Vanilla ribeiroi Hoehne (1910: 28)

Engels, Mathias Erich & Koch, Ana Kelly, 2021, Vanilla ribeiroi Hoehne (Orchidaceae: Vanilloideae): notes on taxonomy and geographical distribution, Phytotaxa 490 (1), pp. 99-106 : 100-102

Vanilla ribeiroi Hoehne (1910: 28) . Figs 1–3 .

Type:— BRAZIL, Mato Grosso: locality not specified, Jaurú River , XI.1908, fl., F . C . Hoehne 997 (holotype: R-2512!, illustration!). Epitype (here designated): BRAZIL, Mato Grosso: Itaúba , Teles Pires River , 24.XII.2019, fl., M . E . Engels 7771 ( MBM!, UFMT!, UPCB-spirit!, RB!) .

Hemi-epiphyte. Roots 1–2 mm diameter, terete, whitish-castaneous. Stem 5–7 mm diameter, terete to subterete, flexuous, glabrous, green; internodes 10.8–13.6 cm long. Leaves (4.9)-7.9–11.7 × (1.1)- 1.5–1.9 cm, fleshy, straitlanceolate to linear-lanceolate, entire margin, acute apex, reflexed, green. Inflorescence racemose, 2.2–2.6 × 0.4- 0.5 cm, 4–9-flowered, green; bracts 3–8 × 3–8 mm, deltoid, obtuse, green. Flower resupinate, pedicellate; ovary and pedicel ca. 2.9 × 0.3 cm, terete, white with green apex, sepals and petals white; dorsal sepals 4.0–4.1 × 1.1 cm, oblanceolate, acute base, entire margin, obtuse apex; lateral sepals 3.1–3.5 × 1.1–1.3 cm, oblanceolate, acute base, entire margin, obtuse apex; petals 3.6–3.9 × 1.1–1.3 cm, oblanceolate, sub-rounded base, entire margin, obtuse apex; lip 3.8–3.9 × 3.6–3.8 cm, obovate in general ambit, trilobed, white with lobes and trichomes orange-yellowish; base inconspicuously pilose; lateral lobes ca. 1.0 × 1.4–1.5 cm, oblanceolate, undulate and irregular margin; central lobe ca. 1.6 × 0.3–0.4 mm, wide-rounded, undulate and irregular margin, emarginate apex; central disc with trichomes, trichomes 1–4 mm long., simple to multifurcated, with a papillose surface (in fresh material); callus penicillate 4–5 × 4 mm, obdeltoid. Column 2.6-2.7 × 0.25-0.3 cm, subclaviform, ventral portion slightly flattened and papillose. Anther ca. 3 × 3 mm, subrounded to subobovate; stigma ca. 1 × 1 mm, subquadrate; rostellum ca. 2 × 3 mm, wide-rounded. Fruits 8.1–15 × 0.5–0.7 cm, oblong, terete, dehiscent along two lines when mature, green; inconspicuous vanilline scent. Seeds black.

Other specimens examined: — BRAZIL, Mato Grosso: Itaúba, Teles Pires River , 28.VII.2016, fr., M . E . Engels & A. S . Bezerra 4715 ( MBM); idem, 24.XII.2019, fl., M . E . Engels 7771 ( MBM, UFMT, UPCB-spirit, RB). Pará: Altamira, 10. I .2020, fl. [photo] and fr., M. E . Engels & D. Chiracava 7743 ( MBM) .

Distribution, habitat, and phenology: —This species has previously only been recorded in Brazil, in the Mato Grosso State ( BFG 2015, 2018, Flora do Brasil 2020). Its range is here extended to the Pará State. The species was found in paludose riparian forests, usually reaching 3 to 4 meters in height. Flowering has been observed from November to December, with immature fruits in January and mature fruits in July.

Conservation status: — Vanilla ribeiroi was initially collected in 1908, being rediscovered in Brazil after 100 years. According to the categories and criteria of IUCN (2001) the species is Critically Endangered in the country (CR [B1ab(iii) + B2ab(iii)]) due to its restricted distribution, the decrease and fragmentation of the natural environment where it occurs, and for being known only by few samples.

