Ormocarpopsis anosyana Thulin & Razafim., 2016

Thulin, Mats & Razafimandimbison, Sylvain G., 2016, Ormocarpopsis anosyana Thulin & Razafim. (Fabaceae), a new species from southern Madagascar and its phylogenetic position, Candollea 71 (2), pp. 281-286 : 282-285

Ormocarpopsis anosyana Thulin & Razafim. , spec. nova ( Fig. 2 ).

Typus: MADAGASCAR. Prov. Toliara: Anosy Region, Ambatoabo, Ankoba, 2 km E of Imonty, 24°47’54’’S, 46°40’24’’E, 160 m, 16.III.2010, fl., Ratovoson 1559 (holo-: UPS!; iso-: K!, MO-6038420!, P, TAN).

Ormocarpopsis anosyanaThulin & Razafim. differs from O. mandrarensis Dumaz-le Grand by its generally smaller leaflets (5-15 × 4-10 mm vs 10-35 × 5-18 mm) with secondary and tertiary venation, but not midrib, drying more or less blackish beneath (not with midrib drying dark brown or blackish beneath for a half to two-thirds of its length), by its 1-2 mm (not 3-4 mm) long hypanthium, by its c. 4 mm long calyx with the lowest tooth about as long as the others (not with calyx 5-7 mm long and with lowest tooth clearly longer than the others), by its corolla with wings much longer than the keel (not with wings about as long as or slightly longer than the keel), by its glabrous ovary (ovary not with glandular pubescent stipe and margins), and by its articulated fruits slightly constricted between the segments (not with unarticulated fruits).

Shrub, 3-4 m tall, DBH 3 cm; twigs glabrous to sparsely pubescent when young, greyish or purplish brown. Leaves alternate on long shoots or clustered on short shoots covered by closely spaced and overlapping stipules, pinnate, with alternate leaflets; stipules narrowly triangular, acute, c. 3 mm long; petiole up to 8 mm long, sparsely pubescent with appressed hairs; rhachis up to 25 mm long, sparsely pubescent with appressed hairs; leaflets 6-8, broadly elliptic to obovate, 5-15 × 4-10 mm, cuneate to rounded at the base, obtuse to truncate or emarginate and shortly mucronate at the apex, glabrous to sparsely pubescent with appressed hairs on both sides, midrib prominent beneath and not drying black, secondary and tertiary venation forming a fine reticulum beneath that is drying more or less blackish; petiolules 1-1.5 mm long, glabrous to pubescent. Flowers 17- 18 mm long, solitary from tips of short shoots; bracts 1-2 mm long, ciliolate; pedicels 4-11 mm long, glabrous or sparsely pubescent with appressed hairs; bracteoles inserted at top of pedicel, opposite, narrowly elliptic, 2-2.5 mm long, ciliolate. Calyx c. 4 mm long, glabrous except for sparsely ciliolate teeth; hypanthium 1-2 mm long, reddish; teeth subacute, the lowest tooth about as long as the others. Corolla yellow; standard erect or curved backwards, subcircular, the limb c. 13-14 × 12-13 mm, notched at the apex, with 2 callous protuberances at the base inside, the claw c. 3 mm long; wings narrowly and asymmetrically obovate, the limb c. 16 × 6 mm, rounded at the apex, oblique and auriculate at the base, the lower margin rounded, with crescent-shaped folds between the veins near the base, with a claw c. 2.5 mm long; keel-limb semicircular, c. 7 × 4 mm, with claws c. 3 mm long. Stamens 10, fused into 2 lateral groups of 5 situated on either side of the ovary, 12-15 mm long; anthers c. 0.8 mm long. Ovary with a 3-6 mm long stipe, linear, glabrous, with 4-9 ovules; style 6-8 mm long; stigma minute, capitate. Fruits articulated, with 1-3 segments developing and only slightly constricted between the segments; fertile segments ellipsoid, thinly coriaceous, reticulately veined, c. 12-15 × 10-12 × 8-10 mm, with thin endocarp, 1-seeded, apparently indehiscent. Seeds subglobose, 10-11 × c. 9 mm, with a minute excentric hilum.

Etymology. – The epithet of the new species is derived from Anosy, the name of the region to which it is apparently confined.

Distribution and ecology. – Ormocarpopsis anosyana is known only from a single patch of spiny dry forest with the genus Alluaudia (Drake) Drake east of Imonty in south-eastern Madagascar at an elevation of 160- 224 m.

Phenology. – The single flowering and fruiting collections known were made in March and February, respectively.

Notes. – As is clear from the diagnosis above, Ormocarpopsis anosyana differs markedly from its sister species O. mandrarensis , but it also differs markedly from all other species of the genus. The secondary and tertiary venation of the leaflets drying blackish beneath is a character that is not matched in any of the other species. The articulated pods, slightly constricted between the segments, are also unique in the genus. In the not closely related Ormocarpopsis nitida the articulated fruits are strongly constricted between the seeds, whereas all the other species have unarticulated fruits. Also, wing-petals that are much longer than the keel are not found in any of the other species.

Fig. 2. – Ormocarpopsis anosyana Thulin & Razafim. A. Front view of flower; B. Flowering branch; C. Fruiting branch, showing fruit with a single seed developed.

[Photos: A-B: F. Ratovoson; C: R. Randrianaivo]

Conservation status. – Ormocarpopsis anosyana is only known from two collections from a single patch of forest situated in the corridor between the parcels I and II of the Andohahela National Park and currently managed by the WWF Madagascar (F. Ratovoson, pers. comm.). The area holds a mosaic of vegetation types reflecting recent land use practices such as: residual mature forest patches, farmland, and abandoned slash-and-burn fields ( de Wilde et al., 2012). The two collections were made only c. 2 km apart and the occurrence can be regarded as a single location. Similar types of dry forest occur in the adjacent parcel II of this national park and the species should be searched for also there. With only a single location with only two known individuals the species is clearly threatened. Ormocarpopsis anosyana is therefore assigned a preliminary conservation status as “Endangered” [EN C2a(ii)] following the IUCN Red List Categories and Criteria ( IUCN, 2012).

Paratypus. – MADAGASCAR. Prov. Toliara: Anosy Region, Ambatoabo, Ankoba forest , 24°48’23’’S 46°41’13’’E, 224 m, 28.II.2009, fr., Randrianaivo et al. 1768 ( MO-6420454 , P, TAN, UPS).

Figures

Fig. 2. – Ormocarpopsis anosyana Thulin & Razafim. A. Front view of flower; B. Flowering branch; C. Fruiting branch, showing fruit with a single seed developed. [Photos: A-B: F. Ratovoson; C: R. Randrianaivo]