Lijndenia acuminata R.D. Stone, 2017

Stone, R. Douglas, 2017, Revised treatment of the genus Lijndenia (Melastomataceae, Olisbeoideae) in Madagascar, Candollea 72 (1), pp. 67-86 : 71-75

1. Lijndenia acuminata R.D. Stone , spec. nova ( Fig. 1 ).

Typus: MADAGASCAR. Prov . Fianarantsoa: Farafangana , Ihorombe , Morarano (Tokohandra), 23.X.1952, fl., Service Forestier 6391 (holo-: P [ P00257942 ]!; iso-: P [ P00257943 ]!, TEF!) .

Affinis L. memecyloidi R.D. Stone sed laminis foliorum anguste ellipticis (non oblanceolatis vel obovatis) ad apices distincte angusteque acuminatis (non rotundatis vel retusis vel subacuminatis), pedunculis cymarum 7-15 mm (non 1-3 mm) longis, floribus in quoque cyma numero 7-16 (non 3-5) differt.

Habit not specified, presumably a shrub or small understory tree; young branchlets terete; internodes mostly 1.7-3 cm. Leaves apparently 1-nerved (only the midnerve clearly evident, the lateral nerves intramarginal and ± obscure), subcoriaceous, finely granular in dried material, on petioles mostly 3-4 mm; blades narrowly elliptic, (5.3-)5.8-6.5 X 1.9-2.4 cm, the apex distinctly and narrowly acuminate (the acumen 5-12 mm); transverse veins invisible.

[Service Forestier 6391, P] [Drawing: S. Burrows]

Cymes umbelliform and 7-16-flowered, solitary or in fascicles of 2-3 mostly at the leafless nodes of older branchlets, sometimes also solitary or geminate in the leaf axils; peduncles 7-12(-15) mm, compressed, the apex with a pair of persistent, triangular, keeled bracts c. 2 mm, some cymes with an additional axis extending 2-4 mm above the first group of flowers; each flower subtended by a pair of persistent, concrescent bracteoles forming a cupule or involucre from which emerges the pedicel 1-3 mm. Hypantho-calyx cupulo-patellate, 1.5 X 2 mm, the margin shallowly 4-sinuate or with calyx lobes slightly triangular; petals 1.5 X 1.5 mm, unguiculate, limb ± sagittate with apex acute, margins convex and base abruptly truncate to shallowly cordate-auriculate above the claw 0.5 mm; staminal filaments c. 3 mm, anthers dolabriform, 1 X 0.5 mm, the anther sacs positioned fronto-ventrally, connective dorsally incurved by an elliptic oil-gland positioned towards the anterior end, prolonged at the posterior end into an acute beak; style filiform, 8 mm. Fruits not seen.

Etymology. – The epithet acuminata is an adjective referring to the distinctly acuminate leaf apices of this species, this being the main diagnostic feature separating it from the closely related L. memecyloides and L. densiflora .

Distribution and ecology. – Known only from the type collection made in Fianarantsoa Province, along the southeastern coast of Madagascar about 30 km south of the city of Farafangana ( Fig. 2 ). The label of the isotype sheet in TEF indicates the habitat as forest on coastal dunes.

Conservation status. – Lijndenia acuminata is known from a single location with an area of occupancy (AOO) of 4 km 2 (assuming a 4 km 2 grid cell size). The type locality is very near or adjacent to parcelle 2 of the Réserve spéciale de Manombo, but it appears the reserve boundary has been drawn in a way that excludes the area of dunes behind the immediate coast. Given the severe loss of forested habitats in the Farafangana region and the fact that L. acuminata has not been seen in more than 50 years, it is quite possible that the species is already extinct, although more exhaustive surveys would be needed to establish this beyond a reasonable doubt. Lijndenia acuminata is thus provisionally assessed as “Critically Endangered” [CR B2ab(iii)] according to the IUCN Red List Categories and Criteria ( IUCN, 2012).

cyme (versus cymes mostly 3-5-flowered). The type locality of L. acuminata is also isolated by a distance of c. 625 km from the nearest known locality of L. memecyloides (i.e. near the town of Foulpointe [Mahavelona] in Toamasina province).

