Maranta gigantea N. Luna & E. M. Pessoa, 2018

Luna, Naédja, Pessoa, Edlley & Alves, Marccus, 2018, A new “ giant ” species of Maranta L. (Marantaceae) from the Atlantic Forest of northeastern Brazil, Phytotaxa 357 (1), pp. 59-65 : 60-64

Maranta gigantea N. Luna & E. M. Pessoa , sp. nov. ( Figs. 1 , 2 )

Type:— BRAZIL. Pernambuco: Jaqueira, Reserva Particular do Patrimônio Natural Frei Caneca, Mata do Jasmim, 08°43’40”S, 35°50’18”W, 600 m, 27 August 2015, N. K. Luna et al. 127 (fl., fr.) (holotype UFP, isotypes NY, RB).

Maranta gigantea is similar to M. anderssoniana , but differs by having larger size (up to 1.8 m tall vs. 1 m tall), tomentose leaf sheath (vs. sericeous), longer narrow-lanceolate leaf blades (8.5 − 35 cm long vs. lanceolate to oblong and 4.5 − 18.3 cm long), longer synflorescence peduncle (6 − 11 cm long vs. 2.9 − 6 cm long), longer corolla tube (9 − 12 mm long vs. 5 − 6 mm long), asymmetrically elliptical corolla lobes (vs. asymmetrically oblong), and larger minor outer staminode (12 − 15 × 6.5 − 8 mm vs. 10 − 11 × 5.5 − 6 mm).

Perennial zingiberoid herbs, unbranched, up to 1.8 m tall; rhizome 0.4 − 0.6 cm thick, without tubers. Leaves distichous; sheath 5 − 32.5 cm long, auriculate, vinaceous, tomentose; petiole sessile to subsessile, vinaceous, adaxially tomentose, abaxially glabrous; pulvinus 0.5 − 1 cm long, light green, adaxially tomentose, abaxially glabrous; leaf blade 8.5 − 35 × 2 − 5.5 cm, shiny, adaxially dark green, abaxially vinaceous, chartaceous, narrow-lanceolate, glabrous, asymmetrical, apex acute, base cuneate. Synflorescence terminal, subtended by one leafy bract and/or rising on a separate leafless shoot; peduncle 6 − 11 cm long, green, glabrescent and composed of 2 − 3 florescences; florescences prophyll 3.5 − 5 cm long, translucent pale, membranaceous, linear, bicarinate, glabrous, apex acute; florescence peduncle 3 − 12 cm long, sparsely tomentose; spathes 3 − 4.3 cm long, ca. 3 per florescence, green, membranaceous, narrow − lanceolate, glabrescent to sericeous, apex acute; prophyll 2.5 − 3 cm long, translucent green, membranaceous, narrow-lanceolate, glabrous, apex acute, 1 − 3 cymules per spathe; cymules 2 − flowered, dolichoblastic; peduncle 2.5 − 4.7 cm long. Sepals 9 − 12 × 1.5 − 3 mm, greenish, membranaceous, oblong, glabrous, apex acute; corolla white; tube 9 − 12 mm long, proximally internally pilose; corolla lobes 7 − 10 × 2.5 − 3.5 mm, membranaceous, asymmetrically elliptical, glabrous, apex acute; outer staminodes 2, unequal, the larger one 13 − 16 × 8.5 − 10.5 mm, white, membranaceous, obovate, glabrous, apex rounded, the smaller one 12 − 15 × 6.5 − 8 mm, white, membranaceous, elliptical, glabrous, apex rounded; callose staminode 11 − 18 × 6 − 9.5 mm, white, membranaceous, obovate, glabrous, apex rounded, basal calli 2, prominent, lobed, pilose; cucullate staminode 5 − 6 × 1.5 − 2 mm, white, membranaceous, oblong, glabrous, apex rounded, revolute, distal appendix 2 − 3 × 1 mm, deflexed; lateral petaloid appendage 5 − 8.5 × 4.5 − 5 mm, white, membranaceous, obovate, glabrous, apex rounded; anther 2 − 3 × 0.8 − 1 mm; style 9 − 12 mm long, projection prominent; ovary 2 − 2.3 mm long, densely sericeous. Fruit 0.5 − 1 cm long, green, obovate-trigonal, sparsely sericeous, sepals persistent.

Distribution and ecology: — Maranta gigantea is endemic to the Atlantic Forest, growing in areas of seasonal submontane to montane forest ( IBGE 2012, Melo et al. 2016) in the states of Alagoas and Pernambuco, Northeastern Brazil ( Fig. 3). This area is rich in endemic species ( Amorim & Alves 2015, Pessoa & Alves 2015, Bazante & Alves 2017), and it is pointed out as a Pleistocene refuge ( Carnaval et al. 2009) as well as one of the centers of endemism of the Atlantic Forest ( Silva & Casteleti 2005). It is also severely affected by anthropic actions, including sugar cane monoculture, livestock raising and urban expansion ( Silva & Casteleti 2005). The type locality includes forest remnants and rock outcrops ( Melo et al. 2016), where M. gigantea is found in small populations. The plants grow in the understory and the flowers have nocturnal anthesis. The flowering period is poorly known, but based on the specimens analyzed, flowers and fruits can be found from August to January.

