Cochlospermum adjanyae Goyder & Amandio Gomes, 2023

Goyder, David J., Davies, Nina, Finckh, Manfred, Gomes, Amandio, Goncalves, Francisco Maiato P., Meller, Paulina & Paton, Alan J., 2023, New species of Asclepias (Apocynaceae), Baphia (Leguminosae), Cochlospermum (Bixaceae) and Endostemon (Lamiaceae) from the Kalahari sands of Angola and NW Zambia, with one new combination in Vangueria (Rubiaceae), PhytoKeys 232, pp. 145-166 : 145

Cochlospermum adjanyae Goyder & Amandio Gomes sp. nov.

Diagnosis.

Cochlospermum adjanyae differs from all African species of the genus in possessing palmatisect rather than palmatifid or lobed leaves, with discrete leaflets rather than partially connate lobes.

Type.

Angola. Moxico Province: Lungué-Bungo valley, 50 km S of Munhango, near Lungué-Bungo bridge, 12°36'50"S, 018°47'59"E, fl. 20 November 2019, D.Goyder & A.Gomes 9002 (holotype: K (K001334241); isotypes: INBAC, LUBA, PRE) .

Description.

Geoxylic suffrutex forming diffuse but discrete patches several metres across; above-ground stems 10-20 cm tall, sub-erect, glabrous, burned off in the dry season. Leaves palmate with (4-)5 leaflets; stipules c. 3 mm long, narrowly triangular; petioles (2-)4-6 cm long, glabrous except for a minute rusty pubescence at the junction with the leaflets; leaflets reducing in size from the central leaflet to the lateral and basal ones, central leaflet 3-5 cm long, 1.2-2 cm wide, elliptic to slightly obovate, acute or occasionally obtuse apically, the base somewhat cuneate, margins serrate at least in the upper half, glabrous except for a minute rusty pubescence at the junction with the petiole adaxially. Inflorescences minutely rusty-puberulent, terminal on the leafy shoots, with 1-3 flowers; peduncles 2.5-3 cm long; sepals subequal, 11-15 × 7-8 mm, broadly ovate or elliptic, rounded apically, minutely rusty-puberulent and with occasional dark streaks, the outer pair more deeply coloured than the inner three; petals c. 3 × 2-2.3 cm, obovate, rounded or slightly emarginate, bright yellow with linear red streaks. Stamens numerous (80+), yellow; anthers c. 5 mm long, straight or weakly curved, apical pore 0.5-1 mm long. Ovary c. 2 mm in diameter, glabrous. Fruit not seen. (Figs 2 , 3 ).

Distribution and ecology.

Found only once in flower in grassland rich in geoxylic suffrutices on deep Kalahari sand. Material in bud had been encountered, but not collected, the day before in a similar grassland some 15 km to the NW along with the new species of Baphia described below and other geoxyles such as Sclerocroton oblongifolius ( Müll.Arg.) Kruijt & Roebers, Parinari capensis , Entada arenaria Schinz and Englerophytum magalismontanum (Sond.) T.D.Penn. The fact that this conspicuously flowered species was seen only on the November 2019 expedition and not on earlier ones through the same valley system (late rainy season; early and mid-dry season) suggests that populations are highly localised and that the flowering period is short, at the end of the dry season, and perhaps dependent on rainfall following fire. Altitude 1285-1340 m. (Map 2 ).

Etymology.

The specific epithet honours Adjany Costa who was part of the core National Geographic Okavango Wilderness Project headwaters team from the first expedition in 2015 until she left to pursue academic studies at Oxford University in 2019. Initially, she supported freshwater fish specialists Paul Skelton and Ben van der Waal, recording and preserving freshwater fish diversity from the Cuito source to the Delta, before developing the communities programme with Chris and Steve Boyes. She was a National Geographic Young Explorer, starred in the National Geographic documentary film "Into the Okavango", and was awarded the United Nation’s Young Champions of the Earth Prize for Africa in 2019.

Conservation status.

While Cochlostemum adjanyae is known from a single locality, these geoxyle-rich grasslands are not currently threatened as this nutrient-poor sandy environment is not conducive to agricultural development. The environment does not support many human settlements, which are few and far between. The species is probably best assessed as Data Deficient.

Taxonomic notes.

Cochlospermum Kunth is a pantropical genus of around 16 species of trees, shrubs and geoxylic suffrutices, or if expanded to include the herbaceous neotropical genus Amoreuxia DC., 20 species. C. noldeae Poppend. from NE Angola, C. macnamarae Hislop, K.R.Thiele & Brassington and C. arafuricum Cowie & R.A.Kerrigan from Australia ( Poppendieck 2004 (see nomenclatural note below), Hislop et al. 2013, Cowie and Kerrigan 2015) were described after Poppendieck’s (1980) monograph of the group where he had recognised 12 species. Irrespective of the circumscription of the genus, molecular evidence presented by Johnson-Fulton and Watson (2017) supports the monophyly of Cochlospermum subgenus Cochlospermum sensu Poppendieck (1980), which comprises two species from Central and South America ( C. vitifolium (Willd.) Spreng. and C. regium (Mart. ex Schrank) Pilg.), and all the paleotropical species. Johnson-Fulton and Watson (2017) argue that the geoxylic habit evolved just once from an ancestral arboreal lifeform - all but one of the African taxa are geoxyles, together with a single neotropical species, C. regium , from cerrado (savanna) regions of Brazil, Paraguay and Bolivia. The remaining species are trees or shrubs.

Species of Cochlospermum subg. Cochlospermum have a single apical pore to the anthers, and in addition to growth form, can be distinguished by leaf indentation or lobing, indumentum, and the position and timing of flowers on the shoots. A collection made in the geoxyle-rich Lungué-Bungo valley grasslands of Moxico in November 2019 is unique in the African species in having palmatisect leaves, divided to the base rather than being merely lobed. The only other taxon in the subgenus with this leaf character is the nomenclaturally illegitimate C. gillivrayi Benth. subsp. gregorii (F.Muell.) Poppend., an Australian tree. The Angolan material is described as a new species. It is perhaps closest morphologically to C. wittei Robyns from the Upemba region of Katanga. Cochlospermum wittei is also associated with savanna and woodland on sand plateaux ( Poppendieck 1980) but these are nearly 1000 km to the NE of the Lungué-Bungo grasslands.

Figures

Figure 2. Cochlospermum adjanyae A, B habit C flower D ovary and style E stamens. Drawn by Margaret Tebbs from Goyder & Gomes 9002.

Map 2. Known distribution of Cochlospermum adjanyae.

Figure 3. Cochlospermum adjanyae. Photographed by Chris Boyes at the type locality.