its salverform corolla (vs. infundibuliform), longer anthers (2.5–2.8 mm vs. 1.2–1.9 mm) and exserted stigma (vs. included). Some samples as D. O. Cerqueira et al. 09, F. França et al. 3050, H. C. de Lima et al. 728 among others were identified as Spigelia pulchella , but this species can be distinguished due its shorter corolla (1.1–2 cm vs. 3–3.3 cm long), a constriction at the apex of the tube (vs. tube without constriction), inserted stamens (vs. exserted), shorter anthers (2.5–2.8 mm vs. 3–3.2 mm long) and shorter metastilo (2–2.2 mm vs. 6–7 mm long) (see Table 1).

Distribution and ecology: — Spigelia alborubra is endemic to northeastern Brazil, where it grows in the Cerrado and Caatinga domains of the state of Bahia and in Caatinga domain in Pernambuco, recorded from rocky soils in areas of 450–1100 m elevation.

Undergound and thick stem as a possible adaptation to drought periods is cited by ( Appezzato-da-Glória 2015). A similar organ is often found on the examined specimens. According to the labels, flowers and fruits can be observed throughout the whole year. The flowers of S. alborubra do not fully open when mature. Only the apex of the corolla lobes open during anthesis, leaving a small aperture for stigma exposure. The corolla lobes remains as in the flower bud, simulating pre-anthesis. Culley & Klooster (2007) pointed out some possible cases of partial to complete cleistogamy in many families which some floral morphological features are also similar to ones found in Spigelia alborubra .

Conservation status:—According to the IUCN (2017) criteria, this species is classified as endangered (EN) = B2+(b-ii), with an AOO less than 500 km ². Most of the specimens were found in the northern portion of Chapada Diamantina, near Jacobina (Bahia) , with other populations on nearby mountains. Spigelia stenocardia (Standl, 1930: 235) F. Casas (2008a: 447–448) , S. cipoensis Zappi (1989: 88) and S. lundiana A. DC. (1845: 3) also occur in the same vegetation type (campos rupestres) and are considered threatened ( Guimarães et al. 2013). Fragmentation and loss of habitat by anthropic pressure, especially urban expansion, tourism, agricultural activity and mining are listed as the main threats in this area ( Guimarães et al. 2013; Martineli 2007). This species has been recorded at some formally established Conservation Units, such as the “Área de Relevante Interesse Ecológico Serra do Orobó” and “Parque Nacional das Sete Passagens”, two protected areas in the state of Bahia.

Etymology: —The name of the new species refers to the color of the corolla tube, which ranges from reddish to pale pinkish with whitish lobes.

Morphological affinities:— Spigelia alborubra belongs to S. subg. Spigelia , according to its salverform corolla and presence of metastilo ( Fernández Casas 2005), and to S. subg. Spigelia sect. Graciles due to its quadrangular stems with interangular ribs, and calyx lobes slightly smaller than the capsules ( Progel, 1868). Among the species included in the section and based on plant size, it is superficially similar to S. schlechtendaliana Mart. (1826: 129) , which occurs in the Brazilian Southeast and Central-west regions ( BFG 2015) and to S. linarioides A. DC. (1845: 6) , S. gracilis A. DC. (1845: 6) and S. spartioides Cham. (1833: 14) , all of which are found in northeastern Brazil. However, the new species can be distinguished from all four by its salverform corolla (vs. infundibuliform) and exserted stigma (vs. included). Furthermore, Spigelia schlechtendaliana has leaves opposite along the stems and verticillate at the apex (vs. leaves always opposite along the stems and at the apex in S. alborubra ), and S. linarioides , S. gracilis and S. spartioides have greenish with whitish to pinkish tones, fully whitish or pink-whitish flowers (vs. reddish corolla starting on the base and gradually becomes pinkish closer to the corolla lobes and finally white on the lobes of the flowers) ( Table 1).

The new species has been misidentified as Spigelia pulchella due to the similarity in the color of the corolla tube, habit and exserted stigma, but S. alborubra differs by its shorter corolla (1.1–2 cm vs. 3–3.3 cm long), with a constriction at the apex of the tube (vs. without constriction), whitish (vs. yellow) corolla lobes, corolla lobes only apically free (vs. entirely free), shorter anthers (2.5–2.8 mm vs. 3–3.2 mm long) and shorter metastilo (2–2.2 mm vs. 6–7 mm long).

