Diospyros angolensis E. Mestre, Meeprom, H. N. Rakouth & Lowry, 2025

1. Diospyros angolensis E. Mestre, Meeprom, H. N. Rakouth & Lowry sp. nov.

Figs 1 A View Figure 1 , 2 A View Figure 2 , 3 View Figure 3

Type

ANGOLA – District de Loanda [= Luanda Prov.] • Coastal region [without precise locality]; 1903; fr.; Gossweiler 789; holotype: P! [ P 04595254 ]; isotypes: BM, FHO, K! [ K 001561020 ] .

Diagnosis

Diospyros angolensis can be distinguished from other African species previously included in D. ferrea by the combination of leaves with a symmetric (not falcate) lamina that has dark, pitted glands in the proximal half and an obtuse to rounded (rarely acute or retuse) apex, a globose to very slightly ellipsoid fruit 7–8 × 7–9 mm, and a fruiting calyx with 3 rounded lobes 1–1.5 × 3–4 mm.

Description

Tree (?). Bark pale to dark grey, smooth to slightly rugose, lenticels pale brown, round. Young stems (sub) terete, pale to dark grey, initially covered in short, translucent hispid hairs ca 0.1 mm long and sparse, appressed, yellowish brown hairs ca 0.4 mm long. Leaves alternate; petiole 1–4 mm long, 0.5–1 mm diam., flat to sulcate above, tomentose, white to yellowish-brown hairs; lamina 1.1–5.5 × 0.7–2.8 cm, elliptic to orbicular or obovate, symmetric (never falcate), chartaceous to thinly coriaceous, with sparse indument above and below (likely caducous, t-shaped), discolourous, dark brown above, chestnut brown below, with dark, pitted glands present in varying number in the basal half of the lamina, base acute to obtuse, margin slightly undulate, thickened, apex obtuse to rounded, or rarely acute or retuse; venation pinnate, midrib slightly impressed to flat above, raised below, secondary and tertiary venation usually visible on both sides, sometimes inconspicuous above, more apparent below, darker in younger leaves and concolourous with blade in older leaves, raised below and very slightly so above; secondary venation emerging at varying angles from the midrib, veins (5) 6 or 7 (8) per side, weakly brochidodromous, forming irregular loops 1 / 2 to 2 / 3 of the way between the midrib and margin, the most apical smaller and more steeply angled; tertiary venation similar to the secondary in size and colour, irregularly reticulate and forming further loops between the secondary veins and the margin. Male flowers (known only from immature material) in (1 to) 3 (4) - flowered axillary cymes, axes densely covered in semi-appressed, brown hairs <0.5 mm long, peduncle 2–4 mm long, pedicel <1 mm long; calyx with dense, straight, appressed, golden to golden-brown hairs 0.25–0.5 mm long outside, sparser and shorter inside, basal portion cupuliform, ca 2 × 2–2.5 mm, lobes 3, triangular, 1.5 × 1.5–2 mm, acute; corolla with dense, appressed, light golden hairs ca 1 mm long outside (only on lobes), glabrous inside, tube narrowly ovoid, 1–1.5 × 1.5–2 mm, lobes 3, rounded-triangular, ca 2 × 1.5 mm, imbricate, apex acute; stamens 10, inserted at the base of the corolla tube, filament 0.2–0.5 mm long, anther 1–1.5 mm long; pistillode discoid, ca 0.5 × 1–1.5 mm, densely covered in erect, straight, golden hairs ca 0.75 mm long. Female flowers axillary (sometimes appearing as elongated spikes when the leaves are lost), solitary, pedicel <1 mm long; calyx densely covered outside and inside with straight, appressed, golden hairs 0.25–0.5 mm long, basal portion cupuliform, ca 2.5 mm × ca 3.5 mm, lobes 3, triangular, valvate, ca 1.5 × 2 mm, obtuse to bluntly acute; corolla glabrous outside except for a rhomboid central area of dense, straight, appressed, golden hairs 0.3–0.5 mm long, glabrous inside, tube cylindrical, ca 4 × 2 mm, lobes 3, rounded-triangular, ca 1 × 1.5 mm, weakly imbricate, apex broadly acute; staminodes lacking; ovary globose, ca 2 × 2 mm, densely covered with straight, appressed, golden hairs ca 0.5 mm long, style 1–1.5 mm long, glabrous. Fruits axillary, solitary, pedicel 1–2 mm long; calyx nearly flat, ca 6 mm wide, with minute, dense, golden hairs ca 0.3 mm long outside, shorter inside, basal portion shallowly cupuliform, 0.5–1 × 4–5 mm, lobes 3, rounded, entire, 1–1.5 × 3–4 mm, apex rounded; fruit globose to very slightly ellipsoid, 7–8 × 7–8 (– 9) mm, reddish brown to orange (in vivo), surface smooth, with sparse, appressed, white hairs ca 0.3 mm long or glabrescent, style persistent at the apex. Seeds 1 or 2, 6–7 × 4–5 mm, ellipsoid or hemi-ellipsoid, irregularly rough, black, dull.

