Mischogyne iddii Gosline & A.R.Marshall, 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 : 14-17

4. Mischogyne iddii Gosline & A.R.Marshall sp. nov.

Type: Tanzania, Bomole – PSP 13. Amani Nature Reserve, East Usambara Mountains, 15 Oct. 2007, Marshall 1567 (holotype K!) [K000875075].

http://www.ipni.org/urn:lsid:ipni.org:names:60478312-2

Tree, 10 – 20 m tall, up to 13 – 45 cm in diam., trunk cylindrical; old branches glabrous; young branches and twigs glabrous to sparsely pubescent quickly becoming glabrous, hairs 0.3 – 0.6 mm long, appressed, brown. Bark light grey, smooth with horizontally-orientated eyes and fine striations; slash: yellow-brown with a dark brown edge. Petioles 6 – 8 mm long, 2 – 4 mm in diam., sparsely pubescent with hairs 0.3 – 0.6 mm long, appressed, white, becoming glabrous, drying black. Leaf lamina elliptic to narrowly elliptic, often slightly falcate, 16 – 32 cm long, 6 – 8 cm wide, length:width ratio 1.2 – 4, apex attenuate to acuminate, acumen triangular 1 – 2 cm long, 1 – 1.5 cm at base, leaf base cuneate; coriaceous, slightly bullate when fresh, glabrous on both sides, glossy green above when fresh, drying matte, lighter below; midrib glabrous; secondary veins 10 – 14, glabrous, ascending at 30° – 45° from midrib, curving upwards to 10 – 20% of length of leaf, anastomosing near margin. Floaeers: buds 1.5 – 2 cm long, 1 cm in diam. No bracts seen. Flowering pedicel 0.5 – 0.8 cm long, 0.5 – 1 mm in diam., pubescent, hairs 0.2 – 0.3 mm long, appressed, white to light brown. Sepals ovate to narrowly ovate, 1.5 – 2 cm long, 0.5 – 0.7 cm wide, length:width ratio 2.5 – 3, base rounded, apex acute, densely pubescent outside, same as on pedicel, tomentose inside with soft semi-erect hairs 0.05 – 0.1 mm long; light green when fresh, light brown in herbarium material. Petals narrowly ovate, 1.5 – 2 cm long, 0.3 – 0.8 cm wide, length:width ratio 2.5 – 3, base truncate, apex acute, outer surface densely pubescent, hairs 0.3 – 0.6 mm long, appressed light brown, inner surface tomentose with soft semi-erect hairs 0.05 – 0.1 mm long becoming glabrous, white when fresh, dark brown when glabrous in herbarium material. Torus cylindrical, 4 – 7 mm. long, 2 – 3 mm diam., densely pubescent with hairs 0.2 – 0.4 mm long. Stamens 4 – 4.5 mm long; connective with an indumentum of white hairs 0.1 – 0.2 mm long, connective extending 0.1 – 0.6 mm beyond anthers ending in a tuft of hairs 0.1 – 0.3 mm long. Carpels 6 – 9, 4 – 6 mm long, 1 – 1.5 mm in diam., densely pubescent, hairs 0.6 – 0.8 mm long, appressed upwards, stigma sessile or on a short style to 0.1 mm long, bilobed, 0.7 – 1.2 mm long and wide, glabrous, yellow drying black. Fruits unknown ( Figs 6 , 7 ).

RECOGNITION. Similar to Mischogyne elliotiana and Mischogyne congensis . Differing in being a mediumsized tree to 20 m tall rather than a small tree to 8 – 10 m tall; in leaves being larger, up to 32 cm long rather than to 20 cm.

DISTRIBUTION. Tanzania. Usambara Mountains ( Map 1 ).

SPECIMENS EXAMINED. TANZANIA. Tanga: Amani Nature Reserve, East Usambara Mts , UTM 457800E, 9436950 S, 15 Oct. 2007, A. R. Marshall 1567 ( K! [holotype]), 1271 ( K!); Masumbai F.R., W Usambaras, Forest below road from Bambuli to Mazumbai c. 2 km before Mazumbai, 8 Jan. 1976, Cribb & Grey-Wilson 10082 ( DAR, EA, K!) .

