Gingersrus Database Taxon ID 3789
CURRENT NAME: Costus productus
PROPOSED NAME: Costus juruanus
NAME CHANGE NOTES: Maas found a duplicate of type for C. juruanus and is proposing to change all C. productus back to C. juruanus as in 1972 monograph.
FULL SCIENTIFIC NAME: Costus juruanus K.Schum.
STATUS : stat. nov.
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.)
GOOGLE PHOTO ALBUM
- Costus productus Gleason ex Maas var. strigosus (Maas) Maas (1976) - Costus productus Gleason ex Maas var. productus
This species has had a history of name changes, back and forth. It was originally described by K. Schumann in 1904 in Engler's Das Pflanzenreich, Vol. IV, based on the collection in 1901 Brazil by the German explorer Ernst Ule. In 1972, Paul Maas in his monograph maintained the same name, but he chose a neotype for the species (Killip & Smith 25317 from Peru) because the type specimen had been destroyed in Berlin in 1943.
In 1976 Dr. Maas described and published a new species, Costus productus Gleason ex Maas based upon that neotype. In 1977 he explained that Costus juruanus had to be excluded and had to be changed to an "insufficiently known species", because only a photograph of the Berlin specimen existed and in that photograph the inflorescence was completely covered by one of the upper leaves. Since that time, these plants have been known as Costus productus and were believed to be endemic to Peru.
More recently, Dr. Maas found another specimen in Hamburg, Germany of the original Ule collection from Brazil, and was able to study it as he had been unable to do from a photograph of the Berlin specimen. This Ule collection was from the state of Acre, Brazil, somewhere along the upper Jurua-Mirim river. Dr. Maas had been there in 1971 but did not see this species, so he asked me to look for it during my planned trip to the region.
In April 2019, with the help of Professor Marcus Athaydes of the federal university in Cruzeiro do Sul, I found a nice population of this species, then known as Costus productus, and was able to document the details and confirm that the plants found there in Brazil were of the same species as those found in Peru and the name Costus juruanus could be reinstated for this species. My article about the search for this plant can be found in the Heliconia Society Bulletin, Vol. 26, No. 1.
The species is generally described as a low plant between 0.3 and 1.5 meters tall, with a long (20-40 mm) two-lobed ligule. The inflorescence (normally terminal) is comprised of red appendaged bracts and tubular red to orange-red flowers. Maas says this species "is easily recognizable by a very well developed, obtusely lobed, often membranous ligule to 60 mm long, a red to orange (or rarely yellow) inflorescence in which the bracts are often reflexed and terminating into a small appendage, and tubular, mostly yellow flowers with red apical lobules of the labellum."
In the field, I have found this species to be incredibly polymorphic, and I expect that separate taxa will be eventually described either as subspecies, formal varieties, or even separate species. Some of these separate forms have been established as registered cultivars, and the details can be found at the links below:
DNA has been extracted from samples of each of these four forms from Peru, plus the 5th sample from the collection near the type locality in Acre, Brazil. All five samples were shown to be in a well supported separate lineage of closely related clades, clearly establishing all 5 as being part of the same species complex despite their morphological differences. The earliest of the lineages were the two from Madre de Dios and Puno in the south of Peru, then the form from Pasco, Peru with the cupped ligules and finally the two nearly identical forms (Acre, Brazil and San MartÃn, Peru) in the same clade thus showing the transitions from south to north. The whole genome of my accession R2693 (the commonly cultivated form) was sequenced in the Chelsea Specht Lab at Cornell University.
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