Paranecepsia andrafiabensis Barberá & O.Lachenaud, 2022

Barberá, Patricia, Lachenaud, Olivier & Riina, Ricarda, 2022, A new species of Paranecepsia (Euphorbiaceae-Acalyphoideae) from Madagascar and its relationships among the ‘ alchorneoids clade’, European Journal of Taxonomy 834, pp. 22-37 : 28-34

Paranecepsia andrafiabensis Barberá & O.Lachenaud sp. nov.

urn:lsid:ipni.org:names:77302734-1

Figs 3–6

Diagnosis

Paranecepsia andrafiabensis sp. nov. is morphologically similar to P. alchorneifolia , but differs from it mainly by having longer petioles (0.6–2.6 vs 0.3–0.8 cm long), stipels shorter or absent (1–2.2 mm when present vs 2.5–5 mm long, always present), shorter staminate inflorescences (<1.3 cm vs 4.5–9 cm long), pistillate flowers with longer sepals (9–15 mm vs 5–9 mm long), bilocular ovary (vs trilocular), and seed coat mottled with dark and pale brown (vs uniformly brown).

Etymology

The specific epithet refers to the type locality, Andrafiabe village, at the western border of the Ankarana tsingy.

Material examined

Type MADAGASCAR ‒ Diana Region • Ambilobe, Andrafiabe, at the base of the wall of Ankarana ; 12°55′40″ S, 49°03′41″ E; alt. 66 m; 21 Nov.2019; pistillate fl.; P.Barberá, P.Antilahimena, J. Razanatsoa and S. Andriazafy 2770; holotype: MO-6956134 ; isotypes: BR, P, TAN .

Paratypes MADAGASCAR ‒ Diana Region • Andrafiabe, PM 200 from the camp, on the circuit to Grotte de Andrafiabe; 12°55′55″ S, 49°03′29″ E; alt. 72 m; 21 Nov. 2019; pistillate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2764; BR, MA, MO, P, TAN • ibid.; staminate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2765; BR, MO, P, TAN • ibid.; offshoot; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2767; BR, MO, P, TAN • Andrafiabe, at the base of the wall of Ankarana ; 12°55′40″ S, 49°03′41″ E; alt. 66 m; 21 Nov. 2019; staminate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2769; BR, MA, MO, P, TAN • ibid.; 12°55′38″ S, 49°03′45″ E; alt. 49 m; 21 Nov. 2019; pistillate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2771; BR, MO, P, TAN • ibid.; 12°55′51″ S, 49°03′32″ E; alt. 48 m; 21 Nov. 2019; pistillate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2772; BR, MO, P, TAN • ibid., 12°56′08″ S, 49°03′22″ E; alt. 37 m; 23 Nov. 2019; pistillate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2797; BR, MO, P, TAN • ibid., 12°56′08″ S, 49°03′20″ E; alt. 38 m; 23 Nov. 2019; pistillate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2798; BR, MA, MO, P, TAN • ibid.; 12°56′05″ S, 49°03′23″ E; alt. 62 m; 23 Nov. 2019; staminate fl.; P. Barberá, P. Antilahimena, J. Razanatsoa and S. Andriazafy 2799; BR, MO, P, TAN • à la base du mur de l’Ankarana ; 16–28 Jan. 1969; fr.; Service Forestier (R. Capuron) 28711_SF; BR [ 0000025668131 V], G, K, MO [ 6911563 ], P [ 05570467 ], TEF • forêt au pied de la falaise de l’Ankarana ; Jan. 1969; fr.; P. Morat 3054; MO [ 5990069 ], P [ 05570468 ], P [ 05570469 ], P [ 05570470 ], P [ 05570471 ], TAN .

