Sinningia minima A.O.Araujo & Chautems, 2015

Araujo, Andréa Onofre De & Chautems, Alain, 2015, A new species of Sinningia (Gesneriaceae) and additional floristic data from Serra dos Carajás, Pará, Brazil, Phytotaxa 227 (2), pp. 158-166 : 159-164

Sinningia minima A.O.Araujo & Chautems , sp. nov. ( Figs. 1–3 )

Sinningia minima is similar to S. muscicola Chautems , differing from the latter by its very small overall size not exceeding 25 mm (vs. 40–80 mm); leaves with serrate margin (vs. deeply crenate); ventricose corolla (vs. narrowly funnel shaped), with vinaceous dots inside the tube. It is readily distinguished from all other species of Sinningia by its androecium reduced to two fertile stamens (vs. four).

Type:— BRAZIL. Pará: Parauapebas, Serra dos Carajás, Serra N 1, cerca de 1 km da estrada, na corredeira do riacho, próximo à cachoeira, 06°02’22.97”S, 50°17’25.94”W, 668 m, 09 February 2014, Araujo & Almeida 1146 (holotype HUFABC!, isotypes G!, BHCB!, MG!, RB!).

Herb, 9.5–25.0 mm in height, arising from perennial globose tuber, ca. 5.6 × 2.9 mm in diam., saxicolous. Stems 1.0– 9.9 mm tall, unbranched, internodes 0.3–2.6 mm, with 2 or 3 leaf pairs. Leaves opposite, petiole 0.8–4.2 mm, green or violet; blade ovate to ovate-elliptic, 1.3–11.3 × 1.2–7.9 mm, apex obtuse, base cordate rarely rounded, above densely sericeous, green, sometimes with broad vinaceous streaks, beneath sparsely sericeous, green, margin serrate, 2–3 pairs of veins. Inflorescence reduced to solitary flower, axillary, lacking peduncle. Flowers obliquely borne on pedicels, 6.4–12.8 mm, vinaceous, sparsely pubescent with glandular and eglandular trichomes. Calyx dialysepalous, sepals 1.3–3 × 0.4–0.7 mm, lanceolate, margin entire, vinaceous to green, densely pubescent with eglandular trichomes. Corolla ventricose, 1.1–1.4 mm in diam. at base, with a little swelling on the dorsal side, tube 1.7–5.7 mm long, lilac outside, white with vinaceous dots inside, mouth 2.6–4.9 mm in diam., white, lobes lilac towards the margin and white towards the mouth, unequal, upper two 0.8–1.8 × 1.2–1.7 mm; 2 lateral 1.4–2.2 × 1.3–2.2 mm, lower one 1.7–2.9 × 1.6–2.1 mm. Stamens 2, included, filaments 3.5–4.8 mm long, white, anthers coherent, staminodes 2, ca. 1 mm long; nectary of 5 glands (2 near each other in dorsal position, 1 ventral of the same size as the dorsal ones and 2 lateral smaller); ovary densely pubescent, stigma bilobed. Fruit a dry capsule, 3.5–5.2 × 1.0– 1.7 mm, apex turned upward; seeds ellipsoid, 0.15–0.19 × 0.28–0.33 mm.

Distribution and ecology:—The species is so far only known from the Serra dos Carajás (Pará, Brazil) where it is locally common (about 8 localities known so far; Fig. 3 ). The plants were observed growing together with mosses, liverworts and Goyazia rupicola Taubert (1896: 451) ( Fig. 1 ) on wet rocks along streams, in shade, at elevation between 500 and 750 m. These rocks have a high concentration of iron and other heavy metals. Porto & Silva (1989) showed that plants in this area can absorb high values of these metals and speculate that this factor led to the establishment of a specific metalophilous vegetation. These growing conditions likely contributed to the restricted distribution of this species. Additionally, this is the only species of Sinningia recorded so far in Pará ( Brazil) ( Araujo et al. 2015).

Phenology:—Collected in bloom and fruit in January–March.

Conservation status:—Endangered (EN) B1b(i,iii,iv)c(iii), according to the IUCN criteria, based on the extent of occurrence not exceeding 5,000 km 2, projected decline of extent, quality of habitat and number of locations or subpopulations ( IUCN 2012). This species occurs in an area that is intensely mined by Vale S.A. Company for extraction of iron, gold and others metals.

Taxonomic relationships:—Preliminary phylogenetic data place this species in clade Corytholoma along with three other micro-miniature species: Sinningia concinna ( Hooker 1861: t. 5253) Nicholson (1887: 436), S. muscicola Chautems, Lopes & Peixoto (2010: 258) and S. pusilla ( Martius 1829: 61) Baillon (1888: 772) (M. Perret, pers. comm.). Table 1 summarizes the characters that allow distinguishing these four species. S. minima is the smallest known species of Sinningia , thus far ( Fig.1 ).

