Solanum lacteum Vell., Fl. Flumin. 82. 1829 [ "1825" ].

Knapp, Sandra, Stehmann, Joao Renato & Giacomin, Leandro L., 2015, New species, additions and a key to the Brazilian species of the Geminata clade of Solanum L. (Solanaceae) in Brazil, PhytoKeys 47, pp. 1-48 : 9-13

Solanum lacteum Vell., Fl. Flumin. 82. 1829 [ "1825"]. Figures 8A, B, 9, 10

Solanum cormanthum Vell., Fl. Flumin. 86. 1829 [1825].

Solanum lacteum Type. Brazil Rio de Janeiro: "Praedii S. Crucis" (no specimens located; lectotype, designated here: Vellozo, Flora fluminensis icones 2: tab. 113. 1831).

Solanum glomuliflorum Sendtn., Fl. Bras. [Martius] 10: 24, tab 3, fig. 11-15. 1846.

Solanum lacteum Type. Brazil. Rio de Janeiro: "Serra d’Estrella” [Serra de Estrela] (fr), H.W. Schott [5412] s.n. (lectotype, designated here: F [F-874710]).

Type.

Brazil. Sin loc. [probably Rio de Janeiro] "Silvis nondum cultis ad rivulae, vel stagna crescit" (no specimens located; lectotype, designated here: Vellozo, Flora fluminensis icones 2: tab. 93. 1831; epitype, designated here: Brazil. Rio de Janeiro: Mun. Nova Friburgo, RPPN Bacchus, Macaé da Cima, near Nova Friburgo, owned by David and Isabel Miller, Trilha da Aguada, 22°23'34.4"S, 42°30'03.4"W, 1470 m, 29 Oct 2012 (fl, fr), M.F. Agra, L. Bohs & L.L. Giacomin 7298 (RB [RB00718282, accession number 551172]; duplicates in BHCB, JPB, UT).

Description.

Shrub or small treelet 1-3 m (occasionally as small as 25-30 cm or as tall as 5 m); young stems terete, glabrous; new growth glabrous or minutely papillate; bark of older stems pale brown, with prominent paler lenticels. Sympodial units difoliate, geminate or more usually not geminate; leaves of a pair usually differing in size but not in shape. Leaves simple, 9.5-25 cm long, 3.5-9 cm wide, narrowly obovate, widest in the distal half, membranous, glabrous on both surfaces, the abaxial surface paler in dry specimens; primary veins 6-10 pairs, drying dark abaxially; base attenuate; margins entire; apex bluntly acute to attenuate; petiole 1-3 cm long, glabrous; minor leaves, if present, differing only in size from the majors. Inflorescences 0.1-0.5 cm long, terminal, more or less leaf-opposed or internodal and appearing pseudoaxillary, unbranched or occasionally furcate, with 5-10 flowers, glabrous; peduncle 0.1-0.5 cm long, the flowers in an apical clump; pedicels 0.9-1.1 cm long, <0.5 mm in diameter at the base and apex, filiform, spreading at anthesis, glabrous, articulated at the base, with a constriction at the apex just below the calyx lobes, this becoming more pronounced in fruit; pedicel scars congested and overlapping at the tip of the very short inflorescence. Buds ovoid, the corolla strongly exserted form the calyx tube before anthesis. Flowers 5-merous, perfect. Calyx tube ca. 0.5 mm long, conical, the lobes 0.5-0.75 mm long, ca. 0.5 mm wide, deltate, with scarious margins and rounded tips, glabrous. Corolla 0.9-1 cm in diameter, white, stellate, lobed ca. 2/3 of the way to the base, the lobes 3-4.5 mm long, 1.5-3 mm wide, spreading or somewhat reflexed at anthesis, the tips and margins minutely papillose. Stamens 2.5-3 mm long; filament tube ca. 0.5 mm long, the free portion of the filaments <0.5 mm long, glabrous; anthers 1.5-2 mm long, ca. 1 mm wide, ellipsoid to almost globose, yellow, poricidal at the tips, the pores lengthening to longitudinal slits with age. Ovary glabrous; style ca. 4 mm long, glabrous; stigma minutely capitate, the surface papillose. Fruit a globose to somewhat ellipsoidal berry, 0.5-1 cm in diameter, greenish white, occasionally pointed at the apex, the pericarp thin, shiny, brittle when dry; calyx lobes in fruit not markedly enlarging; fruiting pedicels 1-1.3 cm long, 0.5-1 mm in diameter at the base, enlarging gradually to 1.5-2 mm in diameter at the apex, with a slight constriction just below the calyx lobes, not markedly woody, pendant; calyx lobes in fruit not markendly enlarged. Seeds 10-20 per berry, 3-4 mm long, 2-3 mm wide, somewhat flattened-reniform (perhaps immature?), dark to blackish brown, the surfaces minutely pitted, the margins paler and thickened; testal cells pentagonal in outline.

