Catasetum × humaitaense (Orchidaceae: Catasetinae), a new nothospecies from the Brazilian Amazon Krahl, Dayse R. P. de Oliveira, Miguel S. Schmal, Philippe da Silva, João B. F. Chiron, Guy Krahl, Amauri H. Cantuária, Patrick de C. Biota Colombiana 2025 2025-06-04 26 1 14 Krahl, D.R.P.Krahl, Schmal & Cantuaria Krahl, D. R. P. Krahl, Schmal & Cantuaria Liliopsida Orchidaceae Catasetum true Plantae Asparagales 4 5 Tracheophyta species humaitaense sp. nov.  Diagnosis:  Catasetum × humaitaense hybridanaturalis inter C. boyiet C. ivanae cumcharacteribus intermediis est. inflorescentia arcuatis et descendentibus, flores pallidi sparsim brunneomaculati, sepala oblongo-elliptica, petala elliptica, labelum ovatum subtrilobatum margine irregulariter denticulum cum duobus callis in loborum lateralium basi.   Type.  BRAZIL. Amazonas, Humaitá, Madeira River, Carapanatuba Lake, igapóforest, 6°46´22.11´´ S-62°42´36.51´´W,  33 ma.s.l.,  23 march 2023,  R. R. P .  Nascimentoex A. H.  Krahl& P.   Schmal1690 ♂( holotype: HUAM012581!).   Description.Epiphytic caespitose plant. Roots fasciculate, filiform, whitish, ca. 0.4-0.5 cmdiam. Rhizome inconspicuous. Stem swollen into a pseudobulb, 6.4-7.9 × 1.9-2.5 cm, fusiform, covered by leaf sheaths, multi-leaved, greenish. Leaves 7.1- 16.6 × 2.5-3.9 cm, oblanceolate, plicate, abaxially clearly 5-6-nerved, entire and slightly undulate margin, acute apex, green. Staminate inflorescence 8.2-9.9 cmlong, lateral, racemose, arched descending, 5-6-flowered; peduncle 0.2-0.3 cmlong, cylindrical, greenish becoming purplish towards apex; bracts at the peduncle base 0.6-0.7 cmlong, amplective, entire margin, acute apex, greenish; floral bract 0.8-0.9 × 0.3-0.4 cm, lanceolate, concave, symmetrical, entire margin, acute apex, greenish. Staminate flowers light green with brown-spotted, spaced by about ca. 1 cm, resupinate, pedicelled; pedicel 1.6-1.8 cmlong, cylindrical, sinuous, brownish; sepals 2.5-2.8 × 0.9-1.1 cm, ellipticlanceolate, involute, symmetrical, entire margin, acute apex; petals 2.2-2.4 × 0.8-0.9 cm, ellipticlanceolate, slightly revolute at base, symmetrical, entire margin, acute apex; lip 1.2-1.4 × 1.0- 1.1 cm, ovate, subtrilobed, tough and fleshy, with an ovoid bottom ca. 0.5-0.6 cmdeep and two discreet calli at the base of the lateral lobes; calli 0.1-0.2 × 0.1-0.2 cm, transversely laminar, obtuse; lateral lobes 0.5-0.6 × 0.7-0.8 cm, semi-ovate, irregularly denticulated margin; apical lobe 0.5-0.6 × 0.7-0.8 cm, deltoid, discreetly denticulated margin, obtuse and revolute apex; column 1.8-2.0 cm long, oblanceoloid, thick, contracted at base, rostrate apex, greenish with brown-spotted; antennae 0.6-0.7 cmlong, filiform, symmetrical, convergent, brownish; anther cap 0.6- 0.7 × 0.3-0.4 cm, subtriangular, purplish brown, rostrate apex; viscidium ca. 0.1 × 0.1 cm, rounded, sticky; stipe ca. 0.3 × 0.1 cm, blade-shaped, rolled, yellowish; pollinia 2, 0.1-0.2 × 0.1 cm, oblong, hard, sulcate, compressed, yellowish. Pistillate and staminate + pistillate inflorescences not seen. Fruit not seen.   Etymology.The specific epithet refers to the name of the municipality of Humaitá (Amazonas, Brazil), where the new nothospecies was found.   Distribution, habitat and ecology.The new nothospecies flowered in cultivation during March, a period that corresponds to the rainy season in the Brazilian Amazon ( Braga, 1977). It is currently known only from the typelocality: Lake Carapanatuba, situated in the municipality of Humaitá, Amazonas state, Brazil( Figure 2). The species was observed growing epiphytically on thin tree branches in igapó forest, a typical Amazonian environment subject to seasonal flooding. Field observations indicate that  C. × humaitaensegrows in sympatry with one of its putative parental species,  C. ivaneae, and both share the same locality (see Petini-Benelli,2016b; vouchers: CNMT6768!, CNMT6769! and RB01017642!). This typeof flooded habitat is also known to support other congeneric nothospecies, such as  C. × sheyllaeKrahl, Cantuária & J.B.F.Silva, recently described from the state of Pará( Cantuária et al., 2021). 5197090301 2023-03-23 R, P Brazil Carapanatuba Lake 33 -6.772808 Amazonas 1 -62.710144 Madeira River 4 5 1 5197090304 [189,433,1518,1542] A, H Brazil Nascimento 4 5 1 5197090303 [453,577,1518,1542] P Brazil Krahl 4 5 1 5197090302 HUAM Brazil Schmal 4 5 HUAM012581 1 1 holotype