Pseudocoptosperma menabense Capuron ex 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

Pseudocoptosperma menabense Capuron ex De Block sp. nov. Figs 10 , 13 A-C, J

Diagnosis.

Differing from Coptosperma mitochondrioides Mouly & De Block by the triangular, keeled stipules with a robust awn (vs. stipules of the "bec du canard" type with rounded tip) and the smooth fruits (vs. fruits with ca. 10 longitudinal ribs).

Type.

MADAGASCAR. Mahajanga Province, forêt Tsimembo, dans la concession Barthe , 19 Dec 1953 (fl.), Martin 8252-SF (holotype: P!; isotypes: BR!, TEF!) .

Shrub or small tree to 8 m tall, dbh to 10 cm; young shoots bisulcate, dark brown, densely covered with short erect hairs; older branches pale brown or fawn, glabrescent, in dried condition strongly contrasting with the blackish-brown stipules and dark brown petioles. Leaves 5-12 × 1-2.5 cm, narrowly elliptic or narrowly obovate; blades coriaceous, drying glossy and brown or more rarely greenish above, somewhat paler and dull below, glabrous on both surfaces; base cuneate to attenuate; apex acuminate, acumen 5-12 mm long; midrib raised and secondary and tertiary nerves somewhat raised on the lower leaf surface; midrib impressed on the upper leaf surface; 10-16 secondary nerves on each side of the midrib. Petioles 2-6 mm long, glabrous. Stipules drying blackish-brown, rapidly becoming corky, caducous, triangular with the robust awn as long as or longer than the basal sheath, glabrous outside, glabrous but with 2-3 basal rows of colleters inside; sheaths 1-2.5 mm long; awns 2-4 mm long. Inflorescences consisting of numerous flowers, 1-3.5 × 2-7 cm, sessile; inflorescence axes, pedicels, bracts and bracteoles densely covered with short erect hairs, green but drying dark brown; bracts with stipular parts reduced and foliar parts triangular and vaulted, 1-2 mm long, densely covered with appressed hairs and with a basal row of colleters inside, margins ciliate; central first order bracts often with stipular parts reduced and foliar parts leaf-like, 0.5-4 × (0.2-) 0.4-0.9 cm, elliptic or narrowly elliptic, base attenuate or cuneate, petiole 1-2 mm long; bracteoles at the base of the ovary, broadly triangular, 0.4-0.7 mm long, tips rounded to obtuse, with appressed hairs mostly in the upper half and a single colleter at each side of the base inside; first order axes 0.5-2.5 cm long. Flowers sessile or shortly pedicellate, pedicels 0-1 mm long with central flowers mostly sessile. Calyx green, glabrous outside; tube ca. 0.25 mm long, glabrous and without colleters inside; lobes ovate, 0.2-0.3 mm long, bases not overlapping but closely joining, tips rounded to obtuse, rarely acute. Corolla tube 1.5-2.5 mm long, ca. 0.4 mm in diameter at the base, ca. 1 mm in diameter at the throat, glabrous outside, throat and upper third to half moderately to densely covered with erect hairs inside; lobes oblong, 2-2.5 × 0.75-1 mm, glabrous on both surfaces, tip blunt and emarginate. Stamens completely exserted at anthesis; filaments <0.5 mm long; anthers 1.3-1.5 mm long. Ovary 0.5-1 mm long, green, glabrous. Style and stigma white, exserted from the corolla tube for 2-5 mm at anthesis; style densely covered with spreading, upwardly directed hairs in upper half; stigma with upper 1.5-2 mm fusiform, longitudinal papillate lines running down for a further 1-1.5 mm. Fruits spherical, 3-3.5 mm in diameter (persistent calyx not included), glabrous, drying dark brown, somewhat glossy and wrinkled when ripe; seeds ca. 2.5 mm in diameter, dark brown.

Habitat.

Dry deciduous forest, on sand (white sand and laterite); alt. 0-800 m.

Distribution.

Occurring in western Madagascar from 23° to 15° 30'S; recorded in the Atsimo-Andrefana, Menabe, Melaky and Sofia Regions. Fig. 14D .

Phenology.

Flowering: December-January; Fruiting: January-March.

Vernacular names.

Kerehetika (Martin 8252-SF); masonjohany (dialect Sakalava; Rabarivola 19861-SF); taolakena (dialect Sakalava; Ravelosaona 6592-SF); vahona (Harmelin 10202-RN bis).

Vernacular uses.

Wood used by Sakalava against headaches (Razafimandimbison & Bremer 487).

Critical notes.

