Novelties from the Northern Mountains Complex of Madagascar V: A new threatened Pandanus (Pandanaceae) from the Kalobinono massif

Abstract Callmander, M.W., R. Razakamalala, I. Luino, R.L. Andriamarisoa & S. BUERKI (2020). Novelties from the Northern Mountains Complex of Madagascar V: A new threatened Pandanus (Pandanaceae) from the Kalobinono massif. Candollea 75: 99–105. In English, English and French abstracts. A new species of Pandanus Parkinson (Pandanaceae) endemic to Madagascar is described as Pandanus kalobinonensis Callm., Razakamal. & Luino and illustrations are provided. The new species is restricted to the north-western lowland moist evergreen forests of the Kalobinono massif. Pandanus kalobinonensis can easily be morphologically distinguished from other members of the genus by its small solitary globose syncarp borne on a short peduncle, monocarpellate drupes, and single spiniform stigma with an adaxial stigmatic groove. Despite the occurrence of both collections within limits of the newly designated Galoko-Kalobonino Protected Area, the new species is preliminary assessed as “Endangered” [EN] using the IUCN Red List Criteria.

These botanical discoveries have shed light on the unique biodiversity of the Galoko-Kalobinono region, which is facing high human pressure as demonstrated by a deforestation rate in the Galoko of 158,36 ha/year (Ranirison et al., 2014). A multidisciplinary biodiversity inventory has been published by a consortium of Malagasy NGOs (the Missouri Botanical Garden-Madagascar, the Vahatra association, and the Bibikely Biodiversity Institute from the California Academy of Sciences). This biodiversity inventory was prepared in the context of the "Protected Areas of Managed Resources" (MRPA) program, which aimed at expanding the protected areas network of Madagascar within representative ecoregions, while considering regional population growth (see Ranirison et al., 2014). Following this effort, a new protected area of 74,205 ha was designated for this region in 2015 (MEEF, 2015), the "Paysage Harmonieux Protégé de Galoko-Kalobinono". This protected area includes 11,739 ha of strict conservation ("noyau dur"). The Missouri Botanical Garden has been managing the protected area between 2013 to 2017 and the Famelona association has taken over management duties since 2018 [www.famelona.mg].
Pandanaceae of the Galoko-Kalobinono region have been well studied and currently comprises five species distributed into two genera. Martellidendron cruciatum (Pic. Serm.) Callm. & Chassot, Pandanus boivinii Solms, P. grallatus B.C Stone, P. sambiranensis Martelli, and P. mammillaris Martelli & Pic. Serm. have been recorded from the Protected Area. Those latter five species are not endemic to the region and occur in several neighboring forests (see Madagascar Catalogue, 2020).

