Erythroxylum confertifolium M.J. Silva, 2023

Silva, Marcos José Da & Santos, Igor Soares Dos, 2023, Erythroxylum confertifolium, a new species from Chapada dos Veadeiros National Park, Goiás, Brazil, unveiled by morphology and leaf anatomy, Phytotaxa 600 (2), pp. 55-72 : 56-70

Erythroxylum confertifolium M.J. Silva , sp. nov. (Figs 1 and 2)

Type:— BRAZIL. Goiás: Cavalcante, Serra do Pouso Alto, acessada a partir da estrada do Cruzeiro , 500 metros a partir do rio em direç„o ao primeiro bloco de rochas, 13°56’32.8”S, 47°29’43.8”W, 1461 m a.s.l., fl, 27 January 2017, fl., M. J. Silva 8224 (holotype UFG!; isotypes CEN!, UB!) .

Diagnosis:— Erythroxylum confertifolium differs from E. campestre and E. partvistipulatum , its most similar congeners, by having shrubby habit with single stem branched from the upper third, the branches shortened up 8 cm long, and distichously distributed, stipules and cataphylls always 3-setulose and non-striated, fascicles with 3–5 flowers, bracteoles 1-setulose, calyx lobes with margin glandular-ciliate, as well as by sizes of floral parts, and fruits.

Description — Shrubs 0.6–1.9 m tall; single stem, densely branched from the upper third; cinereous and with tiny lenticels when adults, and reddish-green when very young, glabrous; adult branches densely lenticellate lengthwise, conspicuously keeled; branches, 4–8 cm long, shortened, distributed in the distal portion of the stem, slightly flattened; cataphylls 1.6–1.9 mm long, triangular, cymbiform, shortly 3-setulose, congested at the base of the branches shortened, margin entire, non-striated; stipules 1–1.5 mm long, triangular, persistent or tardily caducous, appressed to branches, apex obtuse, non-striated, shortly 3-setulous, the 2 lateral setae ca. 0.6–0.9 mm long, the medial setae ca. 0.4 mm long, keels conspicuously subulate, margin entire, non-striated; leaves always persistent, discoloured, adaxial surface light green, abaxial surface opaque-green or brownish; petiole 1.8–2 mm long, brownish, rough longitudinally, glabrous; leaf blade 1.7–4.3(6.8) × (0.9)1.1–1.5(3.1) cm, coriaceous, elliptical, elliptical-obovate, sometimes ovate, base obtuse, margin entire, flat, apex obtuse, sometimes shortly mucronulate; venation brochidodromous, midrib and secondary impressed on the adaxial surface, the secondary ones slightly prominent on the abaxial surface, 7–9 per side. Fascicles with 3–5 flowers, in axils of leaves or cataphylls; bracteoles 2, ca. 0.9 mm long, 1-setulose, keel slightly subulate, scarious, cymbiform, triangular, margin entire, glabrous; flower buds 5.9–6 × 2–2.1 mm long, obovoid, glabrous; flowers including pedicel 10–11 mm long pedicel 3–5 mm, glabrous, 5-angled; calyx 1.9–2.1 × 1.9–2 mm, greenish, lobes 0.9–1 × 1 mm, ovate-triangular, margin glandular-ciliate, apex acute, glabrous on both surfaces; petals 3.9–4.2× 1.8–1.9 mm, elliptical, slightly concave, apex obtuse, margin entire, white spotted greenish in the central portion; appendages ligulate, ca. 1.4 mm long, 4-lobed, anterior auricles 2, 0.7–0.75 mm long, posterior auricles 2, 0.9–1 mm long, margin entire, both erect, discreetly undulate, central appendage developed 0.8 mm long, margin crenulate, thickened; staminal cup 1–1.5 mm, equal or slightly more than calyx and smaller than ovary, the margin 10–denticulate. Brevistylous flowers with stamens 3.5–4 mm long, cream-yellowish, anthers 0.8–0.85 mm long, oblong, light yellowish; styles 1.1–1.2 mm long, free, stigmas 0.1 mm long, depressed-capitate. Longistylous flowers with antesepalous stamens ca. 1 mm, antepetalous stamens 1.7–1.8 mm, anthers 0.75–0.8 mm long, oblong; styles 1.3–1.4mm long, free, stigmas 0.1–0.2 mm long, depressed-capitate; ovary 1.9–2 mm, ellipsoid. Drupe 5–6.7 × 2–3 mm, ovoid, cylindrical in cross section, red when mature.

