Monograph of the western Indian Ocean genus Paracephaelis (Rubiaceae - Pavetteae), with description of thirteen new species Author Block, Petra De Meise Botanic Garden, Nieuwelaan 38, BE- 1860 Meise, Belgium. petra.deblock@meisebotanicgarden.be text European Journal of Taxonomy 2022 2022-03-10 801 1 99 http://dx.doi.org/10.5852/ejt.2022.801.1685 journal article 92002 10.5852/ejt.2022.801.1685 9e07b749-7497-4b4e-8168-2aca6a9543b2 2118-9773 6358810 Paracephaelis gautieri De Block sp. nov. urn:lsid:ipni.org:names:77260708-1 Figs 2E , 10 Diagnosis Differing from Paracephaelis aristata sp. nov. by having rounded to retuse leaf tips (vs shortly aristate), glabrous lower leaf surfaces (vs densely covered with long erect or spreading hairs), shorter bracteoles ( 0.7–1.2 mm vs 3–5 mm long), shorter calyx lobes ( 1.2–1.5 mm vs 2.5–3 mm long in flowering stage, 4–5 mm long in fruiting stage), and the inner surface of the calyx tube densely covered with long appressed hairs (vs glabrous). Etymology The species is named in honour of Dr Laurent Gautier from the Conservatoire et Jardin botaniques de la Ville de Genève (G), who collected the type specimen. Type material MADAGASCAR – Antsiranana Province , Sava Region , Vohemar District • commune Daraina , Daraina , forêt de Bobankora , partie nord, 1 km NNE du point coté 607 , ruisseau à côté du campement ; 330 m a.s.l.; 2 Mar. 2003 ; fl; Gautier , Wohlhauser & Nusbaumer 4188 ; holotype : G scan; isotype: BR[BR00000929990]. Other material studied MADAGASCAR – Antsiranana Province , Sava Region , Vohemar District • commune Daraina , Daraina , forêt de Bobankora , partie nord , à 460 m du point coté 454 au 196° ; 313 m a.s.l. ; 17 Jan. 2005 ; fl; Nusbaumer & Ranirison 1423 ; BR , G n.v . Description Shrub, 5–6 m tall; pubescence whitish. Young shoots blackish brown, glabrous; older branches greyish, glabrous; internodes short, 0.3–2.5 cm long. Petioles 2–6 mm long, glabrous. Leaf blades narrowly obovate or narrowly elliptic, 4–7 × 0.4–1.7 cm , coriaceous, drying dark brown or greenish and not discolorous, upper surface glossy, both surfaces glabrous; base attenuate; tip rounded to retuse; ciliate pit domatia sometimes present; 5–8 secondary veins on each side of midrib; secondary and higher order venation inconspicuous on both surfaces. Stipules caducous, triangular with short needle-like awn, outer surface of youngest stipule pairs sparsely to moderately covered with short appressed hairs at the base and tip, inner surface glabrous with row of colleters at the base; sheath 1.5–2.5 mm long; awn 1–1.5 mm long. Inflorescences sessile, 1.5–2.5 × 1.5–3.5 cm , with 12–35 flowers; inflorescence parts sparsely or moderately (base of inflorescence) to densely (higher up) covered with short appressed hairs; first order axes 0.5–1.5 cm long; higher order bracts with stipular parts reduced or absent, foliar parts narrowly triangular and vaulted or linear leaf-like, 1.5–6 mm long, tips acute; bracteoles on pedicel somewhat below ovary, subopposite, stipular parts absent, foliar parts narrowly triangular or linear, 0.7–1.2 mm long, tips acute. Flowers shortly pedicellate, pedicels 2–6 mm long. Calyx densely covered with appressed hairs outside; tube ca 1 mm long, inner surface with ring of long appressed hairs; lobes oblong, 1.2–1.5 mm long, somewhat keeled, inner surface moderately covered with short appressed hairs in lower half, ± glabrous in upper half, margins ciliate, tips obtuse or rounded. Corolla tube 8–9 mm long, inner surface moderately covered with spreading hairs except at base; lobes 4–4.5 mm long, margins ciliate. Anthers 4.5–5 mm long, completely exserted from corolla tube at anthesis; filaments ca 1 mm long. Ovary 1–1.2 mm long, longitudinally ribbed (when dried), densely covered