Friday, December 31, 2010

Macroinvertebrates of the Rio Cuareim, Uruguay



Coleoptera (beetles)

Dytiscidae (adult)

Hydrophilidae (larvae)

Trichoptera (caddisflies)

This particular species is predatory and do not appear to rely heavily on a retreat. I was able to observed one predating a Leptophlebiid larvae on the underside of a rock. Similar behavior was easily observed in collection jars. They are very common in riffles in the headwaters.


Ephemeroptera (mayflies)


Hemiptera ("true bugs")


Decapoda (shrimp and crabs)

Aeglidae (Aegla uruguayana)

Aegla are probably the dominant invertebrates in the Rio Cuareim (and all of Uruguay). Juveniles are common in riffles and adults can be found in rocky bank zones. Carapace color is highly variable, ranging from green to rusty brown.

Trichodactylidae (Trichodactylus panoplus)

While seemingly not as abundant as Aegla, Trichodactylidae are common along rocky bank zones and are readily collected at night. 

Not pictured: Aeshnidae (Odonata), a very small Ephemeroptera, a small Plecoptera, a huge Belostomatidae, multiple mussels and invasive clams. 


Wednesday, December 29, 2010

Chestnut-sided Warbler (Dendroica pensylvanica)


Crenicichla saxatilis species-group of Uruguay

This is a photolog of the Crenicichla saxatilis species-group of Uruguay. The relationships of these species to Crenicichla lepidota (from Rio Guapore, Bolivia) and Crenicichla saxatilis (from Suriname) is unknown. However, the Uruguayan "saxatilis" can be split into two groups according to geographic locality. Herein, I refer to the Rio Uruguay drainage fishes as C. cf. lepidota and the coastal drainage fishes as C. cf. saxatilis. The middle Rio Uruguay-drainage populations display red dorsal stripes (sometimes two) in females (e.g. Rio Uruguay, Rio Cuareim) while the lower Rio Uruguay populations display purple dorsal stripes in females (e.g. Rio Yi). All Rio Uruguay drainage fishes display 10-12 transversal bars. In contrast, the coastal populations display white dorsal stripes in females (e.g. Arroyo India Muerta, Arroyo las Pavas) and display 7-8 transversal bars. 

Crenicichla cf. lepidota "Rio Uruguay"

Crenicichla cf. lepidota "Canada de Sauce"
Crenicichla cf. lepidota "Arroyo de la Invernada"
Crenicichla cf. lepidota "Rio Yi"
Crenicichla cf. saxatilis "Arroyo India Muerta"

Crenicichla cf. saxatilis "Arroyo el Tigre"
Crenicichla cf saxatilis "Arroyo las Pavas"


Tuesday, December 28, 2010

Fishes of the genus Gymnogeophagus

Gymnogeophagus are the dominant cichlid fish of Uruguay, along with Crenicichla. Below is a photolog of the described species and potential undescribed species of Uruguay.

Gymnogeophagus balzanii "Rio Uruguay"


Described species: G. rhabdotus, found in the west of Uruguay (e.g. Velazquez) and G. meridionalis, found in the Rio Uruguay near Bella Union, and major tributaries (e.g. Rio Cuareim).
Undescribed species: G. ex-meridionalis, found in the south of Uruguay (e.g. Rio Santa Lucia, Arroyo Sarandi) and G. cf. meridionalis, found in the northwest of Uruguay, in headwater streams of Rio Uruguay tributaries (e.g. upper Rio Cuareim, Arroyo de la Invernada). Some will say there are more (e.g. G. sp. "blue neon" which in my opinion are a nice population of G. rhabdotus).

Gymnogeophagus cf. meridionalis "Arroyo de la Invernada"

Gymnogeophagus meridionalis "Rio Uruguay"
Gymnogeophagus meridionalis "Rio Cuareim"
Gymnogeophagus ex-meridionalis "Arroyo Sarandi"
Gymnogeophagus ex-meridionalis "Rio Santa Lucia"
Gymnogeophagus rhabdotus "Arroyo India Muerta"
Gymnogeophagus rhabdotus "Velazquez"


Described species: G. labiatus, found in the west of Uruguay and G. gymnogenys, found all over of Uruguay).
Undescribed species: There are three forms (in my opinion of course), G. aff. gymnogenys from the Rio Santa Lucia drainage (e.g. Rio Santa Lucia, Aguas Blancas, Arroyo Campanero Grande) which can be identified by the dorsal coloration (anteriorly yellow, red posteriorly) and G. aff. gymnogenys from the northwest of Uruguay (e.g. Rio Cuaro, Tres Cruces, Rio Cuareim, Catalan Grande) which have enlarged lips and shallower head profiles. The third is from the west of Uruguay which have completely red dorsal fins. I think the later are probably the "real" G. gymnogenys. Some will say there are more undescribed spp.

Gymnogeophagus gymnogenys "Arroyo de la Invernada"
Gymnogeophagus gymnogenys "Rio Cuareim"

Gymnogeophagus gymnogenys "Rio Santa Lucia"
Gymnogeophagus gymnogenys "Campanero Chico"
Gymnogeophagus gymnogenys "Campanero Grande"
Gymnogeophagus gymnogenys "Aquas Blancas"
Gymnogeophagus gymnogenys "Arroyo India Muerta"

Gymnogeophagus gymnogenys "Laguna de Arnaud"

Gymnogeophagus gymnogenys "El Tigre"
Gymnogeophagus gymnogenys "Arroyo Valentin"
Gymnogeophagus labiatus "El Tigre"
Gymnogeophagus labiatus "Arroyo las Pavas"

Gymnogeophagus labiatus "Laguna de Arnaud"
Gymnogeophagus tiraparae "Rio Yi"
The only described Uruguayan Gymnogeophagus species not pictured herein is G. australis