Overview

After the success of my first expedition to South America, my labmates and colleagues expressed unanimous interest in returning to the upper Orinoco with a larger team and a longer itinerary that would allow us to explore further up the Ventuari River. Serendipitously, a proposal to discover and describe all species of catfish had recently been funded by the US National Science Foundation, and my advisor was a co-PI. With funding secured, I embarked again to southern Venezuela in March and April 2004, this time with my labmates Lesley de Souza and David Werneke, fellow ichthyologist Mark Sabaj Pérez (from the Academy of Natural Sciences), and my Venezuelan colleague Oscar Leon Mata (from the University of the Llanos Ezequiel Zamora).

        Together, we travelled further up the Ventuari River and its tributaries than any ichthyologist had previously, yielding specimens that have kept us busy with research ever since. The most exciting discoveries of this trip were made during an overland trek that Oscar and I took to habitats above Salto Tencua, a 60 m high waterfall and rapid that blocks all upstream navigation on the Ventuari River. Many of the species that we collected above Salto Tencua were new to science, including new species of Lithoxancistrus (L. yekuana Lujan et al., 2007), Lithoxus (L. jantjae, 2008), Harttia (H. merevari Provenzano et al., 2005), and Geophagus (a still undescribed species being studied by Hernán López-Fernández and myself).

        Discoveries from this and my previous expedition to southern Venezuela were so intriguing and abundant that I returned to the upper Orinoco again in 2005 and traveled even further up the Ventuari River in 2010. I hope to be able to return again in the near future. Specimens collected during my 2004 trip are now cataloged at AUM, ANSP and MCNG (field number prefix VEN04), where they continue to benefit ichthyological research. Published papers that have already benefited from collections and observations made during this trip include the following:

Cerro Moriche in the Middle Ventuari, photo by M. Sabaj Pérez

Work

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1. The basalt bedrock slab that constitutes Puerto Samariapo, one of two low-water ports from which all boats headed up the Orinoco, upstream of the Raudales Autures, must depart. 2. Loading our gear into the small voladora boat that would take us to San Fernando de Atabapo. 3. In the house of Augusto Luna in Macarucu, with his wife Olivia and son Augustico, looking at photos from our trip the previous year. 4. Ornamental fish holding pins at an indigenous village along the banks of the lower Ventuari River. 5. Dozens of loricariid catfishes, most of them undescribed species at that time, being held in a dugout canoe draped with plastic in anticipation of being sold to a middle man who would bring them to Colombia for export. 6 & 7. Collecting at points along the Ventuari River. 8. A mapanare snake (Bothrops sp.) that David Werneke almost stepped on near one of our camps. 9. On the landing at San Juan de Manapiare celebrating the last night in the field for Lesley de Souza and Mark Sabaj Pérez, who would be flying out the next day. 10 & 11. Salto Tencua, a large waterfall and rapid that blocks upstream navigation and serves as a faunal barrier between fishes of the middle and upper Ventuari River. Photos 1–9 by M. Sabaj Pérez.

Fish

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CRENUCHIDAE: 1. Characidium sp. LORICARIIDAE: 2. Baryancistrus demantoides. 3. Pseudolithoxus dumus. 5. Pterygoplichthys gibbiceps. PSEUDOPIMELODIDAE: 4. Batrachoglanis sp. DORADIDAE: 6. Leptodoras linnelli. 7. Hassar orestes. AUCHENIPTERIDAE: 8 & 9. Trachelyopterichthys taeniatus, in and out of the submerged log shelter that these so called 'wood catfishes' hide in during the day. Photos by M. Sabaj Pérez.

Sponsors

This fieldwork was sponsored by NSF grant DEB-0315963, the All Catfish Species Inventory

2004 Expedition to the Middle Ventuari, Venezuela