Additional specimens examined (paratypes): — BRAZIL. Bahia: Sine loco accurato, 1843, fl., fr., J. S. Blanchet ( P 507523 ) ; ibid., s.d., fl., fr., J. S. Blanchet 2530 ( P) ; ibid., fl., J. S. Blanchet ( P 507524 ) ; Itaberaba, Serra do Orobó, Fazenda Gameleira , 06 June 2007, fl., D. O. Cerqueira et al. 09 ( HUEFS) ; Jacobina , sine loco accurato, s.d., fl., fr., J. S. Blanchet ( W 1305 ) ; ibid., sine loco accurato, 01 June 1977, fl., fr., A. Fernandez & Matos ( EAC 3390 ) ; ibid., Bairro Grotinha , 23 June 1999, fl., fr., F. França et al. 3050 ( HUEFS) ; ibid., estrada para Feira de Santana , 03 April 1983, fl., A. M. V. Carvalho et al. 2392 ( CEPEC) ; ibid., Serra do Sincorá, 5 km antes da cidade de Jacobina , 27 October 1978, fr., H. C. de Lima et al. 728 ( RB) ; ibid., Itaitu, Cachoeira Véu da Noiva , 24 April 1999, fl., fr., R. C. Forzza et al. 1315 ( CEPEC, NY, SPF) ; ibid., 27 January 2010, fl., A. P. Fontana et al. 6355 ( HVASF) ; ibid., Serra das Figuras, 14 April 1999, fl., L. P. de Queiroz et al. 5523 ( CEN, HUEFS) ; ibid., Serra da Jaboticaba , 21 September 1980, fl., W. Fonseca 278 ( RB) ; ibid., Monte Tabor , 27 June 1983, fl., fr., L. Coladin et al. 6125 ( CEN) ; ibid., 16 February 1986, fl., fr., A. Fernandez & Matos ( EAC 14064 ) ; ibid., 20 February 1993, fl., A. M. V. Carvalho et al. 4185 ( CEPEC, NY) ; ibid., 24 April 1999, fl., fr., R. C. Forzza & R. Mello-Silva 3873 ( RB) ; ibid., 7 April 2001, fl., fr., N. G. Jesus et al. 1304 ( CEPEC, HUEFS) ; ibid., 01 September 2001, fl., fr., E. F. Guimarães et al. 1707 ( HUEFS, RB) ; ibid., 2 September 2001, fl., fr., F. R. Nonato et al. 831 ( HUEFS) ; ibid., 14 October 2007, fl., fr., J. L. Ferreira & F. França 151 ( HUEFS) ; Miguel Calmon , Serra das Sete Passagens, Parque Nacional das Sete Passagens, 02 September 2001, fl., fr., H. P. Bautista et al. 3011 ( ALCB, HUEFS, CEPEC) ; Morro do Chapéu, Serra da Boa Esperança , 11 March 2002, fl., W. W. Thomas et al. 12879 ( CEPEC, RB) ; ibid., 05 December 2002, fl., fr., A. Rapini et al. 983 ( HUEFS) ; Paulista, cachoeira do Rio das Pedras , 18 September 1999, fl., fr., E. B. Miranda et al. 109 ( HUEFS) ; Pindobaçu , sine loco accurato, 10 March 1981, fl., R. P. Orlandi 336 ( RB) ; ibid., Serra da Fumaça , 01 June 2010, fl., M. Oliveira 4932 ( HVASF) ; ibid., 26 December 2013, fl., fr., D. P. Souza et al. 92 ( HVASF) ; Ruy Barbosa, Serra do Orobó , 28 July 2004, fl., fr., L. P. de Queiroz et al. 9319 ( HUEFS) ; Saúde, Morro da Antena , 14 July 2004, fl., fr., P. Fiaschi et al. 2413 ( CEPEC, RB, SPF) ; Seabra, Lagoa da Boa Vista , 15 November 1983, fl., fr., H. P. Bautista 1338 ( CEPEC, RB) ; ibid., estrada para Água de Rega , 23 February 1971, fl., H. S. Irwin et al. 30799 ( HUEFS, NY) ; Senhor do Bonfim, Serra de Sant’Ana , 27 March 2011, fl., fr., P. B. Schwartsburd et al. 2389 ( HVASF) .