Solanum bradei Giacomin & Stehmann, 2014

Giacomin, Leandro L. & Stehmann, Joao R., 2014, Three new species of Solanum (Brevantherum Clade) endemic to the Brazilian Atlantic Forest, PhytoKeys 38, pp. 69-87 : 70-74

Solanum bradei Giacomin & Stehmann sp. nov. Figs 1 2A, B

Diagnosis.

Differs from all other species of the Solanum inornatum group in its shrub-like, woody habit and long-pedunculate inflorescences (peduncles up to 1 cm). Unlike Solanum inornatum Witasek it has deltate, rather than linear-lanceolate, calyx lobes that are not accrescent in fruit.

Type.

BRAZIL. Rio de Janeiro: Mun. Itatiaia. Parque Nacional do Itatiaia, continuação da BR após posto de vigilância, margens da estrada próximo a casa, 1171 m, 22°26'11.15"S, 44°37'27.55"W, 3 Nov 2008 (fl), L.L. Giacomin, L.H.Y. Kamino & T.E. Almeida 359 (holotype: BHCB [BHCB-012523]; isotypes: BM, NY, RB).

Description.

Herbs to shrubs, woody at base, erect, to 1.8 m tall, usually much-branched, the upper branches decumbent, flexuous on young plants. Stems moderate to densely pubescent with simple uniseriate 2-3(4)-celled trichomes up to 2.8 mm long, these appressed, arcuate, or erect along stems, or sometimes geniculate and antrorse. Bark of older stems turning brownish-green, glabrescent, not exfoliating, normally matte brown on new growth. Sympodial units 3-plurifoliate, mostly geminate, when so markedly anisophyllous, differing in shape and size, with the smaller leaves highly reduced. Leaves simple, the major ones 2-11.5 × 0.9-3 cm, lanceolate to narrowly-elliptic, chartaceous, slightly discolorous, drying light green beneath, dark green above, not shiny, moderate to densely pubescent in both surfaces with unbranched antrorse, appressed, or erect hairs, with up to 3 cells; base attenuate to rounded, sometimes slightly asymmetric, not decurrent onto the petiole; margins entire, sometimes slightly revolute, ciliate, with the trichomes lying antrorsely parallel to the margin; apex acute to acuminate; petioles 2-13 mm long, with pubescence similar to the stems; minor ones 0.35-2.6 × 0.2-1.3 cm, broadly elliptic to circular; the base obtuse to rounded, margins like those of the major leaves; the apex rounded to acute, the petioles absent to 3 mm; venation brochidodromous; midrib and secondary veins visible to the naked eye, prominent abaxially, with only the midrib slightly prominent to impressed adaxially. Inflorescences pedunculate, terminal, lateral or sub-opposite the leaves, unbranched cymes with 3-7 flowers, the axis with pubescence like that of the stems; peduncle 2.2-10 mm long; pedicels 2-8 mm in the flower, 6-14 mm in fruit, articulated at base, spaced up to 8 mm apart. Calyx up to 3 mm long, the lobes 1-2 mm long in flower and fruit, about 1 mm wide, the lobes ovate-deltate, with an acuminate apex, abaxially moderately to densely pubescent with antrorse trichomes like those of the stem abaxially, adaxially densely pubescent with capitate glandular trichomes less than 1 mm long, with single-celled stalks and a multicellular head; calyx not accrescent in fruit. Corolla 6-10 mm in diameter, white, stellate, membranaceous, the lobes 3-5 × 2-3 mm, ovate-lanceolate, glabrous abaxially and adaxially. Stamens 2-3 mm long, equal in length, the filaments ca. 1 mm long; anthers 1-2 mm long, ca. 1 mm wide, oblong-ellipsoid, slightly connivent, yellow, the base cordate, the apex emarginate and poricidal, the subapical pores directed introrsely, not opening into longitudinal slits. Ovary glabrous; style white, 4-6 mm long, exserted beyond stamens, straight, cylindrical, glabrous, the stigma light green, capitate. Fruit a globose berry 4-7.8 mm in diameter, slightly translucent green to dull green when ripe, drying dark, glabrous. Seeds 2-4 per berry, 2-4.5 × 2-3.3 mm, flattened, ovate-reniform, with a small hollow at hilum region; the seed surface undulate; margins flattened.

