Manihot attenuata Muell . Arg. (1874: 442) emend. M.J. Silva

Silva, Marcos Jose da, Inocencio, Lais de Souza, Sodre, Rodolfo Carneiro & Alonso, Alexandre Antonio, 2017, Morphological and anatomical evidence support a new wild cassava: Manihot fallax (Crotonoideae, Euphorbiaceae), from Mato Grosso, Brazil, PhytoKeys 91, pp. 139-156 : 143-145

Manihot attenuata Muell. Arg. (1874: 442) emend. M.J. Silva Figs 5 , 6

Manihot brachystachys Pax & K. Hoffm., Planzenr. (Engler) 4, Fam. 147, II: 97. 1910. Type. Brazil. Südbrasilianishe Provinz, Staat Goiaz, 8 Jan 1898, fl., Glaziou 22126 (lectotype, designated here: P [P04786133!]; isolectotypes: BR [BR000005101320!], G [G00441911!], K [000600417!], P [P04786134!, P04786135!], S [S-R-9076!]).

Manihot robusta M. Mend. & T. B. Cavalc. Arnaldoa 22(2): 297, 2015. Type. BRAZIL. Alto Paraíso de Goiás, Parque Nacional Chapada dos Veadeiros, ca. 0.3 km da GO-239, sentido sede alojamento do ICMBio (lado direito), 14°09'55.92"S, 47°47'25.62"W, 1046 m a.s.l., 31 Oct 2014, M. Mendoza, J.B.A. Bringel, A.A. Santos and T. Reis 4343, syn. nov. (holotype: CEN!; isotypes: HRCB!, HUEFS!, K!, MG, MO!, NY!, RB!, SP!, UB!).

Type.

BRAZIL. Goiás: inter Goyaz et Cavalcante, Burchell 7865 (lectotype, designated here: K [K000600418!]; isolectotypes: BR [BR510866!], G!).

Emended description.

Shrubs 0.5-1.2 m tall erect or decumbent, in which case the stem to 0.6 m tall with lateral branches to 1.3 m long, monoecious, glabrous. Stems and branches angulose, glossy, brownish, the bark exfoliating when adult and purplish, greenish or combinations of these when young; latex yellow or clear. Stipules 10-12 × 0.5-0.1 mm, lanceolate, sparsely serreate, persistent; petiole 3-4 mm long, greenish. Leaves alternate, spiral, sparsely distributed along the branches, but more concentrated near apex; blades 17.5-24 × 4-4.5 cm, elliptic, widely elliptic, ovate-lanceolate, oblong-elliptic or sometimes lanceolate, entire, unlobed, non-peltate, base obtuse or attenuate, apex acute and mucronulate, chartaceous, glabrous on both surfaces, adaxial surface dark purple or greenish purple, abaxial surface glaucous to cinereous, the latter with a smooth wax pattern, venation camptodromous-brochidodromous, primary veins prominent on both surface, secondary veins impressed on both surfaces, diagonally arranged towards the midvein, all pinkish to purplish. Racemes 4.5-10.5 cm long, staminate or bisexual, solitary, terminal or arising from dichotomy of the branches, erect or pendent, congested, glabrous, angulate, glaucous to cinereous, waxy. Staminate flowers: buds 4-7 × 3-6 mm, widely ovoid, yellowish, without purplish pigmentation; bracts 10-15 × 3-7 mm, widely ovate, foliaceous, apex acuminate, margins sparsely and irregularly denticulate, persistent; bracteoles situated along the lower third up to half of the pedicel, 4-4.6 × 1-1.5 mm, ovate or ovate-laceolate, foliaceous, persistent, subopposite; pedicels 3-3.2 mm long, cylindrical, glabrous, light green; calyx 7-15 × 5-10 mm, campanulate, green-yellowish, without purplish pigmentation, shortly tomentose internally, lobes ovate-oblong with apex obtuse or rounded, base truncate; stamens 10, in two whorls of five, glabrous, the longer 7.5-7.6 mm long, the shorter 4.5-4.6 mm long, both thickened, anthers 3-4 mm long, oblong, bright yellow, dorsifixed; disc 10-lobed, intrastaminal, dark yellow. Pistillate flowers: buds 6-8 × 4-6 mm, ovoid, green-yellowish, without purplish pigmentation; bracts 5-9 × 1.5-5 mm long, widely ovate, entire, apex acuminate, margin irregularly serrate, glabrous, persistent; bracteoles 4-6 × 1-3 mm, oblong-elliptic, foliaceous, persistent, margin denticulate, apex acuminate, opposite along the lower third of the pedicel, glabrous; pedicels 4-5 mm long, cylindrical-clavate, glabrous, green; calyx 7-9 × 5-7 mm, campanulate, yellowish green, without purplish pigmentation, glabrous externally, shortly tomentose internally, lobes triangular, base truncate; ovary 5-7 × 2-3 mm, ovoid to oblong, glabrous, green, disc patelliform, lobed, yellow; styles 3, shortly united at the base, densely papillose lobed. Capsules 0.8-1.8 × 0.7-1.2 cm, oblong, light green, smooth, glabrous, without wings, waxy, dehiscence septicidal and loculicidal; columella (carpophore) persistent, 0.78-0.8 × 1.2-1.3 mm (width at narrowest point in middle), dilating to 2-2.2 mm at both tip and base, narrowly alate. Seeds 7-10 × 5-6 mm, oblong, dark grey or cinereous, with black spots; caruncle prominent, widely triangular with entire apex, cream.

