Introduction
The genus Polygala L. (Polygalaceae) was last treated for Madagascar by Perrier de la Bâthie (1955) in the Flore de Madagascar et des Comores series, and later, Paiva (1998) provided a taxonomic conspectus of African and Malagasy species. In the course of re-evaluating species diversity for the Catalogue of Vascular Plants of Madagascar (Madagascar Catalogue, 2013), Polygala longeracemosa var. retamoides H. Perrier stood out as a morphologically distinctive taxon and was found to occupy a geographic range separate from that of the nominate species. In addition, P. longeracemosa var. retamoides is a narrowly distributed edaphic specialist restricted to thin, rocky soils derived from marbles and quartzites in the vicinity of Ambatofinandrahana in the High Plateau of Fianarantsoa Prov. We disagree with Paiva (1998) who placed P. longeracemosa var. retamoides in synonymy under P. longeracemosa H. Perrier. Given the morphological and ecological differentiation as well as the separate distributions of the two taxa, we propose to recognize P. longeracemosa var. retamoides at the rank of species.
Here, we designate lectotypes for P. longeracemosa and P. longeracemosa var. retamoides, and we propose the necessary new nomenclatural combination and status for the latter at the species level. We also provide a key to separate to separate the two species, a distribution map, and preliminary IUCN conservation assessments for both taxa following IUCN Red List Categories and Criteria (IUCN, 2012; calculations following Callmander & al., 2007).
Key to separate Polygala longeracemosa from P. retamoides
1. Stem glabrous to sparsely pubescent with simple white hairs; leaves up to 3.3 cm long, 0.5 cm wide 1. P. longeracemosa
1a. Stem densely pubescent with simple white hairs; leaves absent or up to 1.2 cm long, 0.2 cm wide 2. P. retamoides
Taxonomy
1. Polygala longeracemosa H. Perrier in Bull. Trimestriel Acad. Malgache ser. 2, 14: 9. 1932.
Lectotypus (designated here [second step]): Madagascar. Prov. Toliara: Bassin supérieur du Mandrare (SE): Mont Amboahangy près d'Esira, [24°15′S 46°39′E], 1000–1150 m, 25.XI.1928, fl., Humbert 6830 (P [P00375348]!; isolecto-: P [P00375346, P00375347]!) (Lectotype [first step] designated by Paiva, 1998: 258). Paralectotypus: MADAGASCAR. Prov. Toliara: Massif de Beampingaratra (SE): Mont Papanga, versant NW, c. 1200 m, 3–4.XI.1928, fl. & fr., Humbert 6405 (P [P00375343]!; isoparalecto-: P [P00375344, P00375345]!).
Observations. — Paiva (1998) cited Humbert 6830 (P) as the holotype of the name P. longeracemosa and effected lectotypification in accordance with the ICBN (McNeill & al., 2012, Arts. 9.2, 9.11). However, the gathering of Humbert 6830 at P consists of three specimens. Consequently, we designate the sheet [P00375348] as the [second-step] lectotype as allowed under Art. 9.17 because it is the most complete specimen and the label was annotated with the word “type” in Perrier's hand.
Distribution and habitat. — Polygala longeracemosa is distributed in the mountains of southeastern Madagascar, including the massifs of Andohahela, Kalambatritra and Ivakoany and on the Horombe Plateau at elevations from 900–1750 m. The species occurs in secondary or degraded grasslands, ericoid shrublands, and forests edges, usually in rocky areas (Fig. 1).
Conservation status. — Polygala longeracemosa is known from 13 locations and subpopulations, four of which are situated in Protected Areas (Andohahela National Park and Kalambatritra Special Reserve), but with a somewhat restricted Area of Occupancy (minimum of 140 km2) and Extent of Occurrence (c. 14,000 km2), it is assigned a preliminary conservation status of “Near Threatened” (NT).
Additional material examined. — Madagascar. Prov. Fianarantsoa: Iakora, Begogo, Bekora, forêt de Sahalava au S du village d'Androizaha, 23°32′09″S 46°32′21″E, 1404 m, 27.I.2005, fl. & fr., Andrianjafy & al. 704 (MO!, P [P06241680, P06241681]!). Prov. Toliara: Betroka, Ivahona, Mt. Kalambatritra, forêt d'Analamaro, 23°27′38″S 46°24′40″E, 1540 m, 6.XI 2005, fl., Andrianjafy & al. 536 (MO!, P [P02998108]!); Ampandrandava, [24°05′S 45°42′E], [900 m], s.d., fl. & fr., Herb. Jardin Bot. Tananarive 6276 (P [P06241 684]!); Massif du Kalambatritra (Centre-Sud), [23°22′S 46°29′E], 1600–1750 m, XI.1933, fl, Humbert 11772 (BR, G!, K!, MO!, P [P03008170, P06241683]!, PRE, TAN, WAG); haute vallée de la Manambolo, affluent de l'Ionaivo, [24°30′S, 46°35′E], 900–1100 m, XI.1933, fl. & fr., Humbert 12132 (P [P06241678]!); Massif de l'Ivakoany, [23°50′30″S, 46°26′E], 1250 m, XI–XII.1933, fl. & fr., Humbert 12253 (P [P06241685]!); Vallée de la Sakamalio, affluent de la Manambolo, bassin du Mandrare, [24°32′S 46°41′E], 900–1100 m, XII.1933, fl., Humbert 13412 (P [P06241677]!); Massif de l'Andohahela, 1700 m, I.1934, fl., Humbert 13673 (P [P06241675]!); Horombe, 1300 m, V.1919, fl., Perrier de la Bâthie 12680 (P [P03008 169]!); Mt. Trafonaomby, parcelle I d'Andohahela RNI, 24°33′S, 46°43′E, 1000–1957 m, 7.IV.1994, fl., Randriamampionona 752 (P [P02998110]!); Forêt de Befarafara, Kalambatritra AP, 23°24′44″S 46°27′58″E, 1575 m, 26.V.2005, fl., Razakamalala & al. 2046 (MO!, P [P02998109]!, TAN!); à l'E d'Ampandrandava, entre Bekily et Tsivory, vers la source de la Menakompy, [24°07′S 45°48′E], 1000–1200 m, IV.1943, fl. & fr., Seyrig 646 (P [P06241679]!).
