Melanoxerus antsirananensis Kainul., 2021

Kainulainen, Kent, 2021, A taxonomic revision of Melanoxerus (Rubiaceae), with descriptions of three new species of trees from Madagascar, Candollea 76 (1), pp. 105-116 : 107-108

1. Melanoxerus antsirananensis Kainul. , sp. nov. ( Fig. 2 ).

– Euclinia sp. 1 in KAINULAINEN & BREMER (2014: 820).

Holotypus: MADAGASCAR. Reg. DIANA [Prov. Antsiranana]: Distr. Ambilobe, Mahamasina, Réserve Spéciale d’Ankarana , 12°57 '15"S 49°07 '39"E, 100 m, 10.II.2003, fr., Bardot-Vaucoulon et al. 1406 ( P [ P00455719 ]!; iso-: K [ K000551041 ]!, MO!, TAN).

Melanoxe r us antsirananensis K ainul. diff e rs f r om M. suavissimus (Homolle ex Cavaco) Kainul. & B. Bremer by its pauciflorous inflorescences (vs. solitary flowers), campanulate (vs. funnelform) corollas, and obovate (vs. ovate to lanceolate) leaves. It most resembles M. atropurpureus Kainul. , from which it differs in that the corolla throat is white with purple and sometimes green spots (vs. uniformly purple), and in its smaller (7–18 × 4.5–8.5 cm vs. 10– 30 × 6.5–14.5 cm) and obovate (vs. broadly lanceolate) leaves.

Shrubs or trees up to 18 m tall and 40 cm dbh. Bark beige or whitish pale grey and smooth. Stipules 9–14.5 × 4–7 mm, triangular, interpetiolar, caducous. Leaves deciduous, petioles 0.7–6 cm long, adaxially canaliculate; leaf blades papyraceous, obovate, 7–18 × 4.5–8.5 cm; bases cuneate to attenuate, apices (rounded) obtuse to apiculate or shortly acuminate; adaxial surface: dark green when fresh, drying dark brown to black, smooth and glossy, glabrous; 8 – 12 pairs of conspicuous, ± pinnate secondary veins, tertiary venation reticulate; midribs prominent, whitish green when fresh, ± the same colour as the leaf when dry; abaxial surface green when fresh, drying dark brown to blackish, glabrous except for tuft domatia that are often present in the vein axils. Flowers solitary or few (<10) in a terminal, sessile, congested and umbel-like inflorescence; pedicels up to 30 mm long; hypanthium narrowly urceolate, 5–8 × 3–4 mm, glabrous. Calyces green; calyx tubes 0.5–2 mm long, externally and internally glabrous; calyx lobes 4.3–11 × 0.8–3.5 mm, narrowly triangular, spreading or recurved. Corollas fleshy, campanulate; corolla tubes 1.5–2.6 cm long, externally (yellowish) white, sometimes with purple and pale green streaks, glabrous, internally white with red, purple or violet (and sometimes also pale green) spots, glabrous or with a few trichomes (0.1 –0.5 mm long) at the very base; corolla lobes white (sometimes with purple spots on the external side), 1–4.5 × 0.8–2.5 cm, ovate to deltate, rounded to acute, spreading horizontally at anthesis; stamens subsessile (filaments c. 2 mm long), attached 10–12 mm below corolla sinus and 3 mm from anther base; anthers 11–18 × 1.5–2 mm, linear, included or shortly exserted (to 2 mm above corolla sinus). Styles simple, clavate, with shallow longitudinal grooves, 14–20 mm long, glabrous, included or shortly exserted; stigma shortly bifid (lobes 0.5–3.5 mm long). Fruits (globose) ellipsoid, 3–7.6 × 2.7–6 cm, smooth, glabrous, olive to brown, with numerous beige to pale grey lenticels (1 – 2 mm in diam.), fleshy-indehiscent with yellowish to white pulp; calyx tube sometimes persistent but calyx lobes caducous. Seeds flattened, irregularly angled, 10–15 mm in diam., c. 2 mm thick, smooth, ± translucent, yellowish brown when fresh, drying black.

Vernacular names. – “Mamoampoma” (Rakotondrafara et al. 505); “Mantalana” (Service Forestier 8329); “Voavandrikala” (Manjakahery & Sola 83).

Distribution, habitat and ecolog y. – Melanoxerus antsirananensis is only known from the DIANA and SAVA Regions in Antsiranana Province where it is widely distributed ( Fig. 1 ). The new species grows in littoral forests and in dry deciduous forests from sea level to c. 700 m in elevation on Montagne d’Ambre.

