Mischogyne congensis Gosline, 2019

Gosline, George, Marshall, Andrew R. & Larridon, Isabel, 2019, Revision and new species of the African genus Mischogyne (Annonaceae), Kew Bulletin 74 (28), pp. 1-23 : 8-9

1. Mischogyne congensis Gosline sp. nov.

Type: Congo

(Kinshasa), Yambuya, 9 Nov. 1956, Eorard 2000 (holo-

t y p e B R* [B R6 10 2 0 0 2 2 7 0 3 9 0], i s o t y p e K! [K000874272]).

http://www.ipni.org/urn:lsid:ipni.org:names:60478273-2

Uoariastrum ellioitianum sensu Boutique, non U. elliotianum Engl. & Diels ( Boutique 1951) .

Small tree 3 – 7 m tall, to 9 cm diam.; branches and twigs glabrous; very young twigs with sparse brown appressed hairs 0.1 – 0.4 mm long. Taeigs light grey to brown, roughly striate, glabrescent, youngest shoots and shoot buds covered with light brown hairs 0.1 – 0.4 mm long. Petioles 5 – 10 mm long, 1 – 2 mm in diam., glabrescent, drying black; very young petioles with sparse hairs 0.1 – 0.3 mm long. Leaf lamina narrowly obovate to elliptic, 10 – 18 cm long, 3.5 – 6 cm wide, length:width ratio 2 – 3.5, apex acuminate to caudate, acumen triangular to linear, 1 – 3 cm long, 0.2 – 0.5 cm wide at mid-length, base cuneate, coriaceous, glabrous on both surfaces, glossy green above and below, drying glossy green to matte light green; midrib glabrous; secondary nerves 8 – 9, gradually ascending at 10° – 30° angle to midrib to 10 – 20% of the leaf length before anastomosing, glabrous. Floaeers 1 (– 2?) on leafy branches. Flower buds ovoid, 0.6 – 0.8 cm long, 0.5 – 0.6 cm in diam., with slightly obtuse apex. No bracts seen. Flowering pedicel 0.2 – 0.9 cm long, 0.6 – 1 mm in diam., densely pubescent, hairs 0.05 – 0.2 mm long, appressed, brown. Sepals oblong, 0.8 – 1 cm long, 0.5 – 0.6 cm wide, length:width ratio 1.5, base rounded, apex obtuse, pubescent outside and inside, hairs 0.05 – 0.1 mm long, light green when fresh, brown in herbarium material. Petals narrowly ovate, 2 cm long, 0.5 cm wide, length:width ratio 4, base rounded, apex rounded, outer surface with dense straight appressed hairs 0.2 – 0.5 mm long, inner surface with soft curling hairs 0.1 mm long, glabrescent, white when fresh. Torus cylindrical, 2 – 3.5 mm long, 1 – 1.3 mm diam., densely pubescent with stiff white semi-erect hairs 0.8 – 1.2 mm long directed towards apex. Stamens not seen. Carpels 9 – 16, 3 – 4 mm long, 1 – 2 mm in diam., indumentum as torus; stigma sessile, 0.6 – 0.8 mm diam., drying black. Fruits with only one mature monocarp in specimen seen. Monocarp ovoid, 6 cm long, 3 cm in diam., with a soft brown indumentum when dried, stipe 1 cm long, 0.4 cm in diam. Seeds not seen. Figs 2C , 3 .

RECOGNITION. Similar to Mischogyne elliotiana in being a small rainforest shrub or tree with leaves less than 20 cm long, but differing in: many leaves having a linear acumen arising from the rounded apex of the leaf and 5 times or more as long as wide rather than apex attenuate or acuminate with a triangular acumen 1 – 3 times long as wide; secondary nerves ascendant 10 – 25% of the leaf length before anastomosing at a distinct angle to a marginal nerve vs ascendant 25 – 30% of the leaf length before anastomosing almost parallel with the margin; the leaves drying dark glossy green above and below rather than matte below; the older petioles glabrous rather than having at least some indumentum ( Fig. 3 ).

DISTRIBUTION. Democratic Republic of Congo ( Map 1 ).

SPECIMENS EXAMINED. DEMOCRATIC REPUBLIC OF CON-GO. Équateur province: Yalisenga (Mondombe) 380 m, [0°43'30"S 22°40'32"E], fr, 21 April 1959, C. M. Eorard 6205 ( BR *, K!); ibid., fl fr, 26 Dec. 1958, C. M. Eorard 5376 ( K!) . Orientale province : Busukulu Village , Environs do Yangambi Reserve no. 121/ Agri 1953, [0°43'N 24°36'E], 30 Sept. 1947, J. Leonard 1461 ( BR *) ; ibid., 1 Aug. 1947, J. Leonard 1311 ( BR *, K!, P *); Bengamisa Yangambi Bengamisa Route vers 45 km , 450 m, [0°56'28"N 25°12'23"E], fl, 21 May 1936, G. Gilbert 2321bis ( BR *, K!, P *); Yambuya , 400 m, [1°15'3"N 24°33'5"E], fl, 1 Nov. 1956, C. M. Eorard 2000 ( BR *, K!, P *) .

HABITAT. Riverine forest. Semi-deciduous forest.

CONSERVATION STATUS. This taxon is only known from six specimens and four locations on the Congo, Aruwimi, Lindi, and Tshuapa rivers in the Democratic Republic of Congo. The Meise herbarium has 5339 Annonaceae specimens from the DRC, many collected near the biological research station at Yangambi. The existence of only six specimens indicates that the species is rare. The area around Yangambi on the Congo is subject to continuing urbanisation as seen in satellite images. All the locations appear to be impacted by shifting cultivation (Google Earth 2018). Tree cover loss in the 2000 hectares including Yangambi was 18% from 2000 – 2017. Loss along the Lindi river is 45% in this period ( Hansen et al. 2013). Threats from deforestation along the rivers appear to be substantial. The four locations give an EOO of 11618 km 2 and an AOO of 16 km 2. The indicated IUCN rating is Endangered B1&2ab(iii).

PHENOLOGY. Flowering in November, December, May. Fruiting April.

VERNACULAR NAME. Inaola a loopa (Turumbu, Leonard 1311).

USES. The leaves and crushed fruits are applied by scarification on the bites of snakes. The local people say that snakes eat a lot of the fruit of this shrub (Gilbert 2321bis).

NOTES. These specimens have previously been determined as Mischogyne elliotiana var. glabra . Their geographic isolation led us to take a closer look. The secondary venation and abrupt long linear acumen indicated a distinct taxon and the molecular phylogenetic hypothesis confirms this taxon as being in a clade with M. michelioides and M. iddii , the Angolan and Tanzanian taxa, and in a different clade from M. elliotiana .

Figures

Map 1. Distribution of all species of Mischogyne.

Fig. 2. Flower buds of Mischogyne species. A M. elliotiana var. elliotiana with old flower showing carpels below (Dalziel 761 [K000874259]); B M. michelioides showing large terminal bud (Gossweiler 9379 [K000196792]); C M. congensis (Evrard 5376 [BR0000015312655]); D M. gabonensis buds showing capsule and rupturing at anthesis (Le Testu 1768 [WAG0247284]).

Fig. 3. Mischogyne congensis, fruiting specimen showing linear acumen and secondary veins not ascendant (Evrard 6205 http:// www.botanicalcollections.be/specimen/BR0000015312709).