Notes. – Lijndenia acuminata is closely related to (and previously confused with) L. memecyloides , but distinguished by the combination of leaf blades narrowly elliptic with apex distinctly and narrowly acuminate (versus blades narrowly elliptic to oblanceolate or obovate with apex rounded or retuse to vaguely obtuse-acuminate), cymes borne on peduncles 7-12(-15) mm (versus mostly 1-3 mm), and flowers numbering 7-16 per

2. Lijndenia danguyana (H. Perrier) Jacq. -Fél. in Bull. Mus. Natl. Hist. Nat., B, Adansonia 7: 38. 1985.

÷ Memecylon danguyanum H. Perrier in Mém. Acad. Malgache 12: 210. 1932.

÷ Spathandra danguyana (H. Perrier) Jacq. - Fél. in Adansonia ser. 2, 18: 228. 1978.

Lectotypus (designated here): MADAGASCAR. Prov. Toamasina: Analamazaotra , XI.1925 , fl., Louvel 5 ( P [ P00057564 ]!) . Syntypus: MADAGASCAR. Prov. Toamasina: An a l a m a z ao t r a, I I.1 9 1 9, f r., Thouvenot 123 ( P [ P00057565 , P00257949 , P00257950 , P05207163 , P05207164 , P05207165 ]!, K [ K000276111 , K000313593 ]!) .

Tree 7 to 20 m; young branchlets terete, blackish; older branchlets whitish and often with fine horizontal fissures (lenticels?). Leaves evidently 3-nerved (the midnerve prominent on the lower surface; principal pair of lateral nerves only slightly visible on the lower surface, situated c. 5 mm from the margins at the midpoint of the blade, evanescent toward the apex; an additional, very weak pair of lateral nerves at the revolute margins), coriaceous, granular in dried material, discolored; petiole 5-8 mm; blades mostly obovate to oblanceolate (varying to ± elliptic), 5-9.5(-13) X 2.5-4.5 (-6) cm, attenuate and decurrent on the petiole, rounded to retuse at the apex. Cymes subsessile (peduncle ± absent or to c. 1 mm), umbelliform, fascicled at the leafless nodes of older branchlets; each flower subtended by a pair of fleshy bracteoles fused at the base to form a cupule; pedicel 6-10 mm. Hypanthocalyx campanulate to cupulo-patellate, 2 X 3 mm, the margin sinuate and minutely 4-toothed; petals blue to pale bluish-purple, orbicular, limb 2-3 mm in diameter, apex rounded to apiculate, base abruptly narrowed and ± auriculate above the claw 0.7 mm; staminal filaments 4.5-6 mm, anthers 2 mm, anther sacs fronto-ventral, connective incurved by the median gland, extremity conical; style slender, 10-12 mm; ovary 10-12-ovuled. Fruit globose, 8 mm in diameter, asymmetrical; calycinal crown not prominent.

Distribution and ecology. – An endemic of montane forest at elevations of about 1000 m along the eastern escarpment bordering Madagascar’s central plateau ( Fig. 3 ), in Toamasina province (Moramanga region and to the north near lac Alaotra) and Fianarantsoa province (Ranomafana National Park).

Conservation status. – Lijndenia danguyana is known from six locations and has an extent of occurrence (EOO) of 2,390 km 2. Along Madagascar’s eastern escarpment there is presently very little forest remaining, and this extraordinary loss of habitat must have produced substantial population declines in many formerly common and widespread forest species, including L. danguyana which is an understory tree with very hard wood, a slow growth rate and a projected long generation time. Lijndenia danguyana is thus provisionally assessed as “Vulnerable” [VU B1ab(iii)] according to the IUCN Red List Categories and Criteria ( IUCN, 2012). It should be noted, however, that some occurrences of this species would seem to lie within protected areas, e.g. the Réserve spéciale d’Analamazaotra and the national parks of AndasibeMantadia and Ranomafana.