Martellidendron cruciatum has a widespread distribution in
Malagasy moist forests, whereas the other species are mostly endemic to the Sambirano Domain, a region well known for its high level of endemism (see Gautier, 2002). Currently, P. sermollianus Callm. & Buerki is the only endemic species of the Galoko-Kalobinono region. This species was discovered in 2005 during the first intensive botanical inventory of this region (Callmander et al., 2008).
During the MRPA program, an unidentified collection of Pandanus Parkinson was collected at low elevation in the Kalobinono massif in 2013 by RR (Razakamalala et al. 7586). Another collection tentatively assigned to the same taxon was made by RR and IL in 2015 (Luino & Razakamalala 106) on the first author initiative. These two collections confirmed a further new species endemic to the Galoko-Kalobinono region, which is formally described and illustrated in this publication: Pandanus kalobinonensis Callm., Razakamal. & Luino. The new species description is accompanied by notes on its morphological affinities, its preliminary risk of extinction assessment following IUCN Red List Categories and Criteria (IUCN, 2012), a field photograph and a line drawing.
Treelet to 3 -4 m tall; stem prickly, up to 5 cm dbh. Leaves 125 -160 cm long, 2 -3 cm wide in the middle, 3 cm wide near the sheath, gradually attenuate in the upper third, and tapering to a flagellate apex in the distal 5 cm, coriaceous; longitudinal and transverse veins visible on both surfaces; prickles white in vivo; marginal prickles beginning at (4 -)5 -6 cm above the base and extending to the apex, antrorse, 2 -4 mm and placed 2 -8 mm apart in the lower third, to 2 mm and 5 -10 mm apart in the middle third; to < 1 mm and 2 -4 mm apart in the distal third; midrib armed below in the upper 2/3, prickles small (< 1 mm), irregularly disposed (5 -10 mm); sheath 5 cm long, c. 3.5 cm wide at apex c. 4 -4.5 cm large at base. Infrutescence terminal, a solitary syncarp subtended by naviculate bracts, borne on a straight short peduncle; syncarp 50 × 60 -70 mm, globose to ovoïd; peduncle straight, short, 65 mm long, c. 9 mm in diam at apex, trigonous, 3 -4 remaining bracts, c. 5 -7.5 cm long, positioned near the base of the syncarp, boat-shaped at base and becoming flagellate in the distal part.
Etymology. -The species epithet refers to the Kalobinono massif and its eroded landscape of Isalo Sandstone dominated by a pair of distinctly shaped domes ( fig. 1). The literal translation from the Sakalava dialect means "princess with large breasts". Similarly, the name Galoko refers to a local king. The two summits are sacred for the local Sakalava. According to the legend, the queen embodied in the Kalobinono massif gave birth to the nearby Manongarivo massif, fathered by the king at Galoko (Solo et al., 2008).
Distribution and ecology. -Pandanus kalobinonensis is currently only known from the lowland moist evergreen forest in the Kalobinono massif (northwestern Madagascar) between 420 to 740 m elevation.
Conservation status. -Pandanus kalobinonensis is known from 2 locations from the Galoko-Kalobinono Protected Area collected at a distance of c. 1 km in lowland moist evergreen forests. The holotype collection is located well within the intact forest at 740 m, but the paratype is located at 425 m and was made only a hundred meters from recently cleared forest. This latter location could be projected to disappear in a relatively near future. Lowland moist evergreen forests were highly threatened in the Candollea 75, 2020 A new threatened Pandanus (Pandanaceae) from Madagascar -101  (Fig. 1). The loss of moist evergreen forest area between 2006 to 2016 has reached 1408 ha, which represents 15% of the total cover of the PA (Rabenandrasana et al., 2018). Since mid 2018, slash and burn agriculture is restricted within the strict conservation zone, but the risk of uncontrolled pasture fire is still a threat (P. Ranirison, pers. comm.). With an area of occupancy (AOO) of 4 km2, and despite that both collections ocur within limits of the protected area, P. kalobinonensis is therefore assigned a preliminary conservation status of "Endangered" [EN B1ab(ii,iii,iv,v)+2ab(ii,iii,iv,v)] using IUCN Red List Categories and Criteria (IUCN, 2012).
Notes. -Pandanus kalobinonensis is morphologically distinct among Malagasy species of Pandanus. Its small globose solitary syncarp bearing monocarpellate drupes topped by a spiniform stigma (Fig. 2, 3) resembles several Southeast Asian Pandanus species. Several species in Madagascar were hypothesized to have morphological Indo-Malaysian affinities (Stone 1974;Callmander & Laivao, 2003). Pandanus platyphyllus Martelli was for example placed by Stone (1974) in the Malaysian Pandanus subgenus Rykia (Vrise) B.C. Stone before staminate plants were studied by Huynh (1977) and confirmed to belong to the Afro-Malagasy subgenus Vinsonia (Warb.) B.C. Stone. Phylogenetic analyses further demonstrated that those latter morphological affinities were most likely the result of convergent evolution since all Malagasy species of Pandanus subgenus Vinsonia formed a monophyletic clade (Buerki et al., 2012). In this context, Pandanus kalobinonensis is therefore classified in Pandanus subgenus Vinsonia. The sectional placement of this species remains to be established, like other recently discovered morphologically isolated species in Madagascar (see Callmander et al., 2008Callmander et al., , 2009bCallmander et al., , 2013.