This page contains photos and description of a species, form or cultivar of Costaceae.

Gingersrus Database Taxon ID 7537

Costus convexus

OLD NAME: Costus sp. nov.

NEW NAME: Costus convexus

NAME CHANGE NOTES: New species published March 22, 2023 in PhytoKeys 222: 75-127, common from Putumayo, Colombia to Zamora, Ecuador

FULL SCIENTIFIC NAME: Costus convexus Maas & D.Skinner

STATUS : sp. nov.

CONTINENT: Neotropical

FIELD OBSERVATIONS:(If field observations are available, you can click on the link to open in a new window.)

PHOTOS:(If photos are available, you can click on the link to open in a new window.)


Costus convexus was published March 22, 2023 in PhytoKeys 222: 75-127 by Paul Maas and Dave Skinner. I first saw this species in 2007 in the Podocarpus National Park near Zamora, Ecuador. It seemed to fit best in the species Costus laevis, but was not in flower when first observed in 2007. I also saw this form in 2009 near the town of Mendez in Morona-Santiago, Ecuador. In another trip to the region in February 2015 it was found in full flower and clearly it was different from any form of C. laevis I had seen. The plant was HUGE! It had a globular shaped inflorescence with distinctly convex bracts and pinkish colored, adaxially oriented flowers.

In 2018, Paul and Hiltje Maas traveled with Chelsea Specht and Eugenio Valderrama to Putumayo, Colombia (photo left) where they saw a similar plant that had glaucous young shoots causing Paul to tentitively identify it as C. glaucus. When they showed me the photos I could see that it was the same species I had observed in Ecuador near Zamora. Then later that year I was able to travel to Putumayo and study those plants more closely. I eventually convinced Paul that this should be described as a new species, and I suggested the name Costus convexus based on the convex shape of the bracts.

In January 2022, I visited areas near Mera, Tena and the indigenous region known as Narupa where I found this new species to be quite common, and made several more observations which can be seen on the Inaturalist link above.

Our written description: "Costus convexus can be recognized by its glaucous young parts, a globose inflorescence with the upper leaves wrapped tightly aournd it, and by distinctly convex bracts." Paul selected for the type specimen his collection, Maas 10707, from Putumayo along the road south of Villagarzón. Further explained in the notes: "Plants of Costus convexus can grow to be huge plants, up to 5 meters tall, with large inflorescences and flowers. The younger stems and leaves usually have a glaucous covering making them appear similar to C. glaucus but having an inflorescence with distinctly convex bracts that are reddish or pink instead of the pale green and glaucous bracts of C. glaucus. It is also characterized by the upper leaves tightly wrapping and completely hiding the young inflorescence."

A partial phylogeny was completed by Eugenio Valderrama and his associates in the Chelsea Specht Lab at Cornell University and was published in the journal Frontiers in Plant Science in September 2022. DNA samples have been taken from plants in Putumayo, Colombia and southern Ecuador near Zamora; were included in the molecular phylogeny and found to be in a separate clade close to another new and undescribed species - the plant with a pendent inflorescence known by the cultivar name Costus 'El Gato' which also occurs in Ecuador and Colombia.

I have three accessions still living in my gardens but they have not yet flowered here. To my knowledge this is not in cultivation anywhere else but a distribution is planned for Fairchild Tropical Gardens in Miami.

ACCESSIONS:Click links (if any) to see details of individual collections. R3073- R3196- R3331- R3460- R3467- R3525-

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Photos (if available) of Taxon ID 7537
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Costus convexus, photo from Skinner, taken in Putumayo, Colombia - Click to see full sized image
Photo# 187 Accession# R0
Costus convexus, photo from Skinner, taken in Putumayo, Colombia

Costus convexus, photo from Maas,  Maas 10707  IMG_8503.jpg - Click to see full sized image
Photo# 188 Accession# R0
Costus convexus, photo from Maas, Maas 10707 IMG_8503.jpg