Lampranthus alboroseus Klak, 2020

Klak, Cornelia, Helme, Nick & Bruyns, Peter V., 2020, Lampranthus alboroseus (Ruschioideae, Aizoaceae), a new species from the mountains of the Western Cape, South Africa, Phytotaxa 435 (1), pp. 63-68 : 64-67

Lampranthus alboroseus Klak sp. nov. ( Fig. 1 ).

Type:— SOUTH AFRICA. Western Cape, Wuppertal (3219): Southern Cederberg, Hondverbrand plateau, between Loskop and Hamerkop (- CA), 1471 m, 2 October 2019, Helme 9567 (holotype BOL!, Fig. 2 ).

Diagnosis:― This new species resembles Lampranthus reptans in its creeping habit but differs from it in the length of the pedicels. The flowers are almost sessile, solitary, white to faintly pink without filamentous staminodes and the filaments are without papillae. In these respects our new species is most similar to L. antonii Bolus (1966: 232) . However, it differs from L. antonii in lacking a central clump of leaves and branches, so that the stem and branches are indistinguishable and by having smaller leaves, flowers and fruits.

Description:― Plants perennial, succulent, stems creeping and frequently rooting at nodes, 2 × 1‒10 cm, internodes smooth, light brown, 5‒10 × 0.5‒1.0 mm. Leaves soft, opposite, trigonous, erect, shortly fused at bases into a sheath to 0.5 mm long, acute, 5‒11 mm long, 2.5‒3.5 mm broad and thick, without transparent dark dots below the subepidermal surface, smooth, glaucous and frequently suffused with red. Flowers solitary, 20‒25 mm diam., pedicels to 4 mm long., without bracts; calyx lobes 5, subequal, 3 with membranous edge; petals white, turning faintly pink with age, 3‒4-seriate, obtuse, 10‒12 mm long, 1.1 mm broad; filamentous staminodes absent; filaments white, epapillate, 1.5‒3 mm long, anthers yellow; stigmas 5, slender, narrowly subulate, caudate, 1‒1.5 mm long, shorter than the stamens, top of ovary slightly concave. Capsules 5 locules, with broad valve wings, top raised for 1‒2 mm, 6.5 mm diam., base globose to obconical, keels lacerated towards the tips. Seeds dark brown, D-shaped, surface of testa colliculate, 0.9 × 0.8 mm.

Etymology:― The epithet refers to the white to pale-rose flowers.

Phenology:― Flowering takes place in October; fruiting in November‒January.

Distribution and ecology:― Lampranthus alboroseus is a rare and localized species, which is only known from two localities in the southern Cederberg, south-east of Citrusdal ( Fig. 3 ). The species is associated with Cederberg Sandstone Fynbos, at altitudes between 1200 and 1500 m, where frosts occur regularly and snow may fall during winter. At the type locality the species was very rare (fewer than 50 plants) and was found in seasonally damp, shallow sands overlaying flat outcrops of sandstone. The association of this species with fynbos suggests that it may be most common in the years immediately after fire.

Taxonomic notes:― Lampranthus alboroseus resembles L. antonii and shares the almost sessile flowers with it. L. antonii differs from L. alboroseus in habit (a mat of trailing branches where primary and secondary stems are indistinguishable vs. a central clump of leaves on short branches from which much longer trailing branches arise in L. antonii ) and the diameter of the flowers (2.0‒ 2.5 cm vs. 5.0‒ 6.6 cm in L. antonii ). Similar flowers and a creeping habit are also shared with L. reptans ( Aiton 1789: 185) Brown (1930: 212) , which, however, develops noticeably longer pedicels. In L. reptans the pedicels range between 30‒50 mm in length, whereas in L. antonii and L. alboroseus they are short, at 7‒13 mm and to 4 mm long respectively.

Since Lampranthus alboroseus has epapillate filaments and white flowers, it is likely also to be related to species such as L. antonii and L. reptans . All these are species of acidic sandy soils in fynbos.

Historical note:― The earliest collection of Lampranthus alboroseus was made by Elsie Esterhuysen in April 1961. Since this was collected in autumn, the plants were not in flower and this collection remained for over half a century among the unnamed material of Lampranthus . In May 2019 it was rediscovered by one of the authors (NH), when again the plants were not in flower. This time it was recollected in October 2019, when both flowers and fruits were present.

Additional specimens examined: — SOUTH AFRICA. Western Cape Province, Wuppertal (3219): Southern Cederberg, Apex Peak (-CA), 4000 ft, 1 April 1961, Esterhuysen 28950 (BOL!).

Figures

FIGURE. 1. Flowering plants of Lampranthus alboroseus at the type locality in October 2019, Southern Cederberg, Hondverbrand plateau, between Loskop and Hamerkop. Helme 9567 (BOL).

FIGURE. 2. Type of Lampranthus alboroseus. Helme 9567 (BOL).

FIGURE. 3. Known distribution of Lampranthus alboroseus.