Dictyanthus reflexiflorus Lozada-Pérez, E.B. Cortez & Martínez-Ambriz, 2025

Lozada-Pérez, Lucio, Cortez, Ericka B., Perez-Garcia, Maria De La Luz, González, César Ramiro Martínez & Martínez-Ambriz, Emmanuel, 2025, Dictyanthus reflexiflorus (Apocynaceae: Asclepiadoideae) a new species from Mexico, Phytotaxa 682 (3), pp. 199-213 : 202-205

Dictyanthus reflexiflorus Lozada-Pérez, E.B. Cortez & Martínez-Ambriz , sp.nov. ( Figs. 2 , 3 ).

Type:— MEXICO. Michoacán: Municipio Tacámbaro. Camino de Chipícuaro a Las Ánimas , 19º09’07”N, 101º23’00”W, 1170 m, 12 Sept 2016, L. Lozada-Pérez, E. Martínez-Ambriz & L. Pérez-García 3835 (holotype: FCME!; isotypes: IEB!, MEXU!) .

Dictyanthus reflexiflorus shares a climbing habit with D. altatensis (Brandegee) Stevens (2000: 243) but differs from it by the reflexed corolla 10-lobed at base and inflorescence with peduncles 3–4 mm long (vs. corolla rotate, without lobes at the base and inflorescence with peduncles 4–8 cm long).

Herbaceous climber to 2.5 m long, with a woody base, latex clear. Stems and branches cylindrical, violet to purple, slightly corky, lignified at the base and glabrescent with age; young stems with evenly distributed mixed indumentum composed for multicellular and unicellular trichomes, multicellular ones can be hooked or straight, 0.75–1.25 mm long, yellowish, unicellular trichomes are glandular or eglandular, less than 0.1 mm long, grayish. Leaves opposite, without stipules, petioles 1–3 cm long, with indumentum similar to the stem; lamina membranaceous, 2.0–7.0 × 1.0– 3.5 cm, ovate, 5 or 6 secondary veins, adaxial surface sparsely pubescent with scattered uncinate hairs, slightly denser on the midvein near the base, abaxial surface densely puberulent with short uncinate trichomes and scattered glandular trichomes, veins with scattered long uncinate trichomes; base cordate, apex acuminate, base cordate; colleters 4–6, at the adaxial junction of petiole and lamina. Inflorescence extra-axillary, one per node, umbelliform, with 3–5 flowers; peduncle 3–4 mm long; bracts 3.0–4.0 × 0.3–0.5 mm, narrowly lanceolate; pedicels 9.0–11.0 mm long. Flowers pentamerous. Calix green, lanceolate, 4.5–5.0 × 1.5–2.0 mm, pubescent with widely scattered uncinate trichomes on the outside and shorter trichomes on the margin; colleters 1 per sinus. Corolla reflexed, pale to greenish yellow with dark reticulation, adaxially densely hirsute, abaxially densely hirsute with short uncinate trichomes and scattered glandular trichomes, tube 3.0– 3.5 mm long, formed by erect slightly 10-lobed closely pressed to the side of the gynostegium and reaching to just below the corona, lobes ovate-lanceolate, 4.5–5.0 × 4.0– 4.3 mm; gynostegial corona black, 5-lobed, lobes alternating with anthers, ca. 1.5 × 0.5 mm, each lobe 2-keeled, each keel parallel to the adjacent keel; gynostegium, ca. 4 mm diam., deeply pentagonal, convex above; pollinarium 1.1–1.4 mm long, corpusculum dark brown, slightly sagittate, ca. 0.2 × 0.07 mm, caudicles 0.17–0.2 mm long, pollinia elliptic, 0.8–1.0 mm long, apically excavated. Follicles unknown.

Distribution and Habitat: — Dictyanthus reflexiflorus is distributed in a small area of central Michoacán ( Fig. 4 ), in the Balsas Basin province ( Morrone et al. 2017), in tropical deciduous forest, from 1170–1185 m.

Phenology: —Flowering has been recorded in September.

Etymology: —The epithet reflexiflorus refers to the reflexed corolla, a distinctive feature that is unique in Dictyanthus .

IUCN conservation assessment: —Information about Dictyanthus reflexiflorus is scarce, with only one population known, although the surrounding area was explored, ca. 1 km 2. For this reason, we suggest that it be assigned the category of Data Deficient (DD) ( IUCN 2022) until a thorough evaluation is conducted in the adjacent hills and ravines. The type locality is not part of a natural protected area, and we have not carried out an extensive vegetation survey of the area.

Taxonomic notes: — Dictyanthus reflexiflorus is very distinctive due to its reflexed corolla, with a tube 10-lobed closely pressed to the side of the gynostegium ( Fig. 3 E, G ). All other species have a rotate or campanulate corolla, which is smooth towards its base inside ( Stevens 1988, 1999, 2000; González-Martínez et al. 2019; Alvarado-Cárdenas et al. 2022). Similarly, the very reduced size of the gynostegial corona, which is limited to the base of the limb, is different from that in other species where the corona is almost completely adnate to the corolla. This unusual structure is contrasted by the star-shaped style-head with an unusually dark.

The new species is endemic to the state of Michoacán and known only from two collections from the same locality. The climbing habit is shared with D. altatensis , but in this species the corolla is rotate, and the tube is not 10- lobed at the base.

Additional specimens examined: — MEXICO. Michoacán: Tacámbaro, 2.19 km camino de Chipícuaro a Las Ánimas, 19º09’06”N, 101º23’00”W, 1185 m, 3 Sept 2015, L. Pérez G. et al. 163 ( IEB).

Figures

FIGURE 2. Dictyanthus reflexiflorus. A. Plant with inflorescences. B. Close-up of branch showing mixed indumentum. C. Close-up of thichomes. D. Colleters at base of leaf-blade. E. Inflorescence. F. Close-up of the indument of the abaxial surface of the corolla. G. Gynostegium with style-head. H. Gynostegial corona lobe in posterior view. I. Gynostegial corona lobe in frontal view. J. Pollinarium. Arrows showing the corolla lobes. Illustrations by Ericka B. Cortez, based on Lozada-Pérez et al. 3835.

FIGURE 3. Dictyanthus reflexiflorus. A-C. Plant and inflorescences with mature flowers. D. Side view of corolla and gynostegium. E. Dried flower. F. Flower fixed in alcohol. G. Vertical section of corona and gynostegium. (GC: Gynostegial corona, G: Style head, black arrows = tube lobes, gray arrows = corpuscle and blue arrows = keels). Photos by María de la Luz Perez-Garcia and Lucio Lozada- Pérez.

FIGURE 4. Distribution of Dictyanthus reflexiflorus and their congeners in Michoacan, Mexico.