Callianthe roseangelae Dorr, 2025

Dorr, Laurence J., 2025, The native species of Callianthe (Malvaceae, Malvoideae) in northern South America (Colombia, Venezuela, the Guianas and adjacent Brazil), PhytoKeys 260, pp. 75-95 : 75-95

4. Callianthe roseangelae Dorr sp. nov.

Fig. 3

Diagnosis.

Callianthe roseangelae Dorr differs from C. insignis (Planch.) Dorr in leaf shape (non-apical leaf blades conspicuously 3 - lobed versus unlobed or inconspicuously lobed), leaf surface (smooth versus rugose to slightly bullate), calyx shape (broadly campanulate versus tubular), calyx lobe shape (broadly versus narrowly triangular) and staminal column indumentum (stellate pubescent versus glabrous).

Type.

Venezuela • Trujillo: Municipio [“ Distrito ”] Boconó, abajo del Páramo de La Cristalina: Quebrada de La Cañada , 2400 m elev., 17 Feb 1973 (fl, fr), J. Cuatrecasas, L. Ruiz-Terán, & M. López-Figueiras 28563 (holotype: US [04135468]!; isotypes: NY [04290815]!, US [04135467]!, US [04135469]!) .

Description.

Scandent or vining shrubs with hanging branches; stems stellate-pubescent, glabrate in age. Leaves simple, entire; leaf blades differing in shape and size depending upon location on branchlets; apical leaves relatively smaller, ovate, 2–9 × 1.3–4.8 cm, unlobed or with a slight suggestion of 3 lobes, apices long acuminate, margin crenulate, bases cordate; non-apical leaves relatively larger, broadly ovate, 7–15 × 5–11 cm, 3 - lobed with the lateral lobes diverging and ending in long acuminate apices, central lobes also long acuminate, margin crenulate, bases deeply cordate with sinuses to 2 cm deep; all leaves 7 - nerved at the base, densely stellate-pubescent below with multi-rayed sessile hairs, rays ascending, ± colourless, leaf surface visible between hairs, stellate hairs on principal veins slightly larger, darker and more dense; scattered stellate-pubescent above with multi-rayed hairs, rays ± appressed or slightly ascending, leaf surface visible between hairs, rough to the touch, stellate hairs on principal veins slightly larger, darker and more dense; dark greyish-green above (fide Cuatrecasas et al. 28563), dull green below, smooth (not rugose nor slightly bullate), firmly membranous; petioles 1–6 cm long, densely stellate-pubescent; stipules ca. 5 × 9–10 mm, slightly falcate, stellate-pubescent, caducous. Flowers pendent, solitary in leaf axils, borne on slender peduncles 8–13 cm long (expanding to 22 cm long in fruit), stellate-pubescent, articulated 1–4 cm below the calyx, much more densely ferruginous stellate pubescent above the articulation; flower buds densely ferruginous stellate-pubescent, somewhat globose but coming to an apical point, sepals valvate. Involucel absent. Calyx broadly campanulate, 2–2.5 × 2–3.5 cm at anthesis, gamosepalous, 5 - lobed, lobes broadly triangular, unequal in size and shape, ca. 0.5–1 cm × 0.7–1 cm, external surface densely stellate-pubescent with greenish-brown, brown or ferruginous hairs, internal surface light green, villous, with long simple hairs, nectariferous at base. Petals broadly spatulate, 4.5–5.5 × 2–3 cm, narrowing to a long claw, claw stellate-pubescent internally especially towards base, external surface of petals with scattered simple multicellular hairs, pink or whitish with strong purplish-red or deep rose branching veins, petals turning dark red when dry, evidently spreading slightly at anthesis. Staminal column ca. 4.3 cm long, lower 2 cm stellate-pubescent, filaments clustered apically, ca. 5 mm long, anthers greenish-brownish, not or very slightly exserted beyond the corolla. Styles ± equal to anther mass in length. Stigmas capitate. Fruit schizocarpic, ca. 2.5 × 4 cm, depressed-globose, calyx accrescent; mericarps ca. 8, rhomboid, ca. 2 × 1 cm, dorsally stellate-pubescent, inner wall glabrous, dehiscent. Seeds semi-deltoid, ca. 3 × 2 mm, pubescent, with simple trichomes, trichomes denser near hilum.

Etymology.

The species epithet honours Rose Angela Gulledge who has made substantial organisational contributions to the Flora of Guaramacal ( Venezuela) project ( Dorr et al. 2001; Dorr 2014; Dorr and Niño 2024), which treats the vascular plants of a national park close to the type locality of this new species.

Distribution.

Endemic to Venezuela where it has been found only in cloud forest in the Venezuelan Andes near the Páramo La Cristalina northwest of Boconó; 2300–2500 m elev.

Additional material examined.

Venezuela • Trujillo: Carretera vieja entre Trujillo y Boconó, entre Urbina y San Rafael, 32 km from Trujillo , 2300–2500 m elev., 3–4 Sep 1966 (fl), J. A. Steyermark & M. Rabe 97235 ( NY [04290815], US [01217620]) .

Discussion.

The only fruit available for inspection had already shed seed and the number of seeds per mericarp could not be established apart from there clearly being more than one. The inner walls of the dehisced mericarps are glabrous, which contradicts one of the morphological characters that Donnell et al. (2012) used to define the genus Callianthe . Likewise, the staminal column in C. roseangelae is stellate pubescent below (Fig. 3 D ), which contradicts another morphological character that Donnell et al. (2012) used to define the genus Callianthe . However, the flowers agree with Callianthe as the petal veins are impressed and a darker colour than the petals. Additionally, the petals are not rotate like those of Abutilon s. str. and instead, while the petal apices are spreading at anthesis, their bases remain strongly imbricate.

The paratype collection originally was identified (“ ex char. ”) as Abutilon insigne (≡ Callianthe insignis ). While C. roseangelae and C. insignis are morphologically similar and possibly closely related, they are distinct as noted in the diagnosis. Presumably, these two species also are separated geographically, but because the precise range of the latter species is unknown, this remains conjecture. In any case, whether it is due to geographic isolation, infrequent flowering or some other factor, it is remarkable that two spectacularly beautiful Andean species in a group long favoured by horticulturists are so infrequently collected.

Figures

Figure 3. Callianthe roseangelae Dorr. A. Habit, branch with entire and 3 - lobed leaves; B. Habit, apical portion of branch with reduced entire leaves; C. Petal; D. Flower, petals removed to show anther column and anthers (Vouchers: A. Cuatrecasas et al. 28563, US [04125467]; B. Steyermark & Rabe 97235, NY [04290815]; C, D. Cuatrecasas et al. 28563, US [04125468].