Olinia chimanimani T.Shah & I.Darbysh.

Shah, T., Darbyshire, I. & Matimele, H. Kew Bull (2018) 73: 36. https://doi.org/10.1007/s12225-018-9757-2

Type

Type: Zimbabwe, Manicaland, Chimanimani Mountains, at W base of (Pnt.?) 71, Linder 3990 (holotype K! [K000963156]).

Morphology General Habit

Shrub or small tree up to 5 m

Morphology General Bark

Bark thin, pale grey (white) to brown

Morphology Branches

Branchlets grey to brown, convexly quadrangular with ridges

Morphology Leaves

Leaves sessile, simple, entire, opposite except on young (or sapling) branches when ternate, blade coriaceous, obovate to oblanceolate occasionally elliptic, (19.0 –) 25.0 – 40.0 mm long, 10.0 – 25.0 mm wide, base attenuate, apex retuse with short mucro often with pink tinge, margins involute, sometimes with pink tinge, adaxial lamina green, glossy, glabrous, primary vein slightly impressed drying pink at base, secondary venation 6 – 14 pairs, not prominent, tertiary venation conspicuous, abaxial lamina pale green, glabrous, primary vein raised, secondary veins slightly raised, tertiary vernation conspicuous

Morphology Reproductive morphology Inflorescences

Inflorescences terminal compound cymes, total inflorescence length 21 – 48 mm; primary inflorescence unit 0.4 – 1.5 mm long, puberulent; secondary inflorescence unit 2.1 – 4.4 mm long, puberulent; tertiary and quaternary inflorescence units pubescent, pink (Fig 1)

Morphology Reproductive morphology Inflorescences Bracts

Bracts leaf-like in morphology, located on primary and secondary inflorescence axis, variable, 3.3 – 12.5 mm long, 1.6 – 3.6 mm wide

Morphology Reproductive morphology Flowers

Flowers 5-merous, actinomorphic, pinkish when fresh, in groups of three Galled flowers somewhat swollen but linear, 2.0 – 3.3 (3.9) mm long, 0.35 – 0.7 (1.65) mm wide, drying dark, without conspicuous tubercles

Morphology Reproductive morphology Flowers Gynoecium

Hypanthium glabrous, narrow, thinly walled, 1.5 – 4.7 mm long

Morphology Reproductive morphology Flowers Calyx

Sepals highly reduced and not discernible

Morphology Reproductive morphology Flowers Corolla

Petals 5, slightly thick and fleshy, spathulate, 1.2 – 2.25 (– 4.0) mm long, 0.9 – 1.4 mm wide, apex with short mucro, glabrous, pale yellow when dry

Morphology General Scales

Scales located on the inside of petals, 0.35 – 1.2 mm long, 0.4 – 0.6 mm wide, densely pubescent on both surfaces

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens all attached along the same radius of inner hypanthium tube reaching the mouth of the flower, anthers 0.55 – 0.6 mm long

Morphology Reproductive morphology Fruits

Drupes globose, glabrous, ± 6.0 mm in diam., 5-locular, pinkish, drying pale brown

Morphology Reproductive morphology Flowers Hypanthium

Pericarp thinly fleshy, endocarp brown, woody, not smooth Ovary inferior, glabrous, 1.2 – 2.5 mm long, 5-locular; style puberulent, shorter than the floral tube, approx 0.6 mm; stigma globular

Morphology Reproductive morphology Seeds

Seeds ellipsoid to horse-shoe shaped, smooth, with spiral marking on the surface, ± 2.45 mm diam., usually only one seed per fruit due to abortion of other ovules (only immature seeds seen).

Distribution

Only known from Chimanimani Mountains on the border of Zimbabwe and Mozambique (Map 1).

Ecology

This species is found growing in evergreen scrub within rocky quartzite crags and gullies and at the base of quartzite blocks on steep slopes, between 1500 – 1890 m elevation.

