Paracephaelis comorensis 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 : 38-42

Paracephaelis comorensis De Block sp. nov.

urn:lsid:ipni.org:names:77260707-1

Figs 2J–K , 9

Diagnosis

Differing from Paracephaelis trichantha by having thinner (papyraceous or subcoriaceous vs coriaceous) and larger leaves (6–23 × (2.5–) 4–13 cm vs 2.5–13 × 2.5–8 cm), acuminate leaf tips (vs rounded, obtuse or retuse and mucronate), longer stipular awns (2–4 mm vs 0.5–2 mm long), longer corolla lobes (3–4.5 mm vs 1.2–2 mm long), longer anthers (3–3.5 mm vs 1.5–2.5 mm long), and longer filaments (0.75–1 mm vs 0.1–0.2 mm long).

Etymology

The species epithet is based on the geographic distribution of the species.

Type material

COMORO ISLANDS – Mayotte • Grande Terre, Handrema, Pointe Handrema ; 200 m a.s.l.; 7 Dec. 1996; fl; Labat & Pascal 2887; holotype: P [ P00078874 ]; isotypes: K, MAO n.v., MO, WAG [ WAG.1466458 ] .

Other material studied

COMORO ISLANDS – Anjouan • face NW du mont Tingui, village Hambo , canton Ouani ; 10 Mar. 1957; fr; coll. ignot. 16655-SF; P online • s.loc.; s.dat.; fl; Lavanchie 22; P. – Mayotte • Bandrélé, Choungui Kely, Hauts de M’tsamoudou ; 7 Feb. 2001; fl; Barthelat, M’Changama & Sifary 288; G n.v., K, MAO n.v., MO n.v., P • Ilot Bouzi, Mamoudzou ; 4 Mar. 2002; fl; Barthelat, Gomel & Sifari 732; BR, K, MAO n.v., P • Tsararano, Ironi Bé ; 15 Jul. 2006; fr; Barthelat, Mchangama & Ali Sifari 1654; G n.v., K, MAO n.v., MO n.v., P • Grande Terre, Longoni ; 20 Jul. 2006; fr; Barthelat, Mchangama & Ali Sifari 1656; MAO n.v., MO n.v., P online • s.loc.; 1840; fr; Boivin s.n.; K • s.loc.; 1840; fr; Boivin in Drake s.n.; P • bord de la mer à Pamanzi, côte ouest; 1850; fr; Boivin 3179; K, P • s.loc.; 1850; fr; Boivin 3180; P • centre NE, près du sommet du mont Sapéré; 550 m a.s.l.; 23 Feb. 1975; fl; Floret 1188; K, P • Saziley crête ; 1 Jun. 1999; fr; Mas 224; K, P • Petite Terre, Moya, rocher intermédiaire entre les deux Moyas; 0–60 m a.s.l.; 5 Feb 2007; fl; Mouly 554; BR, K n.v., MAO n.v., P, TAN n.v . • Grande Terre, Combani, Mt. Combani , bordure de Réserve du Mlima Combani, le long du Grande Randonnée; 200–300 m a.s.l.; 8 Feb. 2007; fl; Mouly 580; BR, K n.v., MAO n.v., P • Grande Terre, Sohoa littoral à la base du plateau de Sohon, versant ouest; 0–30 m a.s.l.; 12 Feb. 2007; fl; Mouly 616; BR, MAO n.v., P • Chissioua Mtsamboro , près du sommet ; 221 m a.s.l.; 15 Apr. 1999; fr; Pignal & Pibot 1166; BR, MO, P . – Mohéli • Hamavouno, lac de Boundouni ; 87 m a.s.l.; 26 May 2006; fr; Labat, Yahaya & Abdou 3704; K, P online .

