Ochna oxyphylla N.Robson (Robson 1962: 21)

Shah, Toral, Mashimba, Fandey H., Suleiman, Haji. O., Mbailwa, Yahya S., Savolainen, Vincent, Larridon, Isabel & Darbyshire, Iain, 2023, A taxonomic revision of the ecologically important Ochna holstii (Ochnaceae) complex using molecular and morphological data, Plant Ecology and Evolution 156 (2), pp. 174-200 : 174

3. Ochna oxyphylla N.Robson (Robson 1962: 21)

Figs 2B , 4D , 8

Ochna Ochna sp. 47 of FTEA ( Verdcourt 2005: 39).

Type.

TANZANIA - Morogoro District • Uluguru Mts , Bondwa Hill; 1953: Drummond & Hemsley 1764; holotype: K! [K000431154], isotypes: BR [BR0000009861305], EA! [EA000002038], K! [K000431155], SRGH [SRGH0106493- 0] .

Description.

Shrub or small tree, 2-8(-10) m tall. Bark rough or smooth, red to pale brown. Stems purple to brown, slightly ribbed with numerous, prominent lenticels; young new growth often with prominent white lenticels, brown, puberulous, often densely so, with rusty brown hairs or sometimes glabrous. Stipules orange-brown, narrowly oblong-lanceolate, up to 1 cm, deciduous. Leaves green to brown, often drying brown or rarely blue-green, thin, glabrous, narrowly elliptic to oblanceolate or lanceolate, 2-8 cm long, 1-4 cm wide; leaf base rounded to cuneate, acute at apex, sometimes very acute to acuminate, margins densely serrate or spinulose-serrate with teeth curving inwards; lateral veins numerous, ± 20-25, tertiary vernation reticulate above and below, midrib raised above and below; petiole obsolete or 0.5-3 mm long; buds small, brown, deciduous, annual shoot buds larger, pale brown, bud scales deciduous, up to 9.5 mm long. Flowers solitary, or arranged in short racemes 2-5 flowered, or pseudo-umbellate with up to 10 flowers; rachis 0-2 mm long; pedicels 1.5-3.5 cm long, articulated at or near the base, or up to 5 mm above base, red brown-pink, puberulous, sometimes densely so or glabrous. Sepals green-brown, elliptic-oblong, 6-13 mm long, 3-6 mm wide in flower, turning red in fruit, 9-15 mm long, 5-9 mm wide. Petals yellow, narrowly obovate, 6.5-10 mm long, 3-6 mm wide. Anthers dehiscing by longitudinal slits, 1.5-2.5 mm long, filaments 1.5-3.5 mm long. Carpels 5 (6); style capitate at apex with lobes, 4-7 mm long. Drupelets black, ellipsoid, 8-10 mm long, attached at the base.

Distribution.

Tanzania, Eastern Arc Mountains and Lake Nyasa Highlands (Fig. 8 ).

Habitat.

Upland rain forest, montane forest, grassland/montane forest boundary, riverine forest. Altitude: 1400-2400 m.

Phenology.

Mostly flowering and fruiting from September to March during the short rainfall season (October to December), but before the long rainfall season (April to June).

Preliminary IUCN conservation assessment.

Ochna oxyphylla is restricted to the Eastern Arc Mountains and Lake Nyasa Highlands of Tanzania, with an estimated EOO of 90,440 km2 and an AOO of 116 km2. The species is threatened by encroachment, small-scale logging, and fuel wood collection in the montane forests (Toral Shah pers. obs. 2018). For these reasons, the species is assessed as Near Threatened (NT) as it nearly meets the B2 criteria for Vulnerable; however, it is present in more than 10 locations, up to 16 locations, therefore is assessed as NT.

Additional material examined.

