This is the "El Gato" form that I have seen in Colombia, Ecuador, Peru and in Acre, Brazil. It is either an undescribed species, or possibly is the species described by Loesener as Costus validus. The inflorescences of this species in the Rio Branco area generally have an upright orientation, but in the Cachoeira area and in other countries where I have seen it, they generally are nodding or distinctly pendent.

Some plants in this same species have a waxy texture and dark purple undersides to the leaves - especially in young plants. I have seen this same thing in the Manu National Park in Peru.

This photo taken near the border with Bolivia along the Rio Xipamanú

UPDATE February 2020: In January 2020 I visited the southern part of the state of Acre in Brazil near the Rio Acre, the region of the type for the species Costus acreanus. I have also compared herbaria specimens from that region that were determined by Paul Maas to be the species he described as Costus acreanus. I found that the only plant matching his description and the herbaria specimens he determined as C. acreanus to be forms of the 'El Gato' plant that I had previously found in Colombia, Ecuador and southern Peru. It is by far the most common species in the region. Near Xapurí and points east into Peru, it usually has a pendent inflorescence bourne at the terminus of a leafy stem. In places near the city of Rio Branco and north to Porto Acre, most plants were erect instead of pendent, and it was more common to find them with basal inflorescences on a leafless or near leafless shoot.

I have thus concluded that this observation is an example of the species Costus acreanus (Loes) Maas.