Paratypes:— BRAZIL. Goiás: Alto Paraíso de Goiás , cerca de 16 km de Alto Paraíso de Goiás sentido Vila S„o Jorge, cerca de 900 metros a partir da cerca que delimita o acesso ao PNCV, 14°04’27.2”S, 47°31’39.8”W, 1324 m a.s.l., 19 August 2016, fl., M. J. Silva 7695 ( UFG); ibd., cerca de 1, 2 km da cerca que delimita o PNCV , 14°04’25”S, 47°31’40”W, 1304 m a.s.l., 19 August 2016, fl., fr., M. J. Silva 7718 ( UFG); cerca de 2 km a Oeste de Alto Paraíso de Goiás, entre o Morro do Japonês e Serra do Pouso Alto , 25 February 2017, fl., M. J. Silva 8326 ( UFG), 8327 ( UFG), 8328 ( UFG), 8329 ( UFG), 8330 ( UFG), 8331 ( UFG), 8332 ( UFG), 8333 ( UFG), 8334 ( UFG), 8335 ( UFG), 8337 ( UFG), 8338 ( UFG), 8339 ( UFG); ibd., cerca de 1, 3 km a partir da entrada para o Parque Nacional da Chapada dos Veadeiros, na altura da RPPN Cara Preta , 14°00’11.8”S, 47°31’27.2”W, 1471 m a.s.l., 25 March 2017, fl., M. J. Silva 8452 ( UFG), 8453 ( UFG), 8454 ( UFG), 8455 ( UFG), 8456 ( UFG); ibd., ca. 6 km a N de Alto Paraíso de Goiás, e aproximadamente 2, 5 km a esquerda da GO 118, campo sujo , 14°05’25”S, 47°32’27”W, 1322 m a.s.l., 30 June 2017, fl., M. J. Silva 8674 ( UFG), 8677 ( UFG), 8678 ( UFG), 8679 ( UFG), 8688 ( UFG); ibd., 30 June 2017, fl., fr., M. J. Silva 8701 ( UFG), 8707 ( UFG), 8708 (3), 8715 ( UFG), 8716 ( UFG); ibd., Parque Nacional da Chapada dos Veadeiros, regi„o do Morro do Japonês, depois do morro, campo rupestre , 14°02’50”S, 47°31’38”W, 1537 m a.s.l., 21 July 2017, fl., fr., M. J. Silva 8817 , 8826 ( UFG); ibd., na altura da placa que indica da Serra do Pouso Alto , 14°02’35”S, 47°31’36”W, 1514 m a.s.l., 21 July 2017, fl., M. J. Silva 8807 ( UFG), 8808 ( UFG); ibd., borda de mata de galeria entre o campo rupestre e o morro do Japonês , 14°02’55”S, 47°31’34”W, 1526 m a.s.l., 21 July 2017, fl., M. J. Silva 8830 ( UFG), 8832 ( UFG), 8833 ( UFG), ibd., sopé do Morro do Japonês, campo rupestre , 14°02’00”S, 47°31’22”W, 1490 m a.s.l., 21 July 2017, fl., M. J. Silva 8837 ( UFG); cerca de 1 km a partir do morro do Japonês, cerrado rupestre após mata de galeria , 14°01’59”S, 47°32’07”W, 1464 m a.s.l., 22 September 2017, fl., fr., M. J. Silva 8983 ( UFG), 8984 ( UFG), 8985 ( UFG), 8986 ( UFG); ibd., regi„o do Pouso Alto, 1, 6 km a partir do morro do Japonês, 1 km a partir da estrada para dentro do Parque Nacional da Chapada dos Veadeiros , 