Danais randrianaivoi 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 : 177-178

6. Danais randrianaivoi C. M. Taylor , spec. nova

( Fig. 6 A-C).

Typus: MADAGASCAR. Prov. Toamasina: Analanjirofo Region, Tampolo (Masoala), Ambanizana, Anjahana, Maroantsetra , 15°44’12”S 49°57’24”E, 200-400 m, 12.X. 2001, fl., Randrianaivo 664 (holo-: MO-6055804 ! iso-: G [ G00369980 ]) .

Haec species acongenerisfoliisgrandibus lateellipticis, stipulis bilobis, lobis calycinis linearibus 1.5-4 mm longis atque corolla satis longa distinguitur.

Woody lianas, climbing to 3 m high; stems glabrous, subterete, with internodes sometimes prolonged. Leaves opposite; blades elliptic to broadly elliptic or obovate, 9-18.5 × 4.4-13.5 cm, at base obtuse to rounded or truncate, at apex acute or rounded and rather abruptly acuminate with tips 2- 20 mm, drying papery to chartaceous, on both surfaces glabrous and rather shiny, with margins plane to thinly revolute; secondary veins 6 to 8 pairs, free, reticulating, or sometimes looping to interconnect with each other in distal part of blade, adaxially costa prominent and secondary veins and rather densely reticulated tertiary and quaternary venation prominulous, abaxially costa prominent, secondary veins prominulous, and tertiary and quaternary venation plane to prominulous. Petioles 12-35 mm, glabrous. Stipules interpetiolar or shortly united around stem, deciduous after distalmost 1 to 3 nodes, ovate to broadly rounded, 4-6 mm, abaxially glabrous, shortly 2-dentate to 2-lobed for up to 1/2 of length, lobes narrowly to broadly triangular, acute to obtuse. Inflorescences pseudoaxillary (i.e., borne in only 1 axil of a node), produced below stem apex, cymose, rounded to broadly pyramidal in outline, 6-10 × 4-6 cm (including peduncles but not corollas), several- (ca. 15) to multi-flowered (ca. 40), branched to 1 to 2 orders, with axes cymose, densely puberulous to glabrous; bracts narrowly triangular to linear, 1-3 mm. Flowers in umbelliform to weakly dichotomous cymes of 3 to 7 and all pedicellate on pedicels 0.5- 8 mm, distylous, fragrant; hypanthium ellipsoid to obovoid, 1-2 mm, densely puberulous to glabrous. Calyx limb divided nearly to base, densely puberulous to glabrous, lobes 5, narrowly triangular to linear, 1-2.5 mm and generally equal in length on an individual flower, acute. Corolla salverform, white to yellow, externally glabrous, internally glabrous except pilosulous in throat, tube 14-16 mm, 0.5-1 mm diam. at base, 0.8-1.2 mm diam. at top, at base fenestrate with 5 slits, each slit ca. 1 mm, lobes 5, narrowly triangular to narrowly ligulate, 7-7.5 mm, acute and smooth at apex. Stamens 5, inserted in corolla throat, anthers with color not noted, in long-styled flowers ca. 1.8 mm, partially exserted, and subsessile, in short-styled flowers ca. 2 mm and exserted on filaments 3-4 mm. Stigmas 2, in long-styled flowers ca. 4.5 mm and exserted, with style ca. 16 mm, in short-styled flowers ca. 4 mm and included except tips exserted, with style ca. 10 mm. Capsules oblate, 4-5 × 5-7 mm, subcoriaceous to woody, glabrous, dehiscent for apical 1/3-1/2 of body, beak portion flat. Seeds irregular in shape but generally triangular, ca. 1 mm, with circumferential wing shortly laciniate.

Names. – The scientific name created here for this species honors Mr. Richard Randrianaivo, who collected the type of this handsome species and is one of the Missouri Botanical Garden’s resident field botanists. Mr. Randrianaivo has extensively documented Madagascar’s flora with excellent specimens collected during numerous explorations made throughout the island. No vernacular name is noted in the information available.

Habitat and distribution. – Humid forests at 200-400 m in northeastern Madagascar, on the Masoala Peninsula in Toamasina Province (Analanjirofo Region) ( Fig. 4 , humid bioclimatic zone).

Conservation status. –Danaisrandrianaivoi has an EOO of 230 km 2, which meets the criterion for Endangered; an AOO of <500 km 2, which also meets the criterion for Endangered; and one subpopulation. The species is known only from three localities, one of which is inside the boundaries of a currently protected area (Masoala National Park). The habitat of this species is already significantly fragmented and expected to diminish further in quality. Given the small EOO and its few localities, D. randrianaivoi 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 and similar species. – Danais randrianaivoi is characterized by its woody rounded stems with generally elongated internodes; its relatively broad large leaves that are usually shiny on both surfaces; its bidentate stipules that are sometimes shortly united around the stem; its pseudoaxillary cymose inflorescences; its pedicellate flowers; its rather large, white to yellow corollas with very slender tubes and narrow lobes; and its oblate capsules.

The stipules of D. randrianaivoi are variably free to fused across the intrapetiolar portion, with two short, closely arranged, narrowly acute lobes on each interpetiolar side, or sometimes with two broadly triangular obtuse lobes or sometimes apparently entire. The stipules appear to widen markedly with age, as the stem thickens. PUFF & BUCHNER (1994) documented several Danais species with pseudoaxillary inflorescences that are first produced at the stem apex and then displaced or overtopped by subsequent growth from one of the axillary buds, so the flowers are borne at or near the stem apex but the infructescences are left behind as the vegetative part of the stem continues to grow. However in D. randrianaivoi the inflorescences appear to be produced initially in the pseudoaxillary position, well below the stem apex. This new species is similar to D. longipedunculata Homolle , but the latter differs by its elliptic to obovate leaves 3-7 cm wide and its shorter corollas (tubes 5.5-6 mm long and lobes 2-3 mm long).

Paratypi. – MADAGASCAR. Prov. Toamasina: Analanjirofo, Maroantsetra, Anjahana, Ambanizana , 15°42’35”S 49°58’13”E, 200 m, 20.X.2001, fl., Randrianaivo 719 ( MO!) ; Tampolo ( Masoala ), 15°37’02”S 49°58’46”E, 200 m, 13.IX. 2002, fr., Antilahimena & Aridy 1385 ( MO!).

Figures

Fig. 6. – Danais randrianaivoi C. M. Taylor. A. Flowering branch; B. Portion of inflorescence with four flowers from which the corollas have fallen; C. Corolla at anthesis, separated from rest of flower and showing the fenestrate base. – Danais rakotovaoi C. M. Taylor. D. Flowering branch; E. Flower at anthesis. [A-C: Randrianaivo 664, MO; D-E: Rakotovao & al. 3222, MO] [Drawing: C. M. Taylor]

Fig. 4. – Distribution of Danais disticha C. M. Taylor (crosses) and Danais randrianaivoi C. M. Taylor (squares), mapped over the outlines of the five simplified bioclimatic zones of Madagascar of SCHTZ (2000, following CORNET, 1974).