Lijndenia densiflora R.D. Stone, 2017

Stone, R. Douglas, 2017, Revised treatment of the genus Lijndenia (Melastomataceae, Olisbeoideae) in Madagascar, Candollea 72 (1), pp. 67-86 : 76-80

4. Lijndenia densiflora R.D. Stone , spec. nova ( Fig. 6 ).

Typus: M ADAGASCAR. Prov. Antsiranana: env. de Lohanantsahabe (haute Antsahabe, affluent rive gauche de la Lokoho), entre Sambava et Andapa, 9.XII.1966, fl., Service Forestier 27162 (holo-: P [ P00257945 ]!; iso-: G [ G00341693 ]!, K!, MO-4373720!, S!, TEF!, WAG!) .

Aff inis L. memecyloidi R.D. Stone sed laminis foliorum ellipticis (non anguste ellipticis vel oblanceolatis) ad apices late obtuseque breviacuminatis (non rotundatis vel retusis vel subacuminatis), cymis in quoque fasciculo numero 1-6 (non 1-2), floribus in quoque cyma numero 5-14 (non 3-5) differt.

Tree to 8-10 m; branchlets terete; internodes (0.8-)1.5- 2.5(-3.1) cm. Leaves apparently 1-nerved (only the midnerve clearly visible, the lateral nerves intramarginal and ± obscure), subcoriaceous, finely granular in dried material, on petioles 3-6 mm; blades elliptic, 3.3-5.3(-7.7) X 1.5-2.5(-3.2) cm, the apex shortly and obtusely acuminate (the acumen mostly 3-6 mm); transverse veins not evident or ± faintly visible in dried material, oriented at an oblique angle relative to the midnerve. Cymes umbelliform and mostly 5-9(-14)-flowered, solitary or in fascicles of 2-6 at the leafless nodes of older branchlets, sometimes also in groups of 1-4 in the axils of

[Gautier & Chatelain 4951, CAS] [Drawing: S. Burrows]

[Service Forestier 27162, P] [Drawing: S. Burrows]

uppermost nodes; peduncles mostly 3-5(-8) mm; each flower subtended by a pair of persistent, concrescent bracteoles forming a cupule or involucre from which emerges the pedicel 1-2 mm. Hypantho-calyx cupulo-patellate, 1.25 X 2 mm, the margin shallowly 4-sinuate or with calyx lobes slightly triangular; petals white, reflexed at anthesis, 1.25 X 1 mm, unguiculate, limb orbicular with base abruptly truncate to shallowly cordate-auriculate above the claw 0.25 mm; stamens borne on bluish filaments 1-2.5 mm, anthers dolabriform, 1 X 0.5 mm, the anther sacs positioned at the anterior end, connective dorsally incurved by the medially positioned oil-gland, the posterior end prolonged, extremity obtuse to subacute; style bluish, filiform, 4 mm. Fruits not seen.

Etymology. – The species epithet densiflora refers to the densely flowered aspect which is perhaps the main characteristic setting this species apart from its closely related congeners L. memecyloides and L. acuminata . It is caused by the relatively large number of cymes per fascicle, the relatively large number of flowers per cyme (especially in comparison to L. memecyloides ), and the relatively short pedicels subtending individual flowers, the result being that the individual cymes appear congested with flowers.

Distribution and ecology. – An endemic of northeastern Madagascar (Antsiranana province) in the region to the northwest and southwest of the city of Sambava, the two known localities being approximately 15 to 25 km inland from the coast and about 40 km apart from each other ( Fig. 2 ). Habitat not specified but presumably in lowland humid forest. Elevation estimated as 80 to 150 m above sea level. A concerted effort should be made to relocate L. densiflora , particularly in the protected area Makirovana-Tsihomanaomby (gazetted in 2015) which consists of 53 km 2 of low-elevation forest remnants situated to the north of the river Bemarivo and west of the Route nationale no. 5a (between the towns of Sambava and Antsirabe Avaratra).

Conservation status. – Lijndenia densiflora is a poorly known species that has not been collected again within the past 50 years. There are just two known locations and an AOO of 8 km 2. The possibility exists that the species is already extinct, but there have been some recent examples of other so-called “forest phantoms” having been rediscovered after not being seen for many years ( SCHATZ et al., 1998; STONE, 2012). At present, L. densiflora is provisionally assessed as “Critically Endangered” [CR B2ab(iii)] according to the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – Lijndenia densiflora is closely related to (and previously confused with) L. memecyloides , but distinguished by the combination of leaf blades elliptic with apex shortly and obtusely acuminate (versus blades narrowly elliptic to oblanceolate or obovate with apex rounded or retuse to vaguely obtuse-acuminate), cymes 1-6 per fascicle (versus cymes mostly 1-2 per fascicle), and flowers numbering 5-9(-14) per cyme (versus cymes mostly 3-5-flowered). The type locality of L. densiflora is also isolated by a distance of c. 150 km from the nearest known locality of L. memecyloides (i.e. near Rantabé in the Antongil Bay region of Toamasina province).

The species was previously illustrated by JACQUES-FÉLIX (1985b: tab. 27: 1-4, as L. lutescens ).

There is still a lack of precision about the second collecting locality (south of Analamanara between Sambava and Antsirabe Avaratra), but it is evidently close to a remnant forest block called Tsihomanaomby, north of the river Bemarivo and about 3-5 km to the west of the Route nationale 5a (P. Phillipson & J. Razafitsalama, pers. comm.).