Distribution.

south-eastern Brazil in the states of Espirito Santo, Minas Gerais and Rio de Janeiro (Figure 11).

Ecology.

Solanum lacteum grows in wet Atlantic forests (Mata Atlântica, Floresta Ombrófila Densa) in forest understory of well preserved sites, from 600 to 1500 m elevation.

Phenology.

No apparent pattern in flowering or fruiting; specimens are often collected with only inflorescences, each plant is very few-flowered.

Etymology.

The species epithet was coined by Vellozo (1829) to refer to the whitish colour of the plant - "Color albescens totius plantae nomen triviale dedit" (the white color of the entire plant gives it its trivial name [epithet]). We have not observed entire plants that are white in colour, but suspect Vellozo (1829) was referring to the congested inflorescence that is completely white.

Preliminary conservation status ( IUCN 2014).

Near Threatened (NT) B1, 2 a, b(ii, iii); EOO 32,466 km2 (NT); AOO 28 km2 (EN). In spite of its large extent of occurrence, Solanum lacteum is only known from six locations and we consider it to be at risk due to the fragmentation and loss of its primary forest habitat. Populations in all three states of occurrence, however, are from within protected areas. It is possible that it is more common than it appears, considering that the flowers are so small and inconspicuous that it is easily overlooked.

Notes.

Solanum lacteum is characterized by its tiny inflorescences with tightly packed flowers and the difoliate sympodia that are usually not conspicuously geminate. The leaves are narrowly obovate and widest in the distal third. They dry a characteristic blackish brown above and paler brown beneath. The inflorescences often occur internodally and are completely white, including the peduncle and pedicels. The colour of the leaves on herbarium specimens is similar to that of Solanum caavurana and Solanum campaniforme , but those species always have leaf pubescence on the lower leaf surfaces and more elongate inflorescences. The highly congested inflorescences of Solanum lacteum are distinctive and the species is not easily confused with any other growing sympatrically. It is somewhat similar to Solanum psilophyllum , which is similarly glabrous; differences between these two species are noted in the discussion of Solanum psilophyllum .

Solanum lacteum grows in the understory of undisturbed forest and can vary from being a tiny subshrub (see Figure 8B) to a small treelet ca. 5 m tall. This variation in height is common in members of the Geminata clade and may have to do with plant age and maturity.

Vellozo’s (1831) illustration (Figure 9) is not particularly clear, but the congested inflorescences and swollen fruiting pedicels with a slight distal constriction are clearly depicted. In addition, Solanum lacteum usually has prominent lenticels on the stems; these are also depicted in Vellozo’s plate. We have selected an epitype from Rio de Janeiro State to support this suboptimal plate with material that is fertile and shows the key characters (Agra et al. 7298).

We have recognised Solanum cormanthum here as a synonym of Solanum lacteum ; after detailed study we consider the plate of Solanum cormanthum (t. 113) to represent flowering material of the same taxon as that shown in fruit in Vellozo’s plate of Solanum lacteum (t. 93). Solanum cormanthum was used by both Sendtner (1846) and more recently in the Lista de Especies de Flora do Brasil ( Stehmann et al. 2014) to refer to a different taxon we here recognise as a narrow endemic from Minas Gerais (see Solanum psilophyllum below). Both these authors expressed reservations about the correct application of this name. As is the case with the plate of Solanum lacteum , the depiction of the plant is not particularly clear, but the small flowers, small anthers and inflorescences that appear axillary (although they are not) are characteristic of Solanum lacteum . The locality cited for Solanum cormanthum ("silvis maritimis Regii Praedii S. Crucis"; Vellozo 1829: 86) is well within the geographic range and habitat of Solanum lacteum , although today it is part of the city of greater Rio de Janeiro.

