Paracephaelis russata 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 : 62-63

Paracephaelis russata De Block sp. nov.

urn:lsid:ipni.org:names:77260714-1

Figs 1L , 2G–H , 16

Diagnosis

Differing from Paracephaelis tiliacea by having shorter petioles (0.5–1.2 cm vs 1–3 cm long), a higher number of secondary veins (8–16 vs 5–8), longer stipular sheaths (0.8–2 cm vs 0.4–0.7 cm long), more lax inflorescences (first order axes 2–7 cm vs 0.5–1.5 cm long and pedicels 0–12 mm vs 0–2 mm long), longer calyx tubes (1–1.5 mm vs 0.5–0.7 mm long), a lower number of ovules (1–4 per placenta vs 4–10), and by not having a Terminalia branching pattern (vs present).

Etymology

The species epithet is based on the reddish colour of the pubescence on most of the specimens.

Type material

MADAGASCAR – Antsiranana Province, Diana Region, Ambilobe District • Ankarana , close to Mahamasina ; 82 m a.s.l.; 27 May 1999; fr; De Block, Rapanarivo & Randriamboavonjy 1048; holotype: BR [ BR000000933669 ]; isotypes: BR[BR000000855054], K, MO, P, TAN .

Other material studied

MADAGASCAR – Antsiranana Province, Diana Region, Ambilobe District • plateau calcaire de l’Ankarana , W de Mahamasina, Antanatsimanaja ; 23 Apr. 1963; fr; Capuron 22674-SF; BR, P, TEF • Ankarana, tsingy , ca 3 km NE of Mahamasina, not part of Ankarana PN, on right side of road (going towards Antsiranana) at the second bridge from Mahamasina; 16 Jan. 2002; fl; De Block, Rakotonasolo & Randriamboavonjy 1252; BR, G, K, MO, P, TAN • Tanambao-Marivorahona, 5 km E du hameau Betsimiranjana, au lieu dit Andohanantsohihy, partie sud; 65 m a.s.l.; 4 Jul. 2005; fr; Leopold, Razafitsalama, Guittou & Ndaza dit Tsimihetibe 112; CNARP n.v., MO n.v., P online, TAN n.v . • Marivorahona, Betsimiranja, Andohan’Antsoha ; 40 m a.s.l.; 16 Jul. 2005; fr; Rakotondrafara, Rakotonandrasana, Randrianaivo, Leopold, Bezara & Benjara 310; BR, MO, P • Ankarana RS ; 11– 14 Jan. 2002; fl, fr; Razafimandimbison & Andrianatoanina 466; UPS . – Sava Region, Vohemar District • commune Daraina, Daraina , forêt de Solaniampilana-Maroadabo ; 120 m a.s.l.; 9 Mar. 2004; fl; Gautier, Wohlhauser, Nusbaumer & Ranirison 4526; BR, G • commune Daraina, Daraina, forêt d’Ambohitsitondroina ; 140 m a.s.l.; 16 Mar. 2004; fr; Gautier, Wohlhauser, Nusbaumer & Ranirison 4597; BR, G .