with appressed hairs; per locule 3–4 ovules arranged at periphery (mostly at base and top) of placenta attached to middle of septum. Style and stigma 15–16 mm long, exserted for 6–8 mm ; style densely covered with long spreading hairs from ca 3 mm from base to somewhat below papillate zone; stigmatic lobes 6–7 mm long. Fruits, pyrenes and seeds unknown. Distribution Only known from Daraina in Vohemar District, Sava Region ( Antsiranana Province ) ( Fig. 23A ). Habitat and phenology Low-elevation semi-deciduous forest; elev. ca 300 m . Flowers: January–March; Fruits: unknown. Provisional IUCN assessment Critically Endangered: CR B2ab(iii). Since P. gautieri sp. nov. is only known from two collections (collected in 2003 and 2005), the extent of occurrence (EOO) cannot be calculated. The area of occupancy (AOO) is 8 km 2 , which complies with the Critically Endangered category under criterion B2. The species is known from a single location, which also complies with the Critically Endangered category under subcriterion ‘a’ of criterion B2. The type specimen is from Bobankora Forest within the Loky-Manambato Protected Landscape, created in 2005 and managed by a Malagasy non-governmental organization, Association Fanamby ( Wahlert et al. 2019 ). Before 2005, no protective measures had been taken for this region, which forms the junction between humid and dry forests and lowland and montane forests and is therefore very variable in vegetation types ( Nusbaumer et al. 2010 ). Loky-Manambato is known as a region with high species diversity and endemicity ( Rakotondravony 2006 ). Recent large-scale collecting resulted in the discovery of ca 50 new plant species ( Nusbaumer et al. 2010 ), among which P. gautieri sp. nov. (and P. ranirisonii sp. nov. ). Paracephaelis gautieri sp. nov. occurs in lowland semi-deciduous forest. The main threat to the species is loss of habitat as a result of subsistence farming, illegal logging for timber and charcoal, burning for pasture, and artisanal gold mining ( Rakotondravony 2009 ; Nusbaumer et al. 2010 ), activities that also take place within the protected area. Therefore, a reduction in the extent and quality of the habitat of P. gautieri sp. nov. is inferred. This fact, in combination with the low AOO and the single location, qualifies the species for Critically Endangered status. Fig. 10. Paracephaelis gautieri De Block sp. nov. A . Flowering branch. B . Vegetative branch showing short internodes. C . Stipule. D . Bracteole, ovary and calyx. E . Corolla, stamens, style and stigma. Drawn by Mr A. Fernandez. From Gautier, Wohlhauser & Nusbaumer 4188 . Notes 1. Paracephaelis gautieri sp. nov. is similar to P. aristata sp. nov. by the relatively small and narrow leaves, the small inflorescences with relatively few flowers, the short internodes and the greyish branches. Paracephaelis gautieri sp. nov. differs from P. aristata sp. nov. by the glabrous petioles and young shoots (vs densely covered with ± short appressed hairs in P. aristata sp. nov. ), the glabrous lower leaf surfaces (vs densely covered with tawny, erect or spreading hairs), the shape of the leaf tips (rounded or retuse vs shortly aristate), the shorter stipular awns ( 1–1.5 mm vs 2–4 mm long), the longer pedicels ( 2–6 mm vs 0–3 mm long), the shorter bracteoles ( 0.7–1.2 mm vs 3–5 mm long), the shorter calyx lobes ( 1.2–1.5 mm vs 2.5–3 mm long in flowering stage), the fewer ovules per locule (3–4 vs 6–10), and the shape of the ovary in dried condition (longitudinally ribbed vs smooth). Furthermore, P. gautieri sp. nov. occurs in northern Madagascar whereas P. aristata sp. nov. is restricted to south-eastern Madagascar . 2. Ciliate pit domatia are present in Gautier et al. 4188 but absent in Nusbaumer & Ranirison 1423 .