Sinningia sulphurea Chautems & D.B.O.S. Cardoso

Chautems, Alain, Cardoso, Domingos B. O. S. & Perret, Mathieu, 2022, Two new species of Sinningia (Gesneriaceae) endemic to Bahia, Brazil, Candollea 77 (2), pp. 137-144 : 140-143

Sinningia sulphurea Chautems & D.B.O.S. Cardoso , sp. nov. ( Fig. 4 ).

Holotypus: BRAZIL. Bahia: Itaberaba , ARIE da Serra do Orobó , Fazenda Leão dos Brejos, 12°51'01"S 40°30'59"W, 398 m, 15. VII . 2006, Queiroz, Cardoso & Messias 12277 (HUEFS-110686!; iso-: G [ G00412505 ]!) .

Sinningia sulphurea is morphologically related to S. barbata (Nees & Mart.) G. Nicholson , but differs by having numerous underground round tubers around 5 mm diam. (vs. a single tuberous base measuring 2–3 cm diam.), stem 15–32 cm tall (vs. 30–70 cm tall), crenate leaf margin (vs. serrate), pubescent calyx lobes (vs. gabrous), and yellow, tubular-campanulate corolla(vs. white, greenish or yellowish, tubular and strongly ventricose corolla).

Herb 15–32 cm tall, usually terrestrial, underground storage system with numerous round tubers, c. 5 mm diam.; stem semi-prostrate or erect, usually unbranched, greenish, densely pubescent, internodes 3–6 cm long. Leaves 3–7 pairs, decussate, isophyllous; petiole 2.5–5 cm long, green on both sides, with eglandular trichomes; lamina elliptic, base attenuate, apex obtuse, margin crenate, adaxially puberulous, abaxially shortly pubescent, 6–8 pairs of veins. Inflorescence frondose, composed of cymes composed of 1–3 flowers in the axils of the 1–4 upper leaf pairs. Flowers subtended on erect pedicels, 2.2–3 cm long, green, pubescent. Calyx campanulate, shortly fused at base, lobes 2.2–2.7 × 0.9–1.1 cm, broadly ovate, broadly cordate at base and winged at their junction, acuminate at apex, green, pubescent adaxially. Corolla obliquely inserted in the calyx, tubular-campanulate, ventricose, 3.5–4.9 cm long, outside yellow and pubescent, reddish trichomes toward the base of the tube, dorsally forming 2 longitudinal grooves, throat yellow with fine vinaceous streaks ventrally, lobes plain yellow, ventral one with diffuse vinaceous streaks at base. Stamens 4, included, filaments 2.2–2.8 cm long, anthers coherent by their apex and side, forming a rectangle, pollen white, nectary formed by 2 dorsal separate glands, c. 1.5 mm long. Gynoecium with a conical, densely pubescent ovary, style 2.6–2.8 cm long, puberulous, stigma stomatomorphic. Fruit a dry capsule, 1.3–1.6 cm long, greenish outside, dehiscent, the two valves opening 180° at maturity, cream inside; seeds spheroid-fusiform, c. 0.4 mm long, brown.

Etymology. – The name refers to the pale-yellow color of the corollas, an uncommon trait in the genus Sinningia .

Distribution and ecology. – Sinningia sulphurea is known only from a single location in the Serra do Orobó in the municipality of Itaberaba ( Fig. 2 ). This mountain is considered as a side elevation somewhat isolated from the large range of Chapada Diamantina located to the west (CARDOSO & HARLEY, 2015). It culminates at 1,014 m. The Serra do Orobó mountain range lies within the Caatinga domain. Several vegetation types are found according to altitudinal gradients, with shrubby caatinga with palm trees commonly occuring at lower altitude, dry forest fragments dominating between 400 and 700 m, followed by submontane humid forest between 700 and 850 m and savanna-like vegatation or campo rupestre surrounding the mountain peak (CARDOSO & QUEIROZ, 2008). Sinningia sulphurea grows on the ground of forest fragments with trees up to 20 m tall. Populations of a few dozen individuals were observed growing among small rocks mixed with plant litter. The vegetation of the area was described as Seasonally Dry Tropical Forest by CARDOSO & QUEIROZ (2008).

Phenology. – Flowering specimens were collected in June and July.

Notes. – Habit and floral morphology of Sinningia sulphurea are quite similar to S. barbata (Nees & Mart.) G. Nicholson. However , S. sulphurea differs in having underground storage system composed of numerous tiny spherical tubers ( Fig. 4 ), a shorter habit, a denser indumentum on stem, leaves and calyx, and pale-yellow corollas that are not strongly ventricose and narrowed just below the lobes. Phylogenetic results based on the analyses of four DNA regions support a sister-group relationship between S. sulphurea and S. barbata (SERRANOSERRANO et al., 2017: fig. S4). Sinningia sulphurea is restricted to the Serra do Orobó area, whereas S. barbata has a much wider distribution between the states of Espírito Santo and Pernambuco in the humid forest that are part of the Mata Atlântica domain ( Fig. 2 ). In the Serra do Orobó, S. sulphurea is distributed in dry forest around 400 m, whereas S. barbata is registered in submontane humid forest above elevations of 700 m. The Serra do Orobó lies within the drier vegetation type belonging to the Caatinga domain where several endemics have recently been described (CARDOSO & HARLEY, 2015), but its summit is characterized by higher precipitation that facilitates the existence of a more humid forest (CARDOSO & QUEIROZ, 2008). The speciation event between S. sulphurea and S. barbata may have been favored by these contrasting climatic conditions.

Yellow colored corollas are found in a few other Sinningia species that do not occur in Bahia state and they differ by their rosette habit ( S. richii Clayberg ), the long pedicellate flowers ( S. conspicua (Seem.) G. Nicholson ) or the spicate inflorescence ( S. lutea Buzatto & R.B. Singer , currently treated as a form of S. allagophylla (Mart.) Wiehler ).

Additional specimen examined. – BRAZIL. Bahia: Município Itaberaba, ARIE da Serra do Orobó, Fazenda Leão dos Brejos, 12°51'01"S 40°30' 59"W, 398 m, 16.VI.2007, Cardoso et al. 2066 ( G, HUEFS) .

Figures

Fig. 4. – Sinningia. sulphurea Chautems & D.B.O.S. Cardoso. A. Habit in the wild; B. Flower close-up; C. Underground storage system with numerous round tubers; D. Holotype at HUEFS.

Fig.2.– Distribution of Sinningia ganevii Chautems & Mat. Perret (black triangle) and S. sulphurea Chautems & D.B.O.S. Cardoso (black square), including their related species S. harleyi Wiehler & Chautems (white triangle) and S. barbata (Nees & Mart.) G. Nicholson (white square).