14°02’18”S, 47°32’21”W, 1426 m a.s.l., 22 September 2017, fl., M. J. Silva, R.C. Sodré, I.S. Santos, R.G. Matos, K.M. Macedo, K.A.F. Xavier, & B.L. Pereira 9011 ( UFG), 9012 ( UFG), 9013 ( UFG); Cerca de 5 km de Alto Paraíso de Goiás, 2 km a oeste para dentro do Parque Nacional da Chapada dos Veadeiros , 14°05’31.3”S, 47°32’20.9”W, 1341 m a.s.l., 27 January 2017, fl., M. J. Silva, R.C. Sodré, K.E. Ferreira & T.P. Mendes 8157 ( UFG), 8160 ( UFG), 8163 ( UFG), 8164 ( UFG); ibd., Serra do Pouso Alto, 200 metros a partir do rio, campo sujo , 14°05’08.5”S, 47°32’49.9”W, 1313 m a.s.l., 27 January 2017, fl., fr., M. J. Silva 8179 ( UFG), 8180 ( UFG), 8181 ( UFG), cerca de 5 km de Alto Paraíso de Goiás a oeste, 200 metros antes do rio , 27 January 2017, fl., fr., M. J. Silva 8204 ( UFG), 8205 ( UFG). Cavalcante, Serra do Pouso Alto, ca. 600 metros da casinha abandonada a esquerda dela , 13°56’13.9”S, 47°29’46.1”W, 1423 m a.s.l., 23 September 2016, fl., M. J. Silva 7830 ( UFG); ibd., regi„o do Pouso Alto, acessada a partir da estrada do Cruzeiro, 500 metros a partir do rio em direç„o ao primeiro bloco de rochas, 13°56’32.8”S, 47°29’43.8”W, 1461 m a.s.l., fl, 27 January 2017, fl., M. J. Silva 8225 ( UFG); ibd., descida após o primeiro morro , 13°56’18”S, 47°29’49”W, 1454 m a.s.l., 21 April 2017, fl., M. J. Silva 8493 ( UFG), 8494 ( UFG), 8495 ( UFG), 8496 ( UFG); ibd., cerca de 1 km a partir da descida do primeiro morro , 21 April 2017, fl., fr., M. J. Silva 8514 ( UFG), 8515 ( UFG), 8516 ( UFG); ibd., 32 km de Alto Paraíso de Goiás, sentido Teresina de Goiás, ca. 1.2 km a partir da cerca delimitativa do PNCV, lado esquerdo , 13°55’21”S, 47°26’20”W, 1516 m a.s.l., 23 September 2017, fl., M. J. Silva 9030 ( UFG), ibd., cerca 1.5 km a partir da estrada delimitativa do PNCV , 13°55’21”S, 47°26’20”W, 1507 m a.s.l., 23 September 2017, fl., fr., M. J. Silva 9040 ( UFG), 9041 ( UFG); ibd., cerca de 1, 6 km da estrada em topo de morro, cerrado rupestre , 13°55’21”S, 47°26’18”W, 1483 m a.s.l., 23 September 2017, fl., fr., M.J. Silva 9046 ( UFG), 9047 ( UFG); ibd., 13°55’29”S, 47°26’08”W, 1447 m a.s.l., 23 September 2017, fl., M. J. Silva 9053 (2), 9054 ( UFG); 6 km do Pouso Alto sentido Cruzeiro, Alto Paraíso de Goiás para Teresina de Goiás, 100 metros a entrada do PNCV , 13°56’41”S, 47°27’17”W, 1495 m a.s.l., 05 December 2017, fl., M. J. Silva 9084 ( UFG) .