Morphological relationships and characterisation.

Manihot attenuata is easily recognised by its shrub habit; erect or decumbent habit; large leaves (17.5-24 × 4-4.5 cm) that are purplish; sparsely serrate, persistent stipules; bracts and bracteoles of both staminate and pistillate flowers widely ovate, pubescent externally and acuminate at the apex; usually pendent inflorescences; and pubescent stigmatic branches. It is morphologically similar to M. fallax . However, it differs by the set of characters cited in Table 1 and also according the anatomical characters previously discussed.

Distribution and ecology.

A species endemic to the northern portion of the state of Goiás, Chapada dos Veadeiros and neighbouring regions (municipalities of Niquelândia and Minaçu) (Fig. 3 ). It grows in cerrado rupestre, cerrado sensu stricto, near to rocky outcrops and in rocky fields, in flat sites, slopes or hilltops on clay-sandy soils, or in rock cracks, at altitudes from 440 and 1477 metres.

Phenology.

The species has been collected with flowers from November to March, with the flowers more common from September to December and with fruits from December to March.

Conservation Status.

Manihot attenuata is here classified as Vulnerable (VUVU) according to the IUCN Red List Categories and Criteria ( IUCN 2014) because it has an extent of occurrence of ca. 9850 km2. However, the species has populations with more 20 individuals and it grows in environments inappropriate for farming and habitations, as well as in protected areas such as the Chapada dos Veadeiros National Park.

Typification.

Müller (1874) described M. attenuata in Flora Brasiliensis based on Burchell 7865 from Goiás state. Pax (1910) recognised M. attenuata as a good species without comment about its typification and established M. brachystachys . Rogers and Appan (1973) subordinated M. brachystachys Pax & K. Hoffm. as a synonym of M. attenuata without comment or typification of the latter. Analysing all type collections of both species confirmed that both species need to be lectotypified. The collection Burchell 7865 (Fig. 7 ) deposited in the herbarium K (K000600418) as lectotype of M. attenuata was designated here because it complies with the protologue and has flowers. Based on this same principle, the collection Glaziou 21126 at P (P04786133) was proposed as a lectotype of M. brachystachys ; isolectotypes are BR (BR0000005101320), G (G00441911), K (K000600417), P (P04786134, P04786135) and S (S-R-9076). M. brachystachys was also recognised as a synonym for M. attenuata because the characters used by Pax (1910) to differentiate them (e.g. leaf type, habit, fusion of floral parts) overlap and are variable within populations.

Recently, Mendoza et al. (2015) published M. robusta as a new species from Chapada dos Veadeiros region in Goiás state. Reviewing all collections used by the authors in the description of M. robusta , based on the images provided by them and the characters cited to differentiate M. robusta from M. attenuata (e.g. habit and aspect of growth, secondary vein numbers, inflorescence position and numbers, bract shape and length), it is concluded that the characters cited by the authors overlap and are variable within populations. Furthermore, all collections of M. robusta are from the same location as the type of M. attenuata . It is therefore considered that M. robusta is a synonym of M. attenuata .

Additional specimens examined.

