Operculicarya calcicola Randrian. & Lowry, 2015

Randrianasolo, Armand & Lowry II, Porter P., 2015, A new species of Operculicarya H. Perrier (Anacardiaceae) from western dry forests of Madagascar, Candollea 70 (1), pp. 57-60 : 59-60

Operculicarya calcicola Randrian. & Lowry , spec. nova ( Fig. 1 ).

Typus: M ADAGASCAR. Prov. Mahajanga: Région Melaky, Beanka, S de la Kimanambolo, 18°07’14’’S, 44°33’34’’E, 350 m, 25.XI.2014, fr., Gautier et al. 5829 (holo-: G [ G00377897 ]!; iso-: BR, K, MO-6605509!, P [P00641020]!, TAN) .

Operculicarya calcicola Randrian. & Lowry differs from its most similar congener, O. gummifera (Sprague) Capuron , by its larger leaflets [(2.5-) 6-11 × (1.3-)2.5-4.7 vs. (2)3-6.3 × (0.9) 1-1.9 cm] and fruits [10-12 × 7-10 × 5-7 vs. 6-9 × 5-7× 3-5 mm], as well as the thickness of its infrutescence axis [0.9-1.3(-1.8) vs. 0.3-0.9(-1.3) mm].

Small to medium trees ca. 5-10 m tall, trunk ca. 11-20 cm in diam. with smooth bark; twigs short-lanate. Leaves imparipinnate, alternate and usually well-spaced on long shoots, more closely clustered on lateral short shoots, (14-) 19-28.5 cm long; petiole 5-8.5 cm long, short-lanate; rachis not winged, terete, short-lanate; leaflets (9-)11-13, lateral ones opposite, petiolules 2-5 mm long, short-lanate, blade membranaceous to chartaceous, ovate, (2.5-)6-11 × (1.3-) 2.5-4.7 cm, median ones largest, discolorous, dark greenish brown to dark green above when dried, paler green beneath, densely lanate on both surfaces when young, with longer and somewhat denser trichomes along the midvein and secondary veins, glabrescent on upper surface except along midvein and secondary veins, venation craspedodromous, tertiary venation visible, more so on lower surface, base oblique to subcordate, asymmetric in lateral leaflets, margin entire, apex acuminate, the acumen rounded. Flowers unknown. Infructescence axes 2-7.5(-17) cm long, 0.9-1.3(-1.8) mm in diam. at base; pedicel ca. 1-3 mm long, glabrous. Fruits 6-8(-16) per infructescence, ellipsoid, slightly compressed laterally, 10-12 × 7-10 × 5-7 mm; endocarp bony, with a single operculum.

Distribution and ecology. – Operculicarya calcicola is only known from dry, deciduous forest on karstic limestone (“tsingy”) in western Madagascar ( Fig. 2 ), at elevations between 50 and 600 m. The flowers of this species are as yet unknown, but fruiting material has been collected in November and December.

Conservation status. – Operculicarya calcicola has an extent of occurrence (EOO) of 1,426 km 2 and would thus qualify as Endangered under the Criterion B1 of the IUCN Red List ( IUCN, 2012) if other qualifying conditions were met. However, as O. calcicola is restricted to karstic limestone areas, one of the few natural habitats in Madagascar that does not appear to be subjected to noticeable human-caused destruction or alteration, it may well be under little if any threat, and should thus be assigned a preliminary status of Least Concern [LC].

Notes. – Using the key provided by RANDRIANASOLO & LOWRY (2006), material of this new species would be identified as O. gummifera (Sprague) Capuron. It can, however, be distinguished by several features, as summarized in Table 1.

All but three of the known collections of O. calcicola were made since RANDRIANASOLO & LOWRY (2006) completed their review of the genus. The two oldest gatherings (Leandri 2017 and Service Forestier 6778) were not cited by them because they are fragmentary and could not be assigned with confidence to any of the eight species they recognized, whereas the most recent one (Jongkind et al. 3228) was regarded as a somewhat atypical individual of O. gummifera .

Paratypi. – MADAGASCAR. Prov. Mahajanga: Region Melaky, Tsingy de Bemaraha , S of the Manambolo River, 19°09’S 44°09’E, 50 m, 26.XI.1996, fr., Jongkind et al. 3228 ( G [ G00404134 ], MO-5968354 , P [P04800703], TAN, WAG); env. de Tsiandro (Ouest) , forêt de Behandrao , [18°49’37’’S 44°52’25’’E], 500-600 m, 25.XI-3.XII.1952, fr., Leandri 2017 ( P [ P00633854 , P00633857 ]); aux env. de Tsiandro , [18°49’37’’S 44°52’25’’E], 4.XII.1952, fr., Service Forestier 6778 ( P [ P00120510 , P06242028 , P06633856 ]); Beanka , partie centrale , Ambinda Nord , 17°55’48’’S 44°28’34’’E, 223 m, 16.XI.2011, fr., Gautier et al. 5625 ( G [G 00376040 ], MO-6605511 , TAN); forêt d’Amboloando , Tsingy de Beanka , 18°04’35’’S 44°32’02’’E, 269 m, 12.XI.2012, fr., Rakotovao et al. 6185 ( G [ G00377809 ], MO-6605512 , TAN); ibid. loc. , 18°04’56’’S 44°32’20’’E, 269 m, 13.XI.2012, fr., Rakotovao et al. 6213 ( G [ G00377810 ], MO-6605510 , TAN) .

Figures

Fig. 1. – Operculicarya calcicola Randrian. & Lowry. A. Fruiting branch; B. Detail of indument on lower surface of leaflet; C. Fruit on pedicel (lateral view); D. Fruit on pedicel (dorsal view).

Fig. 2. –Geographic distribution of Operculicarya calcicola Randrian. & Lowry; darker areas indicate remaining natural vegetation (insert map shows the bioclimatic zones of Madagascar (after CORNET, 1974; see SCHATZ, 2000).

Tables

Table 1. – Morphological features distinguishing Operculicarya calcicola Randrian. & Lowry from O. gummifera (Sprague) Capuron.

	O. calcicola	O. gummifera
Size of largest leaflet [cm]	(2.5-)6-11 × (1.3-)2.5-4.7	(2-)3-6.3 × (0.9-)1-1.9
Inflorescence axis [mm in diam.]	Robust,0.9-1.3(-1.8)	Filiform, 0.3-0.9(-1.3)
Fruit size [mm]	Large, 10-12 × 7-10 × 5-7	Small, 6-9 × 5-7 × 3-5