Intense green with a metallic sheen, rarely found in scientific collections and sought after by hobbyists—one catfish became mythical, because all we know of it is based on a poor formal description.
IN AUGUST 2012 I was on top of the world. At the Río Ibare (inlet of the Río Mamoré in Bolivia) we managed to catch wonderfully green shining armoured catfish, which we later identified as Corydoras latus. This classification was also supported by our proximity to the fish’s known origins, as we were only 220km away from its type locality (the spot from where the first example of a species is caught).
In the rainy season, the type locality and our capture locality are connected by numerous small rivers and a large intervening swamp- and lake-landscape. Such a range would not be unusual. However, since there were few live photographs of a true C. latus at the time for us to compare our fish with, some uncertainty remained.
This uncertainty was amplified when the holotype of C. latus was examined and assigned to the C. elegans group, placing it in lineage 5. My captured specimen belonged to lineage 8, and so it seemed to be something else after all. Thus thwarted, finding the species ID slipped down my list of immediate priorities.
We had been active several times in the vicinity of the type locality of C. latus, but apparently had never been successful. Now other regions of Bolivia were on my agenda, and so the latus myth lived on.
Uncertain beginnings
The ichthyologist Nathan Everett Pearson described Corydoras latus in 1924, based on a single specimen from either Lago Rogagua or its surroundings in Bolivia. The lake is located in the middle basin of the Río Beni. Pearson writes that the holotype measured 64mm in total length (TL), describing it in colour as: "body and fins uniformly blackish, body high, rather strongly compressed, a dark stripe along the meeting of the dorso- and ventrolateral lateral plates". This holotype suggests a large, high-backed and short-snouted species, and this is all we know about the character of the fish. The colour description should be taken with some caution, because the fish’s chromatophores had probably been destroyed by preservation.
Fast forward to 1980 and ichthyologists Han Nijssen and Isaäc Isbrücker measured the holotype again, stating the standard length (SL) as 41.5mm. They assigned C. latus to the C. elegans group (now known as lineage 5). Joachim Knaack (in work from 2002 and 2004), on the other hand, stated that the anatomy of the pectoral spines of the holotype w