Sendtner’s (1846) plate of Solanum glomuliflorum (f. 11-15) clearly shows the scarious-margined calyx with rounded lobes and very plump anthers characteristic of Solanum lacteum . In his protologue Sendtner (1846) cited two collections of Solanum glomuliflorum ; a flowering specimen of Schott from "Serra d’Estrella” (Serra de Estrela, in Rio de Janeiro State) and a fruiting specimen of Sellow’s from an unspecified locality in Brazil (F neg. 2823; presumably from Berlin]. We select here the Schott specimen at F (accession number 874710; barcode F0073278F) as the lectotype of Solanum glomuliflorum , as it bears a label with the locality and collector in J.F. MacBride’s handwriting and presumably comes from Berlin where the original is now destroyed. The collection number 5412 noted on this sheet was not mentioned by Sendtner (1846), but he rarely mentioned collection numbers in his citations.

Specimens examined.

BRAZIL. Sin. loc., Herb. Miers 2724 (BM). Espírito Santo: Mun. Cariacica, Reserva Biologica Duas Bocas, Alegre, trilha do Pau Oco, 20°17'29"S, 40°31'10"W, 600 m, 4 May 2008 (fr), A.M. Amorim et al. 7324 (BHCB); Mun. Cariacica, Reserva Biológica de Duas Bocas, localidade de Alegre, trilha do Pau-Oco, 20°17'29"S, 40°31'10"W, 600 m, 20 Jul 2008 (fr), A.M. Amorim et al. 7563 (BHCB, CEPEC, MBML, RB, UPCB); Mun. Santa Teresa, São Lourenco, Mata do Martinelli, trilha subindo o rio lado direito, 11 Apr 2000 (infl), V. Demuner et al. 885 (BHCB); Mun. Linhares, Reserva Florestal Linhares, km 0, 23 Jun 1999, D.A. Folli 3441 (BHCB); Mun. Santa Teresa, Nova Lombardia, terreno de Sr. Furlani, 19°48'14"S, 40°32'17"W, 813 m, 3 Feb 2011 (infl), L.L. Giacomin et al. 1200 (BHCB); Mun. Santa Teresa, Santo Henrique, terreno Waldecir Frey, 15 Apr 2005 (fr), L. Kollmann & A.P. Fontana 7642 (BHCB); Mun. Santa Teresa, Nova Lombardia, Reserva Biologica Augusto Ruschi, corrego entre os marcos 130 e 131, 2 Apr 2003 (fl), R.R. Vervloet & E. Bausen 2110 (BHCB). Minas Gerais: Mun. Matão, Estação Biológica de Caratinga, 23 Sep 1984 (fl, fr), P.M. Andrade & M.A. Lopes 346 (BHCB); Mun. Coronel Pacheco, Estação Experimental de Café Coronel Pacheco, 12 Aug 1941 (fl), E.P. Heringer et al. 702 (VIC); Mun. Caratinga, Fazenda Montes Claros, Estação Biológica de Caratinga, mata do Rafael, 19°43'53"S, 41°49'02"W, 5 Sep 1998 (fr), J.A. Lombardi et al. 2334 (BHCB); Mun. Caratinga, Fazenda Montes Claros, 10 Jan 1991 (st), J.R. Stehmann & C.V. Mendonça s.n. (BHCB); Mun. Tombos, Fazenda de Cachoeira, 12 Jul 1935 (fl), Mello Barreto 1577 (BHCB); Mun. Tombos, Mata do Banco, 13 Jul 2007 (fl), L. Leoni 6947 (BHCB). Rio de Janeiro: Mun. Nova Friburgo, RPPN Bacchus, Macaé da Cima, near Nova Friburgo, owned by David and Isabel Miller. Trilha da Antena, 22°22'31"S, 42°29'47"W, 1420 m, 29 Apr 2010 (fl, fr), M.F. Agra et al. 7296 (JPB, UT); Mun. Rio de Janeiro, Caminho do Macaco, 8 Aug 1878, A.F.M. Glaziou 9549 (B); Mun. Nova Friburgo, 1883, A.F.M. Glaziou 14177 (G).