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| Costus maasiorum D.Skinner, J.L.Clark, & C.D.Specht, in Skinner, Valderrama, Clark, Landis, Harden et Specht, C.D. 2026. |
Abstract
We here describe Costus maasiorum, a new species from western Ecuador. This new species shares morphological similarities with Costus macrostrobilus, but differs in having plicate leaves, erect and triangular bract appendages, and semi-tubular elongate flowers. A phylogeny based on 5.9+ million single nucleotide polymorphisms (SNPs) strongly supports a sister relationship between C. maasiorum and C. macrostrobilus. Additional taxonomic sampling in subsequent analyses indicates a close relationship with C. gibbosus and C. antioquiensis. A comprehensive taxonomic description, including detailed photographs and information about the habitat and ecology of the new species are provided. A preliminary conservation status is recommended as Least Concern (LC).
Keywords: COSTACEAE; Costus; Genome resequencing, Neotropics, SNP-based phylogeny, Zingiberales
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| Costus maasiorum sp. nov.: A. Stem from D.Skinner 3071 (BH) showing red striations; B. Close-up of lower side of leaf showing pubescence; C. Red lower side of leaf from a plant observed in Buenaventura in southern Ecuador; D. Close-up of upper side of leaf showing pubescence; E. Plant in habitat, Bilsa, Ecuador; F. Inflorescence from Bilsa, Ecuador. Photos A-F by Dave Skinner. |
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| Costus maasiorum sp. nov. specimen D.Skinner 3202: A. Stem and ligule with red striations. B. Flower with attached immature fruit and bracteole. C. Inflorescence close-up of same plant showing appendaged bracts. D-E. Upper (D) and lower (E) side of leaves showing variation in indument and red coloration as compared with Fig. 3. F. Plant in habitat at Siete Cataratas, Ecuador. G. Close up of young inflorescence showing sequential flowering with spiromonistichous phyllotaxy. Photos A-G by Dave Skinner. |
Costus maasiorum D.Skinner, J.L.Clark, & C.D.Specht, sp. nov.
Costus maasiorum sp. nov. can be recognized by its plicate leaves, often dark purple underneath, the presence of appendaged bracts with the appendages being erect and triangular in shape, and the primarily yellow flower with the labellum presenting as a narrow, elongate floral tube. The overall morphology of the plant is similar to that of Costus macrostrobilus, but the species differs in having a more tubular labellum, plicate leaves (non-plicate or flat leaves in C. macrostrobilus) and in the shape of the bract appendages that are concave and somewhat pungent (ending in a stiff, sharp point in C. macrostrobilus).
Etymology — Costus maasiorum is named in honour of the botanical couple Professor Paul J.M. Maas and Hiltje Maas-van de Kamer and the contribution of this couple to systematic and taxonomic work within the Costaceae. It was Dr. Paul Maas who visited Bilsa in 1997 and first noted this species as undescribed. Paul began working on Costaceae during his PhD in which he completed two monographs on New World Costoideae for Flora Neotropica, establishing himself as the expert on this and other families of Neotropical Zingiberales. The two Flora Neotropica volumes, which included revisions of the Costoideae, provided species level descriptions and detailed understanding of taxonomic limits, biogeographic distributions, morphological variation, and relationships among species of Costaceae that still stand today, often being confirmed by subsequent DNA-based phylogenetic studies. Paul’s observations of differences between closely related species and awareness of variation noted in living plants and in herbarium specimens enabled and inspired decades of research on this interesting and charismatic tropical family. ...
Skinner, D.; Valderrama, E.; Clark, J.L.; Landis, J.B.; Harden, J.J. and Specht, C.D. 2026. Costus maasiorum: A New Species of Neotropical Costaceae from western Ecuador. Blumea - Biodiversity, Evolution and Biogeography of Plants. 70(1);116-124(9).DOI: doi.org/10.3767/blumea.2026.70.01.02 [January 1, 2026]