Description

Shrub or small tree, 1.5–6 m tall; pubescence tawny to reddish brown. Young shoots brown to reddish brown, densely covered with long erect hairs; older branches brown to reddish brown, flaking, glabrous. Petioles 0.5–1.2 cm long, densely covered with long erect hairs. Leaf blades ovate, broadly ovate or elliptic, 11.5–21 × 5–11 cm, papyraceous to subcoriaceous, drying blackish brown above and dark brown below, upper surface glossy and sparsely to moderately covered with long erect hairs (more densely pubescent on midrib and secondary veins), lower surface densely covered with long erect hairs; base obtuse, rounded, unequal or somewhat cordate; tip shortly acuminate with acumen 0.3–1 cm long; domatia absent; 8–16 secondary veins on each side of midrib, somewhat raised above, raised below; higher order venation inconspicuous on both surfaces. Stipules ovate or broadly ovate with needle-like awn, keeled, outer surface densely covered with long erect hairs at the base and along the midrib, elsewhere sparsely pubescent or glabrous, inner surface sparsely covered with short appressed hairs and with row of colleters at the base, margin ciliate; sheath 0.8–2 cm long, awn 2–6 mm long. Inflorescences sessile, 4–10 × 5–13 cm, with numerous flowers; inflorescence parts densely covered with long erect hairs; first order axes 2–7 cm long; branchings often subopposite with bracts displaced 1–4 mm above branching point; higher order bracts with stipular parts reduced or absent and foliar parts narrowly triangular, up to 10(–15) mm long or rarely leaf-like, up to 1 × 0.5 cm long; bracteoles on pedicel somewhat below ovary, subopposite, stipular parts absent, foliar parts linear, 3–5 mm long, tips acute. Flowers pedicellate, pedicels 0–5 mm long in flowering stage (central flower in triad often sessile), 0–12 mm long in fruiting stage. Calyx densely covered with long erect hairs outside; tube 1–1.5 mm long, inner surface densely covered with long appressed hairs; lobes oblong to triangular, 2–4 mm long, inner surface moderately to sparsely covered with appressed hairs, tips acute. Corolla tube 9–11 mm long, inner surface densely covered with long spreading hairs in upper half; lobes 4–6 mm long. Anthers ca 4 mm long, completely exserted or basal part (ca 1 mm long) included in corolla tube at anthesis; filaments 0.2–0.3 mm long. Ovary 1.5–2 mm long, very densely covered with long erect hairs; per locule (1–)2–4 ovules arranged at periphery of placenta attached to middle of septum. Style and stigma 15–19 mm long, exserted for 7–8 mm; style densely covered with long erect hairs for 2–3 mm below papillate zone; stigmatic lobes 7–9 mm long. Fruits ovoid, faintly ribbed longitudinally and glossy (when dried), ca 10 × 8–9 mm, moderately covered with long erect hairs; fruit wall thin, with sclerified vascular bundles; pyrenes hemiovoid, ca 9 × 6.5 mm, crustaceous, with rounded or truncate base, acuminate 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 2–6(–8) per fruit, 3.5–4.5 × 2.5–3.5 mm.

Distribution

Endemic to northern Madagascar. Only known from Ambilobe District, Diana Region, and Vohemar District, Sava Region (Antsiranana Province) ( Fig. 23D ).

Habitat and phenology

Low-elevation dry deciduous or semi-deciduous forest; on limestone or limestone covered with sand; elev. 40– 150 m. Flowers: January–March; Fruits: January–July.

Provisional IUCN assessment

Endangered: EN B1ab(iii) B2ab(iii). This assessment is based on seven herbarium specimens, collected between 1963 and 2005. The EOO is estimated to be 627 km 2, which complies with the Endangered category under criterion B1. The AOO is estimated to be 24 km 2, which also complies with the Endangered category under criterion B2. Paracephaelis russata sp. nov. is known from five locations, which is the upper limit for the Endangered category under subcriterion ‘a’ of criterion B2. Three of the seven specimens are found in the Ankarana Special Reserve (1 location), two are found in different forests of the Loky-Manambato New Protected Area (2 locations) and three specimens were collected outside protected areas (2 locations). The main threat to the species is loss of habitat as a result of anthropogenic factors. This loss of habitat even takes place inside the protected areas. In the Loky-Manambato New Protected Area, an archipelago of forests of different size and different ecology (dry, humid, lowland, montane; Nusbaumer et al. 2010), natural vegetation is lost by conversion into fields for subsistence farming, bushfires, and traditional gold mining. Furthermore, there is logging for timber and charcoal, extraction of natural resources, and hunting ( Rakotondravony 2009; Nusbaumer et al. 2010). All these factors also play an important role in habitat destruction in the Ankarana Special Reserve, although mining there is for sapphires ( Nicoll & Langrand 1989; Cardiff & Befourouack 2008). Because of the above-mentioned facts, we infer a reduction in the extent and quality of the habitat of P. russata sp. nov. This fact, in combination with the low EOO, low AOO and the low number of locations, qualifies the species for Endangered status.

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. 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. 16. Paracephaelis russata De Block sp. nov.A. Fruiting branch. B. Stipules. C. Bracteoles, ovary and calyx. D. Corolla, stamens, style and stigma. E. Fruit. F. Pyrene, adaxial view. Drawn by Mr A. Fernandez. From De Block et al. 1048 (A–C, E–F) and Gautier et al. 4526 (D).

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).