HABITAT. Mature forest. Growing with Alchornea hirtella Benth. , Allanblackia stuhlmannii (Engl.) Engl. , Alsodeiopsis schumannii (Engl.) Engl. , Anisophyllea obtusifolia Engl. & Brehmer , Anthocleista grandiflora Gilg , Aoranthe penduliflora (K.Schum.) Somers , Bersama abyssinica Fresen. , Blighia unijugata Baker , Celtis africa- na Burm.f., Cephalosphaera usambarensis (Warb.) Warb. , Chrysophyllum sp. cf. gorungosanum Engl., Clematis dolichopoda Brenan , Cola sp. cf. greenaeayi Brenan, Cynometra brachyrachis Harms , Diospyros loureiriana G.Don , Diospyros occulta F.White , Drypetes usambarica (Pax) Hutch. , Englerodendron usambarense Harms , Entandrophragma excelsum (Dawe & Sprague) Sprague , Ficus lutea Vahl , Ficus natalensis Hochst. , Isoberlinia schefflerii (Harms) Greenway , Maesopsis eminii Engl. , Magnistipula butayei De Wild. , Maranthes goetzeniana (Engl.) Prance , Mesogyne insignis Engl. , Myrianthus holstii Engl. , Neaetonia buchananii (Baker f.) G.C.C.Gilbert & Boutique, Parinari excelsa Sabine , Placodiscus amaniensis Radlk. , Polyalthia suaoeolens Engl. & Diels var. suaoeolens , Pouteria adolfi- friedericii (Engl.) A.Meeuse, Quassia undulata (Guill. & Perr.) D.Dietr. , Raaesonia lucida Harv. & Sond. , Schefflerodendron usambarense Harms ex Engl. , Shirakiopsis elliptica (Hochst.) Esser , Sorindeia madagascariensis DC., Suregada zanzibariensis Baill. , Synsepalum cerasiferum (Welw.) T.D.Penn. , Trichilia dregeana Sond. , Trilepisium madagascariense DC., Xylopia aethiopica (Dunal) A.Rich. , Xymalos monospora (Harv.) Baill. , Zanthoxylum gilletii (De Wild.) P.G.Waterman , Zenkerella capparidacea (Taub.) J.Léonard subsp. grotei (Harms) Temu ( Marshall et al. 2012) .

CONSERVATION STATUS. This tree is known from two locations, one each in the Eastern and Western Usambara Mountains, one in the nationally recognised Amani Nature Reserve and the other in the private Mazumbai reserve managed by the Sokoine University of Agriculture. Both reserves are well managed ( Santos 2017). However, a study of ecotourism in Amani shows little benefit to local villages ( Shoo & Songorwa 2013). Cutting of trees for poles continues to be a problem in many Eastern Arc reserves (W. R. Q. Luke, A. R. Marshall, pers. obs.). The reserves are “islands” within a deforested landscape with extensive clearance of forest in neighbouring areas. Invasive tree species, particularly Maesopsis eminii Engl. are also growing extensively in the forest and hence competing with native trees for space (A. R. Marshall pers. obs.). The forest inventory of the Amani Nature Reserve records just six trees of this taxon (A. R. Marshall pers. com.). The Usambaras have been intensively studied for decades. The fact that only seven trees have ever been observed indicates a very small population. We estimate that it is likely that less than fifty individuals remain and that an IUCN category of Critically Endangered under criterion D is applicable. We take a slightly more conservative approach and, with an AOO of 8 km 2 based on a 2 km grid and two locations, suggest an IUCN category of Endangered B2ab(iii).

PHENOLOGY. Flowering in January, November.

VERNACULAR NAMES. Zonozono (Msofu).

USES. None recorded.

ETYMOLOGY. Named in honour of Iddi Rajabu, resident botanist at the Amani Nature Reserve and co-author of the Trees of Amani Nature Reseroe field guide.

NOTES. The biological importance of the Eastern Arc Mountains in Kenya and Tanzania is well known ( Burgess et al. 2007). Mischogyne iddii joins the long list of Eastern Arc endemic species (ibid.), and new species of Annonaceae continue to be discovered (Couvreur et al. 2006; Couvreur & Luke 2010; Deroin & Luke 2005; Marshall et al. 2016; Verdcourt 1986). Couvreur et al. (2006) summarise the high diversity of Annonaceae in Tanzania and this species brings the number of genera in Tanzania to 29.

Figures

Map 1. Distribution of all species of Mischogyne.

Fig. 6. Mischogyne iddii. A habit, flowering branch; B opening flower bud; C vein network detail; D open flower; E inner face of sepal; F inner face of outer petal; G inner face of inner petal; H detail of hairs on outer face of petal; J detail of hairs on inner face of petal; K carpels on androgynophore with two stamens in situ; L carpel; M stigmatic region of L viewed from left side; N outer face of stamen; P inner face of stamen. From Marshall 1567 (K) and photos. DRAWN BY ANDREW BROWN.

Fig. 7. Mischogyne iddii. A flower; B post-anthesis flower and bud (petals and anthers fallen); bud showing reduplicate calyx similar to Uvariastrum (Marshall 1567). PHOTOS: ANDREW R. MARSHALL.