Petalidium hoarusibense (Acanthaceae), a new species from Namibia

• DOI: 10.11646/phytotaxa.681.1.1
• Publication Date: 2025-01-07T22:55:56Z
• Authors: WESSEL SWANEPOEL; ABRAHAM E. VAN WYK
• Keywords: Trichome; Indumentum; Eudicots; Acanthaceae; Endemism

Petalidium hoarusibense, hitherto misidentified as P. rossmannianum and ohopohense, is here described a new species. It range-restricted species, only known from the area to south southeast of Okandjombo in Kaokoveld Centre Endemism, northwestern Namibia, where it grows on arid hillsides along ephemeral riverbeds drainage lines. Diagnostic characters for hoarusibense include pale grey appearance plants, single or multi-stemmed thick rootstock, vegetative parts with dense white indumentum short dendritic, simple bifurcate trichomes appearing matted, flowers borne short, few-flowered dichasia, bracteoles narrowly ovate elliptic, deeply concave, cobwebbed due mixture loosely entangled long dendritic trichomes. The are distinctive having lobes magenta anterior lobe sometimes slightly lighter shaded than others two separate triangular yellow nectar guides. A comparison key morphological features distinguishing kaokoense, its closest relative appearance, well rossmannianum, sesfonteinense, welwitschii, provided. Based IUCN Red List criteria, provisional conservation assessment Vulnerable (VU) recommended