Additional material examined. – MADAGASCAR. Prov. Antsiranana: env. S d’Analamanara (près de Tsaratanana), entre Sambava et Antsirabe-Nord, XII.1966, fl., Service Forestier 27175 ( BR, G, K, MO, P, TEF, WAG) .

5. Lijndenia melastomoides (Naudin) Jacq. -Fél. in Bull. Mus. Natl. Hist. Nat., B, Adansonia 7: 38. 1985 ( Fig. 4C ).

÷ Memecylon melastomoides Naudin in Ann. Sci. Nat., Bot., ser. 3, 18: 265. 1852.

÷ Spathandra melastomoides (Naudin) Jacq. - Fél. in Adansonia ser. 2, 18: 228. 1978.

Typus: MADAGASCAR: sine loc., s.d., fl., du PetitThouars s.n. (holo-: P [ P00057571 ]!; iso-: BR [ BR0000006422448 ]!) .

= Memecylon cauliflorum H. Perrier in Mém. Acad- Malgache 12: 209. 1932. Typus: MADAGASCAR. Prov. Toamasina: env. de la baie d’Antongil , c. 100 m, X.1912, fl., Perrier de la Bâthie 2080 (holo-: P [ P00057572 ]!; iso-: P [ P00057573 ]!).

Tree 6-15 m; branchlets 4-winged, the wings greater than 0.5 mm and eventually excoriating, the older branchlets terete and thickened at the nodes. Leaves 3-nerved (the midnerve and pair of lateral nerves clearly visible, prominent on the lower surface of the blade), coriaceous, granular on both faces in dried material; petiole 2 mm; blades lanceolate to oblanceolate, 5-14 X 2-4 cm, attenuate at the base and decurrent on the petiole, short-acuminate at apex. Cymes umbelliform, solitary or in fascicles of 3-5 at the leafless nodes and the older wood; peduncle 7-15 mm, 4-winged; bracteoles subtending individual flowers very short, truncate, forming a cupule from which emerges the pedicel 2-6 mm. Hypantho-calyx cupulo-patellate, 1.5 X 2 mm; calyx limb truncate to sinuate; petals pale blue, mostly elliptical to suborbicular, 1.5 X 2 mm, auriculate above the claw 0.5 mm; staminal filaments 3-4 mm, anthers 1 X 0.5 mm, the locules fronto-ventral, connective incurved with a well-developed median gland on the dorsal side, the extremity of the connective subacute; style 5 mm; ovary 8-ovuled. Fruit unknown.

Distribution and ecology. – An endemic of low-elevation forests along the eastern coast of Madagascar ( Fig. 3 ), in Antsiranana province (south of Antalaha near Ambohitralanana [Cap-Est]) and in Toamasina province (region of Antongil Bay and recently collected at Pointe à Larrée to the north of Soanierana-Ivongo). The habitat in Pointe à Larrée was described by the collector as “swamp forest”. New localities for L. melastomoides should be sought in the Masoala National Park, particularly the “parcelle détachée d’Andranoanala”, a 13-km 2 area of littoral forest, flooded forest and swamps that is close to one of the historical collecting localities near Ambohitralanana.

Conservation status. – Lijndenia melastomoides is a poorly known species that had been considered as possibly extinct until its rediscovery at Pointe à Larrée in Nov. 2008. There are just two locations known with any degree of precision, yielding an AOO of 8 km 2. The location near Ambohitralanana (CapEst) was formerly protected in the “Réserve naturelle intégrale no. 2”, but this area was degazetted in 1964. The other location at Pointe à Larrée includes 51 km 2 of littoral forest and swamp forest and was gazetted as a “Réserve speciale” in 2015. However, the site in recent years has been subjected to threats from logging, wildfires and shifting agriculture, and its status as a protected area is still in the early stages of implementation. Lijndenia melastomoides is thus provisionally assessed as “Critically Endangered” [CR B2ab(iii)] according to the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – The conspicuously quadrangular-alate young branchlets of L. melastomoides are unique in the genus. The original material of du Petit-Thouars was labeled “ Madagascar ou Ile Maurice ” and was supposed by PERRIER DE LA BÂTHIE (1932, 1951) to be from Mauritius. This is considered very unlikely, however, because all subsequent collections of L. melastomoides are from Madagascar. The species was previously illustrated by PERRIER DE LA BÂTHIE (1951: fig. 45: 1-8, as Memecylon cauliflorum ) and JACQUES-FÉLIX (1985b: tab. 27: 5-9).

Additional material examined. – MADAGASCAR. Prov. Antsiranana: Distr. Antalaha, Cton Ambohitralanana, RN II [Masoala], 10.II.1954, fl., Réserves Naturelles 6619 ( P) . Prov. Toamasina: Pointe à Larrée, forêt Menagisy , 16°48’51”S 49°42’02”E, XI .2008, fl., Nikolov 1812 ( G, MO) .

Figures

Fig. 6. – Lijndenia densiflora R.D. Stone. A. Flowering branchlet; B-C. Leaves; D. Detail of lower leaf surface; E. Detail of branchlet showing cymes fascicled at an older, defoliated node; F. Cyme (side view); G. Floral bud (side view); H. Petal; I. 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. 4. – Living material. A. Lijndenia darainensis R.D. Stone, flowering branchlets; B. Lijndenia darainensis R.D. Stone, flowers; C. Lijndenia melastomoides (Naudin) Jacq.-Fél., flowers.

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).