Ancistrus gymnorhynchus

[Shane]

Just noticed that range information for

Ancistrus gymnorhynchus

is off. This sp was described from Puerto Cabello.

In 2010 its range was enlarged to coastal rivers of the Venezuelan states of Falcon, Lara, Yaracuy, and Carabobo.

Of interest, this same paper recognizes that there is an undescribed brown Ancistrus from the Rio Chirgua. This sp is in the catelog.

Sorry, should posted this to the catelog thread.

-Shane

[bekateen]

Shane, are there any Ancistrus articles you need that you don't have access to?

Cheers,
Eric

[bekateen]

Of interest, this same paper recognizes that there is an undescribed brown Ancistrus from the Rio Chirgua. This sp is in the catelog.

I was a bit surprised to see the 2010 paper considered the brown specimens to be simply a "color morph" of the otherwise gray

Ancistrus gymnorhynchus

rather than setting them aside as a different species, or at least saying they need more study to confirm they're just a color morph of A. gymnorhyncus.

I was also struggling to understand how the Pao and Chirgua become part of the Orinoco drainage, since they are so close to Valencia. Upon reading the old 1949 paper by Schultz (excerpt below) and looking at websites like Mindat.org and Geohack.toolforge.org, the Schultz paper was in conflict with the websites in that the Schultz paper puts the Pao as a tributary of the Chirgua and the Chirgua leading back to the Rio Portuguesa (and then to Apure and Orinoco), but the Mindat and Geohack websites appear to make the Chirgua a tributary of the Pao, with the Pao reaching down to the Portuguesa. Compounding that, there are two different Rio Chirgua on the maps, both tributaries of the Pao, but one north near the city of Chirgua and the other, probably a much larger river, along the western boundary of the "Area Boscosa Bajo Proteccion Pueblito."

Overview map of region in Venezuela (from Mindat)

Inset 1: Blue stars = collection sites of brown A. gymnorhyncus (from Mindat)

Inset 2: The Pao and the Chirgua reconnect here then diverge again (from Mindat)

Inset 3: The Chirgua branches off the Pao here (from Mindat)

To compound the confusion, our PCF website had lat/long coordinates for the Chirgua that seemed to be nowhere close to any mapped portion of either of the Rio Chirgua as they appear in satellite images. By the time my head was done spinning, I came to the conclusion that the Chirgua was a tributary of the Pao, and based on the lat/long coordinates provided by Taphorn et al. in 2010, the Ancistrus were collected from a segment of the Chirgua that is near the city of Chirgua (one in an area marked on my figure in red and the other in an area I marked in green - that segment of the Chirgua isn't marked on any of the online maps I viewed, but wrinkly lines on the map following roads or governmental borders would be consistent with a river along there).

But no, it's still not solved. Taphorn et al. wrote that these brown color morphs are found "in the Chirgua River and tributaries (upper Pao River drainage) in Cojedes state." The museum specimen they list is "MCNG 14257, 80, Cojedes, Río Chirgua, between Tinaquillo and Campo Carabobo, 09° 58' 20"N, 68° 12' 40"W, 4 August 1985, D. Taphorn et al." But that set of coordinates is just inside Carabobo State, not Cojedes, although it's close enough that either the map-drawn lines might be off, or the authors were mistaken when the listed the locality as Cojedes (conversely, the distance from the location to the Cojedes border is about 1km, so that might be considered "margin of error" in the past, although I think by 2010 the standard was higher than that). The other entry they offer from the Chirgua (10° 08' 30"N, 68° 11' 30"W) is clearly in Carabobo state, and they list it as such. The other Chirgua, the more southerly river, is located on the border between Cojedes state and Guarico state.

Shane, when you talk about the undescribed

Ancistrus sp`rio_chirgua`

, do you know which "Chirgua" it's from?

Cheers,
Eric

Here's a textual recounting of the screeen-image I took from Schultz (1949. Proc USNM 99(3235): pp 5-7). The text shows the Pao as a tributary of the Chirgua (I've highlighted them in bold/blue), and also the footnote states that at one time, it's thought the Pao flowed to the Orinoco. I suppose the discrepancy between Schultz and modern maps might not represent an error on Schultz's part, if it were that the waterways shifted in the last 80 years and now the Pao has a direct connection to the Portuguesa but in the past was connected to the Chirgua. That would resolve one confusion but wouldn't address the issue of the more northern Chirgua in Carabobo State, which is clearly not a tributary of the Portuguesa.

