Afrocalliandra E.R. Souza & L.P. Queiroz, Taxon 62(6): 1213. 2013.

Bruneau, Anne, de Queiroz, Luciano Paganucci, Ringelberg, Jens J., Borges, Leonardo M., Bortoluzzi, Roseli Lopes da Costa, Brown, Gillian K., Cardoso, Domingos B. O. S., Clark, Ruth P., Conceicao, Adilva de Souza, Cota, Matheus Martins Teixeira, Demeulenaere, Else, de Stefano, Rodrigo Duno, Ebinger, John E., Ferm, Julia, Fonseca-Cortes, Andres, Gagnon, Edeline, Grether, Rosaura, Guerra, Ethiene, Haston, Elspeth, Herendeen, Patrick S., Hernandez, Hector M., Hopkins, Helen C. F., Huamantupa-Chuquimaco, Isau, Hughes, Colin E., Ickert-Bond, Stefanie M., Iganci, Joao, Koenen, Erik J. M., Lewis, Gwilym P., de Lima, Haroldo Cavalcante, de Lima, Alexandre Gibau, Luckow, Melissa, Marazzi, Brigitte, Maslin, Bruce R., Morales, Matias, Morim, Marli Pires, Murphy, Daniel J., O'Donnell, Shawn A., Oliveira, Filipe Gomes, Oliveira, Ana Carla da Silva, Rando, Juliana Gastaldello, Ribeiro, Petala Gomes, Ribeiro, Carolina Lima, Santos, Felipe da Silva, Seigler, David S., da Silva, Guilherme Sousa, Simon, Marcelo F., Soares, Marcos Vinicius Batista & Terra, Vanessa, 2024, Advances in Legume Systematics 14. Classification of Caesalpinioideae. Part 2: Higher-level classification, PhytoKeys 240, pp. 1-552 : 1

Afrocalliandra E.R. Souza & L.P. Queiroz, Taxon 62(6): 1213. 2013.

Figs 197 , 198 , 199 , 201

Type.

Afrocalliandra redacta (J.H. Ross) E.R. Souza & L.P. Queiroz [≡ Acacia redacta J.H. Ross]

Description.

Shrubs to 2.5 m, densely branched (Fig. 197D ), the branches provided with brachyblasts from which leaves and inflorescences emerge, armed with tapering branches becoming spinescent at the tips ( A. gilbertii ) or with spinescent stipules ( A. redacta ). Stipules either leafy or modified into long, paired, straight or slightly curved, rigid spines (Fig. 199B ), persistent. Leaves bipinnate; petioles without extrafloral nectaries; pinnae 1 pair; leaflets 3-9 pairs per pinna, small. Inflorescences capitate, pedunculate, homomorphic, few-flowered (Fig. 198C ). Flowers sessile or subsessile; calyx cup-shaped, 5-merous; corolla 5-merous; stamens 10-34, long exserted from the corolla, with their bases fused forming a conspicuous tube, this slightly exserted above the corolla, creamy white or pink, the anthers eglandular; pollen in (7) 8 (10)-grained acalymmate polyads, bilateral, flattened-ovoid, with the basal grain acutely narrowed, with a rather inconspicuous sticky appendage; stigma capitate ( A. gilbertii ). Fruits narrowly oblanceolate, erect, flattened, slightly curved, with thickened margins, the valves thick coriaceous (Fig. 199B ), dehiscing elastically along both margins, recurving from apex downwards, 2-4 seeds per fruit. Seeds rounded, ca. 5 × 3 mm, compressed, flattened, pointed towards the hilar end, areolate.

Chromosome number.

Unknown.

Included species and geographic distribution.

Two species distributed allopatrically in distant arid areas of Africa. Afrocalliandra redacta is endemic to a restricted area of the Northern Cape Province, across the mountains of the Richtersveld, South Africa, and A. gilbertii is found in the Mandera District, Kenya and in adjacent Somalia (Fig. 201 ).

