Danais masoalana C. M. Taylor, 2013

Taylor, Charlotte M. & Rogers, Zachary S., 2013, Six new species of Danais Vent. (Rubiaceae, Danaideae) from Madagascar, Candollea 68 (1), pp. 167-180 : 175-176

4. Danais masoalana C. M. Taylor , spec. nova

( Fig. 1 D-G).

Typus: MADAGASCAR. Prov. Toamasina: Analanjirofo Region, Masoala Peninsula , S of Ambanizana, Andranobe, Piste A, 15°41’S 49°58’E, 50 m, 12.II.1999, fl., Hoffmann, Robinson, McPherson & Harimalala 36 (holo-: MO-5938276 ! ; iso-: G [ G00369979 ], K, TAN) .

Haec species a congeneris stipulis aristatis circum caulem breviter connatis, foliis satis grandibus, inflorescentia axillari atque floribus sicut fructibus papyraceis satis parvis pedicellis gracilibus insidentibus distinguitur.

Woody lianas or climbing shrubs, climbing to 6 m high; stems glabrous, rounded or weakly laterally flattened. Leaves opposite; blades elliptic to obovate, 6.5-19 × 3-11 cm, at base cuneate to obtuse, at apex rounded to obtuse or acute and sometimes abruptly acuminate with tips 2-10 mm, drying chartaceous, glabrous on both surfaces, with margins plane; secondary veins 5 to 11 pairs, not looping to interconnect with each other, with intersecondary veins not, shortly, or occasionally well developed, adaxially costa prominulous, secondary veins plane, and laxly reticulated tertiary venation prominulous, abaxially costa and secondary veins prominent, laxly reticulated tertiary venation prominulous, and densely reticulated quaternary venation plane to thickened or prominulous. Petioles 15-28 mm, glabrous. Stipules shortly united around stem, rather quickly deciduous, triangular, 4-5 mm, abaxially puberulous to glabrous, acute to acuminate or weakly aristate, margins ciliolate to entire. Inflorescences axillary with leaves or sometimes borne in axillary arrangement at nodes below leaves, paniculiform, pyramidal in outline, 6-11 × 3-10 cm (including peduncles), multiflowered (ca. 35 to 60), branched to 2 or 3 orders, with axes cymose, puberulous to glabrous; bracts narrowly triangular to narrowly ligulate, 0.8-4 mm. Flowers in umbelliform groups of 5 to 9 and all pedicellate on pedicels 1-3 mm, with floral biology unknown; hypanthium subglobose to ellipsoid, ca. 1 mm, glabrous. Calyx limb divided nearly to base, lobes 5, triangular, 0.3- 0.8 mm, acute. Corolla slenderly salverform, pale green on tube and bright orange on lobes, externally and internally glabrous, tube ca. 6 mm, ca. 0.5 mm diam. at bottom and at top, at base fenestrate with 5 slits, each slit 0.3-0.5 mm, lobes 5, ligulate to narrowly triangular, ca. 3 mm, acute and smooth at apex. Stamens 5, inserted in corolla throat, anthers black, ca. 2 mm and exserted, filaments ca. 8 mm. Stigmas 2, linear, 3-5 mm, positioned in upper part of corolla tube with tips exserted, style ca. 4.5 mm. Capsules ellipsoid to oblate and laterally flattened, 3-4 × 3.5-5 mm, woody to stiffy chartaceous, glabrous and sparsely to moderately granular, dehiscent from apex for 1/4-1/2 of body, beak broadly triangular to rounded. Seeds generally lenticular, 0.5-0.8 mm, flattened, with circumferential wing irregular (i.e., not entire and smooth) and often reduced.

Names. – This species is so far only known from the Masoala Peninsula, and the scientific name created here for it refers to this locality. No vernacular name is noted in the information available.

Habitat and distribution. – This species is documented from humid forests at 0-400 m in eastern Madagascar, on the Masoala Peninsula in Antsiranana Province (SAVA Region) and in Toamasina Province (Analanjirofo Region; Fig. 5 , humid bioclimatic zone).

