Paracephaelis ranirisonii De Block, 2022

Block, Petra De, 2022, Monograph of the western Indian Ocean genus Paracephaelis (Rubiaceae - Pavetteae), with description of thirteen new species, European Journal of Taxonomy 801, pp. 1-99 : 59-62

Paracephaelis ranirisonii De Block sp. nov.

urn:lsid:ipni.org:names:77260713-1

Figs 1F , 15

Diagnosis

Differing from P. gautieri sp. nov. by having densely pubescent young shoots, petioles, and leaves (vs glabrous), longer stipules (7–12 mm vs 3.5–4 mm long), longer bracteoles (ca 3 mm vs 0.7–1.2 mm long), sessile flowers (vs pedicels 2–6 mm long), longer calyx tubes (2–2.5 mm long in flowering stage, up to 4 mm long in fruiting stage vs ca 1 mm long), and a different pubescence on calyx and ovary (densely covered with long, tawny hairs, appressed to spreading on the calyx and erect on the ovary in P. ranirisonii sp. nov. vs densely covered with shorter, whitish, appressed hairs in P. gautieri sp. nov.).

Etymology

The species is named in honour of Dr Patrick Ranirison, who collected the type specimen in northern Madagascar.

Type material

MADAGASCAR – Antsiranana Province, Sava Region, Vohemar District • commune Daraina , Daraina , forêt d’Antsahabe , à 1060 m du point côté 938, au 287°; 840 m a.s.l.; 2 May 2004; fr; Ranirison 781; holotype: G n.v.; isotype: BR [BR0000022757579] .

Description

Shrub, ca 1.5 m tall; pubescence tawny. Young shoots brown or greyish brown, densely covered with short erect hairs; older branches corky, brown to greyish brown, glabrescent; internodes short, 1–2 cm long. Petioles 3–6 mm long, densely covered with short erect hairs. Leaf blades obovate, 4–6.5 × 1.5– 3 cm, coriaceous, drying brown above, tawny (because of abundant pubescence) below, upper surface glossy, moderately to densely covered with short erect hairs, lower surface sericeous; base cuneate; tip obtuse to retuse; domatia absent; 7–8 secondary veins on each side of midrib, somewhat impressed above, somewhat raised below; higher order venation inconspicuous on both surfaces. Stipules caducous, triangular, keeled, 0.7–1.2 cm long, gradually tapering into an acute tip or with short awn <2 mm long, outer surface of youngest stipule pairs moderately to densely covered with short erect to spreading hairs, inner surface glabrous with 1–3 rows of colleters at the base, margin ciliate. Inflorescences sessile, 2–3 × 3–5 cm, with 15–30 flowers; inflorescence parts densely covered with short erect to spreading hairs; first order axes 0.5–1.5 cm long; higher order bracts trilobed, lobes triangular or narrowly triangular, central lobe 3–5 mm long, lateral lobes up to 2 mm long; bracteoles on pedicel just below ovary, opposite, stipular parts absent, foliar parts triangular, ca 3 mm long, tips acute. Flowers sessile. Calyx densely covered with long spreading to erect hairs outside, inner surface densely covered with short appressed hairs all over but most dense at the base; tube 2–2.5 mm long in flowering stage, reaching 4 mm in fruiting stage; lobes triangular or ovate, 1.2–2 mm long, tips acute or shortly acuminate. Mature corolla, stamens, style and stigma unknown. Ovary ca 2.5 mm long, densely covered with long spreading to erect hairs; per locule 5–6 ovules arranged at periphery of placenta attached just below middle of septum. Fruits ovoid, 0.8–1 × 0.6–0.9 cm, strongly ribbed longitudinally and glossy (when dried), densely covered with long spreading to erect hairs; fruit wall ± thick, with sclerified vascular bundles; pyrenes hemi-ovoid, ca 7 × 5 mm, crustaceous, with rounded base, acute tip, small adaxial opening somewhat below the middle and faint longitudinal central ridge running from the apex to the top of the adaxial opening and continuing into a longitudinal depression below it. Seeds 4–8 per fruit, 3–4 × 2.5–3 mm.

