A new species of the genus Rivulus from Ecuador with additional records of Rivulus from the Upper Amazon and Ucayali rivers

During August 1961 I received from Mr. E. Roloff (Karlsruhe, Germany), a well-known aquarist, three specimens of an unidentified Rivulus. The specimens were collected by Mr. Roloff during his journey to Ecuador early 1961. The sampling place is described by him in the followinig words: „Die Rivulus stammen aus einem kleinen, sehr schattigen Bach, der in die Lagune von Limoncocha mündet. Das Wasser ist sehr weich (etwa 1° DH) und hat eine Temperatur von etwa 26° Celcius, die sich natürlich zeitweilig noch erhöht. Der Bach ist nur etwa 1 Meter breit und hat einen geringen Wasserstand, oft nur 20 bis 25 cm. Die Rivulus halten sich hauptsächlich zwischen den Baumwürzeln und den hineingefallenen Zweigen auf. Büsche und Bäume überschatten diesen Bach sehr stark.” This first sample, 1 male and 2 females, was tentatively identified as closely related to or identical with Rivulus peruanus (Regan, 1903), though they did not agree in several technical features with that species. In my key to the genus Rivulus 1 placed peruanus in the isthmensis-complex, though the frontal pattern of this species is not known. Moreover it has as many as 45—47 rows of scales. The male of our sample had only 37 scales in lateral direction, whereas the females were both damaged and in bad state of preservation. I could not make out the proper number of scales.