Distribution.

Restricted to the Brazilian states of Minas Gerais, Rio de Janeiro and São Paulo ( Fig. 3 ). The known specimens are mainly from the Mantiqueira mountain range in the border area between those states, with one disjunct collection from Serra do Mar, in the Bocaina region of northeastern São Paulo State.

Ecology.

Occasional in the understory or shaded forest edges of well-preserved or secondary fragments of the Brazilian Atlantic coastal rainforest (Floresta Ombrófila Densa of Veloso et al. 1991), normally close to water courses, in elevations ranging from 1,000 to 2,000 m. In cultivation in Belo Horizonte, Solanum bradei flowered year round. Preliminary crossing studies suggested it was self-incompatible as no fruits were produced in selfed plants, but more individuals should be used for a definitive conclusion.

Phenology.

Solanum bradei seems to produce flowers year round but a flowering peak is observed in the rainy season, as most of the collections are from between the months of October and March. None of the examined collections are from December or January. Most of the specimens flowering in October and November and fruiting from February through May. The only well developed fruit was found in a collection from May.

Etymology.

The epithet honors the German botanist Alexander C. Brade [1881-1971] who greatly contributed to the growth of botany in Brazil in the middle 1900s. His efforts to better understand the flora of Itatiaia led to the earliest known collections of Solanum bradei .

Preliminary conservation status

(IUCN, 2013). Endangered (EN) B1; B2 ab (ii,iii,iv). The EOO and AOO calculated were 4,076.04 km2 and 48 km2 respectively resulting in the assessment of the Endangered category. The species is known from eight localities only, most of which are subject to urban expansion and deforestation due to tourism and agriculture. Although the species is known to occur in three protected areas [ Área de Preservação Ambiental Serra da Mantiqueira (APA Mantiqueira), Parque Estadual de Campos do Jordão and Parque Nacional de Itatiaia] we suggest to maintain it as Endangered due to: the effectiveness of APAs in protecting the species is doubtful, the Parque Estadual de Campos do Jordão have considerable areas with exotic species, and both it and Parque Nacional do Itatiaia have considerable areas with habitats not suitable to Solanum bradei (such as outcrops and highland grassfields). Although Solanum bradei is known to grow on secondary fragments and in a wide elevation range, threats to it are clear, considering that the southern Mantiqueira range, where most collections are from, is situated between the two main urban centers in Brazil and has become a tourism hub. In addition, over the past few decades the montane forests and the highland fields of Mantiqueira have been increasingly converted to pastures, monocultures or urban centers.

Discussion.

Solanum bradei is the most widely distributed and morphologically variable species of the Solanum inornatum species group. It is the only species of the group not necessarily associated with well-preserved sites, although always found in shaded environments, and is also the one that has the broadest elevational range. Despite the usual shrubby, robust habit of the species, specimens as small as 20-25 cm tall were found flowering, these mainly from the municipalities of Camanducaia and Gonçalves, in southern Minas Gerais State. The species has distinctive geminate sympodia, with leaves differing in shape and size to a degree not observed in any other species of the group. Although this character was observed in all specimens in the field, some branches preserved on herbarium sheets do not retain well-developed minor leaves. Due to this, anisophylly was not used as a diagnostic character to separate the species, but it is certainly a useful character in the field.

Some plants seem to develop diseased flowers, possibly the result of fungal or viral infection, as has been previously reported in other species of Solanum (see Hernández and Hennen 2003). In these cases an unusual form of calyx growth is observed where the expanded calyx covers the entire flower, making it resemble a fruit. This has resulted in misleading annotations on some labels [e.g. Polisel et al. 228 (SPSF) has "Fruto imaturo verde" written on the label but the specimen is actually flowering]. When dissected, the diseased flowers show an opened and lobed corolla, retained in the expanded calyx, and purplish blue anthers (in dried material) that produce less pollen than normal. These putatively infertile flowers are more common in young plants from disturbed areas.

