Gingersrus Database Taxon ID 7624
CURRENT NAME: Costus guanaiensis
PROPOSED NAME: Costus guanaiensis
NAME CHANGE NOTES: Previous proposal was for a red flowering sp. nov. Costus bolivianus, but it was discovered that the type for C. guanaiensis was actually that form, so the name C. guanaiensis will now be applied to that form.
FULL SCIENTIFIC NAME: Costus guanaiensis Rusby
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 longifolius Rusby (1934)
Costus guanaiensis is another of the species that will be completely changed when our revision to new world Costaceae has been published. As was the case with Costus laevis, the type specimen for Costus guanaiensis was incorrectly interpreted. All the varieties of that species as it was formerly known will have new names, and the species name Costus guanaiensis will be applied to an entirely different group of plants. A full explanation of these changes can be found at http://gingersrus.com/Costus_guanaiensis_changes_explained.pdf
This page is for the "new" C. guanaiensis that produces small bract appendages and red flowers. Paul Maas had proposed to describe and publish a sp. nov. to be called Costus bolivianus, but then realized that the type specimen from Guanay, Bolivia that was described by Rusby as C. guanaiensis was actually this form and not the form we have all come to know as C. guanaiensis.
This was originally described by H. H. Rusby in the Torrey Botanical Club Bulletin, Vol. 29, in 1902, named there as Costus guanaiense. In his description, Rusby described the bracts as being "about 5 cm long, 3 cm broad, thick, rigid, brown, strongly nerved, the foliaceus tips about 1 cm long, and 6 or 7 mm broad , obtusish, appressed or reflexed at the tip". He did not include any information about the flower. The type was his collection No. 2225 at Guanai (now usually spelled Guanay), Bolivia, collected in May 1886.
Schumann included this species in Englers, Das Pflanzenreich, Vol. IV, 1904. He changed the species name from C. guanaiense to C. guanaiensis. He basically repeated the same description, translated into Latin, and did not include any description of the flower.
In 1934 in Phytologia, Vol. 1 No. 2, page 50, Rusby described another species from Mapiri, Bolivia (Tate 442) which he called Costus longifolius, described as having a slender stem, leaves to 25 cm long by only 4 cm wide, lanceolate to oblanceolate in shape. He described the bracts as "scales", spreading, ovate, 5 cm by 2.5 cm with a "broad base and acute summit". Again, he did not give any information about the flowers. Dr. Maas believes this to be a synonym to this reconfigured species, and I agree.
Plants that we have determined to belong to this new characterization of the species Costus guanaiensis have very distinct and unusual looking flowers. They are basically red flowers, more or less tubular in shape, and with distinctive labellum and corolla lobes. The labellum is almost flat with reflexed margins. The corolla lobes are triangular shaped and tend to fan out from the flower. I first saw this species in Peru at two locations in the Manu Area of Madre de Dios and bordering parts of Cusco department. I have also seen it farther to the south in Madre de Dios Tambopata area, in Cusco at Quincemil and and in Puno. My observations of this newly described Costus guanaiensis may be found at the Inaturalist link above.
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