Octomeria giordanii T.F. Santos & E.L.F.Menezes, 2023

Santos, Thiago Faria Dos & Menezes, Euler Da Luz Fernandes, 2023, Octomeria giordanii (Orchidaceae-Pleurothallidinae), a new species from Brazil and nomenclatural notes on João Barbosa Rodrigues’s species that occurs in Bahia and Minas Gerais, Phytotaxa 620 (3), pp. 235-243 : 236-240

Octomeria giordanii T.F. Santos & E.L.F.Menezes , sp. nov. ( Figures 1–2 ).

Type: — BRAZIL. Minas Gerais: Felício dos Santos, Serra do Gavi „o, 11 September 2020, rupicolous in the ground near waterfall, 11.IX.2020, E.L.F.Menezes & S. C.O. Giordani 848 (holotype: HDJF 10055!) .

O. giordanii is most similar to O. fusiformis but differs by one or rarely two flowers opening successively (vs. congested inflorescence with one to multiple simultaneous flowers blooming). Additionally, O. giordanii petals are oblong (vs. elliptical to ovate).

Description:— Plant 20.0–77.0 mm long, rupicolous, caespitose. Rhizome inconspicuous. Roots 10.0–22.0 mm, cylindrical, flexuous. Ramicauls 1.0–50.0 mm long, erect, cylindrical, thicker at the apex, 3 internodes covered by pale, amplexicaul, glabrous, ephemeral sheaths. Leaves 15.0–65.0 × 5.0– 10.4 mm, subcylindrical, succulent, erect, several longitudinally grooves present, base cuneate, apex acute to acuminate. Inflorescence 1–2 flowers in fascicle; inconspicuous floral bracts; flowers pedicelled; pedicel 1.0– 1.1 mm long., semi-curved; ovary 0.5 mm long. Sepals whitish to yellowish, pink stained at the apex, glabrous, free, 3 dark rose veins; the dorsal sepal 3.0–4.0 × 1.0– 2.2 mm, elliptic-lanceolate, apex obtuse to slightly acute; the lateral sepals 3.1–4.2 × 1.1–2.2 mm, oblong-lanceolate to elliptic-lanceolate, apex obtuse to slightly acute. Petals whitish to yellowish, pink stained at the apex, glabrous, 3 dark rose veins, 3.0–4.2 × 1.3–2.5 mm, oblong to oblong-lanceolate, apex slightly acute. Lip 1.8–3.2 × 1.2–2.4 mm, yellow, dark rose stained, glabrous, trilobed, margin entire, base truncate, concave between a pair of longitudinal parallel calli, which extend from the base of the lateral lobes to more than half of the lip; lateral lobes rounded, margin entire; median lobe oblong to sub-rhombic, apex truncate. Column 1.8–2.0 × 1.0– 1.2 mm, yellow, rose stained, erect to slightly arched, cylindrical, wings rounded, rostellum present, eight pollinia.

Distribution and ecology:— Octomeria giordanii has only been found with rupicolous habit and exposed to the sun in the ground rocks next to a waterfall ( Figure 3A–C ) in a low elevation area (ca. 730m) in Felício dos Santos municipality of the Minas Gerais state, region inside an ecotone between the Cerrado and the Atlantic Rainforest Biomes in the Serra do Espinhaço.

Etymology:— the name of the species is an honor to one of its discoverers, Samuel Cunha Oliveira Giordani.

Conservation status:— Due to being found only in one place, the species does not have enough information to propose an appropriate conservation status, therefore, we indicate that it should be treated as (DD) category ( IUCN 2022).

Taxonomic Discussion:— O. giordanii is most similar to O. fusiformis . However, they can be differentiated ( Figure 3 , 4 ). Octomeria giordanii typically has one or rarely two flowers opening successively, whereas O. fusiformis exhibits a congested inflorescence with one to three flowers simultaneously blooming.Additionally, there are differences in the flower morphology. The floral parts of O. giordanii are smaller, measuring approximately 4.0 × 2.5 mm each, while those of O. fusiformis can reach 8.0 × 3.0 mm each. Moreover, the petals of O. giordanii are oblong, whereas those of O. fusiformis are elliptical to ovate in shape. In terms of flower coloration, O. giordanii features pink-stained sepal veins, and the lip displays yellow coloration in the lateral lobes and margin, but is entirely reddish in the inner portion. In contrast, O. fusiformis exhibits stronger red staining in the sepal veins, and the lip is yellow or white, sometimes with a purple spot in the inner portion or apex.

Regarding the ecology of these two taxa, O. giordanii occurs in the Serra do Espinhaço, while O. fusiformis is found in the Chapada Diamantina . Both species are rupicolous, growing exposed to sunlight, and they occur in connected mountain ranges, being part of the Espinhaço mountain range complex. However, there are notable differences in their distribution patterns. O. giordanii is known from a single location in the state of Minas Gerais, at a lower altitude of around 730 meters, in close proximity to a waterfall and far from the mountain summits. Differently, O. fusiformis is exclusively found in the state of Bahia at higher elevations, specifically on the peaks of mountains in the Serra das Almas and Serra do Barbado, at approximately 1900 meters above sea level.

