Salvia fimbriaticalyx Mart.Gord. & Fragoso, 2021

Fragoso-Martínez, Itzi, Martínez-Gordillo, Martha & Salas, Silvia, 2021, Salvia fimbriaticalyx, a new species of Salvia (Lamiaceae) from Oaxaca, Mexico, Phytotaxa 518 (4), pp. 241-250 : 242-247

Salvia fimbriaticalyx Mart.Gord. & Fragoso , sp. nov. ( Figs. 1 , 2 )

Salviae leptostachydi affinis , sed bracteis lanceolatis, base cuneatis, calycis margine dense fimbriato, corollae tubo 3–3.5 mm longo, incluso in calyce; labio infero 3–3.5 mm longo.

Type:— MEXICO. Oaxaca, San Pedro Huamelula, Piedra Sola , 16°0’16.9’’N, 95°44’1.6’’W, 272 m, 29 October 2010, S . Molina 651 (holotype MEXU!; isotype SERBO!) .

Perennial herb, 0.4–0.7 m tall. Stems pubescent, trichomes short, multicellular. Leaves with petioles 1.4–3.8 cm long, blade broadly rhomboid-ovate, base cuneate, decurrent, apex acuminate, margin crenate-serrate, ciliate, trichomes multicellular, upper leaf surface pubescent on veins, trichomes minute, lower leaf surface pubescent. Inflorescence in racemes, 14.5–17 cm long, verticillasters 0.6–2.3(–3.1) cm apart, 9–12 flowers per verticillaster, peduncles 0.6–1.2 cm long. Bracts persistent, lanceolate, 0.6–1.2 cm long, apex caudate. Pedicel 2.5–4(–7) mm long, with simple trichomes. Calyx 5.5–7.5 mm long, almost the same length as the corolla tube, outer surface pubescent with yellow spherical glands, inner surface glabrous; upper lip 3-veined, margin densely fimbriate. Corolla blue, 6–7 mm long, tube 3.5–5 mm long, completely included in the calyx, slightly ventricose, internally epapillate, lobes subequal, upper lobe 2–3 mm long, margin ciliate, lower lobe 3–3.5 mm long, tetralobate, deflexed, with glands on the apex. Stamens included in the upper corolla lobe, fused close to the corolla opening, filaments ending with a glabrous tooth, gubernaculum entire with a retrorse tooth, glabrous, junction between the filament and the thecae with glands. Style densely pubescent, dorsal and ventrally, 6–7 mm long. Nectary disc surface with yellow glands, nectary horn long and terete, twice the length of the immature mericarps. Mericarps ovoid, 2 mm long, brown and smooth.

Distribution, habitat and phenology:— Salvia fimbriaticalyx is endemic to Mexico and is known from the District of Tehuantepec in the state of Oaxaca. This species is found in tropical deciduous forests, growing on rocky substrates; at 90 to 272 m. The new species has been collected with flowers and fruits during the rainy season in the months of September and October.

Etymology:— The epithet “ fimbriaticalyx ” refers to the margin of the calyx lobes, which is densely fimbriate ( Fig. 1 , 2 ).

Discussion:— Due to its morphological characteristics Salvia fimbriaticalyx should be placed in section Angulatae , one of the most diverse of subgenus Calosphace (52 spp.; González-Gallegos et al. 2020). However, molecular evidence suggests that this section is not monophyletic, with most of its species found in two different clades and being related to species from sections: Briquetia Epling (1939: 267) , Carneae ( Epling 1935: 89) Epling (1939: 228), Curtiflorae Epling (1939: 337), Farinaceae, Maxonia Epling (1939: 263), Pennellia, Potiles Epling (1939: 105) , Scorodonia Epling (1939: 166) , among others ( Fragoso-Martínez et al. 2018).

In the phylogenetic analysis we conducted ( Fig. 3 , Supplementary material 1), Salvia fimbriaticalyx is included in the Angulatae clade (98% Bootstrap Support; BS), possibly related to a clade formed by species of sections Farinaceae and Pennellia (BS 100%). Nevertheless, this relationship lacks support (BS <80%) and is inconclusive. The species that resembles Salvia fimbriaticalyx the most in morphological terms, Salvia leptostachys , is included in the sister subclade to that where the new species is, along with other species of sections Angulatae and Potiles ( Fig. 3 ; BS 100%). Although the relationships within this subclade are resolved and supported, the relationships among the three subclades (i.e., the one that includes S. leptostachys , the one with the new species and a third one including species from section Curtiflorae) remain unsupported (BS<80%).

The fact that the new species is not closely related to morphologically similar taxa suggests that some of the characters employed to define sections are labile and/or homoplastic ( Fragoso-Martínez et al. 2018) or need to be re-analyzed considering the phylogeny. Additionally, the lack of resolution and support exhibited in the relationships of the new taxon show the need to explore new molecular markers or high-throughput sequencing strategies (e.g., Anchored Hybrid Enrichment; Fragoso-Martínez et al. 2017), to tackle recalcitrant relationships in this subgenus.