Description

Medium sized tree, 5–15 m high, 14–40 cm DBH; bark smooth when young, with numerous warty lenticels, gray; older bark scaly forming small or medium-sized loosely attached plates; twigs cylindrical, glabrous, soon woody with pale buff-grey bark. Bud scales triangular to ovate, 2–5.5× 0.7–2 mm, apex acuminate to very long acuminate, glabrous to densely pubescent on both faces. Stipules linear-lanceolate, 3–8 mm long, caducous, densely pubescent with simple trichomes to 0.8 mm long. Leaves with petiole 0.6–2.6 cm long, canaliculate above and obscurely bipulvinate, eglandular, glabrous to puberulous, trichomes sometimes confined to upper side of petiole in the older leaves; leaf blade elliptic to oblanceolate, 4–15.5× 1.2–5.5 cm long; chartaceous to papyraceous, glabrous above, below with scattered short simple trichomes on the midrib and domatia present as hairy tufts in the axils of the secondary veins; midrib prominent above and more strongly so below; secondary veins 10–13 pairs, prominent on both sides, strongly ascending and irregularly arching near the margin; tertiary veins scalariform, prominent and rather dense beneath; quaternary veins very densely reticulate forming small squares, only visible with hand lens; base rounded to subcordate; apex acute to acuminate, sometimes rounded, and rarely emarginate; margin serrate with 20–30 glandular teeth per side; leaf glands absent, or 1–4(–5) present near the base of the lamina on the lower surface, rarely reaching upper parts of the leaf, flat, elliptic to rounded, 0.3–0.6× 0.2–0.3 mm; stipels setaceous, 1–2.2× 0.1– 0.15 mm, glabrous, inserted on the petiole distinctly below the blade insertion, erect, sometimes absent. Staminate inflorescences up to 1.3 cm long; axis slightly pubescent or with scattered trichomes, bearing up to 3 bracts and (1–)2–6 flowers and 1–3(–5) flowers per bract; bracts ovate to lanceolate, sometimes oblong, 2–3× 1–1.5 mm, acute, densely pubescent outside, glabrous inside; bracteoles 1 per pedicel, linear, ca 1× 0.2 mm, sparsely pubescent outside, sometimes absent. Staminate flowers with pedicel 3–5.5 mm long, jointed 1–2 mm from the base; bud subglobose, 1.8 mm in diameter, pubescent, greenish; calyx lobes 3–5, ovate-lanceolate, 2.7–4.8× 0.4–2.5 mm, acute to shortly acuminate, papyraceous, appressed-pubescent outside at least towards apex, glabrous inside, yellowish to greenish; stamens 20–33, filaments 2–3.5 mm long, greenish, anthers 0.4–0.7mm long, yellowish,thecae elliptic, connective minutely apiculate; disk glands elongated, glabrous, greenish. Pistillate inflorescences 1(–2)-flowered, axis glabrous; bract very narrowly lanceolate, 1.1–3× 0.2–0.3 mm, acute, pubescent. Pistillate flowers with pedicel 0.6–1.6 cm long, articulate (0.1–) 0.4–1 cm from the bract; sepals 4–5, separate from each other, slightly unequal in size, narrowly elliptic or elliptic to oblanceolate, sometimes oblong, 7–15×2–6(–7) mm, papyraceous, glabrous inside, sparsely pilose on the central part outside, hairy apically, conspicuously veined, apex acute to acuminate, rarely rounded, margins entire; petals (1–)2–5, unequal, linear or narrowly elliptic to narrowly oblanceolate, (0.2–)0.6–5(–5.4)×(0.05–)0.1–0.8(–1.2) mm, acute, glabrous, yellowish to greenish; staminodes 1 or absent, extending to the same length as the disc, basally terete, apically enlarged; disc 1.8–2.6 mm wide, yellowish to greenish, glabrous; ovary 2-locular, 2–4.2×3.5–7.3(–8.3) mm, greenish-yellowish; styles 2, 2.5–3.2 mm long, connate, pilose, greenish, stigmas bifid, shortly fimbriate. Fruits strongly bilobed, 7–8×13× 7.5 mm, minutely tuberculate, covered with a dense rufous puberulous indumentum, and with sparse longer whitish trichomes ca 0.2 mm long (one at the top of each tubercle), brownish when dry; pedicel 1.4–1.9 cm long; calyx and petals persistent; columella ca 5 mm long; seeds globose, ca 6× 6 mm, testa mottled with dark and pale brown, hilum broadly ellipsoid, ca 2.2 × 2 mm.