Description

Shrub or tree, to 8 m tall, dbh to 20 cm; pubescence whitish or more rarely tawny. Young shoots brown or dark brown, glabrous; older branches corky, greyish or pale brown, glabrous. Petioles 10–25 mm long, moderately to sparsely covered with long appressed or spreading hairs. Leaf blades ovate or, more rarely, elliptic or broadly obovate, 6–23 × (2.5–) 4–13 cm, papyraceous to subcoriaceous, drying brown or more rarely greenish and hardly discolorous, upper surface somewhat glossy, glabrous or with midrib and, more rarely, secondary veins sparsely covered with long appressed hairs, lower surface glabrous or with midrib sparsely to moderately and secondary veins sparsely covered with long appressed hairs; margin sometimes sparsely ciliate; base cuneate or, more rarely, obtuse, rounded or truncate; tip acuminate, acumen 5–15(–25) mm long; hair tuft domatia present; midrib and secondary veins often somewhat paler than blade on the lower surface; (6–)8–12 secondary veins on each side of midrib, somewhat raised below; higher order venation often somewhat discolorous below. Stipules triangular with needle-like awn, keeled, outer surface moderately to sparsely covered with long appressed or spreading hairs at the base or along the keel, inner surface glabrous with row of colleters interspaced with sparse hairs at the base; sheath 2.5–4 mm long; awn 2–4 mm long. Inflorescences sessile, compact, 2–4.5 × 3.5–7 cm, with numerous flowers; inflorescence parts densely covered with appressed or spreading hairs; first order axes 0.3–1.3(–2.5) cm long; higher order bracts with stipular parts reduced or absent, foliar parts triangular and vaulted, 2–6 mm long; bracteoles present or absent, if present then on pedicel somewhat below ovary, usually not opposite, stipular parts absent, foliar parts linear, 0.75–1 mm long, tips acute. Flowers shortly pedicellate or rarely subsessile, pedicels (0–)1–3(–5) mm long. Calyx densely covered with appressed hairs outside; tube 0.4–0.6 mm long, inner surface with ring of long appressed hairs; lobes triangular, 0.4–0.6 mm long, inner surface glabrous or sparsely covered with short appressed hairs, margins ciliate, tips acute. Corolla tube 5–7 mm long, inner surface densely covered with long erect hairs in upper half or upper ⅔; lobes 3–4.5 mm long, margins ciliate. Anthers 3–3.5 mm long, completely exserted from corolla tube at anthesis; filaments 0.75–1 mm long. Ovary 0.75–1.2 mm long, densely covered with ± short appressed hairs; per locule (1–)3–5 ovules pendulous from small placenta attached to upper half of septum. Style and stigma 9–14 mm long, exserted for 4–6.5 mm; style densely covered with long erect hairs from 2–4 mm above base to somewhat below papillate zone; stigmatic lobes 4–4.5 mm long, upper 2–2.5 mm fusiform; papillate grooves running along fusiform part and further down for ca 2 mm. Fruits spherical, 0.4–0.5 cm in diam., wrinkled when dried, moderately to densely covered with short appressed hairs; fruit wall thin, with sclerified vascular bundles; pyrenes hemispherical, 3.5–4 mm in diam., membranous adaxially, thinly crustaceous abaxially, with rounded base, shortly acuminate tip and small adaxial opening somewhat below the apex. Seeds (1–)2–4 per fruit, 2–2.5 × 2.5–3 mm.

Distribution

Mostly collected from Mayotte, but also occurring on Mohéli and Anjouan ( Comoro Islands) ( Fig. 24 ).

Habitat and phenology

Dry forest or thicket, mesophyllous (intermediate) forest; on rocks; elev. 0– 550 m. Flowers: December– March; Fruits: March–July. According to Barthelat (2019), flowering continues until May, but this was not observed by the author.

Vernacular names

Botinati (coll. ignot. 16655-SF); mora folaka malandy (Barthelat et al. 732); mora folaka tamtam (Barthelat et al. 288).

Provisional IUCN assessment

Vulnerable: VU B1ab(iii) B2ab(iii). This assessment is based on 14 herbarium collections with detailed locality data, collected between 1850 and 2007. The EOO of P. comorensis sp. nov. is estimated to be below 1009 km 2 (the sum of the surface areas of Mayotte, Anjouan, and Moheli), which complies with the Endangered category under criterion B1. The AOO is estimated to be 56 km 2, which also complies with the Endangered category under criterion B2. The species is known from 10 locations, which is the upper limit for the Vulnerable category under subcriterion ‘a’ of criterion B2. In 8 of these 10 locations, the presence of the species was confirmed relatively recently (between 1999 and 2007). The species is present in the Réserve Forestière de Majimbini and was also collected near the border of the Réserve Forestière de Combani. In the Comoros, 80–90% of the natural vegetation has been destroyed and replaced by fields for subsistence farming, secondary forests of which the understory is planted with, e.g., bananas, as well as plantations, grassland, and very degraded uncultivable areas known as padza ( Stafford 2001). The Comoro islands, e.g., Anjouan, are densely populated and population densities continue to rise, with ca 90% of the inhabitants depending on subsistence farming for their livelihood ( Doulton et al. 2015). The islands’ deforestation has been the highest in the world between 2000 and 2010 ( Doulton et al. 2015). Remaining forests are cleared for subsistence farming and the grazing of livestock, targeted for construction wood, firewood, wood for the production of charcoal, and other resources such as, e.g., medicinal plants, with secondary damaging factors being volcanic eruptions, cyclones, and invasive exotic species ( Louette 2004). Because of these facts, a reduction in the extent and quality of the habitat of P. comorensis sp. nov. is inferred. This threat, in combination with the low AOO and the 10 locations, qualifies P. comorensis sp. nov. as Vulnerable.

