Buchnera nudicaulis Eb.Fisch., 2025

Fischer, Eberhard, 2025, Taxonomic novelties in Buchnera (Orobanchaceae) in Central and East Africa (Rwanda, Burundi, Democratic Republic of the Congo, Tanzania), Phytotaxa 704 (1), pp. 1-17 : 5-9

Buchnera nudicaulis Eb.Fisch. sp.nov. ( Figs. 4–5 )

Type: — DEMOCRATIC REPUBLIC OF THE CONGO. Haut Katanga, E’ville (Elisabethville=Lubumbashi), route de Sakania, sur terre humide près de la route, 26 April 1957, P. Duvigneaud 2861B (holotype BRLU!).

Diagnosis: — Buchnera nudicaulis sp. nov. closely ressembles B. subglabra Philcox (1987: 208) ( Fig. 6 ) but differs in the long whitish to reddish hairs on leaves, stems, bracts, bracteoles and flowers, the inflorescence more condensed and not elongating in fruit, the larger and broader bracts, and the longer calyx with shorter lobes ( Tab. 2). Buchnera subglabra is endemic to the Chimanimani Mts. in Zimbabwe and Mozambique while B. nudicaulis is restricted to Haut Katanga.

Description: —Annual erect herb, 30–38 cm tall, stems simple, occasionally with 2 ramifications (paracladia) arising from a pair of alternate bract-like leaves below inflorescence and ending in a capitate spike, densely covered with long whitish to reddish hairs up to 1–1.5 mm long. Leaves in a basal rosette appressed to the soil, in 2 to 3 pairs, sessile broadly ovate, opposite, 35–45 × 14–20 mm, densely covered with whitish to reddish hairs, discolorous, the upper face dark green, the lower face pale green, apex rounded to obtuse, stem otherwise leafless except a pair c. 1–6 cm above the basal rosette, 11–17 × 2–3 mm, and 1–2 pairs of small bract-like leaves, 1.5–2 × 0.4–0.7 mm, 15 cm above rosette and 5–6 cm below inflorescence. Inflorescence racemose, in terminal short and compact spikes, 10–15 mm, long; bracts ovate-lanceolate, (2.9 3.5–4.2 × 0.5–1.2 mm, acute at apex, densely hairy. Flowers sessile or pedicel, up to 0.5 mm; bracteoles linear-lanceolate, 3.1 × 0.5 mm, densely hairy; calyx tubular, 5.6–6.4 mm long, densely hairy, with 5 lanceolate lobes 0.3–0.4 mm long; corolla blue, with cylindrical tube 5–7 × 0.5–0.7 mm, densely hairy outsid, lobes oblong, emarginate at apex, 1.3–1.6 × 1.8–2 mm; stamens with filaments of the longer pair 1 mm long, filaments of the shorter pair 0.5 mm long, and with 1 mm long anther, acute,. Capsule not seen.

Additional specimens seen (Paratype):— DEMOCRATIC REPUBLIC OF THE CONGO. Haut Katanga, E’ville (Elisabethville=Lubumbashi), route de Sakania, dembo humide, 20 April 1957, P. Duvigneaud 2863 Bu (BRLU).

Distribution: — Democratic Republic of the Congo, only known from the type locality in Haut-Katanga.

Habitat: —Dembo in savanna, 1214–1220 m altitude

Etymology: —The specific epithet refers to the almost leafless stem.

Conservation status:— The habitat, according to Google Earth Pro images (https//Google-Eart- Pro.de.softtonic. com) is today destroyed and part of the settlements of Lubumbashi with numerous buildings. The major threat is thus habitat destruction.As the species was known only from one locality and two collections from 1957, it is assessed here as Critically Endangered (CR) and possibly extinct.

Figures

FIGURE 4. Buchnera nudicaulis.—Holotype (BRLU). Reproduced with permission. © Universié Libre de Bruxelles.

FIGURE 5. Buchnera nudicaulis.—A–B. habit.—C. basal rosette.—D–E. inflorescence.—F. calyx and bracteole.—G.bract.—H. corolla from above.—I. calyx with corolla—Drawn from the holotype (A, C–I) and Duvigneaud 2863 Bu (B) by Eberhard Fischer.

FIGURE 6. Buchnera subglabra.—A. detail of habit.—B. inflorescence.—C. flowers from above.—D. leaves on stem. E–F. basal rosette.—Photos par Bart Würsten (©, B, C, Mozambique, Chimanimani Mts.)