Distribution and ecology:—Species known so far to Chapada dos Veadeiros National Park, Goiás state (municipalities of Alto Paraíso de Goiás and Cavalcante), ( Figure 3 ), where it grows in “campo limpo”, ‘campo sujo”, “cerrado típico”, “cerrado rupestre”, and “campo rupestre” on clay, clay-sandy soils or between rock crevices, in flat areas, hillside or hill tops, between 1313 and 1537 meters of altitude.

Phenology:—Collected with flowers from December to September and with fruits from April to January.

Etymology:—The specific epithet “ confertifolium ” is derived from the Latin “confertus”+ “folium”, that means “dense foliage” alluding to the fact that the new species has dense leaves on the branches.

Preliminary conservation assessments:— Erythroxylum confertifolium forms populations with fewer than 25 mature individuals and has an Extent of Occurrence estimated at 70.938 km 2, which led us to classify it as Critically Endangered (CR), Criteria B1ab(iv, v). However, it grows in the Chapada dos Veadeiros National Park, an area protected by law, in highly rugged relief area unsuitable for cultivation or housing construction, which in a way ensures its conservation.

Notes:— Erythorxylum confertifolium can be recognized by its slender shrubby habit up to 1.9 m tall, main stem densely branched distally, flattened with 1st-order branches shortened laterally, distichous and similar in size; glabrous, cinereal and with tiny lenticels when adults, triangular stipules smaller than the petiole, 3-setulose non-striated; coriaceous leaves, ascending and aggregated at the ends of the branches with a flat margin, venation brochidodromous with 7–9 secondary veins conspicuously visible per side, as well as fascicles 3–5 flowers, and ovoid red drupes. By having non-striated stipules and cataphylls, flowers with free styles, calyx with valvate aestivation, and lobes triangular, the species could be positioned in Erythroxylum sect. Archerythroxylum O.E. Schulz (1907: 69) , an exclusively Neotropical taxon composed of 70 species recently recovered by White et al. (2019) as paraphyletic. For this reason, we chose not to suggest including it in any of the sections of the genus proposed by Schulz (1907).

In Goiás state, Erythroxylum is represented by 16 species (Flora e Funga do Brasil 2023). Among these, E. parvistipulatum ( Figure 4 ) is the most similar morphologically to E. confertifolium , as both share the stems apparently thickened, brownish or darkish, the leaves with symmetrical base, flat margin, and apexes sometimes shortly mucronulate, with 7–9 veins per side, the stipules, and cataphylls non-striated as well as the flowers with pedicel clearly distinct from the calyx, and fascicles up to 5 flowers. However, E. parvistipulatum is a subshrub up to 50 cm alt, has a stem with numerous basal tillers in a caespitose appearance, these do not ramified distally (vs. shrub up to 1.9 m tall, the single main stem with secondary branches distichously distributed and similar in size), leaves membranaceous or coriaceous and obovate (vs. coriaceous, elliptical, elliptical-obovate, sometimes ovate in E. confertifolium ), stipules 2-setulose 4.5–5 mm long (vs. 3-setulose, 1–1.5 mm long); cataphylls 2-setulose (vs. 3-setulose), fascicles with 1–3 flowers (vs. 3–5 flowers), pedicel subcylindrical (vs. 5-angled), calyx 1.2–1.4 mm long (vs. 1.9–2.1 mm long), stamens of brevistylous flowers with 2–2.5 mm long (vs. 3.5–4 mm long), petals 3.9–4.8 × 1.3–2.7 mm, oblong (vs. 3.9–4.2 × 1.8–1.9 mm, elliptical), as well as styles of longistylous flowers united (vs. free).

This new species also resembles superficially E. betulaceum Martius (1840: 339) , a taxon belonging to E. sect. Archerythroxylum , and has been confused in herborized collections with E. campestre ( Figure 5 ) from E. sect. Rhabdophyllum by the habit, leaf aspect and consistency, calyx with lobes ¾ free as well as oblong petals. However, the characteristics listed in table 1 safely serves to differentiate such species.

