Ruschia lawsonii (L.Bolus) L.Bolus

Klak, Cornelia, Hanáček, Pavel & Bruyns, Peter V., 2023, Six new species of Ruschieae (Aizoaceae) and further notes in Ruschia, South African Journal of Botany 156, pp. 144-161 : 156-157

1 Ruschia lawsonii

(L.Bolus) L.Bolus had been transferred to Antimima , as Antimima lawsonii (L.Bolus) H.E.K. Hartmann , with some apparent hesitation as it grows far from any other member of Antimima and also lacks the characteristically large closing bodies of Antimima ( Hartmann, 1998) . This species falls within the typical distribution range of Ruschia , which extends over large parts of southern Africa, including its summer rainfall areas ( Hartmann, 2017c). In addition, R. lawsonii possesses the smaller closing bodies which are diagnostic for Ruschia ( Hartmann, 1998) . Superficially, R. lawsonii ( Fig. 15 ) closely resembles R. indurata ( Fig. 11 ). Both species form compact cushions where the internodes are hidden. The leaves in both species are whitish grey, but R. indurata has several small teeth along the keels of its leaves ( Fig. 11 ), whereas in R. lawsonii ( Fig. 15 ) the leaves are apically sharply pointed but without any teeth along the keels.

Both species are restricted to outcrops of calcrete. Like R. indurata , R. lawsonii is rare and is only known from a few collections near Kimberley ( Fig. 14 ). Here we re-instate Antimima lawsonii (L.Bolus) H.E.K. Hartmann in Ruschia and place it in subg. Ruschia in accordance with the results of our molecular analysis (Klak et al., in prep.).

Ruschia lawsonii (L.Bolus) L.Bolus , Notes Mesembryanthemum [H.M.L. Bolus] 3: 219 (1950),

Mesembryanthemum lawsonii L.Bolus, Annals of the Bolus Herbarium 4: 85 (1927),

Antimima lawsonii (L. Bolus) H.E.K. Hartmann , Bothalia 28: 74 (1998).

Type: South Africa, Kalahari Region, Hay division, Papkuil (2823BC), Aug. 1912, L. Lawson s.n. sub BOL18551 ( BOL!, barcode: BOL129312 ) .

3.2.5. Additional specimens investigated

South Africa. NORTERN CAPE: 2823 (Griekwastadt): Postmasburg , farm Silverstream (-BC), 5 Jan. 2016, Klak 2508 ( BOL) ; 15 km NNW of Campbell (-DC), Haumann s.n. ( BOL) .

Figures

Fig. 15. Illustration of Ruschia lawsonii. Artist:B.Carter.

Fig. 11. Lectotype of Ruschia indurata designated by H.E.K.Hartmann on 22nd June 1995. Collection by J.W.Mathews sub NBG 2393/17 (barcode BOL134738) made at Beaufort West.

Fig. 14. Distribution of Ruschia indurata (square) and R. lawsonii (circle). Missing syntype collections of R. indurata, which are likely to refer to other species, are indicated: H.de Villiers sub NBG 266/16 from Steynsburg (triangle) and E.Pillans sub NBG 383/16 from Steytlerville (star).