Mandevilla hansenii J.F. Morales, 2025

Morales, J. Francisco, 2025, A New Species, New Records, And New Synonyms Of Mandevilla (Apocynaceae) From Ecuador, With Comments On Morphological Characters, Journal of the Botanical Research Institute of Texas 19 (1), pp. 39-50 : 42-45

Mandevilla hansenii J.F. Morales , sp. nov. ( Figs. 3–4 ). TYPE: ECUADOR. MORONA-SANTIAGO: Mendez-Bella Union , shady ravine, 700 m, 1 Apr 1974 (fl), G. Harling & L . Andersson 13046 (HOLOTYPE: USF) .

Diagnosis.— Mandevilla hansenii resembles M. hirsuta (Rich) K. Schum. , but it is distinguished by its leaf blade tomentose abaxially (vs. hispid to hirsute or rarely glabrescent), sepals 3.5–4.2 mm wide (vs. 1–3 mm), corolla tomentose with the apex of the floral bud obtuse to rounded (vs.hirsute and floral buds shortly acuminate or shortly apiculate) and larger anthers (5.5–6 mm long vs. 4.5–5.2 mm).

Description.— Vine; branchlets cylindrical to subcylindrical, without wings, tomentose; interpetiolar colleters inconspicuous, less than 1 mm long. Leaves opposite; petioles 35–36 mm long; leaf blades 14–15 × 5.5–6 cm, elliptic, the apex abruptly long acuminate, the base truncate, with colleters irregularly distributed along the midrib adaxially, membranaceous, sparsely villose adaxially, tomentose abaxially, not bullate, without domatia, not revolute, secondary veins slightly impressed on both sides, tertiary veins more or less impressed abaxially, usually not visible adaxially. Inflorescences axillary, tomentose, many-flowered, peduncle 30–40 mm long, pedicels - 3–4.5 mm long, bracts 25–35 × 2–3 mm, narrowly elliptic, foliaceous; sepals 8–9 × 3.5–4.2 mm, equal, narrowly ovate, the apex short-acuminate, not reflexed, subfoliaceous, tomentose, colleter 1, irregularly lobed or erose; corolla infundibuliform, yellow to pale yellow, internal part of the tube with red striae or totally red, rarely brown, tomentose, the tube gibbous basally, the lower part 2.4–2.5 × 5–7 mm, the upper part 1.4–1.5 mm long, conical, 14–15 mm in diameter at the orifice, the apex of the floral bud broadly obtuse to rounded; lobes 14–15 × 11–12 mm, obovate; stamens inserted at the base of the upper part of the corolla tube, anthers 5.5–6 mm long, glabrous dorsally, the base auriculate, the auricles obtuse to truncate, style-head 2.5–3 mm long; ovary 2.1–2.3 mm long, glabrous; nectary disc equalling or slightly shorter than the ovary, 5-lobed. Follicles 13–14 cm × (2.5) 4–7 mm, free, only united at the apex, sometimes the apices free when mature, tomentose, slightly articulated; seeds 11–12 mm long, comma 1.7–2 cm long, tannish-yellow.

Distribution.— Endemic to Ecuador (Morona-Santiago, Pastaza, Zamora-Chinchipe provinces), growing in open areas, forest edges, and riverside woods at 700–1100 m.

Phenology.— Flowering March, April, June, and August. Fruiting in April and August.

Conservation status.— Mandevilla hansenii has a minimum AOO of 24 km 2 and an EOO of 2,569.230 km 2. It is known from six localities, none of which are located within protected areas, four of them threatened by forest clearing for agriculture and cattle, confirmed by author’s field observations, resulting in a continuing decline of EOO, AOO, quality of habitat, number of locations, and subpopulations. This species is provisionally assessed as Endangered [EN B2ab(i,ii,iii,iv)] based on the IUCN Red List Categories and Criteria ( IUCN 2012, 2024).

PARATYPES.— ECUADOR. Morona-Santiago: Tunantza, Jibaro settlement in the vicinity of Macuma , ca. 50 km NE of Macas, 25 Mar 1973 (fl, fr), Lugo 3740 ( USF) ; Bomboiza, Mision Salesiana-Shuar , 8–10 Jun 1986 (fl), Zaruma & Arguello 496 ( MO, USF) . Pastaza: trail to Cotopaza , 10 km S of Sarayacu, 19 Aug 1979 (fl), Lugo 5550 ( USF) , 4 km E of Sarayacu , 21 Aug 1979 (fl), Lugo 5570 ( USF) . Zamora-Chinchipe: Guadalupe-San Jose de Yacuambi (28 de Mayo),along rio Yacuambi , 24 Apr 1974 (fl), Harling & Andersson 13925 ( USF) .

Discussion.— Mandevilla hansenii is vegetatively similar to M. hirsuta , but it differs by its tomentose branchlets (vs. hispid to hirsute, rarely glabrescent), leaf blades tomentose abaxially (vs. sparsely to densely hirsutulous), sepals 3.5–4.2 mm wide (vs. 1–3 mm), corolla tomentose (vs. hirsute), the apex of the floral buds broadly obtuse to rounded (vs. shortly acuminate or shortly apiculate), and anthers 5.5–6 mm long (vs. 4.5–5.2 mm). The floral bracts are larger in M.hansenii than M. hirsuta (25–35 × 2–3 mm vs. 15–20 × 6–12 mm).

Mandevilla hirsuta has the largest distributional range in the genus ( Mexico to Brazil, Bolivia, and northern Paraguay), followed by M. subsagittata (Ruiz & Pav.) Woodson ( Mexico to Perú, Trinidad and Tobago, and the Lesser Antilles), M. scabra (Hoffmanns.ex Roem.& Schult.) K. Schum. , and M.rugellosa (Rich.) L. Allorge (both Colombia to Brazil and Bolivia) (Morales 2011; Alvarado-Cárdenas & Morales 2014). The Mandevilla hirsuta complex ncludes several species with hirsute (rarely glabrate) leaf blades, foliaceous or subfoliaceous inflorescence bracts, yellow or cream infundibuliform corollas corollas, usually with the mouth red inside, and moniliform follicles ( Morales 2007b). In preparation for a revision of the genus, several species of this complex have been described in the last 20 years (e.g., Morales 2005b, 2006, 2007b; Coelho et al. 2020). In Ecuador, M. hansenii also resembles M.sagittarii Woodson , but the former could be separated by its sepals 8–9 mm long (vs. 11–18 mm) and corolla tube with the upper part 1.4–1.5 mm long (vs. 27–31 mm). A key to the species of the exothostemon group is provided here, including records reported for the first time in Ecuador.

Etymology.— This species epithet honors Dr.Bruce F. Hansen (USF), a Neotropical Apocynaceae specialist who made the revision of Forsteronia (unpublished) in 1985. Several new taxa were published recently ( Hansen & Morales 2019). For many years Bruce was the curator of the USF herbarium in Tampa (the second largest in Florida) and the leading authority of the Atlas of Florida Plants. He did fieldwork in the United States, Mexico, the Caribbean, and Ecuador and is the senior collector on more than 8500 collected specimens. I appreciate his support for several years.

Figures

FIG.3.Mandevillahansenii (Lugo3740,USF).A.Fertile branch,B.Detailof thecolleters alongthemidrib adaxially,C.Calyx andcorolla inbud,D.Adaxial view of two sepals,showing opposite colleters at the base,E.Anther,dorsal view,F.Style-head,G.nectary and ovary,H.Seed.

FIG. 4. Distribution map of Mandevilla hansenii.