Distribution

Angola (Fig. 4 View Figure 4 ).

Habitat

Diospyros angolensis has been collected in coastal and riverine forests, likely at comparatively low elevations, although no information is provided on any of the specimen labels.

Phenology

Flowering material has been collected in September and October, and fruiting material in June.

Etymology

This species is named after the only country from which it has thus far been recorded.

Preliminary IUCN conservation assessment

Diospyros angolensis has an Extent of Occurrence of 33,236 km 2 and a minimum Area of Occupancy of 24 km 2. The species is known from ten collections made between 1904 and 1959 representing four different occurrences, none of which fall within any present-day protected area and are therefore likely subjected to various threats such as fire and land clearing for agriculture. Targeted collecting at all these sites is needed to confirm the status of the extant subpopulations. A continuing decline is inferred for the extent of occurrence, area of occupancy, area, extent, and / or quality of habitat, number of locations, and number of mature individuals. With respect to the most serious plausible threat (land clearing), Diospyros angolensis has been recorded at 4 locations and is thus assessed as Endangered: EN B 2 ab (i, ii, iii, iv, v).

Additional material examined

ANGOLA – Without locality data • Welwitsch 2527; P [ P 04595251 ] . – Bengo Province • Catete, Calucala ; [09°36’36”S, 14°07’48”E]; 70 m; 15 Oct. 1929; Gossweiler 9182; BM, FHO, K [ K 001561021 ], LISC [ LISC 035677 About LISC ], US [ US 03133208 ] GoogleMaps . – Luanda Province • [Without precise locality]; 1903; Gossweiler 2450; FHO, P [ P 04595256 ] . – Namibe Province • Serra da Chela, Bibala ; [14°46’12”S, 13°22’12”E]; 400 m; 7 Sep. 1941; Gossweiler 12956; FHO, LISC [ LISC 035678 About LISC ] GoogleMaps • Serra da Chela, Bibala ; [14°46’12”S, 13°22’12”E]; 800 m; 7 Sep. 1941; Gossweiler 12956 A; LISC [ LISC 035679 About LISC ] GoogleMaps • Serra da Chela, Bibala ; [14°46’12”S, 13°22’12”E]; 700 m; 10 Sep. 1941; Gossweiler 12956 B; LISC [ LISC 035680 About LISC ] GoogleMaps • Moçamedes, Camucuio, Bibala ; [14°09’00”S, 13°14’24”E]; 14 Oct. 1955; Mendes 409; LISC [ LISC 035681 About LISC ] GoogleMaps • Moçamedes, Camucuio, Bibala ; [14°06’00”S, 13°13’48”E]; 730 m; 19 Sep. 1959; Teixeira 4-297; LISC [ LISC 035685 About LISC , LISC 035686 About LISC ] GoogleMaps • Moçamedes, Camucuio, Bibala ; [14°46’12”S, 13°22’12”E]; 730 m; 29 Sep. 1951; Teixeira 509; LISC [ LISC 035682 About LISC ] GoogleMaps • Moçamedes, Camucuio, Bibala ; [14°06’00”S, 13°13’48”E]; 900 m; 18 Sep. 1959; Teixeira 4-559; LISC [ LISC 035687 About LISC ] GoogleMaps .

Notes

Diospyros angolensis is the only species formerly included in D. ferrea known to occur in Angola. It has not been documented since 1959 and newer collections are thus urgently needed to ascertain the persistence of this species and to develop a better understanding of its biology, ecology, and conservation status.

Our attempts to locate duplicates of the type collection of Diospyros angolensis (Gossweiler 789) in the two main herbaria in Portugal with important holdings from Angola ( COI and LISC) were unsuccessful.