Spigelia xochiquetzalliana S. Islas, Lozada-Pérez et L.O. Alvarado, 2017

Islas-Hernández, C. Sofia, Lozada-Pérez, Lucio & Alvarado-Cárdenas, Leonardo O., 2017, A new species of Spigelia L. (Loganiaceae) from Mexico, Phytotaxa 303 (2), pp. 118-124 : 119-122

Spigelia xochiquetzalliana S. Islas, Lozada-Pérez et L.O. Alvarado sp. nov.

Type:— MEXICO, Guerrero: Municipio de Acapulco de Juárez. Cerro Cebadilla, 16º57’12.8’’ N, 99º39’47.5’’ W. 3 August 2003, L. Lozada, C. Gallardo & R. de Santiago 2588. (Holotype: FCME!). Figure 1 , 2 .

Spigelia xochiquetzalliana is similar to S. humboldtiana in several features, such as the herbaceous habit, elliptic to ovate-lanceolate leaves and infundibuliform corolla, but can be distinguished from this species by its adaxially purple corolla lobes and exserted style prior to anthesis.

Annual erect herbs of 30–40 (–60) cm tall. Stems quadrangular, glabrate, without branches. Root system fibrosus. Leaves opposite, pseudoverticillate at the base of the inflorescence, sessile; stipules 1.8 mm × 2.1 mm, triangular; blades 9.7–17.7 cm × 4.1–7.6 cm, elliptic to ovate-lanceolate, base obtuse to decurrent, apex acute to acuminate, membranaceous, margin slightly cilliate, adaxially glabrate to glabrescent, abaxially glabrate. Inflorescences terminal, in scorpioid cymes, not branched, with 11–17 flowers; peduncles 1.1–1.5 cm long, glabrate; the pedicels 0.8–1.3 mm long, glabrate; bracts 1.5–1.9 mm long and less than 0.5 mm wide, lanceolate, glabrate, persistent. Calyces with sepals fused only at the base, sepals 4.5–5 mm × 0.9–1.3 mm, lanceolate, glabrate. Corollas infundibuliform, lower tube 1.4–1.6 cm × 2.8–3.5 mm, minutely puberulent to glabrescent, upper tube 2.9–4.3 × 4.4–5.1 mm, glabrate, white; lobes 1.9–3.1 mm × 2.7–3.7 mm, valvate, ovate–lanceolate, internally purple; stamens included, filaments 2.8 mm, inserted in the upper half of the corolla tube, anthers 2.6 mm long, ovate–sagittate; ovary 1.3–1.4 mm, spheroid, style 1.6 cm, pubescent at the apex, articulated at 0.6 mm above the ovary, with cylindrical stigma exserted from the corolla prior to anthesis. Capsules unknown, seeds unknown.

Etymology:— Spigelia xochiquetzalliana (zo-chi-ket-za-lee-ana) refers to Xochiquétzalli or Xochiquétzal, the Nahuatl goddess mother of flowers, according to the Telleriano-Remensis and Florentine Codices, which are the manuscripts that explain history,religion, beliefs, practices, and deities from the indigenous Mexicans. In the Florentine Codex, it is mentioned that the flower represents the sexual femininity with a tendency to excess ( Dupey 2013), which could be related to the presumed protogynous flowers that this species presents.

Habitat:—The new species can be found in tropical deciduous and subdeciduous forest, growing on brown soils rich in clay, at 100–350 m elevation, with annual precipitation of 800–1200 mm and average annual temperature of 20–29 ºC (Rzedowski 2006, Challenger & Soberón 2008).

Distribution:—The new species is endemic to Mexico and has only been recorded in the states of Guerrero (Municipalities of Acapulco de Juárez and Mochitlán) and Michoacán (Municipality of Aquila). The distribution of this species is limited to the coastline zone and bordered by the Sierra Madre del Sur of the states of Guerrero and Michoacán. Spigelia xochiquetzalliana corroborates the observations made for many other species of the genus, which suggest that the physical barriers of mountain chains (Sierra Madre del Sur), watersheds and basins (Balsas basin) could represent specific conditions for the isolation and the eventual development of new taxa ( Gould 1999, Alvarado-Cárdenas & Jiménez 2015). With this new species, Mexico reaches 20 species of Spigelia , of which 50% are endemic, highlighting it as a center of diversity for the genus. In the country, the state of Guerrero holds the second place with major specific diversity (11 species), only after Chiapas with 14 species. Michoacán is in the 15th place with only two species registered. However, efforts of recollection are needed to increase the number of known species, as the surface, vegetation and geographical barriers of this state are similar to those of Guerrero; therefore, we can expect more taxa in the future.

Phenology:—The new species flowers from August to September. The fruiting period is still unknown.

Conservation:— Spigelia xochiquetzalliana has been recorded in only two locations in the coastline region of the states of Guerrero and Michoacán, are separated by 500 km. The population in Guerrero was collected in the municipality of Acapulco, which is a locality with important urban growth, but there are no data regarding the abundance of the populations and the search should be intensified between these two locations and nearby states. We propose to assign the category of Data Deficient (DD) for this taxon ( IUCN, 2014).

Discussion:—This species is morphologically similar to S. humboldtiana (fig. 3) for its herbaceous habit, shape of the leaves and infundibuliform corolla. Spigelia xochiquetzalliana can be distinguished for its unbranched inflorescences (vs. branched inflorescences), as well as the innerly purple lobes of the corolla (vs. innerly white lobes). Another interesting attribute is the probable protogynous flowers (vs. flowers not clearly protogynous with included style, even during anthesis). We suggest the probable protogyny because the style and (apparently) fully developed stigma are exserted prior to anthesis. However, it is necessary to evaluate the stigma receptivity to confirm our observations. Additionally, the style articulation 0.6 mm above the ovary (vs. style articulation 1.5 mm above the ovary) and stamens inserted at 2–3.5 mm below the corolla lobes (vs. stamens inserted 5 mm below the corolla lobes). Spigelia xochiquetzalliana has been found at 100–500 m elevation in the states of Guerrero and Michoacán, while S. humboldtiana is known from 500–2300 m elevation in the states of Campeche, Chiapas, Guanajuato, Guerrero, Oaxaca, Puebla, Querétaro, Quintana Roo, San Luis Potosí, Tabasco, Veracruz and Yucatan.

Paratype:— Mexico. Guerrero. Municipio Mochitlán: Mochitlán, 11 September 2012, M.A. Venalonzo 13715 (FCME). Mochitlán, 15 September 2012, R. Santos 13686 (FCME). Michoacán. Municipio de Aquila, 2 km al N del Rancho Barranca del Potrero, 1 September 1979, B. Guerrero 311 (XAL).

Figures

FIGURE 1. Holotype of Spigelia xochiquetzalliana.

FIGURE 2. Spigeliaxochiquetzalliana.A) Plant habit.B) Detailof the interpetiolar stipule.C)Adaxial surface of the leaf.D) Inflorescence. E) Detail of the upper portion of the tube and lobes of the corolla, including the exserted styles. F) Dissection of the flower showing the insertion of the stamens. G) Gynoecium. H) Detail of the stigma. I) Detail of the ovary. J) Detail of the anther. (A–J based in L. Lozada et al. 2588).