TANZANIA - Lushoto District • Tanga, West Usambara Mts, Mtumbi F.R.; 10 Feb. 1985; fr.; Borhidi, Iversen, Mziray & Temu 85657; K [K001082588] • Shume Nature Forest Reserve NE of Lushoto; 21 Feb. 1982; fr., Borhidi, Hall, Hedberg & Mahoo 82062; K [K001082590] . - Morogoro District • Uluguru Mts, Mgeta R. above Bunduki; 7°02'S, 37°38'E; 1 Jan. 1975; fr.; Pollhill & Wingfield 4634; K [K001271348, K001383146] • Uluguru South Catchment Forest Reserve , W-slopes of the forest on the path from N’gungulu village to Lukwangule plateau; 2400 m; 5 Feb. 2001; Jannerup & Mhoro 405; K [K001271445] • Uluguru-Gebirge, Lukwangule Plateau; 23 Feb. 1933; fl.; Schlieben 3564; BM, EA, K [K001383147] • Below Lukwanguli, Uluguru Mountains ; 3 Jan. 1934; fl.; Michelmore 900; EA, K [K001383148] • Nguru Mts 3km S of Maskati Mission; 1750 m; 11 Feb. 1991; fr.; Manktelow & Swenson 91296; EA, K [K001383149] . - Kilolo District • Udzungwa NP, Mt Luhomero; 7°47'S, 36°33'E; 1800 m; 30 Sep. 2000; fl.; Luke et al. 6789; EA, K [K001383165] • Udzungwa Mountains NP, pt 48; 7°41'S, 36°52'E; 1880 m; 31 Oct. 2005; Luke et al. 11337; EA, K [K001383155] • Udzungwa Mountains ; 7°52'S, 36°22'E; 1460 m; 28 Nov. 1999; fr.; Price & Mhoro WK 263; K [K001082568] • Ndundulu FR, pt 604; 7°47'S, 36°30'E; 1800 m; 11 Sep. 2004; Luke et al. 10448; EA, K [K001383150] • Mt Selegu ; 7°30'S, 36°10'E; 2100-2400 m; 28 Dec. 1986; fr.; Lovett & Congdon 1232; K [K001383202] • Mt Selegu ; 7°30'S, 36°10'E; 2100-2400 m; 28 Dec. 1986; fr.; Lovett & Congdon 1244; K [K001383151] • Mt Image , Selegu Peak; 7°30'S, 36°10'E; 2100 m; 13 April 1986; fr.; Lovett & Lovett 639; K [K001271506] • Kidabaga village , New-Dabaga Forest Reserve ; 8°06 ’45.07” S, 35°55 ’45.73” E; 1873 m; 24 Jan. 2020; Shah TS 94; K • Dabaga forest ; 18 Oct. 1937; fr.; Pitt 576; EA, K [K001383156] . - Ledewa District • Mdando Forest Reserve; 15 Nov. 1966; fr.; Gillett 17866; K [K001383209] • Livingstone Mountains , on ridge top ca 1.5 km S of Msalaba Mountain above Luana ; 10°00'S, 34°35'E; 2150 m; 23 Nov. 1992; Gereau et al. 5126; EA, K [K001383164] • Livingstone Mountains , at and near the summit of Ligala Mountain along foot trail from mission at Madunda; 9°51'S, 34°27'E; 2320 m; 12 Feb. 1991; fr.; Gereau & Kayombo 3982; EA, K [K001383166] • Luhega Forest Reserve ; 8°21'S, 35°58'E; 1650 m; 20 Jan. 1997; fl.; Frimodt-Møller et al. TZ122; K [K001383163] . - Kinondoni District • Kigogo; fr.; Dec. 1953; Carmichael 329; EA, K [K001383158] • Kigogo ; fr.; Feb. 1954; Carmichael 354; EA, K [K001383169] • Kigogo fr; 8°40'S, 35°15'E; 1800 m; 12 Nov. 2008; Luke & Luke 12805; EA, K [K001383154] • Mafinga Club; 31 Jan. 1955; fr.; Sangiwe 64; K [K001383200] . - Mbeya District • Poroto Mts, Ikuyu, about 8 km N of Irambo; 1825 m; 10 Feb. 1979; fr.; Cribb et al. 11380; K [K001383161, K001383162] • N. slopes of Poroto Mts , below Mporoto sawmill; 8 Mar. 1932; Clair-Thompson 725; EA, K [K001383167] . - Wanging’ombe District • Nyumbanitu ; 22 Sep. 1958; fl.; Ede 42; EA, K [K001383168] . - Ileje District • Bundali Mts , pts 292; 9°43'S, 33°50E; 2070 m; 20 Nov. 2008; Luke & Luke 12841; K [K001383153] . - Njombe District • Between Lisitu and Lugalawa ; 9°48'S, 34°43'E; 2000 m; 23 Sep. 1970; fl.; Thulin & Mhoro 1120; EA, K [K001383160] . - Rufiji District • Idunduge ; Nov. 1953; fl.; Carmichael 310; EA, K [K001383152] .

Bibliography.

Robson (1963: 241); Verdcourt (2005: 24).

Notes.

Ochna oxyphylla is most often confused with O. stolzii , as both species have few-flowered inflorescences (1-5 flowers), but is distinguished by being a small tree up to 8 m tall, whereas O. stolzii is mostly a suffrutex up to 2 m tall. The specimen Jannerup & Mhoro 405 from the moist forest before Lukwangule Plateau, Uluguru Mountains, Tanzania, is listed as O. sp. 47 in the FTEA ( Verdcourt 2005). Molecular results from a more recent specimen, Shah TS57, collected from the same locality, have confidently placed it within O. oxyphylla , which is further corroborated by morphological characters (having leaf apex sharply acute, leaf margin finely toothed; bark dark brown, slightly fissured and lenticellate, not corky; upland) and found in montane and riverine forest, between 1400-2400 m elevation. Verdcourt (2005) separated this specimen as it had been previously determined as O. holstii ; however, it has solitary flowers rather than several-flowered racemes as in O. holstii. The specimen cited in FTEA states that the plant as up to 20 m tall, which is likely erroneous as the maximum height recorded for this species is 10 m.

Figures

Figure 2. Species of Ochna, habit and leaf margin. A. Ochna stolzii (from Richards 22529). B. Ochna oxyphylla (from Carmichael 354). C - D. Ochna holstii (C from Maas Geesteranus 4971, D from Pierlot 1731). Drawn by Andrew Brown.

Figure 4. Dissection of rehydrated drupelets shows that there are no distinguishing morphological characters in the embryo of any of the mentioned taxa, particularly separating Ochna holstii I and II. A. Ochna holstii II. B. Ochna holstii I. C. Ochna stolzii. D. Ochna oxyphylla.

Figure 8. Distribution map of Ochna oxyphylla in Tanzania.