Solanum bradei can be easily distinguished from Solanum inornatum by its tiny deltate calyx lobes (1-2 mm long) that are not accrescent in fruit and its long-pedunculate inflorescence (peduncles up to 1 cm). Solanum inornatum has linear, 3-5 mm long calyx lobes and inflorescences with peduncles 1-4 mm long. The characters that separate it from the other species described in this paper are discussed further below, on each species discussion.

In the past, sheets of Solanum bradei have been determined as Solanum apiahyense Witasek by various Solanum taxonomists, another poorly known species of uncertain affinities from secondary formations in São Paulo, Paraná and Santa Catarina states. More recently, Solanum apiahyense was found to be closely related to Solanum trachytrichium Bitter, a species previously assigned to the Geminata clade ( Knapp 2002b, L.L. Giacomin in prep.). Among species that could be confused with members of Solanum inornatum group and that are not considered part of the Brevantherum clade, these two ( Solanum apiahyense and Solanum trachytrichium ) are the only ones that we judge should be mentioned here. They can be distinguished from all species of the Solanum inornatum group by having inflorescences with fruiting peduncle longer than 1 cm and pedicels apically expanded with a constriction at the receptacle. The pubescence of the species are also distinctive: while Solanum apiahyense has very long, multicellular (up to 7 cells) unbranched trichomes, Solanum trachytrichium has unicellular trichomes that are hooked on a mound-like base, giving the leaves an scabrous aspect, rough to the touch ( Knapp 2002b).

Specimens examined.