Ecology.

Both species of Afrocalliandra occur in arid zones, in areas surrounded by open, shrubby vegetation. Afrocalliandra redacta has been reported to grow on rocky slopes of schistoid granite, at 700 m elevation, whereas A. gilbertii has been found on sandstone ridges at 450-500 m.

Etymology.

African Calliandra , from Greek, calli - (= beautiful) and - andrus (= male), pertaining to the highly attractive stamens.

Human uses.

Unknown.

Notes.

Based on a nuclear and plastid DNA sequence phylogeny, Souza et al. (2013) transferred to Afrocalliandra the two African species originally placed in Calliandra . Although the morphology of the African species is similar to some Calliandra species inhabiting arid areas of the New World, they differ by some fundamental features, such as the (7) 8 (10)-celled, acalymmate polyads, and the presence of axillary branches or stipules modified into thorns, although both types of armature also occur sporadically within Calliandra [spinescent stipules in C. pauciflora and C. haematomma (Bertero ex DC.) Benth., and spinescent shoots in C. spinosa ].

Contrasting with the current view to maintain Calliandra and Afrocalliandra as separate genera, Thulin (2023) recently proposed a return to the circumscription of Calliandra as an amphi-Atlantic genus that includes the two African species, here regarded as Afrocalliandra . As emphasised by Thulin (2023), Calliandra and Afrocalliandra are two closely related monophyletic sister taxa that are morphologically not easily separable. Thulin (2023) noted that the two Afrocalliandra species may be distinguished morphologically from all of the Neotropical Calliandra only by a single microscopic character: the acalymmate polyads, a plesiomorphic character state among mimosoids. However, the calymmate condition in Calliandra is rarely found in other Mimoseae and clearly distinguishes this genus from Afrocalliandra . An associated structure present in all Calliandra species, as well as in Afrocalliandra , is the sticky appendage attached to the basal polyad cell. This appendage, which is destroyed in acetolysed material, seems to be rudimentary in Afrocalliandra ( Thulin et al. 1981, fig. 3G), whereas in the observed Calliandra species it is extremely large and evident (see fig. 2 in Hernández 1986). In addition to the differential polyad characters, all available phylogenies show that the Calliandra and Afrocalliandra clades are supported by long branches reflecting ancient cladogenesis (Suppl. material 2), even longer than the morphologically dissimilar Acaciella . Consequently, considering the important differences in polyad structure, the separation of the two genera by long branches in the existing phylogenies, and their geographic separation in Africa and America, we have opted here to keep the two genera separate.

Taxonomic references.

Souza et al. (2013); Thulin (1993, 2023); Thulin et al. (1981).

Figures

Figure 197. Diversity of plant growth forms of the genera of the Calliandra clade A shrubby habit of Acaciella angustissima (Mill.) Britton & Rose var. angustissima, Texas, USA B treelet of Acaciella angustissima var. angustissima, Chiquimula, Guatemala (Hughes 1487) C shrub of Calliandra mollissima (Humb. & Bonpl. ex Willd.) Benth., Maranon Valley, Peru (Saerkinen 2198) D stunted xerophytic shrublet of Afrocalliandra redacta (J. H. Ross) E. R. Souza & L. P. Queiroz, Kuboes, South Africa E stunted xerophytic shrublet of Calliandra chilensis Benth., northern Chile F small treelet of Calliandra calothyrsus Meisn., Siguatepeque, Honduras G shrub of Calliandra californica Benth., Baja California Sur, Mexico (Hughes 1546) H treelet of Calliandra fuscipila Harms, Serra do Espinhaco, Bahia, Brazil (Queiroz 15626) I, J functionally herbaceous geoxyle of Calliandra longipes Benth. arising from a stout lignotuber and resprouting and fruiting after fire in savanna woodland, Santa Cruz, Bolivia (Wood 26548) K geoxylic shrublet of Calliandra mucugeana Renvoize, arising from a stout woody underground stem and forming carpet-like thickets, Serra do Espinhaco, Bahia, Brazil (Queiroz 15540). Photo credits A Ron Stephens, iNaturalist (https: // www. inaturalist. org / photos / 199321699) B, C, F-K CE Hughes D Pietermier, iNaturalist (https: // www. inaturalist. org / photos / 152398478) E J Jimenez Castillo.