Notes. – In the protologue of Memecylon danguyanum ( PERRIER DE LA BÂTHIE, 1932) there were two collections cited, one with flowers (Louvel 5) and the other with fruits (Thouvenot 123). The flowering collection has been designated here as the lectotype.

This species was previously illustrated by PERRIER DE LA BÂTHIE (1951: fig. 45: 9-16, as Memecylon danguyanum ) and by JACQUES-FÉLIX (1978b: tab. 2b, as Spathandra danguyana ; 1985b: tab. 28: fig. 6-11).

JACQUES-FÉLIX (1985b) described the petals of L. danguyana as abruptly narrowed but not auriculate above the claw. A reexamination of the available flowering material indicates that the petals of the lectotype (Louvel 5, P) are indeed lacking auricles, but these are present in Service Forestier 28436 ( P) and Randrianasolo & Rasabotsy 29 ( CAS) .

Additional material examined. – MADAGASCAR. Prov. Fianarantsoa: Ranomafana NP, parcelle 3, S of National Road 25 at 7 km W of Ranomafana , 21 ° 15’30”S 47 ° 25’00’’E, 30. XI .1993, fl., Randrianasolo & Rasabotsy 29 ( BR, CAS, G, K, MO, P, TAN, WAG). Prov. Toamasina: Périnet , 28.VIII.1952, ster., Service Forestier 153-B-R-172 ( TEF); Befody, lac Alaotra , 27.VII.1952, ster., Service Forestier 503-R-56 ( MO, P, TEF); Distr. Moramanga, Cton Périnet, Antsampandrano , 17.X.1962, ster., Service Forestier 21539 ( P); ibid. loc ., 25.X.1962, ster., Service Forestier 21539-bis ( P [2 sheets]); Ankazomanitra, village le Toby, km 45 route Moramanga-Anosibe , 8.XI .1968 , fl., Service Forestier 26815 (P, TEF); W d’Antanandava, km 45 route MoramangaAnosibe, XI .1968, fl., Service Forestier 28436 ( K, MO, P [2 sheets], S, TEF, WAG); Moramanga, Andasibe, Réserve faune d’Analamazaotra , 16.I .1984 , fr., Service Forestier 32548 (TEF); Andasibe-Mantadia PN, 14 km en voiture au NE de la mine de graphite, 18°53’00’’S 48°27’30’’E, 13. XI .2001, ster., Stone et al. 2377 ( CAS, P, TAN) .

Figures

Fig. 1. – Lijndenia acuminata R.D. Stone. A. Flowering branchlet; B. Leaf; C. Detail of lower leaf surface; D. Detail of branchlet showing cymes fascicled at an older, defoliated node; E. Cyme (side view); F. Open flower (side view); G. Petal; H. Stamen (side view).

Fig. 2. – Geographic distribution of Lijndenia acuminata R.D. Stone (star), L. densiflora R.D. Stone (diamonds), and L. memecyloides R.D. Stone (circles), mapped on the bioclimatic zones of Madagascar (after CORNET, 1974; seeSCHATZ, 2000).

Fig. 3. – Geographic distribution of Lijndenia danguyana (H. Perrier) Jacq.- Fél. (circles), L. darainensis R.D. Stone (black star), L. melastomoides (Naudin) Jacq.-Fél. (squares), L. ramiflora Jacq.-Fél. (triangle), L. roborea (Naudin) Jacq.-Fél. (diamonds), and L. terminalis Jacq.-Fél. (white star), mapped on the bioclimatic zones of Madagascar (after CORNET, 1974; see SCHATZ, 2000).