Phenology. – Flowering material has been collected from September to December and fruiting material from September to July.

Conservation status. – Melanoxerus antsirananensis is known from numerous localities in northern Madagascar. Its distribution includes five protected areas, i.e. Ankarana, Loky-Manambato, Montagne d’Ambre, and Montagne des Français. Melanoxerus antsirananensis is therefore assigned a preliminary conservation status of “Least Concern” [LC] according the IUCN Red list Categories and Criteria ( IUCN, 2012).

Notes. – The specimen Razafitsalama & Ludovic 16 is unusual in having distinctly velutinous leaves and is tentatively included here. The label on Meyers & Boltz 110 reports that the lemur Propithecus tattersalli eats the young leaves of this species. Melanoxerus antsirananensis flowers at the same time or just before the new leaves flush. It resembles M. atropurpureus in having pauciflorous inflorescences and flowers with campanulate corollas. However, the phylogenetic analysis of KAINULAINEN & BREMER (2014) indicates that they are not sister species, a result that suggests that these shared characters may be plesiomorphic rather than synapomorphic.

Melanoxerus antsirananensis is distinguished from M. atropurpureus in its smaller leaves (7 –18 × 4.5–8.5 cm vs. 10– 30 × 6.5– 14.5 cm) that are obovate rather than broadly lanceolate. Furthermore, the corolla throat is white with red to violet spots (vs. uniformly dark purple in M. atropurpureus ).