Figure 198. Variation in inflorescences of the genera of the Calliandra clade. A compound terminal panicle of capitula of Acaciella villosa (Sw.) Britton & Rose, Oaxaca, Mexico (Hughes 1333) B capitula of Acaciella villosa, Piura, Peru (Hughes 2635) C flowers of Afrocalliandra redacta (J. H. Ross) E. R. Souza & L. P. Queiroz, Kuboes, South Africa D erect terminal racemose inflorescence of Calliandra calothyrsus Meisn. flowering at night, Siguatepeque, Honduras (Macqueen 3) E erect terminal racemose inflorescence of Calliandra juzepczukii Standl., Oaxaca, Mexico (Hughes 1675) F erect terminal inflorescence with buds and flowers opening acropetally, Calliandra grandiflora (L'Her.) Benth., Mexico City, Mexico G inflorescence of Calliandra taxifolia (Kunth) Benth., Mollendo, Arequipa, Peru (Hughes 2357) H heteromorphic inflorescence of Calliandra mollissima (Humb. & Bonpl. ex Willd) Benth., Maranon Valley, Peru, showing central flowers with enlarged staminal tubes (Saerkinen 2198) I Calliandra nebulosa Barneby, Serra do Espinhaco, Bahia, Brazil (Queiroz 15624) J flowers of Calliandra longipinna Benth., Serra do Espinhaco, Bahia, Brazil (Queiroz 15603) K long pedicellate flowers of Calliandra leptopoda Benth., Serra do Espinhaco, Bahia, Brazil L leaves, foliaceous stipules and terminal inflorescences of Calliandra lanata Benth., Serra do Espinhaco, Bahia, Brazil. Photo credits A, B, D, E, G-J CE Hughes C Pietermier, iNaturalist (https: // www. inaturalist. org / photos / 15308160) F Mvz-juangonzalezromero, iNaturalist (https: // www. inaturalist. org / photos / 195966667) K, L E de Souza.

Figure 199. Variation in fruits across genera of the Calliandra clade A pendulous fruit of Acaciella angustissima (Mill.) Britton & Rose var. angustissima, Chiapas, Mexico B erect fruit and spinescent stipules of Afrocalliandra redacta (J. H. Ross) E. R. Souza & L. P. Queiroz, Kuboes, South Africa C, D fruits of Calliandra taxifolia (Kunth) Benth., Mollendo, Arequipa, Peru (Hughes 2357) C unripe green erect fruits D ripe fruits elastically dehiscent from the apex, the valves recurved backwards E ripe and unripe fruits of Calliandra luetzelburgii Harms, Serra do Espinhaco, Bahia, Brazil (Queiroz 15618) F unripe, green, erect fruits of Calliandra viscidula Benth., Serra do Espinhaco, Bahia, Brazil (Queiroz 15541) G, H fruits of Calliandra houstoniana (Mill.) Standl., Chiapas, Mexico (Hughes 1271 & 1287) I unripe fruits of Calliandra chilensis Benth., northern Chile J unripe, erect fruits of Calliandra bahiana Renvoize var. erythematosa Barneby, Serra do Espinhaco, Bahia, Brazil (Queiroz 15622). Photo credits A Neptali Ramirez Marcial, iNaturalist (https: // www. inaturalist. org / photos / 199788369) B Pietermier, iNaturalist (https: // www. inaturalist. org / photos / 152398411) C-H, J CE Hughes I J Jimenez Castillo.

Figure 201. Distribution of Afrocalliandra based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.