Aspects of the taxonomy of the Kalanchoe daigremontiana species complex (Crassulaceae subfam. Kalanchooideae) and associated interspecific hybrids in southern Madagascar, with the description of a new nothospecies, K. × descoingsii (= K. laetivirens × K. tubiflora) Author Shtein, Ronen The Steinhardt Museum of Natural History, Tel Aviv University, Klausner St 12, Tel Aviv-Yafo, Israel. Author Smith, Gideon F. 0000-0002-5417-9208 Department of Botany, Nelson Mandela University, P. O. Box 77000, Gqeberha [Port Elizabeth], 6031 South Africa. smithgideon 1 @ gmail. com; https: // orcid. org / 0000 - 0002 - 5417 - 9208 smithgideon1@gmail.com Author Ikeda, Jun Touhoku 2 - 30 - 7, Niiza-shi, Saitama-ken, Japan. text Phytotaxa 2021 2021-11-09 524 4 235 260 journal article 10.11646/phytotaxa.524.4.2 6e96efe4-5c3c-441e-bf2c-aee6f8eb5961 1179-3163 5656381 Kalanchoe ×descoingsii Shtein, Gideon F.Sm. & J.Ikeda sp. nov. ( Figs 3 and 4 ). Type :— MADAGASCAR . Arboretum d’Antsokay , southeastern Madagascar , in a sparse forest floor, collected on 04 October 2018 by Jun Ikeda s.n ., R . Shtein 501 ( holotype TELA [ TELA935 ]; isotype TELA [ TELA936 ]). Material harvested as the holo- and isotypes was cultivated in Israel ( Figs 3 and 4 ) . Suggested parentage :— Kalanchoe laetivirens Descoings (1997: 85) × K. tubiflora ( Harvey 1862: 380 ) Hamet (1912: 44) . Diagnosis :— Kalanchoe × descoingsii differs from all other representatives of K. subg. Bryophyllum by being lowgrowing for most of its vegetative life span; by its densely foliated, solitary pseudo-rosettes that drastically elongate as flowering approaches; by being constitutively phyllo-bulbiliferous; by its oblong leaves that are apically obtuse to rounded; by having deeply dentate leaf blade margins subducted by recurved, spathulate bulbil-carrying pedestals; by its distal leaves and peduncular leaves gradually transitioning from conspicuously petiolate, deeply auriculate, basally broadened, oblong basal leaves , into being subsessile, attenuate, entire bar the apex, and generally not bulbil-forming; by its peduncle indistinctly transitioning from the distal vegetative part of the stem into the flower-bearing portion of inflorescence; by the corolla that is somewhat pinkish to whitish green when emerging, to being predominantly vibrant pink to orange-pink at anthesis; by the free sepal segments being longer than wide, ovate-deltoid, and about as long as to somewhat longer than the fused portion; by the calyx tube being wider than long; and by having nectar scales that are about as wide as long, spreading, and rounded-notched at the apex. Description :— Plants multi-annual, entirely glabrous, non-glaucescent throughout, unbranched, erect, often basally decumbent, about 0.8–1.2 m tall when in flower. Stem mostly herbaceous, lenticular, cylindrical; lower portion 25–35 cm long, 10–13 mm in diam., dense, green to pinkish brown; upper portion 50–80 cm long, 5–8 mm in diam., extremely sparse, purple; leaf scars narrowly crescentiform, conspicuous, slightly protruding, not connate; internodes 0.7–1.5 cm long basally, 4.5–6.0 cm long in distal half, distinctly lighter green to pink. Leaves opposite, decussate, succulent; basal leaves distinctly petiolate, densely arranged, wilting by anthesis; petiole 3.0– 5.5 cm long, 4–6 mm in diam. medially, up to 6–8 mm in diam. at base, subcylindrical, often slightly concave above and convex below, slightly widened around stem, green to purple, distinctly maculate with large dark brown or dark purple blotches; blade 8–12 cm long, 3.5–5.8 cm wide at base, 2.0– 3.5 cm wide elsewhere, adaxially green to green-brown, sometimes ornate with purple veining patterns centrally and basally, minutely dark-maculate, abaxially yellowish grey, strongly striped in dark brown or dark purple, narrowly elliptic to oblong, sometimes basally obtusely trilobate, widened distinctly in basal <⅓, widest at basal ¼, strongly guttered lengthwise, concave above and convex below; margins green-grey to reddish pink, regularly dentate, darkly blotched between dentations, below blotches marked by pale organogenic and/or embryogenic notches, later developing pedestals; dentations 2.0–5.5 × 3–6 mm , acute, broad, increasing in acuity basally and apically; bulbil production fully constitutive, occurs on dedicated pedestals, at least on apical ½ of each leaf blade margin or on its entirety; bulbils large, bearing 3–5 leaf pairs and sometimes their own bulbils while still attached to mother plant, almost round leafed, minutely maculate; pedestals 2.0–5.5 × ± 1.5 mm , spathulate, bent to abaxial blade surface, incurved apically; base strongly auriculate, extending up to 17 mm behind petiole-blade connection, often ornate with two erect, dentate, bulbiliferous auricles; apex obtuse to rounded; apical leaves petiolate to subsessile; petiole 1.5–2.5 cm long; blade 5.0–7.5 × 0.8–1.2 cm , equally wide throughout to widest apically, narrowly elliptic-oblanceolate, mostly entire, few-dentate apically, not pedestalate, apically bluntly obtuse to rounded, basally minutely auriculate-cuneate to attenuate. Inflorescence a compact, many-flowered, capitate thyrse, lacking leaves or barely leafed at anthesis, non-bulbiliferous, i.e., dense bulbil clusters do not develop, but a few, large, discrete plantlets may form post-flowering, dense, terminal, 7.5–15.0 cm wide, consisting of 5–7 short dichasial cymes, each 5–9 cm long; peduncle 14–21 cm long, 4–6 mm in diam., single, cylindrical, indistinctly transitioning from distal vegetative part of stem into flower-bearing portion of inflorescence; bracts 3–5 × ± 1 cm , sessile, attenuate, narrowly oblong, mostly entire, few-dentate and bluntly obtuse apically, wilting soon; floral bracts ± 2 × ± 1 cm , bract-like, wilting soon; pedicels 12–18(–25) mm long, curved, cylindrical, tapering towards flowers from 1.2–1.4 mm to ± 0.60–0.75 mm in diam., purple. Flowers numerous, pendent, campanulate. Calyx 12–15 × 7–8 mm , light or grey-green to purple, dark purple-spotted where free sepal segments fuse, succulent, thick, campanulate-urceolate, rounded, basally ± flat, widest in middle of tube, then gradually constricted upwards; tube 5.5–6.5 mm long; free sepal segments 6.5–8.0 mm long, widest at base at ± 5 mm , ovate-deltoid, very acute, apiculate, adpressed to corolla to slightly spreading. Corolla 30–33 mm long, vibrant pink to orange-pink, whitish green when emerging and where obscured by calyx, non-stipitate; tube 22–24 mm long, especially basally ± 4-angled, basally adpressed around and above carpels, up to 5.5 mm wide, then diminishing to ± 4 mm wide at its thinnest, then gradually inflating to base of petals where it is generally widest at a width of 7–8 mm ; lobes 8.0–9.5 × 6–7 mm [at base], widest at 8–9 mm at ⅓ from tip, broadly obovate, apically rounded, very slightly apiculate, somewhat spreading. Stamens 8, inserted low down in corolla tube, at ± level of carpels, slightly exserted, visible between, and reaching apex of petals; filaments of two similar lengths, fused basally, then adpressed, protruding inside base of corolla, free higher up for ± 20–22 mm , thin, yellow-green basally and apically, strongly infused with purple-pink elsewhere; anthers ± 1.0–1.2 × 0.8 mm , dark grey, producing yellow pollen, ovate-cordate, somewhat longer than wide. Pistil consisting of 4 carpels; carpels ± 7–8 × 1.7–2.0 mm, convergent, fused basally, free above, uniformly dark green, conical lanceolate, widest in lower ⅓, cuneate towards styles; styles ± 15–17 mm long, uniformly yellowish green; stigmas very minutely capitate, dark green; scales ± 1.5–2.0 × 1.5–2.0 mm, yellow-green, free, spreading, rounded-square, about as wide as long, thickened especially basally, incurved, upper corners rounded, emarginate. Follicles not seen. Seeds not seen. Chromosome number : 2 n = unknown. FIGURE 9. All documented occurrences of representatives of the Kalanchoe daigremontiana species complex, and associated interspecific hybrids, in southern Madagascar. The precise locality of the type of K. tubiflora in Madagascar is insufficiently known to be placed (see Figueiredo & Smith 2017: 771 ). Overlapping markers are separated using Point Displacement in QGIS, except of the marker of the locality of the neotype of K. sanctula which is overlapped by the marker of the type of the name and is not displayed. © OpenStreetMap contributors. Locality