Rhadamanthopsis (Oberm.) Speta, 1998

14. Rhadamanthopsis (Oberm.) Speta View in CoL View at ENA

in Phyton (Horn, Austria) 38(1): 74 (1998) ( Fig. 35 View FIGURE 35 ). Typus generis:— R. namibensis (Oberm.) Mart. -Azorín, M.B.Crespo & M.Á.Alonso (holotype).

≡ Rhadamanthus subgen. Rhadamanthopsis Oberm. in Bothalia 13(1-2): 137 (1980). Typus subgeneris:— Rhadamanthus namibensis Oberm. (holotype).

≡ Drimia sect. Rhadamanthopsis (Oberm.) J.C.Manning & Goldblatt in Strelitzia 40: 124 (2018). Typus sectionis:— D. namibensis (Oberm.) J.C.Manning & Goldblatt (holotype).

= Drimia sect. Hyacinthoides J.C.Manning & Goldblatt in Strelitzia 40: 71 (2018). Typus sectionis:— D. hyacinthoides Baker (holotype).

Description:—Medium sized bulbous geophyte. Bulb hypogeal, ovoid to subglobose, 3‒7 cm in diam., solitary or commonly clump forming, with compact or commonly loose, white, fleshy scales. Leaves 1‒6 per bulb, hysteranthous, 4‒25 cm long, narrowly lanceolate, canaliculate and leathery or oblong, soft and commonly with longitudinal furrows, green, smooth, glabrous, sometimes surrounded by transversally barred cataphylls at base. Inflorescence an elongated raceme, 8‒35 cm long, with 8‒90 flowers; peduncle terete, erect, 10‒40 cm long, smooth or rarely scabrid-puberulous at base; pedicels subpatent, arquing downwards, 8‒17 mm long, glabrous. Bracts narrowly lanceolate, 2‒6 mm long, lowermost with spur 2‒8 mm long; bracteoles present and distinct. Flowers campanulate, nodding, diurnal. Tepals 6, 7‒ 14 mm long, white, greenish or purplish, with darker longitudinal band, connate for 2‒5 mm to form basal campanulate tube and suberect to slightly spreading, straight free lobes. Stamens 6; filaments adnate to tepals for 0.5‒3.0 mm from base and free portions suberect to sigmoid and incurved to ovary, 2.0‒ 3.5 mm long; anthers medifixed or subasifixed, dehiscing for their whole length, oblong to sagittate, connivent to style. Ovary ovoid to oblong, trigonous, 2‒5 mm long, pale green to yellowish, well differentiated from style. Style erect, 2‒7 mm long. Stigma trigonous, small and papillose. Capsule ovoid, 5‒16 mm long, valves completely dehiscing from base; tepals cohering and inrolled above ovary after anthesis, circumcissile from base and persisting as a cap at the top of the developing capsules. Seeds 4‒7 mm long, black to dark brown, subellipsoid flattened with prominent central embryo and wide, flat wings, testa, with sinuous anticlinal cell walls.

Number of species and distribution:— Rhadamanthopsis comprises five species restricted to southern and western South Africa and southern Namibia ( Fig. 29 View FIGURE 29 ), which are restricted to the Cape, Karoo-Namib, and Uzambara-Zululand Regions (sensu Takhtajan 1986 and Martínez-Azorín et al. 2023a). For further information on Rhadamanthopsis species see Obermeyer (1980a), Jessop (1977), and Manning & Goldblatt (2018).

Karyology:—2n=12, 16, 18 ( Speta 1998a with no reference).