Additionally, O. giordanii has similarities in terms of morphology with the following Octomeria species from Minas Gerais and Bahia: O. alexandri Schlechter (1922: 53) ; O. aloefolia Barbosa Rodrigues (1882: 113) ; O. campos-portoi Schlechter (1922: 291) ; O. decumbens Cogniaux (1896: 642) ; O. flabellifera Pabst (1975: 56) ; O. fusiformis Luer & Toscano (2010: 144) ; O. geraensis (Barbosa Rodrigues 1877: 26) Barbosa Rodrigues (1882: 295) ; O.juncifolia Barbosa Rodrigues (1882: 110) ; O. leptophylla Barbosa Rodrigues (1882: 112) ; O. lithophila (Barbosa Rodrigues 1877: 26) ; O. ochroleuca Barbosa Rodrigues (1877: 31) ; O. palmyrabellae Barbosa Rodrigues (1937: 38) ; O. praestans Barbosa Rodrigues (1882: 112) ; O. rubrifolia Barbosa Rodrigues (1877: 31) ; O. wawrae Reichenbach ex Wawra (1888: 156) . These taxa can be distinguished morphologically by the following key.

Identification key to Octomeria giordanii and related species with terete, subterete or conduplicate leaves from Minas Gerais and Bahia

1. Plants over 45.0 cm long; sheaths of the ramicauls usually thickened ........................................................................... O. juncifolia

- Plants smaller than 45.0 cm long; sheaths of the ramicauls never thickened.....................................................................................2

2. Inflorescence with 1–3 flowers ..........................................................................................................................................................3

- Inflorescence with more than 3 flowers .............................................................................................................................................8

3. Lip entire ............................................................................................................................................................................................4

- Lip trilobate ........................................................................................................................................................................................5

4. Lip flabellate; two longitudinal calluses in the lip .................................................................................................. O. campos-portoi

- Lip broadly flabellate; three longitudinal calluses in the lip ......................................................................................... O. flabellifera

5. Leaves conduplicate ...........................................................................................................................................................................6

- Leaves terete or subterete .................................................................................................................................................................11

6. Ramicauls thickened in the apex; apex of sepals and petals rounded to slightly acute................................................... O. lithophila

- Ramicauls not thickened in the apex; apex of sepals and petals acuminated.....................................................................................7

7. Lateral sepals free.......................................................................................................................................................... O. ochroleuca

- Lateral sepals partially connate ....................................................................................................................................... O. rubrifolia

8. Lip narrow oblong, elongated.......................................................................................................................................... O. geraensis

- Lip oblong or elliptic-pandurate, non-elongated ................................................................................................................................9

9. Lip oblong; well-developed lateral lobes; mid lobe narrowed; apex emarginate or truncate .................................. O. palmyrabellae

- Lip oblong or elliptic-pandurate; small to medium size lateral lobes; mid lobe not narrowed; apex rounded................................10

10. Leaves and ramicauls thick; sheaths of the ramicaul strongly imbricate; sepals and petals oblong to linear................. O. praestans

- Leaves and ramicauls slender; sheaths of the ramicaul loosely arranged; sepals and petals oblong-lanceolate........... O. decumbens

11. Lateral sepals completely connate................................................................................................................................. O. leptophylla

- Lateral sepals free.............................................................................................................................................................................12

12. Sepals and petals apex strongly acuminate ......................................................................................................................................13

- Sepals and petals apex obtuse or acute.............................................................................................................................................14

13. Plants smaller than 5.0 cm; leaves with an acuminate apex; margin of the lip slightly fimbriated .................................. O. aloefolia

- Plants larger than 5.0 cm; leaves with a rounded to slightly acute apex; margin of the lip entire ..................................... O. wawrae

14. Leaves and ramicauls slender; petals obovate-lanceolate ............................................................................................... O. alexandri

- Leaves and ramicauls thick; petals other formats.............................................................................................................................15

15. Inflorescence with 1–3 flowers opening simultaneously; floral parts approximately 7.0 mm; petals ovate to elliptical .................... ......................................................................................................................................................................................... O. fusiformis

- Inflorescence with 1 to rarely 2 flowers opening successively; floral parts approximately 4.0 mm; petals oblong to oblonglanceolate.......................................................................................................................................................................... O. giordanii

Figures

FIGURE 1. “Lankester Composite Dissection Plate (LCDP)” of O. giordanii. A. Habit. B. Lateral view of the leaf. C. Front view of the flower. D. Lateral view of the flower. E. Lateral view of the lip attached to the column. F. Perianth dissected; frontal view of the flower. (Based on the holotype, and cultivated specimens).

FIGURE 2. Octomeria giordanii A. Habit. B. Lateral view of the flower. C. Dorsal sepal. D. Petal. E. Lateral sepal. F. Lip. G. Lateral view of the lip attached to the column. (Illustration by L.K.R. Hinoshita based on the holotype, and cultivated specimens).

FIGURE 3. Octomeria giordanii on its natural environment. A. Rock formations exposed to the sun near a waterfall. B. Plant in the environment; highlighting the flower. C. Plant in the environment; highlighting the rupicolous growth habit. (photographs of O. giordanii by E.L.F. Menezes).

FIGURE 4. Octomeria fusiformis, photographs and ilustration. A. Flower lateral view; ovate petals observable. B. Flower frontal view; highlight the flower’s colors. C. Luer’s ilustration; highlight the inflorescence with three flowers simultaneously blooming. (photographs of O. fusiformis by A.L.V. Toscano de Brito & Wade L. Collier; and illustration of O. fusiformis modified from Luer (2010).