information is included in the Supplementary file. FIGURE 10. A hybrid between Kalanchoe daigremontiana and K. laxiflora , created and cultivated, in Israel. A. Young plant in vegetative growth, showing some peltate leaves and almost exclusively mid-green colouration. B. A mature plant (top) compared to K. daigremontiana (bottom), showing heterosis with both leaf size and plant height greatly exceeding that of either parent. No bulbil pedestals are present, and a single bulbil is visible at the leaf apex. C. Close up of the abaxial leaf blade surface almost devoid of the dark purple-brown stripes characteristic of K. daigremontiana . D. Deep red flowers with a calyx tube longer than the free sepal segments. Photographs: Ronen Shtein. Eponymy :— Kalanchoe ×descoingsii commemorates Bernard Marie Descoings (born Paris, France , 7 September 1931 –died Largentière, Ardèche, France , 23 October 2018 ) ( Madin 2018 ). He studied agronomy at Montpellier and in 1953 graduated as an agricultural engineer. From 1953 to 1954 he completed a training course at the Phanerogam Laboratory of the Muséum national d’Histoire naturelle, in Paris, where, under the guidance of Jean Henri Humbert, he developed an interest in tropical botany. Descoings ( Fig. 12 ) subsequently spent time in Madagascar (1954–1958) and after having been recruited by the ‘Office de la Recherche Scientifique et Technique Outre-Mer’ (ORSTOM), spent four years in the Congo , where he directed ORSTOM’s Botanical Laboratory from March 1960 to 1965. Between 1965 and 1985 Descoings was variously based in Montpellier, French Guiana , and Burkina Faso , and from 1970 until his retirement in 1995 he additionally held various positions in Montpellier, France . In 1976 he defended his doctoral dissertation, ‘Approche des formations herbeuses tropicales par la structure de la végétation’, in Natural Sciences in the Faculty of Sciences of the University of Montpellier. While Descoings was based at the Paris Herbarium as a young man, the exposure he had to Jean Henri Humbert likely sparked his interest in Kalanchoe , as Humbert himself had more than a passing interest in the genus ( Humbert 1933a , b). From the late 1990s to mid-2000s, Descoings described 16 new species and nothospecies in the genus from Madagascar , including K. laetivirens and K. sanctula , both reviewed in this paper. In 2003 Descoings treated Kalanchoe in the Crassulaceae volume of the Illustrated Handbook of Succulent Plants project ( Eggli 2003 ), which in several respects does not coincide taxonomically with the earlier treatment of Boiteau & Allorge-Boiteau (1995) of the genus as found in Madagascar . In 2005, Descoings paid special attention to the nothospecies of southern Madagascar , being the first to recognise their relatively common occurrence ( Descoings 2005a ). A year later he published an infrageneric classification that proposed the recognition of a morphologically diverse K . subg. Calophygia Descoings (2006: 24) , but not K . subg. Kitchingia , a view with which we do not agree. Smith (2019) was dedicated to Descoings. Distribution :—Southern Madagascar , Arboretum d’Antsokay ( Fig. 9 ). Mr Andry Petignat, Hermann Petignat’s son, an author and the current owner of the Arboretum d’Antsokay informed us that K. × descoingsii was not imported to his garden and therefore most likely spontaneously arose there. He further noted the similarities this plant bears to K. laetivirens , especially in habit and colouration, and that it rarely flowers, remaining rather short, though it has successfully spread in the garden, presumably vegetatively. Kalanchoe tubiflora and K. laetivirens , the parents of K. × descoingsii , are not known to grow sympatrically in the natural distribution range of K. laetivirens (discussed above in detail). In cultivation and in the Arboretum d’Antsokay, K. × descoingsii is able to rapidly reach its bulbil producing phase and spreads easily at a rate on par with that of K . × houghtonii . Detached bulbils may start bulbil production on their fourth leaf pair, or even carry bulbils of their own while still attached to the mother plant. Kalanchoe × descoingsii therefore poses a high invasiveness potential.