BRAZIL. Goiás: Alto Paraíso de Goiás, Chapada dos Veadeiros, estrada GO 327, aproximadamente 1800 metros antes da Vila São Jorge, 14°09'00"S, 47°37'00"W, 1000 m a.s.l., 29 Mar 1988, I. R. S. Costa et al. 19 (UFG); entrada do Parque Nacional da Chapada dos Veadeiros, 14°10'5"S, 47°47'25"W, 27 Jan 1996, fl., fr., W. L. Werneck 706 (CEN); entrada do Parque Nacional da Chapada dos Veadeiros (a esquerda), estrada Alto Paraíso-Colinas, 34 km da GO 118, 14°09'49"S, 47°47'8"W, 1250 m a.s.l., 22 Jan 1997, fl., B. M. T. Walter et al. 3644 (CEN); Parque Nacional Chapada dos Veadeiros (PNCV) área queimada com relevo plano, 15°44'14"S, 47°54'54"W, 1477 m a.s.l., 25 Sep 1995, fl., M. L. Fonseca et al. 549 (IBGE); ib. Cerca de 1 km acima do alojamento dos brigadistas, 20 Jan 2012, fl. fr., M. J. Silva et al. 4063, 4065 (UFG); ib., Proximidades do alojamento dos brigadistas, 25 May 2012, fr., L. C. S. Almeida et al. 42 (UFG); ib., final do acesso da trilha que leva ao Cânion I, entre fendas de rocha, 14°09'6.55"S, 47°48'0.74"W, 1114 m a.s.l., 29 Sep 2012, fl., M. J. Silva et al. 4421 (UFG); 2.5 km em direção ao rio Preto, 26 Oct 2012, fl., M. J. Silva et al. 4502 and 4506 (UFG); na subida para o alojamento dos brigadistas do PNCV, 22 Oct 2011, fl., M. J. Silva et al. 3885 (UFG); Parque Nacional Chapada dos Veadeiros, estrada que leva ao alojamento dos brigadistas, 14°9'53.6"S, 47°47'25.7"W, 1034 m a.s.l., 31 Oct 2014, fl., L. S. Inocencio et al. 180, 181, 182 and 183 (UFG); ib., segundo morro a nordeste do alojamento principal dos brigadistas do PNCV, 27 Oct 2012, fl., M. J. Silva et al. 4503 and 4507 (UFG); topo da serra à direita da estrada que leva ao Cânion I, 14°09'05.7"S, 47°48'00"W, 1130 m a.s.l., 23 Nov 2012, fl., L.C.S. Almeida & I. A. M. Watanabe 67 and 69 (UFG); estrada para Vale da Lua, 24 Nov 2012, fl., M. J. Silva et al. 4589 (UFG); trilha a partir do dos alojamentos do PNCV em direção ao Cânion I, 14°08'S, 47°43'W, 1086 m a.s.l., 29 Nov 2012, fl., L. C. S. Almeida et al. 50 (UFG); afloramento rochoso à nordeste do Cânion I, 14°9'S, 47°48'W, 1082 m a.s.l., 29 Nov 2012, fl., L. C. S. Almeida et al. 51, 52 and 56 (UFG); subida de acesso ao alojamento dos brigadistas do PNCV, 14°09'37.6"S, 47°57'2.3"W, 1034 m a.s.l., 22 Feb 2014, fl., fr., M. J. Silva et al. 5921 (UFG); cerca de 500 m do alojamento dos brigadistas, 14°9'22.4"S, 47°47'38.9"W, 1089 m a.s.l., 13 Dec 2014, fl., L. S. Inocencio et al. 278 (UFG); Parque Nacional da Chapada dos Veadeiros, estrada que leva ao alojamento principal do Parque, 04 Jan 2015, fl., R. C. Sodré, M. J. Silva & C. H. G. M. Filho 1636 (UFG). Cavalcante, exatos 8 km a noroeste de Cavalcante ao longo da estrada de terra que leva à Colinas do Sul, 13°50'S, 47°33'W, 12 Dec 1986, fl., fr., A. C. Allem et al. 11307 (CEN); estrada Minaçu-Cavalcante passando pela balsa Serra Branca (COTERRA), à cerca de 126 km do rio Tocantins, 13°41'07"S, 47°51'22"W, 740 m a.s.l., 10 Nov 2000, fl., G. P. Silva 4421 (UFG); cerca de 4 km da Vila Veneno, na direção do rio São Félix, cerca de 12 km da Balsa da Coterra, 13°32'10"S, 48°03'29"W, 380 m a.s.l., 25 Jan 2001, fl., B. M. T. Walter et al. 4807 (UFG). Chapada dos Veadeiros, imediações da Serra do Ministro, a aproximadamente 500 m da estrada entre Cavalcante e Colinas do Sul, 13°54'34"S, 47°38'55,4"W, 20 Jan 2014, fr., R. C. Sodré et al. 1193 (UFG). Minaçu, 7 km após a entrada norte do canteiro de obras, 13°28'00"S, 48°23'00"W, 920 m a.s.l., 10 Mar 1992, fl., fr., T. B. Cavalcanti et al. 1112 (CEN). Niquelândia, Reservatório em formação do AHE Serra da Mesa, região na margem direita do rio Maranhão, próximo ao rio das Almas, 14°34'50"S, 48°59'07"W, 440 m a.s.l., 16 Oct 1997, fl., B. M. T. Walter 3924 (CEN).

Figures

Figure 3. Distribution map of Manihot fallax sp. nov and M. attenuata.

Figure 5. Manihot attenuata. A Habit B Details of the branch showing the persistent stipule C Stipule D Staminate bracts E Staminate bracteole F Staminate bud G Staminate flower H Staminate flower with calyx split and open I Pistillate bracts J Pistillate bracteole K Pistillate flower, note the gamosepalous calyx L Pistillate flower with calyx split and open M Fruit N Seed, ventral side O Seed, dorsal side. Drawn by Cristiano Gualberto from the holotype.

Figure 6. Manihot attenuata. A Habit B Inflorescence; note the ovoid staminate bud and showy bracts C Portion of inflorescence showing the staminate flowers, lateral view D Staminate flower, frontal view E Pistillate flowers in the inflorescence, frontal view; note the campanulate calyx F Fruit.

Figure 7. Specimen selected as the lectotype of M. attenuata, Burchell 7865 (K 000600418). Image used with permission and provided by the Royal Botanic Gardens, Kew.