Although Erythroxylum , according to Flora e Funga do Brasil (2023), is represented by 16 species in Goiás state, with the discovery of this new species and E. niquelandense M.J. Silva ( Silva & Loiola 2021: 270) published by Silva & Loiola (2021) the genus is now represented in the Brazil and in the state of Goiás by 135 (90 endemic) and 18 species, respectively. Thus, considering that the genus comprises 270 species in the tropics of the world, 200 of which occur in the neotropical region ( Plowman & Hensold 2004, White et al. 2019, Jara-Muñoz et al. 2022), Brazil can be considered one of the most important centers of diversity and endemism of the genus, as it is home to 50% and 67,5% of its species present in the world and Americas, respectively. Erythroxylum species present in the Cerrado are difficult to be identified and commonly found in herbaria without identification or mistakenly identified, pointing to the need for the genus to be studied locally. In fact, species of this genus have been recently described as new to the Cerrado (see Loiola & Sales 2012, Loiola & Cordeiro 2014, 2019, Costa-Lima & Chagas 2020, Silva & Loiola 2021).

Anatomical data: The petiole in the studied species has concave-convex contour with conspicuous lateral extensions on the upper surface in E. campestre ( Fig. 6a ) and flat-convex with discrete lateral extensions in E. confertifolium ( Fig. 6e ), and E. parvistipulatum ( Fig. 6i ). These extensions are constituted by one or two layers of angular collenchyma and parenchyma and have two collateral accessory vascular bundles only in E. campestre ( Fig. 6b ) and phenolic compounds and rhomboid crystals in E. confertifolium ( Fig. 6f ) and E. parvistipulatum ( Fig. 6j ). The epidermis is unistratified with small common cells, usually rectangular, rounded, or irregularly ovate covered by a thick cuticle ( Fig. 6c, g, k ). The cortex is formed by hipodermis unistratified with quandrangular or rectangular larger cells with walls slightly thickened ( Fig. 6c, g, k ), as well as by one or two layers of angular collenchyma, and six to eight layers of parenchyma ( Fig. 6a, e, i ). Phenolic compounds are often in collenchyma, and in epidermis and hypodermis cells ( Fig. 6c, d, g, h, k, l ), while rhomboid crystals were found scattered in the parenchyma (e.g. Fig. 6c, k ).

The vascular system comprises collateral vascular bundles, with a main vascular bundle, three accessories in a central position, and two in each lateral extension in E. campestre ( Fig. 6a, b ); one main and two accessories in a central position in E. parvistipulatum ( Fig. 6i ), and by just one central vascular bundle in E. confertifolium ( Fig. 6e ). The main vascular bundle was shown an open arc in E. campestre ( Fig. 6a , 7a ) and E. confertifolium ( Fig. 6e , 7e ), and a closed arc in E. parvistipulatum ( Fig. 6i , 7i ). This is surrounded by parenchyma cells in E. campestre ( Fig. 7a, b ), cluster of discontinuous fibers in E. confertifolium ( Fig 7e, f ), and by sheath fibers with 3–5 cell layers in E. parvistipulatum ( Fig. 7i, j ). Rhomboid and polyhedral crystals were found dispersed in the phloem and cortical parenchyma of the species studied ( Fig. 7b, c, g, k ), being more common in E. campestre . Sclereids, in general, adjacent to the fibers that surround the main vascular bundles occur in the cortex of these species, being commonly found in E. parvistipulatum ( Fig. 7 j ). The pith of all species comprises rounded parenchyma cells of varying sizes ( Fig. 7d, h, l ), some of them with phenolic compounds in E. confertifolium ( Fig. 7h ).

The leaf blade has unistratified epidermis with quadrangular common cells on the adaxial surface, and rectangular, rounded and quadrangular cells on the abaxial surface in E. campestre ( Fig. 8a, b ), uni and discontinuously bistratified epidermis, with quadrangular common cells on the adaxial surface, and rectangular cells on the abaxial surface of E. confertifolium ( Fig. 8f, g ), and uni or bistratified on the adaxial surface, and papillose on the abaxial surface of E. parvistipulatum ( Fig. 8k, l ), with the common cells covered by a thick cuticle (e.g. Fig. 8a ). The leaves are hypostomatic with diminute stomata and large substomatic chambers distributed at the level of the other common cells of the epidermis on the abaxial surface ( Fig. 8b, g, l ).

