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| Solanum hydroides Gouvêa & Giacomin
in Gouvêa, de Paula, Stehmann & Giacomin, 2020.
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Abstract
Solanum hydroides Gouvêa & Giacomin, sp. nov., is described from central Brazilian Atlantic Forest. It is known from only three localities in Espírito Santo and Minas Gerais states, where granitic/gneissic outcrops (inselbergs or sugar loaves) are ubiquitous. The new species, here described, belongs to Solanum subgenus Leptostemonum (or the Leptostemonum clade; i.e. the spiny solanums) and is morphologically related to S. hexandrum Vell. and S. sublentum Hiern, with which it shares the shrubby habit, decurrent leaf bases and well-developed calyces that become accrescent, covering glabrous fruits. Solanum hydroides is unique in its combination of comparatively more delicate habit, indumentum of exclusively stellate eglandular trichomes, accrescent but never inflated fruiting calyces that only partially cover the fruits and comparatively shortly lobed and strictly white corollas. The species is threatened with extinction and assessed as Vulnerable (VU), based on the IUCN criteria.
Keywords: Leptostemonum clade, Brazil, inselbergs, new species, eglandular trichomes
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| Figure 1. Solanum hydroides Gouvêa & Giacomin. (A, G–I field pictures from specimens L.F.A. de Paula et al. 669, BHCB; B–E Y.F. Gouvêa & G.V.A. Santos 325, BHCB). A Habit (bottom right corner: young plant with larger leaves) B flowering branch C inflorescence and a flower in lateral view (note that calyx does not have a plicate aspect at the base of the calyx tube) D long-styled flower, front view E mature fruit (note the calyx does not completely cover the berry) F scanning electron micrograph of seed G trichomes; upper: the usual morphology of the stellate trichomes of S. hydroides adaxial leaf surface; lower: examples of stellate trichomes with reduced number of rays (note the multiseriate stalks) H stem indumentum; I adaxial leaf surface indumentum.
Scale bars: 30 cm (A); 7.5 cm (B); 1.3 cm (C–D); 1 cm (E); 0.8 mm (F–I).
Photographs: A by L.F.A de Paula B–E, G–I by Y.F. Gouvêa.
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Solanum hydroides Gouvêa & Giacomin, sp. nov.
Diagnosis: Differs from S. sublentum Hiern in its indumentum of strictly stellate eglandular trichomes and in its accrescent, but not inflated, cupuliform fruiting calyx; also differs from S. hexandrum Vell. in its more delicate habit, smaller flowers with white shallowly stellate corollas and in having accrescent, but not inflated, fruiting calyces that partially cover the mature fruits.
Distribution: Endemic to South-eastern Brazil, with records in three localities in north-eastern Minas Gerais (Mun. Teófilo Otoni) and northern (Mun. Nova Venécia) and central (Mun. Santa Teresa) Espírito Santo States (Fig. 2).
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| Figure 3. Distinctive characters of species morphologically related to Solanum hydroides Gouvêa & Giacomin. [A, C, E, G: S. hexandrum Vell. (L.L. Giacomin et al. 875, BHCB); B, D, F, H: S. sublentum Hiern. (J.R. Stehmann et al. 6372, BHCB)]. A–B Habit (note difference in robustness) C long-styled flower, front view D inflorescence and flower in back view (note the inflated and plicate aspect of the calyx tube) E inflorescence with fruits in different stages of development (note that the inflated fruiting calyx completely covers the fruit in all stages of development) F long-styled flower G fruits (note the plicate aspect of the fruiting calyx) H–I indumentum of the adaxial leaf surface.
Scale bars: 15 cm (A); 10 cm (B); 3 cm (C); 2 cm (D, G); 1.4 cm (E); 1 mm (F); 1.2 mm (H). Photographs: A, C, E by L.L. Giacomin B, D, F by J.R. Stehmann G–H by Y.F. Gouvêa.
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Ecology: Solanum hydroides inhabits the edge of seasonal semi-deciduous tropical rainforests associated with granitic or gneissic rock outcrops (inselbergs) and somewhat disturbed sites at their base, like roadsides and clearings; from 300 to 600 m elevation. It also occasionally grows in epilithic vegetation patches lying on the flatter parts of inselbergs.
Etymology: Solanum hydroides is named for the resemblance of the long-stalked stellate trichomes of its calyces to the marine serpulid worm Hydroides Gunnerus, 1768 (illustrative images can be found at the Encyclopedia of Life; e.g. https://eol.org/search?utf88=✓&q=Hydroides).
Yuri Fernandes Gouvêa, Luiza Fonseca Amorim de Paula, João Renato Stehmann and Leandro Lacerda Giacomin. 2020. Solanum hydroides (Solanaceae): A Prickly Novelty from the Land of the Sugar Loaves, central Brazilian Atlantic Forest. PhytoKeys. 139: 63-76. DOI: 10.3897/phytokeys.139.46635
Resumo: Solanum hydroides Gouvêa & Giacomin, sp. nov., é aqui descrita para região central da Floresta Atlântica brasileira. Ela é conhecida apenas para três localidades, nos estados do Espírito Santo e Minas Gerais, em uma região onde afloramentos graníticos/gnáissicos (inselbergues ou pães de açúcar) são onipresentes. A nova espécie pertence a Solanum subgen. Leptostemonum (ou Solanum clado Leptostemonum, i.e. espécies espinhentas com tricomas estrelados) e é morfologicamente semelhante a S. hexandrum Vell. e S. sublentum Hiern, com quem compartilha o hábito arbustivo, a base das lâminas foliares decurrentes e cálices bem desenvolvidos, acrescentes em seus frutos glabros. Solanum hydroides é, contudo, a única espécie que apresenta a seguinte combinação de caracteres: hábito delicado, indumento composto apenas por tricomas estrelados egandulares, cálices frutíferos acrescentes, mas nunca inflados, que cobrem parcialmente os frutos e corolas com lóbulos curtos e estritamente brancas. A espécie é considerada como ameaçada de extinção, na categoria Vulnerável (VU), segundo os critérios da IUCN.
Palavras-chave: Clado Leptostemonum, Brasil, inselbergs, espécie nova, tricomas eglandulares
