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

5. Diospyros suaheliensis E. Mestre, Meeprom, H. N. Rakouth & Lowry sp. nov.

Figs 1 E View Figure 1 , 2 E View Figure 2 , 7 View Figure 7

Type

KENYA – Coast Province • Lamu Dist., Witu Forest ; 2°20’50”S, 40°29’45”E; 16 m; 17 Nov. 1988; ♂ bud, ♂ fl.; Robertson & Luke 5528; holotype: MO! [ MO-4240972 ]; isotypes: EA, K!, US [ US 03133205 ] scan seen, WAG [ WAG.1778716 ] scan seen GoogleMaps .

Diagnosis

Diospyros suaheliensis 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 a few dark, pitted glands toward the base and a retuse, rounded or obtuse (sometimes broadly acute) apex, a globose fruit 8–12 × 8–11 mm, and a fruiting calyx with 3 broadly triangular lobes 3–4 × 6–8 mm.

Description

Tree or shrub 2–12 m tall. Bark pale grey to brownish grey, rugose, lenticels brown, round to longitudinally elliptic. Young stems terete, brown, then pale grey, initially covered in dense, hispid, very short, translucent pale yellow hairs and golden yellow, longer and caducous hairs 0.75–1 mm long. Leaves alternate; petiole 2–8 mm long, 0.5–1.5 mm diam., flat to deeply sulcate, with the same indumentum as the stem or glabrescent; lamina 0.8–8.5 × 0.8–5.6 cm, elliptic to orbicular or slightly obovate, symmetric (never falcate), chartaceous to coriaceous, glabrous above and below, concolourous to slightly discolourous, pale grey-green to dark brown above, often dull-glaucous, pale, dark or reddish brown below, with dark, pitted glands occasionally present in very small numbers in the basal part, base, acute to rounded, rarely cuneate, margin slightly to majorly undulate, thickened, often lighter than the rest of the lamina, apex retuse, rounded, obtuse or less frequently broadly acute; venation pinnate, midrib narrowly impressed to flat above, raised below, secondary and tertiary venation visible on both sides, concolourous with blade, raised on both sides; secondary venation emerging at irregularly acute and decurrent angles from the midrib, (5) 6 or 7 (8) veins per side, brochidodromous, forming irregular loops close to the margin, the most apical ones 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 in short, 3 - flowered axillary cymes, axes with moderately dense, semi-appressed, golden hairs <0.5 mm long, peduncle 1–3 mm long, pedicel <1 mm long; calyx with moderately straight, appressed, golden brown hairs 0.25–0.5 mm long outside, sparse and limited to the margin inside, basal portion cupuliform, ca 2.5 × 2.5–3 mm, lobes 3, round to round-triangular, ca 1 × 2.5 mm, apex shortly acute; corolla with dense, appressed straight, golden inside 0.5–1.5 mm long outside on the lobes, glabrous elsewhere, tube shortly campanulate 3 × 2.5 mm, lobes 3, entire, ovate, spreading, 2.5–3 × 2–2.5 mm, apex acute; stamens 9 or 10, inserted at the base of the corolla tube, filament 1.0– 1.5 mm long, anther 1.75–2.3 mm long; pistillode discoid, 3 - to 6 - lobed, ca 0.5 × 1–1.1 mm, densely covered in erect, straight golden hairs ca 0.25 mm long. Female flowers axillary, solitary, subsessile; calyx moderately covered outside and inside in straight appressed golden hairs 0.25–0.75 mm long, basal portion cupuliform, ca 3 × ca 2.5 mm, lobes 3, triangular, ca 1 × 2 mm, acute (often broadly so); corolla and staminodes not seen; ovary obovoid, ca 3 × 3 mm (post receptivity), covered toward the apex with straight, appressed, golden hairs ca 0.25 mm long, style ca 1 mm long, glabrous. Fruits axillary, solitary, pedicel to 1 mm long; calyx cupuliform, 8–10 mm wide, with dense to very sparse, minute, golden hairs 0.25–0.5 mm long, basal portion shallowly cupuliform to flat, 2–4 × 7–11 mm, lobes 3, broadly triangular, margins ciliate, entire, 3–4 × 6–8 mm, apex broadly acute; fruit globose, (8 –) 10–11 (– 12) × 8–11 mm, bright red at maturity (in vivo), surface smooth, sparsely tomentose, style persistent at the apex. Seeds 4, 7–7.5 × 3.5–6 mm, ellipsoid-wedge shaped, rugose, dark grey, slightly shiny.

Distribution

Kenya, Tanzania, and Mozambique (Fig. 4 View Figure 4 ).

Habitat

Diospyros suaheliensis is known from coastal and lowland riverine forest at 0–250 m elevation.

Phenology

Flowering material has been collected from September to January, and fruiting material in February, May, July, and November.

Etymology

The name chosen for this new species reflects its geographic distribution, which corresponds very closely to the Swahilian regional centre of endemism, as defined by Clarke (1998), which extends from southern Somalia through Kenya and Tanzania south to northern Mozambique.