Distribution

Only known from Antsahabe Forest near Daraina in Vohemar District, Sava Region (Antsiranana Province) ( Fig. 23C ).

Habitat and phenology

Dry forest; elev. ca 840 m. Flowers: unknown; Fruits: May.

Provisional IUCN assessment

Critically Endangered: CR B2ab(iii). Paracephaelis ranirisonii sp. nov. is only known from a single collection, which means that the extent of occurrence (EOO) cannot be calculated. The area of occupancy (AOO) is 4 km 2, which complies with the Critically Endangered status under criterion B2. The species is known from a single location, which also complies with the Critically Endangered status under sub criterion ‘a’ of criterion B2. The type specimen was collected recently (2004) in the Loky-Manambato Protected Landscape (Daraina). The region of Loky-Manambato is very diverse in altitude and rainfall, hence a mosaic of different forest types occurs, from dry to humid evergreen, and from lowland to montane forest ( Nusbaumer et al. 2010). Loky-Manambato is known for its high species diversity and endemicity ( Rakotondravony 2006; Nusbaumer et al. 2010). As a region of transition it is of high conservation value ( Nicoll & Langrand 1989; Ganzhorn et al. 1997). While nominally protected within the Loky-Manambato Protected Landscape, P. ranirisonii sp. nov. is threatened by habitat loss as a result of clearing for subsistence farming, burning for pasture, logging for timber and charcoal, and artisanal mining for gold ( Rakotondravony 2009; Nusbaumer et al. 2010). Therefore, a reduction in the extent and quality of the habitat of P. ranirisonii sp. nov. is inferred. This fact, in combination with the low AOO and the single location, qualifies the species as Critically Endangered. For further details on the Loky-Manambato Protected Landscape, see P. gautieri sp. nov.

Note

The description is based on a single specimen without flowers. Ovary and calyx details are taken from undeveloped fruits. Label information on Ranirison 781 indicates the habitat as “forêt de transition sèche de haute altitude sur substrat pauvre”.

Figures

Fig. 1. Flowers, fruits and stipules of Paracephaelis Baill. A–D. Inflorescences. E–H. Fruits. I–J. Stipules. K–L. Infrutescences. A, E, I. P. cinerea (A.Rich. ex DC.) De Block. B. P. pauciflora De Block sp. nov. C, G. P. saxatilis (Scott Elliot) De Block. D. P. sericea (Arènes) De Block. F. P. ranirisonii De Block sp. nov. H. P. tiliacea Baill. J–K. P. capitulifera De Block sp. nov. L. P. russata De Block sp. nov. Photographs: P. De Block (B–E, G, I–L); S. Dessein (A, H); L. Gautier (F).

Fig. 15. Paracephaelis ranirisonii De Block sp. nov. A. Fruiting branch. B. Stipules. C. Bracts, bracteole, ovary and calyx. D. Fruit. Drawn by Mr A. Fernandez. From Ranirison 781.

Fig. 23. Distribution maps of Malagasy species of Paracephaelis. A. P. aristata De Block sp. nov. (black dot), P. bardotiae De Block sp. nov. (blue dot), P. capitulifera De Block sp. nov. (green dot), P. gautieri De Block sp. nov. (red dot), and P. grandifructa De Block sp. nov. (yellow dot). B. P. cinerea (A.Rich. ex DC.) De Block (black dot). C. P. longipedicellata De Block sp. nov. (black dot), P. orientalis De Block sp. nov. (blue dot), P. pauciflora De Block sp. nov. (green dot), P. ranirisonii De Block sp. nov. (red dot), and P. seyrigii De Block sp. nov. (yellow dot). D. P. russata De Block sp. nov. (black dot), P. sambavensis De Block sp. nov. (blue dot), P. saxatilis (Scott Elliot) De Block (green dot), P. sericea (Arènes) De Block (red dot), and P. tiliacea Baill. (yellow dot).