Discussion:— Vanilla ribeiroi was described based on a sample collected by Dr. Alipio de Miranda Ribeiro at Jaurú river margins, in Mato Grosso State, and taken to the botanist Frederico Carlos Hoehne during the Rondon Commission ( Hoehne 1910, 1945, 1951). That specimen was then illustrated, described and named in honor of its collector. The materials collected and herborized during the Commission were mostly accessioned at the National Museum Herbarium – Herbarium R ( Hoehne 1951), where the holotype of V. ribeiroi was deposited, being composed of a single stem with two leaves, one inflorescence, and one flower (figure 3A).

The original description ( Hoehne 1910) includes an illustration comprising only the habit with a general flower view, without the flower structures distended (figure 3C). The species was later fully illustrated in Flora Brasílica ( Hoehne 1945), with the flower structures distended (figure 3D). It is likely that Hoehne originally had not distended and assembled the only flower in the herborized specimen, but did so later to prepare the illustration of Flora Brasílica. The flower verticils of the holotype are in a considerable state of degradation, especially the lip. This may explain the discrepancies found when comparing the original illustrations and the one in Flora Brasílica, mainly concerning the lip and trichomes. We note the need for a complementary sample to assist future identifications and thus designate an eiptype of V. ribeiroi (M.E. Engels 7771) here (figure 3B).

Hoehne (1910, 1945, and 1951) was very specific in his comments about some features of this species, especially regarding the narrowly-lanceolate leaves, the white flowers, and the central disc of the lip with yellow trichomes (= fimbriae), trichomes covered with fimbriae (called here as papillae) and fringed lip margin. These are diagnostic for V. ribeiroi and help to distinguish it from morphologically similar species ( Table 1).

When analyzing the type material along with the protologue, as well as Hoehne’s comments, the name Vanilla ribeiroi can be safely applied. However, it became apparent that the name has been misapplied to specimens from Peru, Bolivia, Colombia, Guyana ( Householder et al. 2010, Soto Arenas & Cribb 2010, Sambin 2018, Barona et al. 2019). The record for Peru ( Householder et al. 2010) corresponds to V. karen-christianae Karremans & Lehmann (2018: 305) as noted by Damian & Janovic (2018) and Karremans et al. (2020), while the record for Guiana ( Sambin 2018), most likely corresponds to V. labellopapillata Koch et al. (2013: 975) . Recently, Barona et al. (2019) reported the occurrence of V. ribeiroi for Colombia, nevertheless, the voucher is a fruited sample and we are unable to confirm its identity. The collections cited by Soto Arenas & Cribb (2010) were not found in digital databases of the cited herbariums. Given the issues regarding the application of this name, we cannot confirm the presence of V. ribeiroi outside of Brazil.

Figures

FIGURE 1. Vanilla ribeiroi Hoehne—A. Habit. B. Flower in frontal view. C. Perianth flattened. D. Detail of penicillate callus of the lip. E. Detail of ribs and trichomes of the lip periphery. F. Detail of trichomes of the lip. G. Detail of trichomes of the lip indicating papillate surface. H. Pedicel and ovary. I. Column in lateral view. J. Detail of trichomes of the ventral surface of the column. K–M. Ventral view of anther and rostellum. K. In natural position. L. With anther in a superior position. M. With anther and rostellum in superior view, showing the stigma. Drawn by M.E. Engels from M.E. Engels 7771.

FIGURE 2. Vanilla ribeiroi Hoehne—A. Habit. B. Leaf, abaxial view. C. Detail of the apex of the leaf. D-F. Detail of inflorescence. H. Detail of trichomes of the lip, showing de papillate surface. Photos by M.E. Engels from M.E. Engels 7771.

FIGURE 3. Vanilla ribeiroi Hoehne—A. Holotype at R. B. Epitype at Herbarium MBM. C. Original illustration of V. ribeiroi (Hoehne 1910). D. Illustration of V. ribeiroi in Flora Brasílica (Hoehne 1945).