Conservation status. –Danaismasoal ana has an EOO of 159 km 2, which meets the criterion for Endangered; an AOO of <500 km 2, which also meets the criterion for Endangered; and three subpopulations. The species is known from four collections in two localities; one locality falls inside the boundaries of one protected area (Masoala National Park). The general habitat of this species is already significantly fragmented and expected to diminish further in quality. Danais masoalana is assigned a preliminary conservation status of Endangered due to its limited distribution and threatened habitat [EN B1ab(i,ii,iii,iv)+2ab(i,ii,iii,iv)].

Notes on morphology, biology and similar species. – Danais masoalana is characterized by its relatively large leaves (for Danais ) with the quaternary venation closely reticulated to form narrowly rectangular areoles on the abaxial surface; its stipules that are shortly united around the stem; its axillary multiflowered inflorescences; its mediumsized orange flowers with the anthers exserted on well developed filaments; and its relatively small fruits usually with a granular surface. Only one flowering collection has been seen, with flowers that resemble the short-styled form of distylous Danais species.

This new species is similar in general aspect to D.rhamnifolia Baker , which is found in the same region; however D. rhamnifolia differs in its usually smaller leaves, with the blades 2-11 × 1-5.5 cm and the petioles 2-17 mm long; its interpetiolar, shorter stipules, 1-2.5 mm long; its usually terminal inflorescences, although these may sometimes also be borne in the uppermost leaf axils; its smaller corollas, with the tube 2.5- 5 mm long and the lobes 1.5-2.5 mm long; and its shorter filaments, 2-4.5 mm long. Danais masolana is also similar to D. magna Puff & R. Buchner , which is also found in the same region; however D. magna differs from this new species in its smaller leaves, 7-11 × 2.5-6 cm, with the densely reticulated tertiary and quaternary venation forming subcircular areoles on the lower surface; its shorter inflorescences, 1-3 cm long, with the flowers all sessile to subsessile and without developed secondary axes; its shorter filaments, 5-6 mm long; and its woody fruits with their bases or their short stipes or pedicels (to ca. 1 mm long) significantly thickened, so the fruits sometimes appear fused together. PUFF & BUCHNER (1994) did not see the fruits of D.magna , but these have been documented by recent collections (e.g., Antilahimena & al. 1147, MO!, see image at TROPICOS, 2013) and resemble those of D. aurantiaca Homolle. Danais magna is also notable for its habit, which was reported by PUFF & BUCHNER (1994) to be a liana climbing 18 m or more into the forest canopy; all the specimens seen of D. masoalana were gathered from much smaller plants.

Paratypi. – MADAGASCAR. Prov. Antisiranana: SAVA, Masoala Peninsula , W of Ambohitralanana, near Sahafary, 15°16’S 50°22’E, 100 m, fr., 20.VIII.1977, McPherson 17126 ( MO!) . Prov. Toamasina: Analanjirofo, S of Ambanizana, Andranobe, Piste A , 15°41’S 49°58’E, 205 m, 16.II.1999, y. fr., Hoffmann, Robinson, McPherson & Harimalala 54 ( K, MO!, TAN) ; Parc National de Masoala , Ambanizana, 15°37’S 49°58’E, 0-400 m, 2.IV.1996, y. fr., Aridy & Moïse 227 ( MO!) .

Figures

Fig. 1. – Danais antilahimenae C. M. Taylor. A. Flowering branch; B. Portion of inflorescence, with young fruits; C. Flower at anthesis. – Danais masoalana C. M. Taylor.D. Flowering branch; E. Stem node with stipule, bases of two petioles, and bases of two axillary peduncles; F. Flower at anthesis; G. Flower at anthesis, partially dissected. [A, B: Antilahimena & al. 1627, MO; C: Antilahimena 2340, MO; D-G: based on Hoffmann & al. 36, MO] [Drawing: C. M. Taylor]

Fig. 5. – Distribution of Danais laciniata C. M. Taylor (asteriks) and Danais masoalana C. M. Taylor (circles), mapped over the outlines of the five simplified bioclimatic zones of Madagascar of SCHTZ (2000, following CORNET, 1974).