Etymology:—The epithet ” minima ” refers to the minute size of this plant, it is likely the tiniest known Gesneriaceae .

Additional specimens examined (paratypes):— BRAZIL. Pará: Canaã dos Carajás , S11C, mata baixa sobre canga, 750 m, 6°22’58’’S, 50°23’6’’W; 20 March 2012, Arruda et al. 723 (BHCB). Canaã dos Carajás , S11D, Transição entre mata baixa sobre canga e floresta ombrófila densa, 635 m, 6°24’8’’S, 50°18’7’’W, 22 January 2013, Arruda et al. 1333 (BHCB). Canaã dos Carajás , S11D, Floresta ombrófila densa, 610 m, 6°23’30’’S, 50°19’6’’W, 24 January 2013, Arruda et al. 1343 (BHCB). Canaã dos Carajás , S11B, Interior de floresta, próximo de drenagem, 690 m, 6°20’40’’S, 50°24’32’’W, 24 January 2012, Paula et al. 431 (BHCB). Canaã dos Carajás , S11C, floresta ombrófila, 650 m, 6°20’54’’S, 50°25’47’’W, 13 February 2010, Silva et al. 752 (BHCB). Canaã dos Carajás , S11A, floresta ombrófila, 600 m, 6°19’27,5’’S, 50°27’8’’W, 16 February 2010, Silva et al. 770 (BHCB). Canaã dos Carajás , S11A, floresta, 613 m, 6°20’24’’S, 50°26’2’’W, 08 February 2012, Silva et al. 1202 (BHCB). Canaã dos Carajás , S11- C, floresta ombrófila, erva, 743 m, 6°24’1’’S, 50°23’18’’W, 18 March 2009, Viana et al. 4147 (BHCB, G). Marabá, Serra dos Carajás , mina de ferro N-1; 28 April 1985, Rosa & Silva 4725 (MG, RB 238023). Marabá, Serra Norte (carajás), N1, corredeira de água sobre pedras, no centro da vegetação de canga aberta, 19 March 1985, Secco et al. 510 (MG). Parauapebas, Serra dos Carajás, Serra Sul, Corpo C , floresta de galeria, nas rochas do leito do córrego, 707 m, 06°23’47.85”S, 50°23’0.17”W, 10 February 2014, Araujo & Almeida 1151 (HUFABC). Parauapebas, N1, floresta ombrófila densa associada a encosta, 550 m, 6°2’S, 50°16’1’’W, 14 February 2012, Arruda et al. 624 (BHCB). Parauapebas, N8, floresta ombrófila densa, 700 m, 6°11’11’’S, 50°7’51’’W, 17 May 2012, Arruda et al. 1130 (BHCB). Parauapebas, N4SW, mata ombrófila densa, sobre afloramento rochoso, 505 m, 6°4’22’’S, 50°11’42’’W, 24 March 2012, Mayer et al. 1200 (BHCB).

Floristic data:—In addition to Sinningia minima , described here, we identified in the studied area three other taxa which probably are new Gesneriaceae species, but more studies are needed to confirm their identities. So far, a total of twelve Gesneriaceae species have been registered in Carajás , distributed in four subtribes: 1) G. subtrib. Columneinae: Codonanthopsis crassifolia ( Focke 1852: 199) Chautems & Perret (2013: 152) , Drymonia serrulata ( Jacquin 1798: 290) Martius (1832: 192) , Episcia fimbriata Fritsch (1906: 484) , Nautilocalyx cf. kohlerioides ( Leeuwenberg 1964: 61) Wiehler (1978: 34) , Nautilocalyx cf. fasciculatus Skog & Steyermark (1991: 219) , Nautilocalyx sp. ; 2) G. subtrib. Gloxiniinae : Goyazia rupicola Taub. , Mandirola rupestris ( Gardner 1842: t. 480) Roalson & Boggan (2005: 230), Phinaea albolineata ( Hooker 1847: t. 4282) Bentham ex Hemsley (1882: 472) and Phinaea sp. ; 3) G. subtrib. Ligeriinae : Sinningia minima A.O.Araujo & Chautems ; and 4) G. subtrib. Besleriinae: Besleria cf. flavo-virens Nees & Martius (1823: 49) .

Figures

FIGURE 1. Sinningia minima. A. Wet rocks along streams, showing its saxicolous habitat. B. Habit with bud, flower and fruit. C. Individuals growing together with Goyazia rupicola. D. Individuals growing among mosses. (A–D: A.O.Araujo & Almeida 1146).

FIGURE 2. Sinningia minima. A. Habit. B. Flower, side view. C. Gynoecium, nectary and calyx. D. Nectary in detail. E. Androecium. F. Seed.

FIGURE 3. Distribution map of Sinningia minima in the Serra dos Carajás.