Gingersrus Database Taxon ID 7629
OLD NAME: Costus laevis
NEW NAME: Costus weberbaueri
NAME CHANGE NOTES: newly recognized species, formerly a syn. of C. laevis R & P
FULL SCIENTIFIC NAME: Costus weberbaueri Loes.
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
Proposed for publication in 2022, this species will become an accepted species. It was previously a synonym for Costus laevis Ruiz & Pav. but it has been determined that there are specimens of the Ruiz collections in herbaria in Spain from two different species that are all tagged as C. laevis, but the one that matches the written description by Ruiz is actually the form of C. tarmicus -- not this C. weberbaueri form.
I first saw Costus weberbaueri in 2013 in Madre de Dios, Peru near the Manu National Park. It was common along the road from Cuzco up to about 1200 meters and I thought it to be just a green bract form of Costus spiralis. In 2017 I visited the type locality near La Merced in department JunÃn, Peru and found that it is the same form that I have now found to be very common in Peru, all along the eastern foothills of the Andes as indicated by the many observations at the Inaturalist link above. Superficially, it looks like the species Costus spiralis but with green bracts instead of red bracts. The flower is nearly identical to that of C. spiralis, red in color, tubular in shape, tightly closed labellum, and adaxially oriented with respect to the bracts. Other than the color of the bracts, the primary visual difference from C. spiralis is the "presence of a distinct, bowl-shaped involcrum of leaves at the base of the inflorescence." In effect the upper leaves form a bowl under the inflorescence.
The holotype for Costus weberbaueri is a specimen collected in 1902 by A. Weberbauer, deposited in Berlin, but destroyed in 1943. A lectotype is in Geneva. Loesener first named the species in December of 1928 on the specimen tag, but just two months later he recognized it as being similar to a specimen of C. laevis R & P that was in the herbarium in Barcelona, and noted on the Berlin tag for the C. weberbaueri specimen: "siehe dort" or "search there". Loesener published the species in Notizblatt des Konigl. botanishen Gartens und Museums zu Berlin, Bd. 10, Nr. 97, July 10, 1929.
The best way to distinguish C. weberbaueri from C. spiralis is by the green color of the bracts and by the leaves at the base of the inflorescence which are tightly spaced and form a bowl-like form beneath the inflorescence. The bracts are red at the base in the hidden part and sometimes that red color extends to the visible part, but are never pure red as in C. spiralis. It is found in Peru and Bolivia along the eastern flanks of the Andes whereas C. spiralis is found in lower elevations of the Amazon basin to the north and east in Brazil and adjacent countries.
DNA has been extracted from three samples of this species, covering its range from near Tarapoto in San MartÃn, Peru to the Ruiz type locality of Costus laevis in Huanuco, Peru and south to Madre de Dios, Peru. These three samples were clustered in a clade well separated from Costus spiralis, close to the new species Costus convexus.
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