Selected additional material examined. – MADAGASCAR. Reg. DIANA [Prov. Antsiranana]: Masorolava, Mahagaga, Antsoroby forest , 12°42'37"S 48°58'11"E, 53 m, 27.IX.2007, fr., Andriamihajarivo et al. 1434 ( MO, P) ; Ankarana SR , 2 km W of Mahamasina village, 12°57'26"S 49°07'46"E, 132 m, 21–30.III.1995, fr., Andrianantoanina & Bezara 792 ( BR, G, K, MO) ; Montagne d’Ambre NP, c. 8 km E of Bobakilandy village, 12°37'37"S 49°06'26"E, 533 m, 5.XII.1995, fl., Andrianantoanina & Bezara 895 ( BR, G, K, MO) ; Andrafiamena , forest near Anjahankely, 12°54'23"S 49°19'30"E, 450 m, 6.I.2011, fr., Burivalova ZB 176 ( G, K) ; Ankarana , 12°50'47"S 49°06'18"E, 82 m, 14.I.2002, fr., De Block et al. 1226 ( BR, MO, P, TAN, UPS, WAG) ; Ankarana , 4–9.III.1951, fr., Humbert & Capuron 25493 ( BR, K) ; ibid. loco, 12°54'42"S 49°06'43"E, 240–260 m, 22.V.1993, fr., Jongkind & Rapanarivo 979 ( K, MO) ; Montagne des Français , 12°19'25.5"S 49°20'11"E, 230–250 m, 5.III.2016, ster., Kainulainen et al. 370 ( TAN) ; Anosy à 4 km au NE du village d’Ambolobozokely [Nosy Voanio], 12°26'49"S 49°33'07"E, 22 m, 30.III.2007, fr., Rakotondrafara et al. 505 ( BR, MO, P) ; Andranovondronina, Andakorobe, village le plus proche Antsaravy , 12°08'51"S 49°20'30"E, 19 m, 17.III.2006, fr., Rakotondrafara et al. 474 ( CNARP, K, MO, P, TAN) ; Montagne d’Ambre , 12°34'59"S 49°05'59"E, 683 m, 5.II.2012, fr., Ramandimbimanana & Randimbiarison SDR 372 ( BR, G, MO) ; Sahafary SF , 12°35'51"S 49°26'31"E, 250 m, 7.XI.2006, fl., Ranaivojaona et al. 1551 ( BR, MO, K, P, TAN) ; Nosy Voanio , 4 km E of Ambolobozokely, 12°26'01"S 49°33'00"E, 15 m, 15.II.2006, fr., Randrianaivo et al. 1364 ( BR, MO) ; Mosorolava, Ampombiantambo, Antsoroby forest , 12°42'13"S 48°58'12"E, 75 m, 23.IX.2007, fl. & fr., Ratovoson et al. 1332 ( CNARP, G, MO, P, TAN) ; Ankarana , 11–14.I.2002, fr., Razafimandimbison & Andrianatoanina 454 ( BR, MO, UPS) ; Ankarongana, Irodo , N of Analamerana forest, Ampandriantsira , 12°39'42"S 49°32'37"E, 50–123 m, 14.II.2001, fr., Razafitsalama & Ludovic 16 ( MO, P) ; Montagne des Français , 250 m, 18.II.1954, fr., Service Forestier 8329 ( P, TEF) ; Ankarefo , 18.V.1954, fr., Service Forestier 10003 ( P) ; Diego-Suarez, Bemaskabe forest , 200–500 m, 17.X.1927, fr., Ursch 231 ( P) . Reg. SAVA [Prov. Antsiranana]: Distr. Vohemar, Daraina, Bekaraoka south , 13°11'S 49°42'E, 9.IV.2008, fr., Bremer et al. 5113 ( MO, S, TAN) ; Hillside next to Daraina, 13°08'S 49°27'E, 10.IV.2008, fr., Bremer et al. 5131 ( MO, S, TAN) ; Daraina, Bobankora forest , 13°12.72'S 49°46.27'E, 200 m, 2.II.2003, fr., Gautier et al. LG 4195 ( G, K, MO) ; Daraina, Bekaraoka forest , 13°03.90'S 49°42.35' E, 420 m, 22.XI.2006, fl., Gautier et al. LG 4911 ( G) ; Nosibe, Anjiabe, Anaborano , 13°04'18"S 49°54'32"E, 33 m, 11.XII.2004, fr., Manjakahery & Sola 83 ( MO) ; Mantamena , 7 km NW of Daraina, 13°08'S 49°42'E, 112–330 m, IV.1990, Meyers & Boltz 110 ( MO) ; Nosibe, Anjiabe, Analabe forest , 13°04'43"S 49°54'04"E, 11.V.2004, fr., Rabehevitra et al. 915 ( MO, P) ; Tsarabaria, Manakana, Ambondrombe forest , 13°42'58"S 50°05'37"E, 3 m, 24.X.2002, fr., Rabenantoandro et al. 1019 ( MO) ; Nosibe , Anjiabe , Anaborano forest, near lake Sahaka, 13°04'42"S 49°54'13"E, 25 m, 2.XI.2002, fl., Rabenantoandro et al. 1091 ( MO, TEF) ; ibid. loco, 13°04'43"S 49°54'04"E, 10 m, 23.II.2003, fr., Rabenantoandro et al. 1272 ( MO, TEF) ; Mosorolava forest , 13°05'44"S 49°54'43"E, 23 m, 5.X.2013, fl., Rakotovao 6482 ( MO) ; Fanambana , Ambohimahazo forest, 13°35'44"S 50°00'04"E, 60–100 m, 30.III.2001, fr., Ranaivojaona et al. 355 ( BR, MO, P) ; Solanampilana forest 35 km N of Daraina, 13°05'42"S 49°34'57"E, 137 m, 9.XII.2006, fl. & fr., Randrianaivo et al. 1433 ( G, MO, P, TAN) ; Daraina , Ambilondomba forest, 13°09'39"S 49°38'47"E, 390 m, 31.I.2004, fr., Ranirison et al. PR 367 ( G) ; Vohimarina , Fanambana, Antsatoby, 13°36'55"S 49°59'55"E, 77 m, 8.VII.2007, fr., Rasoafaranaivo 239 ( MO) ; Analabe forest , near Anaborano village and Sahaka lake, 13°04'59"S 49°54'26"E, 10.VII.2003, fr., Razakamalala 519 ( MO, P, TEF) ; Tsarabaria , Manakana , E of Ambondrobe village, 13°43'08"S 50°05'50"E, 13.III.2004, fr., Razakamalala RZK 1022 ( K, MO, P, TEF) .

Figures

Fig. 2. – Melanoxerus antsirananensis Kainul. A. Habit; B. Fruit and smooth bark of a trunk (c. 20 cm dbh); C. Fruiting branch; D–F. Flowering branch with young leaves; G. Immature fruits; H. Cross-section of a fruit showing the seeds embedded in whitish pulp. [A–B, H: Bremer et al. 5113; C, G: Ramandimbimanana & Randimbiarison SDR 372; D–E: Ratovoson 1332; F: Randrianaivo 1433] [Photos: A–B, H: K. Kainulainen; C, G: S.D. Ramandimbimanana; D–E: F. Ratovoson; F: R. Randrianaivo]

Fig.1.– Distribution of Melanoxerus antsirananensis Kainul. (yellow circles), M. atropurpureus Kainul. (pink circles), M. maritimus Kainul. (triangles), and M. suavissimus (Homolle ex Cavaco) Kainul. & B. Bremer (stars) in Madagascar.[mapped on the bioclimatic zones of Madagascar (after CORNET, 1974; see SCHATZ, 2000)]