Image grab from original Schultz paper

A list of drainage basins or stream systems of northern Venezuela is presented below to aid in the interpretation of this report. Each indentation indicates that the body of water is tributary to the one under which it is indented.

• Gulf of Venezuela
  • Río Cocuiza
  • Río Capatárida
• El Tablazo
  • Río Limón
    • Río Socuy
      • Lago Tulé
  • Lago de Maracaibo 1
    • Río Palmar
      • Quebrada la Gé
    • Río San Juan
    • Río San Ignacio
    • Río Apón
      • Río Cogollo
    • Río Santa Ana
      • Río Negro
    • Rio Catatumbo
      • Río Zulia
        • Río Pamplonita
          • Río Táchira
    • Río Escalante
    • Río Chama
    • Río Motatán
      • Río San Pedro
      • Río San Juan
    • Río Misoa
    • Río Machango
• Caribbean Sen (coastal streams) 2
  • Río Tocuyo (Estado de Falcón)
  • Río Yaracuy (Estado de Yaracuy)
  • Streams near Puerto Cabello (Estados de Carabobo and Aragua)
  • Streams near La Guira and Macuto (Distrito Federal)
  • Río Tuy (Estado de Miranda)
    • Río Guaire
  • Río Unare (Estado de Anzoategui)
  • Río Manzanares (Estado de Sucre)
  • Golfo de Paria
    • Río San Juan
      • Guanoco or Pitch Lake
    • Río Guanipa
    • Orinoco Delta
      • Caño Mánamo
        • Río Morichal Largo
          • Rio Tigre
        • Río Uracoa
      • Río Orinoco
        • Río Coroni
        • Río Caura
        • Río Suata
        • Río Manapire
        • Río Apure
          • Río Guárico
          • Río Portuguesa
            • Río Guanare
            • Río Chirgua
              • Río Pao
                • Lago de Valencia 3
            • Río Cojedes
            • Río Uribante
              • Río Frío
                • Rio Torbes

Footnotes:

1. All rivers listed in a counterclockwise direction around this lake.
2. Listed from west toward the east beginning on the eastern side of the Peninsula de Paraguana, opposite Coro, and continuing to the Gulf of Paria. Lago de Valencia is an enclosed basin at present, but it is listed below under the Orinoco system.
3. Lago de Valencia is said to have been much larger at one time and to have had an outlet to the Orinoco system through the Rio Pao.

[Shane]

"I was a bit surprised to see the 2010 paper considered the brown specimens to be simply a "color morph" of the otherwise gray Ancistrus gymnorhynchus rather than setting them aside as a different species, or at least saying they need more study to confirm they're just a color morph of A. gymnorhyncus."

You and me both....

Yes, there is a weird bit of geography there where a dip in the Serrania del Interior actually causes Some drainages to the west of Lake Valencia to flow south.

For Ancistrus "Rio Chirgua" we are talking about the small river in Carabobo State that originates just NE of Bejuma. I never explored the larger Rio Chirgua in Guarico State as there are very few roads in that area.

Multiple rivers with the same name are our bane. However, for all I know "Chirgua" is the local indigenous word for river. I can picture some poor Spanish explorer asking his native guide the name of this river and that river and only getting the reply "Chirgua."

Don's collection coordinates could be slightly off. Keep in mind that when he collected the specimens in 1985 there was no GPS or internet maps.

Attached are two maps. One is a very old, but great, macro map of Venezuela's river systems. The other is the actual map I marked with the exact collection locale at Camburito.

-Shane

[Jools]

I think we got this updated, right?

Cheers,

Jools

[bekateen]

I think we got this updated, right?

Cheers,

Jools

Yes I believe so. To address Shane's original comment on the distribution of A. gymnorhynchus, the four Venezuelan states are covered by Venezuela Caribbean waters. If you want more granularity, I can create a separate body of water for each state (Falcón, Lara, Carabobo and Yaracuy). The Rio Yaracuy exists already in our bodies of water database, but since the distribution is not limited to that one river in the state, I chose not to include that in the CLOG page.

As for all the other conversation about the mystery brown Ancistrus, that's fixed too.

Cheers,
Eric