BRAZIL. Minas Gerais: Mun. Camanducaia. Próximo a Gonçalves, Na mata do Sr. Altair, 1900 m, 23 Oct 2001 (fl), J.R. Stehmann & I.B. Castro 3022 (BHCB, RB); Mun. Camanducaia. Divisa com Gonçalves, Próximo a Pedra de São Domingos, 1727 m, 22°42'27.1"S, 45°56'1.39"W, 12 Mar 2003 (fl, fr), J.R. Stehmann & G.S. França 3415 (BHCB); same locality, 12 Mar 2003 (fl, fr), J.R. Stehmann & G.S. França 3416 (BHCB); same locality 12 Mar 2003 (fl, fr), J.R. Stehmann & G.S. França 3417 (BHCB). Mun. Delfim Moreira. Margens da estrada que liga Delfim Moreira a Campos do Jordão, 1781 m, 22°34'40.84"S, 45°15'49.07"W, 1 Nov 2008 (fl), L.L. Giacomin et al. 319 (BHCB); same locality, 1673 m, 22°35'40.93"S, 45°19'19.81"W, 1 Nov 2008 (fl), L.L. Giacomin et al. 346 (BHCB); Fazenda da Onça ( área mantida pelo Exército Brasileiro), próximo ao pórtico de entrada da fazenda, 1674 m, 22°36'41"S, 45°20'56"W, 15 Mar 2011 (fl), L.L. Giacomin et al. 1372 (BHCB). Mun. Gonçalves. Às margens da estrada de terra que liga Gonçalves a BR-381, Próximo a mata do Altair, 1786 m, 22°42'15.33"S, 45°56'20.16"W, 13 Jul 2008 (bs), L.L. Giacomin & J.R. Stehmann 180 (BHCB); same locality, 1786 m, 22°42'13,57"S, 45°56'18,59"W, 28 Oct 2008 (fl), L.L. Giacomin et al. 257 (BHCB). Mun. Itamonte. [close to] Parque Nacional de Itatiaia, Outskirts of park on road toward Agulhas Negras, 1728 m, 22°22'25", 44°45'17", 6 May 2011 (fr), M.F. Agra et al. 7398 (BHCB, JPB); Margens da BR-354, 1558 m, 22°22'25", 44°45'17" 22°21'47.10"S, 44°46'23.05"W, 12 Jul 2008 (fl), L.L. Giacomin & J.R. Stehmann 171 (BHCB); same locality, 1558 m, 22°21'45.17"S, 44°46'21.52"W, 5 Nov 2008 (fl), L.L. Giacomin et al. 372 (BHCB); Margens da rodovia não pavimentada que leva para o Pico das Agulhas Negras e parte alta do Parque Nacional do Itatiaia (BR-485); ca. 1 km após a entrada, 1711 m, 22°22'24"S, 44°45'19"W, 20 Nov 2013 (fl), L.L. Giacomin et al. 2028 (BHCB, BM, UT); Estrada para Rio de Janeiro, 1576 m, 22°21'49.13"S, 44°46'26.67"W, 22 Nov 2006 (fl, fr), J.R. Stehmann et al. 4503 (BHCB; ESA). Mun. Passa Quatro. Serra da Mantiqueira, Fazenda São Bento, 1700 m, Nov 1948 (bs, fr), J. Vidal s.n. (R 209896). Rio de Janeiro: Mun. Itatiaia. Maromba, Arbusto nas pedras, 3 Feb 1945 (fl), A.C. Brade 17391 (BHCB, RB); Caminho Rio Bonito, 2 Feb 1948 (fl, fr), A.C. Brade 18802 (RB); Parque Nacional do Itatiaia, Trilha do Hotel Simon para o Três Picos, 1500 m, 22°15'S, 44°34'W, 23 Nov 1994 (fl), J.M.A. Braga 1629 (RB); Parque Nacional do Itatiaia, próximo a cachoeira da Maromba, 1186 m, 22°26'10.43"S, 44°37'29.14"W, 3 Nov 2008 (fl, fr), L.L. Giacomin et al. 357 (BHCB); Parque Nacional do Itatiaia, Trilha do Hotel Simon para o Três Picos, 1087 m, 22°26'7.5"S, 44°36'38.14"W, 3 Nov 2008 (fl), L.L. Giacomin et al. 361 (BHCB); Parque Nacional do Itatiaia, Trilha do Véu da Noiva, 1163 m, 22°26'4"S, 44°37'24"W, 16 Oct 2009 (fl), E.K.O. Hattori et al. 914 (BHCB); Parque Nacional do Itatiaia, Trilha para o Rebouças, 16 Oct 2009 (fl), E.K.O. Hattori et al. 927 (BHCB). São Paulo: Mun. Bananal. Serra da Bocaina, Sertão do Rio Vermelho, 1200 m, 6 Oct 1949 (fl), A.C. Brade & A.Duarte 20106 (RB). Mun. Campos do Jordão. Parque Estadual de Campos do Jordão, Trilha da cachoeira, 22°41'30"S, 45°27'52"W, 27 Apr 2007 (bs, fl), R.T. Polisel et al. 228 (SPSF).

Figures

Figure 1. Solanum bradei Giacomin & Stehmann. A Habit B Inflorescence detail, showing the long peduncle C Corolla cross section showing stamens D Fruit, note the small, deltate calyx lobes. All from Giacomin et al. 359 (BHCB). Scale bars A = 5 cm; B and D = 5 mm; C = 2 mm. Drawings by B. Raddichi.

Figure 2. Photographs of the species in the field. A-B Solanum bradei Giacomin & Stehmann A Shoot showing the anisophyllous sympodia and lateral emergence of the inflorescence [from Hattori et al. 914 (BHCB)] B Translucent fruit [from Agra et al. 7398 (BHCB, JPB)] C Inflorescence of Solanum friburgense Giacomin & Stehmann in cultivation showing its hispid indumentum [from Giacomin 940 (BHCB)] D Inflorescence of Solanum kriegeri Giacomin & Stehmann [from Giacomin et al. 770 (BHCB); photo by F. D. Gontijo]. Scale bars A = 2 cm; B-D = 1 cm.

Figure 3. Known distribution of Solanum bradei Giacomin & Stehmann (circles), Solanum friburgense Giacomin & Stehmann (stars) and Solanum kriegeri Giacomin & Stehmann (triangles) in the states of Minas Gerais (MG), Rio de Janeiro (RJ) and Sao Paulo (SP) in southeastern Brazil.