Lobelia saturnini Art.Castro & I.Gutiérrez, 2018

Gutiérrez-Sánchez, Rosa Ivonne, Castro-Castro, Arturo, Gallegos, Jesús Guadalupe González-, López-Enríquez, Irma Lorena & Frías-Castro, Alfredo, 2018, Synopsis of the spurred species of Lobelia section Stenotium (Campanulaceae) in Sierra Madre Occidental, Mexico, and the description of two new species, Phytotaxa 338 (1), pp. 33-48 : 43-45

10. Lobelia saturnini Art.Castro & I.Gutiérrez , sp. nov. ( Figures 5–6 )

Lobelia saturnini is morphologically similar to L. knoblochii , but differs by leaves (2–)4–14(–17) mm long, petioles 2–6(–17) mm long, flowers 12–16 mm long including hypanthium, hypanthium 1.2–2.5 mm long, spur 2–3 mm long, pedicels (1.3–)2–9(–12) cm long and anthers 1–2.2 mm long.

Type:— MEXICO, Durango, Canelas, km 8.6 carretera vieja entre Cañada del Macho y Canelas, 25.126944° N, 106.499722° W, 2129 m, 18 May 2017, Castro-Castro et. al. 4246 (holotype CIIDIR!, isotypes CIIDIR!, IBUG!, IEB!, MEXU!, SLPM!, USON!).

Perennial herbs; stems procumbent, rooting at nodes, green during flowering and purple during fruit maturation, puberulent; leaves cauline; petiole 2–6(–17) mm long, green, pilose; blade ovate, (2–)4–14(17) × 4–13(–24) mm, cordate at base, rounded at tip, the margins shallowly dentate, pilose with slender white trichomes throughout; flowers solitary, borne on leaf axils; pedicels (1.3–)2–9(–12) cm long, green with purple shades and glabrous; bracteoles absent; corolla 12–16 mm long including hypanthium; hypanthium asymmetrical, upper side 2.8–3.6 mm long, the lower side extending with corolla tissue into spur; spur conic, 2–3 mm long measured from the base of the upper segments of the calyx; calyx lobes subulate, 2.5–2.9 mm long, the two lower ones slightly shorter, positioned 0.2–0.3 mm above base of the spur; corolla tube white, 4–6.5 mm long, slit dorsally to base; corolla lobes blue to purplish, the upper lobes spatulate, 4–6 × 1–2 mm, the lower lobes obovate, narrowly divergent, 5–6 × 2.8–3.5 mm, apiculate, with 2 small circular yellow spots opposed to sinuses at throat; staminal tube 2.4–6.6 mm long; anthers 1–2.2 mm long, connate, blue, the three upper anthers slightly longer and curved distally toward the lower two and often covered with short slender trichomes, the two shorter anthers bearded with a white-tuft of stiff trichomes at tip; style 4–4.4 mm long, stigma 0.5–0.6 mm long, capsule 3–4(–6) × 1–4 mm; seeds 0.3–0.5(–6) × 0.2–0.3 mm, ellipsoid, dark brown, testa sculpturing striate and shining.

Distribution, ecology and phenology: — Lobelia saturnini inhabits northwestern Durango, in the Madrean Tropical region of the Sierra Madre Occidental. It was collected from two localities in oak forest, on humid hillsides where it grows at an elevation range of 2129–2380 m. The associated species are Arbutus madrensis González-Elizondo (1992: 8) , Alnus acuminata Kunth (1817: 20) , Bocconia arborea Watson (1890: 141) , Cunila sp. , Lupinus sp. , Pinus herrerae Martínez (1940: 76) , Quercus sp. , Salvia elegans Vahl (1804: 238) , S. iodantha Fernald (1900: 547) and Verbesina sp. Individuals of Lobelia saturnini were collected in flower and fruit from April to May.

Conservation status: — Lobelia saturnini is represented by five collections. Using GeoCAT ( Bachman et al. 2011) the Extent of Occurrence (EOO) was of 113.3 km 2 and the size of the Area of Occupancy (AOO) is 16 km 2, based on cells of 2 × 2 km. According to EOO and AOO results and following the IUCN (2013) criteria (Area of Occupancy estimated to be less than 500 km 2 and known to exist at no more than five locations), a preliminary category of endangered is proposed (EN/B2a).

Etymology: —The taxon is named in honor of Saturnino Acevedo Santoyo, prolific botanical collector working for CIIDIR herbarium from 1981-2004 who contributed 1363 specimens to the flora of Durango, and who first collected the new species here described.

Additional specimens examined: — MEXICO, Durango, Canelas, 10 km road to Santiago Papasquiaro , 25.127959° N, 106.505117° W, 2060 m, 16 April 1985, S. Acevedo 201a ( CIIDIR!) ; km 15 de la carretera Canelas- Durango, 25.0875° N, 106.497778° W, 2133 m, 19 May 2017, Castro-Castro et al. 4247 (CIIDIR!, IBUG!, IEB!, MEXU!, SLPM!, USON!) ; km 8.5 del camino antiguo Cañada del Macho-Canelas , 25.12580° N, 106.50079° W, 2154 m, 7 July 2017, Castro-Castro et al. 4255 (CIIDIR!, IBUG!, MEXU!) ; Otáez, 10 km de Otáez, camino a Los Altares , 24.73485° N, 105.9754167° W, 2380 m, 24 March 1990, A. Benitez 1176 (CHAP, CIIDIR!) .

Discussion: — Lobelia saturnini is within the L. macrocentron species complex that includes L. knoblochii , L. macrocentron , L. mcvaughii and L. villaregalis Ayers (1987: 419) . This set of species may be easily separated into two groups by the presence of an inflorescence of racemes or of solitary flowers ( Ayers, 1987). Lobelia knoblochii and L. saturnini share solitary flowers, development of adventitious roots at the nodes, and similar flower length. However, L. saturnini differs mainly by the size of the leaves, petioles, flowers, hypanthium, spur, pedicels and anthers. The morphological and distributional differences between both species are highlighted in the identification key, diagnosis and Table 2.

Figures

FIGURE 5. Lobelia saturnini Art.Castro & I.Gutiérrez. A. Habit. B. Frontal view of a staminate and pistillate-phase flower, showing the position of staminal tube. C. Lateral view of staminate and pistillate-phase flower. D. Mature capsule with remainder of style and calyx. Drawn by Lesslie Martínez Rubí from the type material.

FIGURE 6. Lobelia saturnini Art.Castro & I.Gutiérrez. A. Habit. B. Frontal view of staminate and pistillate-phase flower. C. Lateral view of staminate and pistillate-phase flower. D. Lateral view of a fruit with persistent hypanthium.