History, diagnostic characters, and taxonomic relationships:— Obermeyer (1980a) and Martínez-Azorín & Crespo (2014) described Rhadamanthus namibensis Obermeyer in Martínez-Azorín & Crespo (2014: 1331) from southern Namibia and R. karooicus Obermeyer in Martínez-Azorín & Crespo (2014: 1331) from western South Africa. Obermeyer (1980a) also proposed Rhadamanthus subgen. Rhadamanthopsis Oberm. to include these two species, that differed from typical Rhadamanthus species (sensu Nordenstam 1970) by the loculicidal dehiscence of anthers instead of by apical pores or slits. These two species show a very distinct and easily recognizable flower syndrome within Urgineoideae , characterised by a combination of diurnal, nodding and campanulate flowers, with tepals distinctly connate at the base for about a third to 2/5 of their length and free apical lobes that are suberect to only slightly spreading, with included stamens, shortly adnate filaments, and free portions connivent to the style. Further, they produce distinct bracteoles and wide leaves, that are usually longitudinally striate (except in the type species), strongly differing from Rhadamanthus species in the sense of this work, as that genus always lacks bracteoles and produces morphologically different leaves and flowers. Other species sharing the flower and leaf morphology of R. subg. Rhadamanthopsis had previously been described, including Drimia hyacinthoides Baker (1874c: 6) , Ornithogalum haworthioides Baker (1878: 322) [= Drimia bolusii Baker (1897: 443) nom. nov., not to be confused with Drimia haworthioides Baker (1875: 366) ], and D. monophylla Oberm. ex Manning & Goldblatt (2018: 128) .

Speta (1998b) raised Rhadamanthopsis to genus rank based on the reproductive and vegetative characters mentioned above, and cited the chromosome numbers 2n=16, 18 for this genus, suggesting a clear difference from common chromosome counts in the subfamily. The phylogenetic analyses of Pfosser & Speta (1999) included a sample of this group named “ Karoophila bolusii ” (a genus name not formally published), that is sister to Charybdis (= Squilla in this work). Pfosser & Speta (2001, 2004) added a sample of Rhadamanthopsis from Namibia that nested sister to the “ Karoophila ” sample. Pfosser et al. (2012) found four samples of Rhadamanthopsis forming a clade with moderate support. The phylogenetic analyses of Martínez-Azorín et al. (2023a) include 14 samples of this group. The combination of plastidial and nuclear regions place samples of Rhadamanthopsis namibensis in a clade sister to a sample of Aulostemon . Within a large polytomy, including also the latter clade, the remaining samples of Rhadamanthopsis in the sense of this work are monophyletic and strongly supported. However, when morphological data are included in the plastid phylogenetic analyses, Rhadamanthopsis recovers monophyly in the sense of this work. The Rhadamanthopsis samples are divided in three biogeographically congruent subclades with collapsed relationships. The first subclade includes four samples of R. namibensis from southern Namibia while the second subclade comprises four samples of R. karooicus sensu lato from western South Africa, mostly Namaqualand. Finally, six samples of Drimia hyacinthoides , O. haworthioides , and D. monophylla from central southern and eastern South Africa form another clade. Some morphological differences exist among taxa included in the three biogeographic subclades. Firstly, the Namibian samples show compact bulbs and narrowly lanceolate, canaliculate, not striate, suberect to spreading leaves. Secondly, the northwestern samples present mostly compact bulbs with closely imbricate scales and flat, mostly prostrate, oblong, leaves with longitudinal furrows. Finally, samples from southern and eastern South Africa show bulbs with loose, fleshy and pediculated scales, sharing the longitudinal furrows of leaves with the Namaqualand samples. Despite the differences in vegetative morphology between those groups, we here accept Rhadamanthopsis to include all above mentioned taxa that share a distinct syndrome of morphological characters: the mostly wide hysteranthous leaves, the long racemes with distinct bracteoles, and the distinct nodding campanulate flowers.

Manning & Goldblatt (2018) placed the species accepted here in Rhadamanthopsis in two sections: Drimia sect. Rhadamanthopsis to include D. namibensis , D. karooica , and D. monophylla ; and their monotypic D. sect. Hyacinthoides to include Drimia hyacinthoides . Although these sections were separated in the key of Manning & Goldblatt (2018) by the presence or absence of bracteoles, all species in both sections have distinct bracteoles and nearly the same flower morphology. As the segregation of these sections is supported neither by phylogenetic relationships nor by morphology, sect. Hyacinthoides is not accepted here.

Accepted species and required new combinations:—

Rhadamanthopsis haworthioides (Baker) Mart. -Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Ornithogalum haworthioides Baker View in CoL in J. Bot. 16: 322 (1878), basionym ≡ Drimia bolusii Baker, Fl. Cap. (Harvey) 6(3): 443 (1897), nom. nov. [non D. haworthioides Baker View in CoL in Gard. Chron. 1: 366 (1875)] ( Figs 2.20 View FIGURE 2 , 35.1 View FIGURE 35 ). Type:— SOUTH AFRICA. Graaf Reinet, Cave Mountain, 2900 feet, Bolus 814 (Collection not found at K, S. Rokni pers. comm.; neither at BOL, PRE, nor NBG).

