Mezcala C.E. Hughes & J.L. Contr., PhytoKeys 205: 197. 2022.

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

Mezcala C.E. Hughes & J.L. Contr., PhytoKeys 205: 197. 2022.

Figs 146 , 151

Type.

Mezcala balsensis (J.L. Contr.) C.E. Hughes & J.L. Contr. [≡ Desmanthus balsensis J.L. Contr.]

Description.

Unarmed multi-stemmed treelet or large shrub to 3.5 m, brachyblasts present, sheathed in persistent stipules. Stipules setiform with striate membranous wings. Leaves bipinnate, a stipitate nectary between basal pinnae pair; pinnae 2-4 (5) pairs, opposite; leaflets 8-14 pairs per pinna, oblong, opposite. Inflorescences capitate, 1-2 per leaf axil, composed of 30-50 functionally sterile, functionally staminate and hermaphrodite flowers, proportions of each flower type variable; bracteoles subtending each flower peltate or deltate setiform. Flowers with sepals and petals valvate in bud; each inflorescence with 0-5 sterile flowers proximally, staminodia filamentous, white; similar to the hermaphrodite flowers but smaller and lacking anthers and ovary; functionally staminate flowers 12-30 per inflorescence, lacking an ovary, borne above the sterile flowers; hermaphrodite flowers apical, 5-25 per inflorescence, the calyx obconic, petals 5, free, white or pale green, stamens 10, cream-white, anthers with a minute orbicular gland on a filiform stalk; pollen in tetrahedral tetrads with striate exine ornamentation; ovary sessile, glabrous, stigma narrow funnelform. Fruits held erect above shoots, linear-oblong, straight or weakly arcuate, terete or sub-terete, 3-10 cm long, 5-13-seeded, seeds longitudinally inserted, valves initially fleshy becoming woody or sub-woody when ripe, elastically but tardily dehiscent from the apex along both sutures (Fig. 146F, G ). Seeds square to rhomboidal, pleurogram deeply U-shaped, often asymmetric with unequal arms.

Chromosome number.

Unknown.

Included species and geographic distribution.

Monospecific ( M. balsensis ), narrowly restricted, endemic in the Balsas Depression of Mexico (Fig. 151 ).

Ecology.

Seasonally dry tropical forest and semi-arid thorn scrub on shallow calcareous rocky soils. Seed dispersal passive. Strongly deciduous. Nodulation status unknown. Bee-pollinated ( Xylocopa and other generalist bee species).

Etymology.

Named for the Mezcala culture which blossomed from 700 to 200 BC in the central Balsas Depression in Guerrero Mexico where the genus is endemic.

Human uses.

Unknown.

Notes.

Mezcala was established as a monospecific genus to account for the non-monophyly of Desmanthus ( Hughes et al. 2022c) by segregating the single species D. balsensis which differs from the remaining species of Desmanthus in possessing anther glands, pollen in tetrads as opposed to tricolporate monads, and erect woody, as opposed to chartaceous, fruits.

Taxonomic references.

Contreras-Jiménez (1986) including an illustration; Hughes et al. (2022b); Luckow (1993).

Figures

Figure 146. Fruits of genera of the Dichrostachys clade A leaves and pod of Lemurodendron capuronii Villiers & P. Guinet, north-eastern Madagascar (Koenen 429) B Neptunia plena (L.) Benth. fruits dehiscing along the dorsal suture (Wood 26650) C ripe pods of Leucaena cruziana Britton & Rose, Oaxaca, Mexico (Hughes 1300) D cluster of unripe pods on a single inflorescence of Leucaena leucocephala (Lam.) de Wit subsp. glabrata (Rose) S. Zarate, Honduras (Hughes 1557) E ripe pods of Desmanthus leptophyllus Kunth dehiscing along both sutures (Hughes 3098) F unripe fruit of Mezcala balsensis (J. L. Contr.) C. E. Hughes & J. L. Contr., held erect, Guerrero, Mexico G ripe fruits of Mezcala balsensis dehiscing from the apex along both sutures H, I unripe and ripe fruits of Kanaloa kahoolawensis Lorence & K. R. Wood, cultivated at the Olinda rare plant propagation facility, Maui, Hawaii, USA J ripe fruits of Schleinitzia insularum (Guilemin) Burkart, the valves tardily splitting along both sutures but indehiscent K winged fruits of Gagnebina pterocarpa (Lam.) Baill., Madagascar L unripe, lomentiform fruits of Prosopidastrum globosum (Gillies ex Hook. & Arn.) Burkart which break up into one- or few-seeded fragments when ripe M ripe fruits of Mimozyganthus carinatus (Griseb.) Burkart, S Bolivia (Hughes 2476) N ripe fruits, elastically dehisced from the apex, Calliandropsis nervosa (Britton & Rose) H. M. Hern. & P. Guinet, Puebla, Mexico (Hughes 1784) O unripe coiled fruits of Dichrostachys cinerea (L.) Wight & Arn. P ripe fruits dehiscing elastically from the apex, Dichrostachys venosa Villiers, southern Madagascar Q ripe fruits of Alantsilodendron pilosum Villiers, Madagascar. Photo credits A E Koenen B-E, M, N C Hughes F, G J Luis Contreras H, I A Palomino J G McCormack, Cook Islands Biodiversity K, P, Q D Du Puy L I Specogno, Flora Mendocina O Atamari (CC-BY-SA- 3.0).

Figure 151. Distribution of Mezcala based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.