Fig. 1.
Distribution of Polygala longeracemosa H. Perrier (circles) and Polygala retamoides (H. Perrier) Wahlert, G. E. Schatz & Phillipson (triangles) in Madagascar mapped on the biogeographic zones of Cornet (1974).
2. Polygala retamoides (H. Perrier) Wahlert, Phillipson & G. E. Schatz, comb. et stat. nova (Fig. 2).
≡ Polygala longeracemosa var. retamoides H. Perrier in Bull. Trimestriel Acad. Malgache ser. 2, 14: 10. 1932.
Lectotypus (designated here): Madagascar. Prov. Fiana rantsoa: Rocailles cipolins [marble outcrops], Ambatofinandrahana [20°35′S 46°49′E], II.1919, fl., Perrier de la Bâthie 12441 (P [P00375349]!; isolecto-: P [P00375350]!).
Observations. — Perrier de la Bâthie (1932) designated his own collection, Perrier de la Bâthie 12441, as the type of P. longeracemosa var. retamoides. The only known material of the collection are two specimens at P, both of which are annotated with this name in Perrier de la Bâthie's handwriting and both bear “Type” labels. We designate the sheet [P00375349] as the lectotype because it includes complete stems and inflorescences, as well as the woody base of the stem - an important morphological feature lacking on the sheet [P00375350].
Polygala retamoides is similar to P. longeracemosa by its habit, racemose inflorescence, and morphology of the flowers and seeds, but it differs by its densely pubescent stems (vs. glabrous to sparsely pubescent in P. longeracemosa) and its smaller leaves (when present) up to 1.2 × 0.2 cm (vs. leaves up to 3.3 × 0.5 cm). Polygala retamoides also differs ecologically by being restricted to marble and quartzite substrates, whereas P. longeracemosa grows on soils derived from laterite and gneiss.
Distribution and habitat. — Polygala retamoides is restricted to high elevation grasslands on thin, rocky soils overlaying marble and quartzite substrates from 1300–1800 m, near Ambatofinandrahana, Fianarantsoa Province in the eastern part of the Itremo Complex (Fig. 1).
Conservation status. — Data on the occurrence of P. retamoides is very limited, with only two of the eight known gatherings bearing precise geo-references. However all of these were apparently made near the town of Ambatofinandrahana, and none are known from the western part of the Itremo Complex which is now under temporary protection as a new protected area. These gatherings probably represent a single location and sub-population with a highly restricted Extent of Occurrence and Area of Occupancy of no more than a 10 km2 in an area that is under considerable human pressure from fire and mining; Polygala retamoides is therefore assigned a preliminary conservation status of “Critically Endangered” [CR B1ab(i,ii,iii,v)+2ab(i,ii,iii,v)]. It is interesting to note that other species also appear to be endemic to the marble outcrops near Ambatofinandrahana but are not known from elsewhere in the Itremo Complex, for example Buxus cipolinica Lowry & G. E. Schatz (Lowry & Schatz, 2006), suggesting the importance of this area to be brought into the protected area network of Madagascar.
Additional material examined. — Madagascar. Prov. Fianarantsoa: Ambatofinandrahana, [20°35′S 46°49′E], X.1963, fl., Bosser 18119 (P!); ibid. loc., 1964, fl., Bosser 19611 (P!); au S d'Ambatofinandrahana, [20°35′S 46°49′E], 13.XII.1976, fl., Cremers 3645 (P!, TAN!); env. d'Ambatofinandrahana [20°37′19″S 46°50′09″E], 1600–1800 m, 21.II.1938, fl., Decary 13174 (MO!, P [2 sheets]!); Ambatofinandrahana [20°35′S 46°49′E], III.1960, fl., Keraudren 219 (P!); Mahavanino, 7 km au S d'Ambatofinandrahana, sur la route de Fenoarivo, lieu-dit de Analalehibe, Ambatofinandrahana, 20°37′43″S 46°50′32″E, 1350 m, 19.XI.1993, fl., Labat & al. 2370 (K!, MO!, P [P001718]!, TAN!); Ambatofinandrahana, 9 km from Ambatofinandrahana, 20°36′47″S 46°49′56″E, 1398 m, 18.III.2004, fl., Skema & al. 46 (MO!, TAN).
Acknowledgements
We are grateful to the curators of the herbaria in G, K, MO, P, and TAN for providing access to their collections. We also acknowledge our late friend and colleague Jean-Noël Labat who collected and photographed Polygala retamoides. The authors were supported by grants from the U.S. National Science Foundation (0743355) and the Andrew W. Mellon Foundation.
