Mixtecalia Redonda-Mart., García-Mend. & D. Sandoval, 2020
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publication ID |
https://doi.org/ 10.11646/phytotaxa.438.2.5 |
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persistent identifier |
https://treatment.plazi.org/id/03C68780-FFFA-5302-FF15-F884998D56F7 |
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treatment provided by |
Felipe |
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scientific name |
Mixtecalia Redonda-Mart., García-Mend. & D. Sandoval |
| status |
gen. nov. |
Mixtecalia Redonda-Mart., García-Mend. & D. Sandoval View in CoL , gen. nov.
Type:— Mixtecalia teitaensis Redonda-Mart., García-Mend. & D. Sandoval
Plantae arborescentes monocarpicae, caulibus erectis, teretibus, carnosis, lanatis. Capitula discoidea, in corymbo disposita; pedunculi terminales et axillares, lanati; involucrum turbinatum. Corolla infundibuliformis, quinqueloba, flava. Cypsela teres, sericea. Pappus uniserialis, setis albis capillaribus.
Monocarpic arborescent plants, 0.8–4 m tall. Stems simple, erect, terete, pachycaulous, densely lanate. Leaves verticillate, marcescent, absent during the flowering period; blades ovate-elliptical, margin revolute, dentate, acute at the apex, cordate at the base; with petioles overlapping at the base; foliage with indumentum tomentose on both surfaces, comprising flagelliform trichomes. Synflorescence 1.5–2.3 m long, 0.2–0.7 m wide, paniculiform, with bracts tomentose. Heads discoid, with peduncles short, lanate; involucre turbinate, uniseriate, phyllaries 6–8, oblong-lanceolate, with a conspicuous rib in the middle, lanate. Calyculus with 4–6 bracts, linear-lanceolate, lanate. Receptacle flattened, alveolate, naked. Florets 10–12 bisexual, corolla infundibuliform, 5-lobed, yellow, tube glabrous, lobes triangular, papillose at the apex. Anthers 5, apical appendages lanceolate, endothecial tissue polar, base auriculate, collar cylindrical, filaments fused at the base. Style bifurcated, with branches obtuse, papillose on both surfaces, stigma surface continuous. Cypselae terete, 5–6-ribbed, sericeous. Pappus uniseriate, capillary bristles 195–198, subequal ( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 ).
Etymology:—The genus name refers to the Mixteca region, where the San Juan Teita municipality (Tlaxiaco District) ( García-Mendoza et al. 2004, INAFED 2019), the site where the type locality is located, is found. This region is in Oaxaca, the state with the highest diversity of Asteraceae in Mexico ( Suárez-Mota & Villaseñor 2011; Suárez-Mota et al. 2018).
Taxonomic affinities:— Mixtecalia is classified in the tribe Senecioneae because the morphological characteristics of its heads coincide completely with all the diagnostic characters of the tribe. It is included in the subtribe Tussilagininae because it has heads that are discoid; phyllaries with a central vein that is thickened at the base, anthers with a cylindrical collar, polar endothecial tissue, and a continuous stigma surface.
Mixtecalia has some morphological characters in common with other Mexican taxa of the Tussilagininae , mainly Pittocaulon , Roldana La Llave (1825: 10) and Telanthophora Robinson & Brettell (1974: 424) .Among other characters, the most notable are: pachycaulous stems, verticillate leaves that are absent during the flowering period (except in Telanthophora ), and yellow florets. However, there are differences between Mixtecalia and the aforementioned genera, the most evident being its reproductive strategy (monocarpic vs. polycarpic). It also differs in the indumentum of the stem (densely lanate vs. pilose ( Pittocaulon p.p., and Roldana p.p.), and either tomentose or glabrous ( Pittocaulon p.p., and Telanthophora ), the leaves (tomentose vs. glabrous (except in some species of Roldana and Pittocaulon ), and the cypselae (sericeous vs. glabrous); as well as the types of synflorescences (paniculiform and bracteate vs. corymbiform or subumbellate and ebracteate or bracteolate) and heads (discoid vs. radiate, except in Roldana and some species of Telanthophora ) and number of ribs on the cypselae (5–6 ribbed vs. 5–10 ribbed) ( Table 1).
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Mixtecalia also shows morphological affinity with Dendrosenecio , a genus included in the subtribe Senecioninae ( Pelser et al. 2007) , with which it shares the following characteristics: pachycaulous stem, marcescent verticillate leaves ( Figs. 1A–D View FIGURE 1 , 2A, C View FIGURE 2 ), a synflorescence that is paniculiform and bracteate and lanate peduncles ( Figs. 1E View FIGURE 1 , 2C–E View FIGURE 2 , 3 View FIGURE 3 ). However, these genera differ in vegetative characters, including the ramification of the stem (simple vs. branched, except in D. keniensis (Baker f.) Mabberley (1986: 100)) , the size of the leaves (8.7–13.8(–30) cm long vs. 10.5–65 cm long), and the presence of indumentum on both surfaces of the leaves (tomentose vs. glabrous, except in D. keniensis ). They also differ in some of the characters of the heads, such as the type (discoid ( Figs. 1E View FIGURE 1 , 2E–F View FIGURE 2 , 3 View FIGURE 3 ) vs. radiate), the indumentum of the phyllaries and peduncles (lanate ( Figs. 1E View FIGURE 1 , 3 View FIGURE 3 , 4D–E View FIGURE 4 ) vs. glabrous), the shape of the apex, the indumentum of the branches of the style (obtuse and papillose on both surfaces ( Fig. 4M–O View FIGURE 4 ) vs. truncate, glabrous on the external surface and papillose on the internal surface) and the disposition of the endothecial tissue on the anthers (polar ( Fig. 4L View FIGURE 4 ) vs. intermediate). In cypselae, the most conspicuous difference is the indumentum (sericeous ( Figs. 1F View FIGURE 1 , 2M View FIGURE 2 , 4G View FIGURE 4 ) vs. glabrous).
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