Research Article |
Corresponding author: Laurence J. Dorr ( dorrl@si.edu ) Academic editor: Clifford Morden
© 2022 Laurence J. Dorr.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Dorr LJ (2022) A new species of Hibiscus (Malvaceae, Malvoideae) from Guyana. PhytoKeys 214: 1-6. https://doi.org/10.3897/phytokeys.214.91586
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Hibiscus marioniae Dorr, sp. nov. is described and illustrated. It evidently is restricted to central Guyana, northeast of the Kanuku Mountains near the Rewa River, a tributary of the Rupununi River. The new species is most similar morphologically to H. amazonicus Fryxell, which was described from Amazonas, Brazil.
Guyana, Hibiscus, Malvaceae, Malvoideae
A collection of Hibiscus L. (Malvaceae, Malvoideae) made by Marion J. Jansen-Jacobs in central Guyana northeast of the Kanuku Mountains near the Rewa River in 1999 was identified by the late Paul A. Fryxell as “Hibiscus aff. verbasciformis Klotzsch ex Hochr. vel sp. nov.” No additional material of this taxon has been collected since then, nor have additional specimens been found in searches of herbaria (CAY, K, Naturalis, NY, P, US, W) with rich collections of specimens from the Guianas. Likewise, nothing that matches the Jansen-Jacobs collection has been reported from Brazil (
Hibiscus marioniae Dorr differs from H. amazonicus Fryxell in having elliptic (versus ovate) leaf blades with cuneate (versus cordate to truncate and often asymmetrical) bases, a crenulate (versus coarsely toothed) margin, and long acuminate (versus acute) apices; more numerous (12 versus 8) and narrower (ca. 1.0 versus (2.0–)3.0–6.0 mm broad) involucellar bracts that are very slightly spathulate (versus distinctly spathulate, broadly lanceolate or imperfectly stipitate-peltate); and glabrous (versus minutely scaberulous) seeds.
Guyana. [Upper Takutu-Upper Essequibo]: Upper Essequibo Region, Rewa River, Spider Mountains, 03°08'N, 058°32'W, 400–500 m alt., 20 Sep 1999 (fl, fr), M.J. Jansen-Jacobs, B.J.H. ter Welle, P.P. Haripersaud, O. Muller & M. van der Zee 6011 (holotype: U barcode 0067247!; isotypes: NY!, TEX barcode 00568796 as image!).
Suffrutescent herbs, to 50 cm tall; stems woody at base, unarmed, sparingly to moderately pubescent, with appressed 4–8-armed stellate hairs ca. 1 mm in diameter. Leaves simple, elliptic, 8.5–13.0 × 2.5–4.0 cm, base cuneate, palmately 3-nerved at base, midrib and 2° nerves slightly raised above, prominent below, margin crenulate, apex long acuminate, leaf blades sparingly pubescent above and below with yellowish, bifurcate and stellate hairs, stellate hairs 4–8-armed, arms ca. 1.0 mm long, erect, bifurcate hairs more frequent below than above; petioles 1.5–2.5 cm long, with a ventral line of short whitish stellate-hairs and more conspicuous and abundant yellowish stellate hairs, the latter hairs not in a line and denser distally; stipules almost linear, ca. 1.0–2.0 mm long, caducous. Flowers solitary or paired in leaf axils toward apices of stems; pedicels 3.5–7.0 cm long, not articulated, pubescent with ± appressed stellate hairs and more conspicuous, 4–8-armed stellate hairs with arms to 2.0 mm long. Bracts of involucel 12, distinct, 10.0–15.0 × ca. 0.75–1.0 mm, not or scarcely exceeding united portion of calyx at anthesis, very slightly spathulate apically, plane, with simple, bifurcate, and stellate hairs, hairs or arms of stellate hairs to 2.0 mm long. Calyx 5-lobed, united ca. half way, lobes 1.0–1.2 × 0.5–0.6 cm at anthesis, broadly triangular, apices acute, papery, light green with 3 darker but not thickened veins, nectaries absent, outer surface with yellowish simple and mostly 4-armed stellate hairs, arms to 2.0 mm long, inner surface with a few scattered simple hairs, accrescent in fruit, turning blackish (on herbarium specimens, at least), lobes expanding to 2.0–2.5 × 1.2 cm. Petals ca. 2.5 cm long (only one flower seen and not dissected), white (fide Jansen-Jacobs et al. 6011), corolla shape unknown. Staminal column shorter than the petals; anthers purple (fide Jansen-Jacobs et al. 6011). Styles and stigmas not seen. Capsules enclosed in accrescent calyces, 5-locular, chartaceous, capsule walls undulate and molded around individual seeds, walls covered with minute whitish hairs and more conspicuous yellowish simple hairs to 2.0 mm long. Seeds ca. 2.0 × 2.0 mm, globose-reniform, brownish (the hilum blackish), glabrous.
The species epithet honors Marion J. Jansen-Jacobs who has contributed greatly to our understanding of the flora of the Guianas as collector, herbarium curator, author, and executive director of the Flora of the Guianas project.
Known only from the type collection, which was made in central Guyana, northeast of the Kanuku Mountains; 400–500 m alt. According to information on the specimen label, the plant was found in an open spot in forest on rock in the “Spider Mountains.” The name of these mountains does not appear in standard gazetteers (
Hibiscus as traditionally treated is a species-rich genus of ca. 200 (
Morphologically, Hibiscus marioniae is most similar to H. amazonicus. The two species share unarmed stems, an involucel comprised of distinct bracts, a papery or chartaceous 5-fid calyx that is ca. half-divided and accrescent in fruit, and a staminal column shorter than the petals. When
Earlier,
No members of Hibiscus sect. Trionastrum (or sect. Spatula) were included in the analysis of
I appreciate the courtesies extended by curators of the herbaria visited or consulted (CAY, K, Naturalis, NY, P, US, W) while preparing a treatment of the Malvaceae for the Flora of the Guianas. In addition, George Yatskievych (TEX) kindly confirmed the presence of type material in Austin, Texas. The new species was illustrated by Alice Tangerini (US).