Aptosimum eriocephalum E.Mey. ex Benth.

Kolberg H., van Salgeren M. 2016. A synopsis of Aptosimum and Peliostomum (Scrophulariaceae) in Namibia, including the description of a new species, Aptosimum radiatum, and keys to all accepted species. Kew Bulletin 71:16. DOI 10.1007/S12225-016-9628-7

Type

Type: South Africa, Zwischen Natvoet und Gariep [III B 7], Drège s.n. (lectotype P-3411765!, selected here; isolectotypes HBG-511578!, S-10-27363!, TUB-4035!) — see Notes.

Morphology General Habit

Shrub, prostrate, mat-forming, to 10 cm tall, 30 cm diam., not spinescent

Morphology Stem

Stems prostrate, much divaricately branched, forming compact centre with few longer, trailing branches, to 15 cm long, rigid, long lanate

Morphology Leaves

Leaves spathulate, 4 – 15 (– 20) × 2 – 4 (– 5) mm (inclpetiole), glabrous or with minute, sessile glands; apex mucronate; base long petiolate; petioles narrow, long crisped ciliate, those of leaves at stem tips 4 – 7 mm, those at base 1 – 2 mm long

Morphology Reproductive morphology Flowers

Flowers solitary, axillary

Morphology Reproductive morphology Flowers Calyx

Calyx lobed to about halfway, 5 mm long, densely covered with 3 – 5-cellular, crisped hairs (lanate) on outside except on lobe tips that are multicellular glandular-hairy, inside glandular-hairy; lobes linear, c. 3 mm long, apex long acute

Morphology Reproductive morphology Flowers Corolla

Corolla 6 – 12 mm long, sparsely glandular hairy outside and inside; tube narrow at base, widening towards mouth, whitish to lilac outside with lilac venation, white inside; lobes circular to obovate, inside lilac to pale purple, somewhat darker patches at base

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens four, unequal, filaments of shorter pair about half as long as those of longer pair; anthers reniform, sparsely ciliate, those of longer pair of stamens about 8 times larger than those of shorter pair

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary elongate-compressed; nectary disc-like; style filiform, as long as longer pair of stamens, stigma capitate

Morphology Reproductive morphology Fruits

Capsule globose, c. 5 mm long; apex indistinctly emarginate, with unicellular papillae

Morphology Reproductive morphology Seeds

Seeds elongate, angular, both ends somewhat acute; immature seeds whitish (no mature seed available)

Distribution

Africa: Namibia, South Africa.

Ecology

Grows in sand on plains and dry river banks of the dwarf shrub savanna, desert, desert - dwarf shrub savanna transition and succulent steppe vegetation zones (Mendelsohn et al. 2010). Occurs in the Gordonia, Huns-Orange, Southern Namib Succulent Desert, Escarpment and Highlands to 1500 m phytogeographical groups (Craven 2009). Altitude: 810 – 1555 m.

Conservation

Although this species is not widespread in Namibia and does not form very large populations, the EOO and AOO are still above thresholds for threatened categories under criterion B (IUCN 2012, 2013), and the evaluation therefore is LC in the absence of any threats identified.

Phenology

Flowering and fruiting throughout the year. Peak flowering and fruiting: Aug. – Oct.

Note

The Drège specimen in P (P-3411765) is selected here as lectotype because it is a complete specimen with the label in the collector’s handwriting.

Dinter 1126 (Z-64449) was initially listed by Weber (1903) under Aptosimum pubescens and is a syntype of that name. It definitely belongs to A. eriocephalum, however, something Weber also seemed to have noticed in his 1907 publication. See the Notes under A. elongatum.

This species is similar to Aptosimum elongatum in that it forms dense prostrate mats; the woolly indumentum, especially on the calyx, combined with glabrous leaves and differing leaf shape distinguishes it.