Gomesa caatingana J.M.P.Cordeiro, L.P.Felix & M.W.Chase, 2018

Gomesa caatingana J.M.P.Cordeiro, L.P.Felix & M.W.Chase View in CoL , sp. nov. ( Fig. 1 View FIGURE 1 )

Type: — BRAZIL. Paraíba: Município de São João do Tigre, Distrito de Lagoa da Serra do Paulo , 36°40′39″W, 8°5′39″S, 1152m, 1 December 2017 (fl.), Cordeiro, Felix, Chase & Christenhusz 1.222 (holotype: EAN GoogleMaps ; isotypes: IPA GoogleMaps , UEFS GoogleMaps , K GoogleMaps ).

Diagnosis: — Gomesa caatingana is morphologically similar to G. flexuosa in its elliptical and laterally compressed pseudobulbs, long and emarginate labellum and sepals connate up to half their length. Gomesa caatingana differs in its rupicolous habit, elongate lateral lobes (0.50 × 0.45cm), short isthmus (0.00– 0.25 cm), eight to twelve papillae at the base of its callus and a chromosome number of 2 n = 168. In contrast, G. flexuosa exhibits an epiphytic habit, small lateral lobes (0.20 cm × 0.15 cm), an isthmus of the labellum greater than 0.50 cm, 15–25 small papillae on the basal callus of the lip and chromosome number of 2 n = 56. In addition, these species have distinct geographical distributions; G. caatingana grows exclusively on inselbergs in caatinga of Paraíba and Pernambuco States, whereas G. flexuosa is widely distributed in the Atlantic Forest.

Description: —Terrestrial (rupiculous) herbs with an elongate rhizome, 4.0–9.0cm between pseudobulbs that are laterally compressed with one or two basal foliaceous bracts, elliptic, smooth or slightly grooved, 3.70–5.87 cm × 1.90–3.51 cm, yellowish-green to greenish, completely covered with paleaceous bracts, 0.73 cm wide and long, whitish, distantly spaced roots 0.12 cm in diameter. Leaves 1–2, apical, 6.18–14.29 cm × 1.85–3.00 cm, oblanceolate, attenuate at base, apex retuse, obtuse, apiculate. Inflorescence a raceme or panicle, nearly erect to slightly pendent, 45–100 cm long, with 5–30 flowers; stem bracts 0.46–0.93 cm long. Flowers pedicellate, pedicel plus ovary 0.81–1.35 cm long. Dorsal sepal 0.40–0.53 cm × 0.37–0.47cm, base truncate, margin entire to slightly undulate, apex apiculate; lateral sepals concave at base, 0.53–0.71 cm × 0.21–0.29 cm, connate up to about half their length, vinous, brown to reddish brown or yellow covered with brown to reddish brown spots; petals 0.54–0.80 cm × 0.28–0.45 cm, base cuneate, margin wavy, apex obtuse, the same color as the sepals; lip auriculiform, 1.5–2.0 cm × 1.7–2.4 cm, midlobe yellow, margin wavy, apex strongly emarginate, 1.3–1.7 cm. × 1.7–2.4 cm; lateral lobes brown up to the middle, yellow in the apical portion, 0.40–0.55 cm × 0.40–0.50 cm, isthmus 0.00– 0.25 cm × 0.30–0.45 cm, fimbriae absent; callus brown with 8–12 papillae in the basal portion, 2–6 papillae in the middle and an apex with 3 variably projecting crests and 1–4 additional papillae; column 0.32–0.43 cm long, yellowish-white, with a pair of stigmatic wings 0.15–0.20 cm × 0.10–0.12 cm; tabula infrastigmata 0.20–0.22 cm × 0.23–0.26 cm, yellow-orange, pollinarium 0.15–0.18 cm long, pollinia obovate 0.10–0.12cm long; fruit cylindrical, 2.5–3.5cm × 1.5–2.3cm ( Fig. 2 View FIGURE 2 ).

Taxonomic notes: — Gomesa caatingana belongs to a group of species (formerly described as Oncidium sect. Synsepala sensu Garay & Stacy 1974 ) that is characterized by the presence of variably connate sepals, inflorescence in an erect panicle (terrestrial species) or arched (epiphytic species) and a glabrous column. Gomesa caatingana can be identified by it rupicolous habit (rarely epiphytic), elliptical and compressed pseudobulbs, long, emarginate labellum and basal callus with 8–12 papillae.

Etymology:— The specific epithet refers to the biome in which the species is found, Caatinga in the Brazilian Northeast.

