Torenia daubyi Eb.Fischer & O.Lachenaud., 2013

Fischer, Eberhard & Lachenaud, Olivier, 2013, A new species of Torenia (Linderniaceae) from Gabon, remarks on Torenia mannii Skan, and a key to the African and Madagascan Torenia species, Phytotaxa 125 (1), pp. 40-46 : 42

Torenia daubyi Eb.Fischer & O.Lachenaud. sp. nov. ( Fig. 1 )

Type:— GABON. Ngounié: Est du Parc National de la Waka, à plus ou moins 5 km au Sud de la rivière Mayi , 581 m, lat. 1.21542°S, long. 11.30553°E, ancien débardage, forêt dense de terre ferme, Dauby, Nguema, Mounoumoulossi, Bissiemou & Bissienguou GD 836, 23.2.2008 (holotype BRLU!, isotypes LBV!, MO, WAG!) .

Diagnosis: —The new species is related to Torenia silvicola A.Raynal and especially Torenia mannii Skan. It differs distinctly from T. silvicola in the acute calyx lobes, the broader calyx wings 1.5–2.5 mm wide, the pink and white corolla, and the geniculate base of the abaxial stamens with a clavate appendage 1.8–2 mm long. Torenia silvicola has obtuse calyx lobes, narrower calyx wings 1 mm wide, a white corolla, the geniculate base of the abaxial stamens forming a Z and lacking a clavate appendage. It differs from Torenia mannii in the shorter and relatively broader leaves (length:width ratio 1:1–1.12: 1), the broader calyx wings, the smaller corolla not exceeding 13 mm of length, the curved appendage of the abaxial filaments that narrows at apex, and the equal thecae of the anthers. The leaves in T. mannii are ovate-lanceolate, the calyx wings are narrower (<0.7 mm broad), the corolla is 17–21 mm long, the appendages are straight to only slightly curved and widest at apex, and the thecae of the abaxial anthers are slightly unequal.

Perennial herbs. Stems creeping to ascendent or procumbent, quadrangular, 20–28 (30) cm long, glabrous. Leaves opposite, long petiolate, petiole 7–15 mm long, lamina broadly ovate, obtuse to subacute, 20–28 × 20– 25 mm, margin dentate, with 7–8 teeth, papyraceous, upper and lower face concolorous. Bracts leaf-like, each node usually with one fertile bract. Flowers pedicellate, pedicel up to 15 mm long, elongating in fruit to 25 mm. Bracteoles minute, at base of pedicel, linear-filiform, 1.2 × 0.3 mm. Calyx bilabiate, broadly winged on mid-veins of lobes, wings 1.5–2.5 mm wide, tube 7–8 mm long, lobes 3–4 mm long, acute, glabrous. Corolla c. 13 mm long, pink and white, tube pink, upper lip pink and white, lower lip 8–9 mm long, upper lip emarginate at apex, 3 (–4) × 3–3.5 mm, lower lip 3-lobed, up to 5 mm long, lobes 3 × 2–2.5 mm, with an area of papillae present on palate of lower lip near throat. Stamens 4, didynamous; abaxial pair 4–5 mm long, filaments curved, base with a clavate appendage 1.8–2 mm long, covered with glandular hairs and papillae; adaxial pair 2 mm long, filaments straight; anthers with equal thecae, 1.5–1.8 mm long. Ovary 2 mm long, style 7 mm long, stigma bilobed. Fruit unknown.

Distribution:—Only known from the type gathering from the northern edge of the Chaillu massif, in south-central Gabon.

Ecology:—The type was collected on a former skidding trail in high forest on firm ground, 581 m in altitude.

Conservation status:—Data deficient (DD). We do not know enough about the natural populations to be able to assess the conservation status of the species, However, the species is only known from the type gathering at an unprotected locality.

Figures

FIGURE 1. Torenia daubyi. A, B, detail of habit; C, leaf; D, leaf with axillary postfloral flower; E, calyx; F, detail of flower, showing corolla and part of calyx; G, corolla expanded showing stamens; H, I, abaxial stamens;; K, adaxial stamen. All from Dauby et al. GD 836. Drawing by E. Fischer.