Distribution, habitat, and phenology

Paranecepsia andrafiabensis sp. nov. is only known from the dry, deciduous forest on karstic limestone (‘tsingy’) that surrounds part of the base of the western wall of the Ankarana tsingy, in northwestern Madagascar, at elevations between 37 and 72 m. The flowering material of this species was collected in November and the fruiting one in January.

Preliminary conservation assessment

Paranecepsia andrafiabensis sp. nov. is endemic to northwestern Madagascar where it grows at the base of the western wall of the Ankarana tsingy. It is presently known from 11 herbarium specimens, two of them collected in fruit by Morat and Capuron in 1969, and recently (in 2019) several collections with flowers and fruits were made at east of Andrafiabe village.All the collections represent seven occurrences and only one subpopulation of the species. We have verified that the species is abundant at this site with many seedlings and mature trees. Based on a 2× 2 km cell size, the AOO is estimated as 4 km 2, which is less than the upper threshold for “Critically Endangered” status under Criterion B2. The EOO is the same as the AOO. All known occurrences are located at the limits of a protected area (Ankarana National Park), and no specific threats have been identified at the present time. However, we estimate that the population size is less than 1000 mature individuals, and that the species presumably has a low dispersal ability. For these reasons, Paranecepsia andrafiabensis is assigned a preliminary status of VU D1.

Notes

The stipels at the base of the leaf blade are present on some specimens and absent in others, even on very young leaves; this appears to be individual variation.

Figures

Fig. 3. Illustration of Paranecepsia andrafiabensis Barberá & O.Lachenaud sp. nov. a. Branch with pistillate flower. b. Bud. c. Leaf base with stipels. d. Detail of the lower leaf surface with domatia. e. Leaf margin. f. Staminate inflorescence. g. Staminate flower. h. Stamen. i. Pistillate flower. j. Petal of pistillate flower. k. Ovary and stigmas, lateral view. l. Fruit with persistent calyx, lateral view. m. Fruit, top view. n. Seed, lateral view. From Barberá et al. 2797 (a–b), Capuron SF-28711 (c–e, l–n), Barberá 2799 (f), Barberá et al. 2765 (g–h), Barberá et al. 2771 (i), Barberá et al. 2798 (j), Barberá et al. 2764 (k). Drawn by O.Lachenaud.

Fig. 4. Field photographs of Paranecepsia andrafiabensis Barberá & O.Lachenaud sp. nov. a. Forest of Paranecepsia andrafiabensis. b. Old trunk. c. Seedlings. d. Detail of old tree trunk. e. Detail of young tree trunk. From Barberá et al. 2769 (b, d), Barberá et al. 2767 (c), Barberá et al. 2798 (e). Photos by P. Barberá.

Fig. 5. Field photographs of Paranecepsia andrafiabensis Barberá & O.Lachenaud sp. nov. a. Bud. b. Domatial hair tufts at primary-secondary vein junctions. c. Leaf base and stipule. d. Stipels. From Barberá et al. 2767 (a, c–d), Barberá et al. 2765 (b). Photos by P. Barberá.

Fig. 6. Field photographs of Paranecepsia andrafiabensis Barberá & O.Lachenaud sp. nov. a. Staminate inflorescence. b. Pistillate inflorescence. c. Detail of the bract of the pistillate flower. d. Pistillate flower, lateral view. e. Pistillate flower, top view. From Barberá et al. 2799 (a), Barberá et al. 2765 (b–c), Barberá et al. 2771 (d), Barberá et al. 2772 (e). Photos by P. Antilahimena (a) and P. Barberá (b–e).