The mesophyll is dorsiventral with two layers of palisade parenchyma and spongy parenchyma with irregularly spaced cells ( Fig. 8a, f and k ) and has distinct organization patterns, considering the palisade/spongy parenchyma ratio, which occupy, respectively, 30/70% in E. campestre ( Fig. 8a ), 70/30% in E. confertifolium ( Fig. 8f ), and 50/50% in E. parvistipulatum ( Fig. 8k ). Branched sclereids occur in the mesophyll of the three studied species ( Fig. 8c, h, m ).

The margin is straight and acute in E. campestre ( Fig. 8d ) and obtuse and slightly inflected towards the abaxial surface in E. confertifolium ( Fig. 8i ) and in C. parvistipulatum ( Fig. 8n ). In this region the common cells of epidermis, on the adaxial surface, are covered by a thick cuticle, and in subepidermal position have angular collenchyma and parenchyma. The vascular bundles in the median portion of the leaf blade of the three species studied are collateral and surrounded by a fiber sheath that extends towards the epidermis on the adaxial surface ( Fig. 8e, j, o ).

The midrib presented a biconvex contour, due to the presence of a crest on the upper surface in E. campestre ( Fig. 9a ) and in E. parvistipulatum ( Fig. 9i ), and plano-convex in E. confertifolium ( Fig. 9e ). The epidermis is unistratified with common cells usually rectangular on the upper surface and rounded on the lower in E. campestre ( Fig 9b, c ); rectangular, quadrangular and rounded on both sides surfaces in E. confertifolium ( Fig. 9f, g ), and quadrangular on the upper surface and rounded and oval on the lower surface in E. parvistipulatum ( Fig. 9j, k ). In this region the cortex has a different tissue composition on the upper and lower surface. On the upper surface, E. campestre has 1–4 layers of angular collenchyma and 2 to 4 of ground parenchyma ( Fig. 9b ), E. confertifolium ( Fig. 9f ) presents 1 or 2 of angular collenchyma, 2 of palisade parenchyma and 1–3 of parenchyma ground, while E. parvistipulatum ( Fig. 9j ) possess only 5 or 6 layers of angular collenchyma; on the lower surface there are 4 or 5 layers of angular collenchyma and up to 4 of parenchyma in E. campestre ( Fig. 9c ), three of angular collenchyma and 2 or 3 of parenchyma in E. confertifolium ( Fig. 9g ) and seven layers of angular collenchyma and 1 or 2 of parenchyma in E. parvistipulatum ( Fig. 9k ). Phenolic compounds, sclereids, and crystals are common in the cortex cells of all species ( Fig. 9d, f, g, h, j, k, l ).

The vascular system is formed by two collateral vascular bundles, the larger one in a central position in a closed arch and the smaller one facing the upper surface in E. campestre ( Fig. 9b ); by a single central vascular bundle in an open arch with an extension of fiber sheath towards upper surface in E. confertifolium ( Fig. 9f ), and by a central vascular bundle in an open arch and two smaller rounded ones facing the upper surface and E. parvistipulatum ( Fig. 9j ). The main vascular bundle is surrounded by a sheath of libriform fibers in E. campestre ( Fig. 9c ), gelatinous fibers in E. confertifolium ( Fig. 9g ), and E. parvistipulatum ( Fig. 9k ). Rhomboid crystals, usually adjacent to phloem cells, are found in the cortex cells of studied species ( Fig. 9d, h, l ).

