Tulearia capsaintemariensis De Block, 2018

Block, Petra De, Rakotonasolo, Franck, Ntore, Salvator, Sylvain G. Razafimandimbison, & Janssens, Steven, 2018, Four new endemic genera of Rubiaceae (Pavetteae) from Madagascar represent multiple radiations into drylands, PhytoKeys 99, pp. 1-66 : 1

Tulearia capsaintemariensis De Block sp. nov. Figs 3E-K , 12 , 13D-F, K

Diagnosis.

Differing from T. splendida by the smaller leaves (5-20 × 3.5-5.5 mm vs. 10-35 × 6-15 mm in T. splendida ), the secondary nerves which are invisible on both leaf surfaces (vs. visible in T. splendida ), the uniflorous inflorescences (vs. 1-5 flowers), the shorter bracteoles (up to 3 mm vs. 8-12 mm long), the shorter calyx lobes (1-2 mm vs. 7.5-10 mm long) and the longer calyx tube (1.5-3 mm vs. ca. 1 mm long).

Type.

MADAGASCAR. Toliara Province, Fort-Dauphin , road between Faux-Cap and Marovato, 124 m, 3 Apr 2010 (fl., fr.), Groeninckx, De Block & Rakotonasolo 309 (holotype: BR!; isotypes: BR!, K!, MO!, P!, TAN!) .

Shrub, 0.5-1.5 m high; young shoots brown, densely covered with spreading hairs, rapidly becoming corky with loss of pubescence; older branches pale brown, fawnish or greyish, corky. Leaves elliptic, narrowly elliptic or rarely broadly elliptic, 5-20 × 3-5.5 mm; blades thickly coriaceous, drying brown to blackish brown and somewhat glossy above, somewhat paler below, densely covered with short erect hairs above, lanate but often with hairs more appressed on midrib below; base obtuse to rounded; apex rounded and mucronate; midrib raised in the basal half on the lower leaf surface, somewhat impressed on the upper leaf surface; secondary nerves invisible on both surfaces. Petioles 1-2 mm long, densely covered with appressed or spreading hairs. Stipules caducous, moderately to densely covered with appressed hairs outside but rapidly becoming corky and losing the pubescence; sheaths triangular, 1.5-2 mm long; tips 0.5-1.25 mm long. Inflorescences uniflorous; bracteoles opposite at the base of the ovary, trilobate or, rarely, reduced to a single lobe; if trilobate, then consisting of a ca. 0.5 mm high basal sheath, 2 linear or narrowly triangular lateral lobes, 0.5-1.5 mm long, and a central lobe, either linear and 1.5-3 mm long or more rarely leaflike (petiole to 2 mm long, blade to 6 × 2 mm, shape identical to that of vegetative leaves), bracteoles moderately covered with appressed or spreading hairs outside, lateral lobes and base of central lobe densely covered with appressed hairs and a few large colleters inside, central lobe higher up round in cross-section and pubescence on adaxial surface identical to that on abaxial surface. Flowers sessile. Calyx green, densely covered with erect or spreading hairs outside, densely covered with appressed hairs inside; tube 1.5-3 mm long, with a ring of colleters at the base inside, the colleters more densely present in the region of the sinuses of the calyx lobes; lobes (4-)5-7, ovate, 1-2 × ca. 1 mm, somewhat keeled when dry, bases not overlapping but closely joining, tips acute to rounded. Corolla sericeous outside; tube 8-10(-18*) mm long, 1.5-2 mm in diameter at the base, 3-4 mm in diameter at the throat, basal half densely covered with erect hairs inside; lobes oblong, 6-7(-12*) × 3.5-4(-5.5*) mm, glabrous inside, margins densely ciliate, tips rounded. Stamens inserted in the sinuses of the corolla lobes ca. 1.5 mm below the level of the throat, only upper half exserted from corolla tube at anthesis; filaments <1 mm long; anthers ca. 4 mm long. Ovary 1.5-2 mm long, green, densely covered with erect or spreading hairs, faintly ribbed longitudinally when dry. Placenta attached to the upper half of the septum with 5-7 ovules arranged along its periphery. Style and stigma white, 12-14(-22*) mm long, exserted from the corolla tube for 4-5 mm; style densely covered with upwardly-directed spreading hairs in the lower half; stigma fusiform, stigmatic tips free and spreading for ca. 1 mm, receptive zone 6-7(-9*) mm long, widened over the entire length. Fruits bilobed or rarely trilobed, 5-5.5(-7*) × 4.5-5(-7*) mm (persistent calyx not included), densely covered with short erect hairs; when mature, fruit and persistent calyx tube black, calyx lobes remaining green; 2(-3) pyrenes per fruit, stony, with a central vertical ridge apically on the adaxial side; 1 seed per pyrene, ca. 3.5-4 × 3 mm.

Habitat.

Open-canopy dry scrub, on calcareous soil, alt. 0-150 m.

Distribution.

Only occurring along the coast in the Androy Region in southern Madagascar. Fig. 14F .

Phenology.

Flowering & fruiting: April.

Critical note.

Measurements indicated with * in the description are from a specimen grown in greenhouse conditions.

Preliminary IUCN assesment.

Critically Endangered: CR B1ab(i, ii, iii, iv) + 2ab(i, ii, iii, iv). The extent of occurrence (EOO) of Tulearia capsaintemariensis cannot be calculated because only two specimens have ever been collected, but it can be estimated that the EOO is below 100 km2. Its area of occupancy (AOO) is 18 km2 using a cell width of 3 km but 8 km2 using a cell width of 2 km. The species was only discovered in 2010 and occurs in a single location which is not included in a protected area. The main threat to the species is habitat loss as a result of grazing, subsistence farming or land clearing for sisal plantations. Based on the above information, the species is assessed as Critically Endangered.

Additional specimens examined.

MADAGASCAR. Toliara Province: près de Cap Sainte Marie National Park, Valala , 21 m, 4 Apr 2010 (fr.), De Block, Groeninckx & Rakotonasolo 2421 (BR, G, K, MO, P, TAN) .

Figures

Figure 3. Tulearia. A-D Tulearia splendida: A habit B flowers C young inflorescence showing calyces and flower buds D young fruits E-K T. capsaintemariensis: E, F habit G branching pattern H top view of flower I lateral view of flower J ovary and calyx K fruit. Photographs: P. De Block (A, B, E, F, J), S. Dessein (C, D), M. Strack Van Schijndel (G-I), I. Van der Beeten (K).

Figure 12. Tulearia capsaintemariensis. A, habit B adaxial view of leaf C bracteole, ovary and calyx D corolla, style, stigma and anthers E young fruit F transverse section through fruit G seed, lateral view H placenta and ovules, abaxial view I placenta and ovules, adaxial view. A, B, E, F Groeninckx et al. 309 C, D, G-I De Block et al. 2421.

Figure 13. Pollen of Pseudocoptosperma and Tulearia. A-C, J Pseudocoptosperma menabense D-F, K Tulearia capsaintemariensis G-I, L, M T. splendida. A, D, G polar view B, E, H equatorial view C, F, I mesocolpium J-L ectoaperture M pollen grain wall. A-C, J Capuron 20569 - SF; D-F, K Groeninckx et al. 309 G-I, L, M Capuron 20777 - SF.

Figure 14. Distribution maps. A Exallosperma longiflora B Helictosperma malacophylla C H. poissoniana D Pseudocoptosperma menabense E Tulearia splendida F T. capsaintemariensis.