Rhadamanthopsis hyacinthoides (Baker) Mart. View in CoL - Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Drimia hyacinthoides Baker View in CoL in J. Bot. 12: 6 (1874), basionym ( Figs 3.1 View FIGURE 3 , 35.2 View FIGURE 35 ). Type:— SOUTH AFRICA. Eastern Cape. Grahamstown (3326): shady valleys near Grahamstown, (–BC), November without year, P. MacOwan 1465 (GRA0000459! lecto. designated by Jessop in J. S. African Bot. 43: 27. 1977; K000400567!, NY00319647! isolecto.).

Rhadamanthopsis karooicus (Oberm.) Mart. -Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Rhadamanthus karooicus Oberm. View in CoL in Taxon 63(6): 1331 (2014), basionym ≡ Rhadamanthus karooicus Oberm. in Bothalia 13(1-2): 138 (1980), nom. inval. ≡ Rhadamanthopsis karooicus (Oberm.) Speta, Phyton (Horn, Austria) 38(1): 74 (1998), nom. inval. ≡ Drimia karooica (Oberm.) J.C.Manning & Goldblatt View in CoL in Strelitzia 9: 712 (2000), nom. inval. ≡ Drimia karooica (Oberm.) J.C.Manning & Goldblatt View in CoL in Strelitzia 40: 126 (2018) ( Figs 3.2 View FIGURE 3 , 35.3 View FIGURE 35 ). Type:— SOUTH AFRICA. Western Cape. Montagu (3320): Laingsburg, Keurfontein farm, (–BB), December 1974 [flowering ex hort.], J. van Zanten s.n. (PRE0240643-1!: plant with inflorescence, holo.).

Rhadamanthopsis monophyllus (Oberm. ex J.C.Manning & Goldblatt) Mart. - Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Drimia monophylla Oberm. ex J.C.Manning & Goldblatt View in CoL in Strelitzia 40: 128 (2018), basionym. ( Figs 3.3 View FIGURE 3 , 35.4 View FIGURE 35 ). Type:— SOUTH AFRICA. Eastern Cape. Somerset East (3225): Stone Fountain farm, (–DA), 19 April 1963 [leafing bulbs], R. Bayliss 1345 (NBG84207! holo.).

Comments:— Drimia monophylla sensu Manning & Goldblatt (2018) fits with Ornithogalum haworthioides Baker (1878) (= Drimia bolusii Baker 1897 ) based on the bulb structure, lorate leaves and campanulate flowers with included perigynous stamens. However, Manning & Goldblatt (2018) considered O. haworthioides as synonym of Drimia haworthioides Baker (1875) , a member of Drimia s.str. When O. haworthioides is placed in Rhadamanthopsis , it apparently only differs from D. monophylla (with 1‒2 leaves) by the 5‒6 leaves per bulb. Further studies are needed to evaluate their exact relationship.

Rhadamanthopsis namibensis (Oberm.) Mart. -Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Rhadamanthus namibensis Oberm. View in CoL in Taxon 63(6): 1331 (2014), basionym ≡ Rhadamanthus namibensis Oberm. in Bothalia 13(1−2): 137 (1980), nom. inval. ≡ Rhadamanthopsis namibensis (Oberm.) Speta in Phyton (Horn, Austria) 38(1): 74 (1998), nom. inval. ≡ Drimia namibensis J.C.Manning & Goldblatt View in CoL in Strelitzia 9: 712 (2000), nom. inval. ≡ Drimia namibensis (Oberm.) J.C.Manning & Goldblatt View in CoL in Strelitzia 40: 125 (2018) ( Figs 3.4 View FIGURE 3 , 35.5 View FIGURE 35 ). Type:— NAMIBIA. Witputz (2716): Witputz-Suid, 1 km SE of Police Station, (–DA), Giess 13781 (PRE0488688-1!: inflorescence in two pieces, holo.; K000257234!, M0107238!, WIND! iso.).