Conservation

Olinia chimanimani is restricted to the Chimanimani Mountains on the border of central Zimbabwe and Mozambique and is currently known from eight collections, with the estimated Extent of Occurrence (EOO) and Area of Occupancy (AOO) of 40 and 28 km2 respectively (calculated using Geocat2015). Furthermore, the total area of Chimanimani sandstone/quartzite is approximately 380 km2. Of this, the area covered by rocky quarzitic crags and associated grassland, which is the favoured habitat for this species, is approximately 270 km2; this could be taken as the maximum possible AOO for this species. The species is only known from two locations; the Zimbabwean side of the Massif which is fairly well-protected under the Chimanimani National Park (CNP) and the Mozambique portion under the National Reserve of Chimanimani (RNC) with limited protection (Schneider et al. 2005). Additionally, although the species occurs in rocky crags, it is highly prone to burning by man, associated with the illegal artisanal mining activity present on the Mozambique side of the Chimanimani massif (Dondeyne et al. 2009). This threat has significantly declined since its peak in 2004 – 2005, as gold discoveries have lessened (Timberlake et al. 2016). However, if it were to rise again in the future, the increase of human habitation would very likely lead to a further increased frequency of fires, which would almost certainly have an impact upon the species’ habitat and number of mature individuals. Severe fire damage was observed on some individuals in 2016. Furthermore, being one of the few woody species occurring at a high altitude, it will burn more easily and may be targeted as a fuel source for the miners. The species was noted to be locally rare in 2016, and with a restricted distribution and a plausible threat to its habitat, it is therefore assessed as Endangered (EN B1ab(iii, v) + B2ab(iii, v)).

Note

Olinia chimanimani is named for the only mountain range on which the species occurs.

This taxon is restricted to the higher elevations of the Chimanimani Mountains. Although once thought to be a pathological form of its close range relative, Olinia vanguerioides by Verdcourt (1978) in Flora Zambesiaca, it is now clear that it is morphologically distinct by having significantly smaller leaves, sessile leaf attachment, smaller flowers and narrow, linear galls that form without tubercles when infected (Table 1). Additionally, Sebola & Balkwill (2009) stated the presence of the variable taxon O. huillensis subsp. discolor in the Chimanimani Mountains. However, they did not cite any specimens of this taxon from the Chimanimani Mountains, Mozambique or Zimbabwe nor gave any indication of this on the distribution map for subsp. discolor. It is possible that the authors included this new taxon within the limits of O. huillensis subsp. discolor, although the specimens of the new taxon that were loaned to Sebola (J) at the time of that revision were not annotated as such. However, when closely examined, O. chimanimani always has a strictly sessile leaf attachment, glabrous inner and outer petals, a glabrous and smaller hypanthium and linear gall formation, characters that differ from O. huillensis including subsp. discolor. Table 1 shows the morphological character differences between O. chimanimani, O. vanguerioides and O. huillensiss.l. because the delimitation of O. huillensis subsp. discolor must necessarily fit within the larger taxonomic concept of O. huillensiss.l. Therefore, the subspecies is not included in the table in order to compare taxa at the species level. With recent developments in molecular analysis it would be desirable to carry out Next Generation Sequencing (NGS) to more accurately resolve the species limits within this genus. However, at present, morphological analysis provides the best conclusions for species delimitation. A modified key to the species of Olinia sect. Rochetiana is presented below to help with the identification of the closely related taxa, a key to the infraspecific taxa of O. huillensiss.l. is available in Sebola & Balkwill (2013).

Olinia chimanimani has previously been confused with O. vanguerioides as their ranges overlap. However, morphologically the two species are clearly distinct. O. chimanimani can be distinguished by its smaller leaf size ((19.0 –) 25.0 – 40.1 mm long), sessile leaf attachment, and galled flowers becoming thinly swollen when infected, without prominent tubercles, compared to O. vanguerioides which has larger (40.1 – 170.0 mm long), petiolate leaves and flowers forming conspicuous elongate-tuberculate galls when infected. Additionally, O. chimanimani may be confused with O. huillensis A. Fern. & R. Fern. and in particular with subsp. discolor (Mildbr.) Sebola; however, O. chimanimani differs from this taxon in having a leaf texture that is strictly coriaceous, smaller leaves ((19.0 –) 25.0 – 40.0 mm long) with a strictly sessile leaf attachment, smaller petals (1.2 – 2.25 (– 4.0)) mm long, 0.9 – 1.4 mm wide), glabrous inner and outer petal indumentum and strictly glabrous hypanthium indumentum (1.5 – 4.7 mm long). O. huillensis subsp. discolor, on the other hand, has a variable leaf texture of chartaceous to coriaceous, larger leaves (33 – 77 mm long) with short petiole (1.0 – 5.8 mm long), larger petals ((1.0 –) 2.0 – 2.9 mm long, (1.2 –) 1.5 – 2.8 mm wide), pubescent inner petals often with stiff hairs on the margin of the inner petal, and a pubescent and larger hypanthium ((2.0) 4.5 – 7.0 mm long). Furthermore, the two taxa differ with the gall formation of O. chimanimani having smaller linear galls (0.35 – 0.7 (– 1.65) mm wide) and O. huillensis subsp. discolor has rounded, more swollen galls (1.2 – 2.1 mm wide). Table 1 shows the diagnostic characters to differentiate the two species and O. huillensis A. Fern. & R. Fern. s.l., a key to species is found in the Notes section.