Preliminary IUCN conservation assessment

Diospyros suaheliensis has an Extent of Occurrence of 404,496 km 2 and a minimum Area of Occupancy of 76 km 2. The species is known from 20 collections representing seven different occurrences, some of which fall within formally protected areas whereas others that do not are likely subjected to several threats, including land clearing for agriculture and fire. Targeted collecting at historic 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. Regarding the most serious plausible threat (land clearing for agriculture), Diospyros suaheliensis has been recorded at seven locations and is thus assessed as Vulnerable: VU B 2 ab (i, ii, iii, iv, v).

Additional material examined

KENYA – Kwale District • South of Kinondo ; [04°24’00”S, 39°33’00”E]; 5 m; 2 Mar. 1977; Faden 77 / 643; FHO [ FHO 0080385 About FHO ], K, US [ US 03133207 ] GoogleMaps • Kaya Kinondo ; [04°23’00”S, 39°32’00”E]; 5 m; 10 Nov. 1992; Harvey 45; MO [ MO-5663315 ] GoogleMaps • Kaya Mgawani ; [04°24’00”S, 39°32’00”E]; 7 m; 4 Jan. 1992; Luke 3036; K, MO [ MO-5659987 ], US [ US 03133204 ] GoogleMaps • Kaya Kinondo ; [04°23’39”S, 39°32’50”E]; 16 Jul. 1987; Robertson 4922; K [ K 001561013 ] GoogleMaps . – Lamu District • 3 km E of Tana river in Home forest ; [02°00’00”S, 40°11’00”E]; 25 m; 14 Feb. 1973; Katende K 1775; MO [ MO-2786187 ] GoogleMaps • Lango la Simba ; [02°14’00”S, 40°12’00”E]; 12 m; 30 Nov. 2004; Luke 10739; K [ K 001561015 ], MO [ MO-2758137 ] GoogleMaps • Boni Forest Reserve ; [01°43’00”S, 41°14’30”E]; 12 m; 29 Nov. 1988; Robertson 5594; EA, K, MO [ MO-4240965 ], US [ US 03133206 ] GoogleMaps . – Tana District • Tana Delta ; [02°22’48”S, 40°18’00”E]; 5 m; 4 May 2011; Leauthaud 145; EA, K, MO [ MO-6854947 )] GoogleMaps .

MOZAMBIQUE – Without locality data • 3 Nov. 1905; Le Testu 863; BM, BR [ BR 0000016101593 ], FHO, MO [ MO-2198289 ], P [ P 04595252 , P 04595253 ] . – Cabo Delgado Province • Nangororo ; [12°25’45”S, 40°30’28”E]; 24 Nov. 1959; Gomes 4526; BR [ BR 0000016101579 ], K [ K 001561001 ] GoogleMaps • Quirimba ; [12°04’00”S, 40°21’00”E]; 60 m; 5 Dec. 2003; Luke 9867; MO [ MO-5761467 ] GoogleMaps .

TANZANIA – Lindi District • Kilwa Kisiwani Island ; [08°57’33”S, 39°29’32”E]; 0 m; 17 Dec. 2003; Abeid 1631; MO [ MO-5901562 ] GoogleMaps • Lake Lutamba ; [09°49’59”S, 39°47’00”E]; 800 ft; Nov. 1953; Eggeling 6730; K, TFD GoogleMaps • Lake Lutamba ; [10°01’48”S, 39°27’36”E]; 240 m; 5 Nov. 1984; Mwasumbi 12684; DSM, K, MO [ MO-2758149 ] GoogleMaps • Lutambasee ; [09°33’36”S, 39°36’00”E]; 240 m; 9 Nov. 1934; Schlieben 5586; FHO [ FHO 0080387 About FHO ], K [ K 001561002 ], WAG [ WAG.1778713 ], MO [ MO-1703876 ] GoogleMaps . – Liwale District • Selous Game Reserve ; [08°27’24”S, 38°32’32”E]; 125 m; 31 Jul. 1975; Vollesen 2605; DSM, K [ K 001561003 ], WAG [ WAG.1778714 ] GoogleMaps • Selous Game Reserve ; 125 m; 6 Oct. 1975; Vollesen 2752; DSM, K, WAG [ WAG.1778715 ] • Selous Game Reserve ; 125 m; 6 Sep. 1976; Vollesen 3979; DSM, K, WAG [ WAG.1778717 ] . – Muheza District • Kigombe ; [05°09’19”S, 39°05’46”E]; 0 m; 20 May 1958; Faulkner 2151; K [ K 001561011 ] GoogleMaps .

Notes

Diospyros suaheliensis displays some morphological resemblance to D. angolensis , sharing leaves that usually have a rounded apex and generally spherical fruits. These similarities may be linked to the coastal and riverine environments they both occupy. Further investigations into the evolutionary origins of these shared and possibly adaptive traits as well as their environmental correlates are warranted.