Although leaf anatomy is poorly studied in Erythroxylaceae , it is useful in separating Erythroxylum taxa (see Ballard 1926, Bohm et al. 1982, Rury 1981, Rury & Plowman 1983, Bieras & Sajo 2004) and discussed as a possible taxonomic marker for some sections of the genus by Bieras & Sajo (2004). The anatomical information gathered in this study for E. campestre , E. parvistipulatum , and E. confertifolium are consistent with those provided by the previously cited authors regarding the species studied having a thick cuticle in the common epidermal cells that are uni or discontinuously bistratified on the adaxial surface and sometimes modified in papillae on the abaxial surface, and always unistratified on the midrib and petiole; leaf blades dorsiventral and hypostomatic leaves with diminute stomata, collateral vascular bundles, the main one on the midrib and petiole in an open or closed arch; presence of fiber sheath involving the bundles, sclereids scattered in the mesophyll and cortex, midrib with crest on upper surface and biconvex contour, as well as cortex composed by angular collenchyma and parenchyma. On the other hand, other characters are first added here, such as: the presence of rhomboid crystals and the number of layers that constitute the cortex on the upper and lower face of the petiole and midrib. Our interpretations of some characters found in E. campestre differ from those cited for this species by Bieras & Sajo (2004), as these authors described the leaf margin in this species as acuminate, the main vascular bundle of the petiole in a closed arch and sheath that surrounds the main vascular bundle on the petiole as sclerenchymatous, while we found it to have the same obtuse margin, the main vascular bundle on the petiole in an open arch, as it was interrupted by parenchyma in its upper portion, and a merely parenchymatic sheath

Regarding the taxonomic value of the anatomical characters studied, we found that the number of vascular bundles and their appearance on the petiole and midrib, aspect of the sheath that surrounds the vascular bundle, presence or absent of papillae on the abaxial surface, palisade parenchyma/spongy parenchyma ratio, presence of sheath extension in the median vascular bundles of the mesophyll and of the main vascular bundle of the midrib, and composition of the cortex in the lower and upper surface of the petiole are useful in the separation of the species, according to the table 2. We reiterate that, except for the last character, the others were used in the separation of Erythroxylum species (see Ballard 1926, Bieras & Sajo 2004, Rury & Plowman 1983) or varieties of E. coca Lamarck (1786: 393) (see Rury 1981, Rury & Plowman 1983). Characters such as the presence of sclereids in the mesophyll have been used by Ballard (1926) and Biera & Sajo (2004) to separate species. However, we observed after consulting the literature that the sclereids are typical of the genus, and thus, should not be used in the separation of their species.

Some characteristics (e.g., presence of sclerenchymatous or parenchymatic sheath involving the main vascular bundles in the petiole and rib, presence of sheath extension, proportion of palisade and spongy parenchyma in the mesophyll, presence of sclereids in the mesophyll, appearance of the leaf margin, among others) were used as possible taxonomic markers of sections of the genus by Bieras & Sajo (2004). However, we believe that the use of such characters as taxonomic markers of sections in Erythroxylum should be carefully reviewed and discussed, as the analysis of the literature on the genus shows that: i) little information exists on the leaf anatomy of species of this genus considering its richness (ca. 270 spp., Jara-Muñoz et al. 2022); ii) such characters evolved independently, and, iii) that species of the genus anatomically studied (see previous authors) belong to non-monophyletic sections (see White et al. 2019).

Regarding the ecological significance, the leaf anatomical characters identified in this study are related to protection against herbivory, pathogen attacks, reduction of excessive loss of water to the atmosphere (e.g. hypostomatic leaves, diminute stomata, hypodermis), protection against ultraviolet radiation (e.g. thick cuticle), support, water retention and maintenance of internal tissues (e.g. collenchyma, sclereids and fibers of the larger vascular bundles of the midrib and petiole), photosynthetic efficiency (mesophyll with more than one layer of palisade parenchyma), ray reflection luminous (e.g. papillae), as evidenced by studies similar to this one with plants also from the Cerrado (e.g. Metcalfe & Chalk 1950, Boeger & Wisniewski 2003, Bieras & Sajo 2009, Javelle et al. 2011).