Distribution:— Gomesa caatingana occurs on inselbergs in the Borborema Plateau, Paraíba and Pernambuco States ( Fig. 2 View FIGURE 2 ), at elevations from 1,000 –1,200 m. The surrounding vegetation corresponds to the caatinga, formed by woody plants deciduous in the dry season.

Ecology:— Occurrence of G. caatingana is generally associated with Hohenbergia catingae Ule (1909: 195 ; Bromeliaceae ), Euphorbia phosphorea Martius (1828: 612; Euphorbiaceae ), Gomesa hydrophila ( Barbosa Rodrigues 1877: 92) Chase & Williams (2009: 397 ; Orchidaceae ) and other endemics of inselbergs, such as Ameroglossum pernambucense Fischer et al. (1999: 529 ; Scrophulariaceae ). Personal observations in the field suggest that G. caatingana is pollinated by bees, like many other species of Oncidiinae . In addition, we verified an overlap of flowering for G. caatingana and Diplopterys lutea ( Grisebach 1849: 15) Anderson & Davis (2006: 10 ; Malpighiaceae ). This orchid species likely exhibits a mimicry strategy to attract pollinators of plants that presents pollen rewards ( Chase et al. 2005, Neubig et al. 2012, Papadopulus et al. 2013).

Phenology:— Flowering and fruiting October–February (the dry season).

Conservation status: — Gomesa caatingana is found on inselbergs in caatinga (in Paraíba and Pernambuco States), forming large populations on these outcrops (6–15 islands, 5–80 plants per island). Certain places where the species is found correspond to reserves in a reasonable state of conservation, such as Lagoa da Serra do Paulo (São João do Tigre, Paraíba) and the indigenous reserve of Xucuru (Pesqueira, Pernambuco). However, the areas where G. caatingana occurs also has human interference, mainly grazing by goats and being collected for cultivation as ornamental plants. However, because those outcrops do not have considerable economic interest, the species can be classified as “of little concern” according to IUCN Red List criteria and categories ( IUCN 2012).

Other specimens examined:— BRAZIL. Pernambuco: Brejo da Madre de Deus, 05 Feb 1965, fl., Lima s.n. ( IPA 13645 ) ; São Caetano, 25 Sep 1984, fl., Dornelas & Felix 31 ( EAN) ; Belo Jardim, Pedra das Guias , 13 Aug 1988, fl., Felix 1720 ( EAN) ; Brejo da Madre de Deus, Fazenda Nova, Pedra do Cachorro , 06 Oct 1999, fl., Liebig & Krause 72 ( PEUFR) ; Brejo da Madre de Deus, Serra do Ponto , 27 Apr 2001, fl., Silva & Nascimento 405 ( PEUFR) ; Bezerros, Distrito de Sapucarana, inselbergue Pedra Antônio Bezerra , 18 Nov 2005, fl., Gomes, Alves, Alves-Araújo, Maciel, Lucena, Oliveira, Martins & Melo 166 ( UFP) ; Caruaru, Lajedo do Cedro, Serra de Jaracatiá, Inselbergue “Pedra de Jaracatiá” , 14 Sep 2009, fl., Sobral-Leite, Maciel & Gomes 1077 ( UFP) ; São Caetano, Pedra do Cachorro , 07 Apr 2010, fr., Pessoa 304 ( UFP) ; Pesqueira, Pedra do Rei , 14 Nov 2011, fl., Medeiros Neto & Almeida 50 ( EAN) ; Belo Jardim, Pedra do Caboclo , 11 Jan 2012, fl., Pessoa, Maciel, Amorim & Lourenço 905 ( UFP) ; Pesqueira, Reserva Indígena , 30 Jun 2015, fl., Felix, Almeida & Araújo 15,656 ( EAN) ; São Caetano, Torres de Comunicação , 02 Jul 2015, fl., Felix, Almeida & Araújo 15690 ( EAN) . Paraíba: São João do Tigre, Serra do Enjeitado , 04 Aug 2011, fl., Nascimento 170 ( EAN) ; São João do Tigre, 12 Nov 2011, fl., Medeiros Neto & Almeida 01 ( EAN) ; São João do Tigre, 23 Aug 2013, fl., Felix 14310 ( EAN) .

Cytogenetic:— All specimens of the proposed new species, G. caatingana , from the two populations (São João do Tigre, Paraíba and São Caetano, Pernambuco) were 2 n = 168, meta- to submetacentric chromosomes, with an average size of 1.72μm. On the other hand, all specimens of G. flexuosa had 2 n = 56, metacentric chromosomes, with an average size of 1.64μm ( Fig. 3 View FIGURE 3 ).