Pseudocoptosperma menabense strongly resembles a Coptosperma species. Like Coptosperma , it has coriaceous, glabrous leaves and terminal, sessile, compact inflorescences with pentamerous white flowers with small-sized corolla tubes, bracteoles, ovaries, calyx tubes and calyx lobes. Furthermore, the fruits have a single ruminate seed. However, P. menabense is unique within the group of species currently brought together under the name Coptosperma by the combination of the keeled triangular stipules with well-developed awn and the placentation (3 ovules pendulous from a small placenta attached to the upper half of the septum). Some Coptosperma species also have three pendulous ovules but their stipules are of a different type, notably, the "bec du canard" type ( Capuron 1973). In this case the stipular sheaths are flat with a rounded or obtuse apex, i.e. they are pressed against each other in such a way that their margins meet without overlapping ( De Block et al. 2001: fig. 1), whereas the stipules in P. menabense are folded around each other (visible only in the youngest stipule pair). Species without the "bec du canard" stipule type usually have ovules (1 to 3) impressed in a large placenta. - Some specimens in the herbarium TEF bear the name Enterospermum menabense Capuron, but the species was hitherto not formally described.

Preliminary IUCN assessment.

Vulnerable: VU B1ab(i,ii,iii,iv) + 2ab(i,ii,iii,iv). The extent of occurrence (EOO) of Pseudocoptosperma menabense , estimated to be 86,558 km2, exceeds the limits for the Vulnerable status under sub-criterion B1 but its area of occupancy (AOO), estimated to be 117 km2, falls within the limits for the Endangered category under sub-criterion B2. The species occurs in five locations, two of which are in protected areas: Zombitse-Vohibasia National Park and Kirindy Mitea National Park. The species is known from 16 collections, half of which were collected after the year 2000. The major threat for this species is habitat loss by logging for charcoal and timber, burning for grazing and slash-and-burn agriculture both inside and outside the protected areas ( Nicoll and Langrand 1989). Hence, based on the above information, the species is listed as Vulnerable.

Additional specimens examined.

MADAGASCAR. Mahajanga Province: Ménabé, forêt de Tsimembo, E d’Ambereny, Antsalova, 29-31 Mar 1966 (fr.), Capuron 24598-SF (BR, P, TEF); Antsalova , Ambereny , 11 Jan 1959 (fr.), Harmelin 10202-RN bis (BR, P, TEF); region of Port Berge , along RN 6, 242 m, 18 Mar 2010 (fr.), De Block, Groeninckx & Rakotonasolo 2354 (BR, G, K, MO, P, S, TAN); forêt Tsimembo, dans la concession Barthe, district Antsalova, 17 Mar 1961 (fr.), Rabarivola 19861-SF (P, TEF) ; Toliara Province: forêt de Jarindrano, rive gauche du haut Fiherenana, E de Maromiandry, Sakaraha , 29 Dec 1961 (fl.), Capuron 20569-SF (BR, P, TEF); forêt d’Andranomena, entre Andranomena et Marofandilia, Morondava, 19 Jan 1962 (fl.), Capuron 20895-SF (BR, P, TEF); Morondava District , forêt de Kirindi, CFPF Morondava ( forêt d’Andalandahalo), jardin botanique 2, c. 45 km NE of Morondava, 10 m, 20 Feb 2000 (fr.), Davis, Rakotonasolo & Wilkin 2564 (BR, K, TAN); Kirindi forest , N part - Conoco 7, 16 m, 19 Jan 2007 (fr.), De Block, Rakotonasolo, Groeninckx & Dessein 2187 (BR, MO, P, TAN); Morondava , Kirindi Forest , close to ecotourist camp, 73 m, 20 Jan 2007 (fr.), De Block, Rakotonasolo, Groeninckx & Dessein 2208 (BR, K, MO, P, TAN); Zombitse-Vohibasia National Park , Zombitse, 31 Jan 2007 (fr.), De Block, Rakotonasolo, Groeninckx & Dessein 2257 (BR, K, MO, P, TAN); Lamboukily, 14 km of base camp in Kirindi, 42 m, 20 Jan 2007 (fr.), Groeninckx, Rakotonasolo, Dessein & De Block 102 (BR, MO, P, TAN); Lamboukily, 14 km of base camp in Kirindi, 42 m, 20 Jan 2007 (fr.), Groeninckx, Rakotonasolo, Dessein & De Block 108 (BR, MO, P, TAN); Menabe, 55 km NE of Morondava, route 8 at CPPF, Kirindy forest , 0.25 to 0.5 km NE of principal concession road, 4.5 km E of route 8, block CN4 and CN5, 35 m, 19-20 Mar 1992 (fr.), Noyes, Harder, Rakotobe, Razafindrabeaza & Abraham 1039 (BR, K, MO, P); forêt d’Andranofotsy situé 5 km N du village du même nom, Belo, Tsirihihina , 4 Jan 1953 (fr.), Ravelosaona 6592-SF (BR, TEF); Atsimo-Andrefana, Zombitse-Vohibasia National Park , along Ritik’ala trail, 700 m from the start at the carpark, 750-800 m, 3 Dec. 2003 (fl.), Razafimandimbison & Bremer 487 (UPS) .

Figures

Figure 10. Pseudocoptosperma menabense. A fruiting branch B stipule C triad of flowers (corollas removed) D bracteole, ovary and calyx E corolla, style, stigma and anthers F placenta and ovules, abaxial view G fruit H pyrene I seed J longitudinal section through seed. A, B Groeninckx et al. 108 C-F Martin 8252 - SF G-J Rabarivola 19861 - SF.

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.