Figures

FIGURE 3. Distribution of Erythroxylum confertifolium M.J. Silva. a. Map of Brazil, highlighting the state of Goiás in gray; b. Map of Goiás state, its limits, and altitude variation, showing the limits of the Chapada dos Veadeiros National Park (dotted and black area); c. Limits of the Chapada dos Veadeiros National Park with the species distribution points. Abbreviations for states (BA, Bahia; GO, Goiás; MG, Minas Gerais; MS, Mato Grosso do Sul; MT, Mato Grosso; TO, Tocantins) and Federation unity (DF, Distrito Federal) of Brazil;

FIGURE 4. Erythroxylum parvistipulatum. a. Habitat and habit; b. Fascicle with flower bud and open flowers; c. Brevistylous flowers; d. Fruiting plant; e. Drupes mature (in red) and immature in advanced stage of maturation (orange). (Images taken by M. J. Silva).

FIGURE 5. Erythroxylum campestre. a. Fruiting branch; b. Flowering branch; c. Fascicles with flower bud and open flowers; d. Drupes mature (detail) and immature in advanced stage of maturation with red apex (Images taken by M. J. Silva).

FIGURE 6. Cross sections of the petiole of Erythroxylum campestre A. St.-Hil. (a-d), E. confertifolium M.J. Silva (e-h), and E. parvistipulatum Peyr. (i-l). a, e, and i. General aspect. b, f, and j. Lateral projections, note the accessory vascular bundles in b; c, g, and k. Detail of epidermis, hypodermis, collenchyma, and portion of the vascular bundles; d, h, and l. Detail of epidermis, cortical parenchyma, and collenchyma of the abaxial surface. c = cuticle. co = collenchyma. ep = epidermis. pa = parenchyma. hi = hypodermis. vb = vascular bundles; asterisks = phenolic compounds; arrows = rhomboid crystals. Scale bars: a, e, and i = 500 μm; b, d, h, and l = 200 μm; c, f, g, j, and k = 50 μm.

FIGURE 7. Cross sections of the petiole of Erythroxylum campestre A. St.-Hil. (a–d), E. confertifolium M.J. Silva (e–h), and E. parvistipulatum Peyr. (i–l). a, e, and i. General aspect of the main vascular bundle. b, f, and j; Detail of the fibers, phloem, sclereids, and xylem; c, g, and k; Rhomboid crystals (in polarized light: g, and k; d, h and l. Detail of vascular bundles and pith. fi = fibers. ph = phloem. pi = pith. sc = sclereids. vb = vascular bundles. xy = xylem. asterisks = phenolic compounds. arrows = rhomboid crystals. Scale bars: a, d, e, h, and l = 200 μm; b, f, and j = 50 μm; c, g and k = 20 μm.

FIGURE 8. Cross sections of the leaf blade of Erythroxylum campestre A. St.-Hil. (a–e), E. confertifolium M.J. Silva (f–j), and E. parvistipulatum Peyr. (k–o). a, f, and k. General aspect of the leaf blade; b, g, and l. Epidermis, vascular bundles, and spongy parenchyma of the abaxial surface. Note the papillae in l; c, h, and m; Sclereids and mesophyll, note polarized light in c and m); d, i and, n. Margin. e, j, o. Detail of the vascular bundles. c = cuticle. ep = epidermis. fi = fibers. p = papillae. ph = phloem. pp = palisade parenchyma. sc = sclereids. sp = spongy parenchyma. vb = vascular bundle. xy = xylem. asterisks = substomatic chamber. arrows = stomata. Scale bars: c, d, i and n = 200 μm; a, b, e–h, j, k–m, and o = 50 μm.

FIGURE 9. Cross sections of the midrib of Erythroxylum campestre A. St.-Hil. (a–d), E. confertifolium M.J. Silva (b–h), and E. parvistipulatum Peyr. (i–l). a, e, and i. General aspect. b, f, and j. Vascular bundles. c, g, and k. Detail of epidermis, fibers, parenchyma, and angular collenchyma (abaxial surface); d, h, and l. Rhomboid crystals in polarized light. c = cuticle. co = angular collenchyma. ep = epidermis. gl = gelatinous fibers. lf = libriform fibers. pa = parenchyma. vb = vascular bundle. asterisks = phenolic compounds. Scale bars: a, e and i = 500 μm; b, f and j = 200 μm; c, g and k = 50 μm; d, h and l = 20 μm.