Epling’s (1939) sectional classification of Calosphace remains the greatest effort made to categorize the diversity of the Neotropical sages into smaller units that can be more manageable. These sections constitute practical units that are defined by combinations of characters that can be evaluated during specimen identification. The new species could potentially be related to taxa from sections Farinaceae and Pennellia , but resembles morphologically species from sect. Angulatae .

Upon analyzing the morphology of these three sections, the number of shared characteristics is overwhelming, while the differences among them seem to be minimal ( Table 1). Some of the characters shared by the species of these sections are: interrupted spikes as inflorescences, mostly 6–12 flowers per node; calyces with upper lips 3-veined (also 5- and 7-veined in Angulatae and Farinaceae, respectively); corolla tubes epapillate; stamens inserted in the galea, stamen connective with a retrorse tooth and style pubescent with the posterior branch longer than the anterior ( Epling 1939). On the other hand, sections Angulatae and Farinaceae differ mainly in the density and quality of the indumentum found on the surface of the calyx, which varies from glabrous to hirtellous in the former and is farinaceous or lanose in the latter. The species from these two sections differ from Pennellia in the size of the flowers, being larger in this section (corolla tube 12–14 mm long vs. 3.5–11 mm in Angulatae and Farinaceae; Epling 1939).

As seen above, there are many similarities among the three sections, that could potentially be used as synapomorphies in future studies in the light of the phylogenetic relationships. The fact that Angulatae and Farinaceae are non-monophyletic sections and/or have disjunct distributions could have obscured these patterns in previous studies. Broadening taxon sampling in these sections will allow uncovering groups of species that are closely related and could aid the search of reliable morphological characters to re-circumscribe more natural infrageneric groups. Clades such as Angulatae , that encompass great morphological and taxic diversity, lacking apparent morphological synapomorphies are a reminder that our knowledge of the subgenus is still under construction, and that there are a number of potential research lines that can be followed.

The new species lacks the farinaceous indumentum characteristic of the species from section Farinaceae and has flowers with corolla tubes shorter than those of Pennellia (3.5–5 mm long vs. 12–14 mm long). Thus, we decided to place Salvia fimbriaticalyx provisionally in section Angulatae , until a more comprehensive taxonomic work in Calosphace is achieved. The new species fits the circumscription of Angulatae , having characteristics such as: the herbaceous habit, the leaf shape ovate with a cuneate base and an acuminate apex, the presence of persistent bracts, and the calyx surface pubescent, but not farinaceous. Moreover, Salvia fimbriaticalyx is included in the Angulatae clade and morphologically resembles species from section Angulatae .

For practicality, we contrast the morphology of the new species with its most similar species: Salvia leptostachys ( Table 2). The vegetative body of S. fimbriaticalyx resembles that of S. leptostachys , but the new species is a perennial herb, while the latter is annual. Salvia fimbriaticalyx has persistent, lanceolate bracts (vs. deciduous, ovate-lanceolate bracts); the margins of the calyx lobes are densely fimbriate (vs. pubescent); the corolla tube is longer (3–3.5 mm long vs. 2–3.1 mm long) and the lower corolla lobe is shorter (3–3.5 mm long vs. 3.5–5.8 mm long).

Finally, Salvia fimbriaticalyx has been collected at elevations of 90–272 m, while the morphologically similar species can be found at higher elevations, of 1000 m or more.

Additional specimens examined:— MEXICO. Oaxaca: San Pedro Huamelula, La Lomita, 90 m, 15°59’24’’N, 95°42’51.6’’W, 29 September 2010, S . Molina 382 (SERBO!, FCME!).

Figures

FIGURE 1. Scanned image from the holotype of Salvia fimbriaticalyx.

FIGURE 2. Salvia fimbriaticalyx. A) Branch with leaves and inflorescence. B) Lateral view of the flower. C) Dissected calyx with style, ovary, and nectary horn. D) Dissected corolla with androecium. Illustration drawn from S. Molina 382 (FCME) by Ramiro Cruz Durán.

FIGURE 3. Phylogenetic relationships of the core Calosphace clade based on three molecular markers (nrITS, trnH-psbA and trnL-trnF) and an increased taxon sampling including the new species. Bootstrap values ≥80% are shown above the branches. The names in pink correspond to the taxa related to the new species; however, the relationship lacks support (BS<80%). The name in blue corresponds to species that resembles Salvia fimbriaticalyx the most. In the phylogram on the left branch lengths are displayed. Some previously reported clades have been collapsed to ease visualization.An extended version of the phylogenetic tree is provided in the supplementary material 1.