Thyrsantheminae Faden & D.R.Hunt, Taxon 40(1): 26. 1991

Pellegrini, Marco O. O., 2017, Morphological phylogeny of Tradescantia L. (Commelinaceae) sheds light on a new infrageneric classification for the genus and novelties on the systematics of subtribe Tradescantiinae, PhytoKeys 89, pp. 11-72 : 28

Subtribe Thyrsantheminae Faden & D.R.Hunt, Taxon 40(1): 26. 1991 syn. nov.

Type genus.

Thyrsanthemum Pichon.

Diagnosis.

Herbs chamaephytes or geophytes, base definite or indefinite, perennial or annual, terrestrial, rupicolous or epiphytes. Roots thin and fibrous or thick and tuberous. Rhizomes absent. Stems all aerial, rarely both underground and aerial stems present. Leaves sessile to subpetiolate; distichously or spirally-alternate, evenly distributed along the stem or congested at the apex of the stem; sheaths closed, rarely split open at maturity; blades flat to falcate and/or complicate, base symmetrical or asymmetrical. Synflorescences terminal or axillary in the distal portion of the stems, sometimes exclusively axillary, composed of a solitary main florescence or a main florescence with 1-several coflorescences. Inflorescences (main florescences) consisting of a variously modified thyrse, sometimes extremely reduced to few cincinni, inflorescence bract leaf-like or hyaline, tubular and inconspicuous, rarely spathaceous; peduncle bracts present or not; supernumerary bracts present or not; cincinni bracts frondose (leaf-like or spathaceous), bracteose, rarely reduced to hyaline crests, saccate or not at base, free from each other or not; cincinni alternate, fasciculate, verticillate or subopposite, free to fused back to back, sessile, contracted or elongated, bracteoles inconspicuous or expanded, imbricate or not, sometimes completely involving the cincinnus. Flowers bisexual, sometimes staminate, rarely pistillate, actinomorphic zygomorphic, chasmogamous, flat or tubular, when present floral tube infundibuliform to hypocrateriform, rarely campanulate; pedicel gibbous at apex or not, upright or geniculate at anthesis and pre-anthesis, deflexed at post-anthesis; sepals equal or unequal, free to conate, membranous or chartaceous, rarely fleshy, cucullate, dorsally keeled or not, persistent in fruit; petals sessile or clawed, equal, rarely subequal, free to conate; stamens (1-3-)6, arranged in two series, equal or subequal or unequal, all fertile or not, filaments free from each other, free from the petals or epipetalous, rarely connate producing a petalo-staminal ring, straight or sigmoid at anthesis, straight or spirally-coiled at post-anthesis, bearded or not with moniliform hairs, rarely hairs non- moniliform, when present hairs basal or medial or apical, sparse to dense, much shorter or as long as the stamens, anthers basifixed or dorsifixed, rimose, connective expanded or not, anther sacs straight or divergent; ovary sessile, variously pubescent, (1-2-)3-locular, locules equal, locules 1-several-ovulate, ovules uniseriate, style straight or sigmoid at anthesis, straight or spirally-coiled at post-anthesis, obconical or cylindrical at base, cylindrical at length, conical or cylindrical to obconical at the apex, stigma punctate or truncate to capitulate or capitate to trilobate. Capsules smooth, glabrous, loculicidal, (2-)3-valved, rarely indehiscent, sometimes apiculate due to persistent style base. Seeds exarillate, ventrally flattened or not, cleft or not towards the embryotega, testa variously ornamented, hilum punctate to elliptic, C-shaped or linear, embryotega dorsal, semilateral or lateral, conspicuous or not, with a prominent apicule or not.

Chromosomes.

Small, medium or large-sized, uni- or bimodal, n = 4-17

Included genera.

Callisia Loefl. (New World, 20 spp.); Tripogandra Raf. (Neotropics, ca. 22 spp.); Tradescantia L. emend. M.Pell. (New World, ca. 90 spp.); Gibasis Raf. (Neotropics, ca. 11 spp.); Elasis D.R.Hunt (Mexico/Guatemala/Ecuador, ca. 4 spp.); Matudanthus D.R.Hunt (Mexico, 1 sp.); Thyrsanthemum (Mexico, 3 spp.); Gibasoides D.R.Hunt (Mexico, 1 sp.); Tinantia Scheidw. (Texas/Neotropics, 13 spp.); Weldenia Schult.f. (Mexico/Guatemala, 2 sp.); Sauvallea C.Wright ex Hassk. (Cuba, 1 sp.).

Notes.

Subtribe Tradescantiinae (sensu Faden and Hunt 1991) is composed by Callisia s.l., Gibasis , Tradescantia , and Tripogandra . The subtribe was characterized by its main florescences reduced to a double-cincinni, fused back to back, or by two to several stipitate and geniculate cincinni arranged in an umbellate thyrse ( Faden and Hunt 1991; Panigo et al. 2010). In this old circumscription of Tradescantiinae , the cincinni are generally contracted, as opposed to the elongated cincinni in subtribe Thyrsantheminae ( Faden and Hunt 1991). Thyrsantheminae represents a rather heterogeneous assemble of genera, with no clear morphological feature linking these groups together. Not surprisingly, both subtribes have been consistently recovered as non-monophyletic, due to the inclusion of Elasis in Tradescantiinae s.s., and to the remaining genera of Thyrsantheminae being recovered in two independent lineages (Bergamo 2003; Evans et al. 2003; Wade et al. 2006; Burns et al. 2011; Zuiderveen et al. 2011; Hertweck and Pires 2014; Pellegrini et al. unpublished data; Fig. 4B ). Nonetheless, if both subtribes are combined, they become equivalent to the Tradescantia alliance (sensu Hertweck and Pires 2014) and monophyletic ( Evans et al. 2003; Wade et al. 2006; Burns et al. 2011; Hertweck and Pires 2014; Pellegrini et al. unpublished data). This clade is exclusively Neotropical, having pollen grains with rugose to rugose-insulate tectum as its synapomorphy (Poole and Hunt 1980; pers. observ.).

Figures

Figure 4. Congruence between morphological and molecular datasets. A, majority-rule tree showing the sections and series proposed by Hunt (1975, 1980, 1986 b) color-coded; the five newly proposed subgenera are represented by the black bars; Tradescantia guatemalensis C. B. Clarke ex Donn. Sm. is depicted in red, to highlight its placement as sister to Elasis hirsuta (Kunth) D. R. Hunt; the ● represents Tradescantia s. s.; Bremer Index support values are depicted over the branches, while bootstrap support values are depicted under the branches B simplification of the current hypothesis for phylogenetic relationships in tribe Tradescantieae, based on molecular data. Thyrsanthemum Pichon and Weldenia Schult. f. are depicted in red since they were not sampled in the present study. Modified from Hertweck and Pires (2014).