Conservations status: —This species is considered critically endangered, CR B1a, with an extent of occurrence (EOO) less than 100 km ² and strongly fragmented. The population of Pernambuco is restricted to a forest fragment of about 1,000 ha with high anthropic pressure. The Alagoas population is known from herbarium specimens only, one of which is an old collection from an area facing similar anthropic pressures.

Etymology: —The name refers to the size of the individuals, which can reach 1.8 m, and have leaves up 35 cm long, making it very distinctive in the genus together with M. zingiberina which is also a tall species.

Morphological affinities: — Maranta gigantea belongs to M. subg. Maranta , characterized by erect caulescent, rosulate or zingiberoid growth, lack of tubers, simple or few-branched inflorescences, and flowers with distinct pedicels ( Andersson 1986). Currently, 19 species of the subgenus are found in Brazil ( Andersson 1986, Braga 2001, Yoshida-Arns et al. 2002), of which 13 grow in the Atlantic Forest ( BFG 2015). Among the species of the subgenus, only two have zingiberoid growth, M. anderssoniana and M. zingiberina ( Andersson 1986, Yoshida-Arns et al. 2002), both endemic to Northeastern Brazil. Maranta anderssoniana is known only from the Atlantic Forest in Alagoas and Pernambuco ( BFG 2015, Yoshida-Arns et al. 2002), while M. zingiberina is found in areas of Caatinga in Bahia, Paraíba, and Pernambuco ( Andersson 1986, Yoshida-Arns et al. 2002, BFG 2015). However, these species differ from M. gigantea in the shape of the leaf blade (lanceolate to oblong or ovate vs. narrow-lanceolate) and number of calli in the callose staminode (one prominent callus vs. two prominent calli). Furthemore, M. zingiberina differs by its glabrous and green leaf sheath (vs. tomentose and vinaceous), glabrous pulvinus (vs. adaxially tomentose), concolorous leaves with cuspidate apex (vs. discolorous and acute), strictly terminal inflorescences (vs. terminal and/ or rising on a separate leafless shoot), and glabrous ovary (vs. densely sericeous). Maranta anderssoniana differs by being shorter (up to 1m tall vs. up to 1.8 m tall.), with a sericeous leaf sheath (vs. tomentose), lanceolate to oblong leaves (vs. narrow − lanceolate), shorter synflorescence peduncle (2.9 − 6 cm long vs. 6 − 11 cm long), shorter corolla tube (5 − 6 mm long vs. 9 − 12 mm long), asymmetrically oblong corolla lobes (vs. asymmetrically elliptical), smaller major outer staminode (10 − 12 × 8 − 9.2 mm vs. 13 − 16 × 8.5 − 10.5 mm), and smaller minor outer staminode (10 − 11 × 5.5 − 6 mm vs. 12 − 15 × 6.5 − 8 mm). Other species, as M. noctiflora Regel & Körnicke (1858: 81) is superficially similar to M. gigantea , based on the discolorous leaves and morphology of the floral parts, but is easily distinguished by the branched, caulescent growth form (vs. zingiberoid), and by the ovate to narrow-ovate leaves (vs. narrow-lanceolate).

Useful characters to distinguish M. gigantea, M. Anderssoniana , and M. zingiberina are presented in Table 1.

Additional specimens examined (paratypes): — BRAZIL. Alagoas: Teotônio Vilela, Reserva Madeiras, 14 August 2014, fl., fr., R.L. Silva 100 (MAC); União dos Palmares, Mata da Serrinha , 2 November 1966, fl., I. Pontual 239 (IPA, PEUFR). Pernambuco: Jaqueira, Reserva Particular do Patrimônio Natural Frei Caneca, Mata do Jasmim, 7 January 2016, fl., fr., N.K. Luna. et al. 210 (UFP); ibid., 20 September 2017, fl., fr., N.K. Luna et al. 445 (UFP); ibid., 21 September 2017, fl., fr., N.K. Luna et al. 449 (UFP).

Figures

FIGURE 1. Maranta gigantea. A. Habit. B. Leaf blade. C. Inflorescence. D. Cymule. E. Flower. F. Spathe. G. Prophyll. H. Corolla lobes. I. Major outer staminode. J. Minor outer staminode. K. Callose staminode. L. Cucullate staminode. M. Stamen with appendix. N. Style and stigma. O. Fruit.

FIGURE 2. Maranta gigantea. A. Habit (leaf blades adaxially dark green, abaxially vinaceous). B. Basal synflorescence. C. Terminal synflorescence. D. Detail of cymules with flowers and fruits.