Notes

1. The three specimens Boivin 3180 (P) bear the name “ Tarenna comorensis ” and are placed in a type folder in P. But this species name was never published. This historical material is not chosen as type of P. comorensis sp. nov. because the material is only present in P and one of the three sheaths is a

mixture of material (the second specimen belongs to Coptosperma mitochondrioides Mouly & De Block ). Furthermore, no flowers and only few fruits are available.

2. The Paracephaelis specimens from the Comoro Islands have historically been placed with P. trichantha (usually as Tarenna trichantha ; Fosberg 1979; Fosberg & Renvoize 1980; Bridson 1979, 1988, 2003). The material from the Comoros is similar to P. trichantha by the densely pubescent, compact inflorescences, the small corolla and calyx, and similar to its glabrous form as regards the pubescence of the vegetative parts. But there are many differences, such as larger, less coriaceous leaves with acuminate tip and longer stipular awns, corolla tubes, corolla lobes, anthers and filaments.

3. In Mouly 554, the dense pubescence on the outer surface of the corolla lobes is restricted to the basal halves while the upper halves are glabrous.

4. This species was recognized as new by several botanists who annotated specimens in the P herbarium. Boivin annotated Boivin 3179 as ” Lamprospermum comorense ” and Baillon labeled Boivin s.n. and Boivin 3180 as “ Tarenna comorensis ”. Homolle (1938) used the name “ Enterospermum comorense ” to indicate this species. All these names are nomina nuda.

5. Paracephaelis comorensis sp. nov. strongly resembles P. cinerea in flower and fruit morphology. This is also the case for P. trichantha , even though in this species the flowers are markedly smaller than in the two other species. In an early stage of the revision process, the author regarded the three species as too morphologically similar to distinguish them at species level. After thorough revision of all Paracephaelis material to evaluate the morphological differences between and within species and taking into account that 1) the three taxa form separate geographic entities that are unlikely to have the opportunity to interbreed, with P. comorensis sp. nov. restricted to the Comoro Islands, P. trichantha to the Seychelles and the East African coast and P. cinerea to Madagascar, 2) the morphological differences between the taxa, and 3) the fact that two taxa already had existing species names, it was decided to recognize them at specific level. The above described process resulted in the annotation of specimens of P. comorensis sp. nov. as “ Paracephaelis cinerea subsp. comorensis ”, a name which was never published. Unfortunately, this nomen nudum was picked up in La Flore Illustrée de Mayotte ( Barthelat 2019: 527).

Figures

Fig. 2. Overview of the placentation in Paracephaelis Baill. A–K. Abaxial views of placenta and ovules. A’. Adaxial view of placenta and ovules with zone of attachment of the placenta indicated. A–C. Typical placentation type of Paracephaelis, with many ovules arranged at the periphery of the placenta.D–E. Idem, with fewer ovules. F–H. Idem, but ovules restricted to the top of the placenta. I. Typical placentation type in P. cinerea (A.Rich. ex DC.) De Block, P. comorensis De Block sp. nov. and P. trichantha (Baker) De Block. J–K. Idem, with fewer ovules. Drawn by Mr A. Fernandez. From Perrier de la Bâthie 13452 (P. tiliacea Baill., A, A’); Pervillé 633 (P. tiliacea Baill., B); Capuron 23451-SF (P. longipedicellata De Block sp. nov., C); McPherson et al. 14875A (P. saxatilis (Scott Elliot) De Block, D); Gautier et al. 4188 (P. gautieri De Block sp. nov., E); De Block et al. 1280 (P. bardotiae De Block sp. nov., F); De Block et al. 1048 (P. russata De Block sp. nov., G–H); Capuron 23073-SF (P. cinerea (A.Rich. ex DC.) De Block, I); Barthelat et al. 732 (P. comorensis De Block sp. nov., J); and Labat & Pascal 2887 (P. comorensis De Block sp. nov., K).

Fig. 9. Paracephaelis comorensis De Block sp. nov. A. Flowering branch. B. Leaf. C. Domatia and pubescence on midrib. D. Stipule. E. Bracteole, ovary and calyx. F. Corolla, stamens, style and stigma. G. Fruit. H. Pyrene, adaxial view. Drawn by MrA. Fernandez. From Labat & Pascal 2287 (A), Mouly 580 (B–D), Mouly 616 (E–F) and Pignal & Pibot 1166 (G–H).

Fig. 24. Distribution map of Paracephaelis comorensis De Block sp. nov.