Reevaluation of Guyanancistrus

[bekateen]

Fisch-Muller, S., Mol, JHA, Covain, R. (2018). An integrative framework's to reevaluate the Neotropical catfish genus Guyanancistrus (Siluriformes: Loricariidae) with particular emphasis on the Guyanancistrus brevispinis complex. PLoS ONE, 13(1), e0189789.

doi:10.1371/journal.pone.0189789

http://journals.plos.org/plosone/articl ... ne.0189789

Read after the abstract (reproduced below) for list of proposed new species, subspecies, and key to the genus.

Abstract
Characterizing and naming species becomes more and more challenging due to the increasing difficulty of accurately delineating specific bounderies. In this context, integrative taxonomy aims to delimit taxonomic units by leveraging the complementarity of multiple data sources (geography, morphology, genetics, etc.). However, while the theoretical framework of integrative taxonomy has been explicitly stated, methods for the simultaneous analysis of multiple data sets are poorly developed and in many cases different information sources are still explored successively. Multi-table methods developed in the field of community ecology provide such an intregrative framework. In particular, multiple co-inertia analysis is flexible enough to allow the integration of morphological, distributional, and genetic data in the same analysis. We have applied this powerfull approach to delimit species boundaries in a group of poorly differentiated catfishes belonging to the genus

Guyanancistrus

from the Guianas region of northeastern South America. Because the species G. brevispinis has been claimed to be a species complex consisting of five species, particular attention was paid to taxon. Separate analyses indicated the presence of eight distinct species of Guyanancistrus, including five new species and one new genus. However, none of the preliminary analyses revealed different lineages within G. brevispinis, and the multi-table analysis revealed three intraspecific lineages. After taxonomic clarifications and description of the new genus, species and subspecies, a reappraisal of the biogeography of Guyanancistrus members was performed. This analysis revealed three distinct dispersals from the Upper reaches of Amazonian tributaries toward coastal rivers of the Eastern Guianas Ecoregion. The central role played by the Maroni River, as gateway from the Amazon basin, was confirmed. The Maroni River was also found to be a center of speciation for Guyanancistrus (with three species and two subspecies), as well as a source of dispersal of G. brevispinis toward the other main basins of the Eastern Guianas.

They recognize and create a whole lot of new species and subspecies:

• Guyanancistrus brevispinis
  brevispinis (Heitmans, Nijssen & Isbrücker, 1983)
• Guyanancistrus brevispinis
  bifax, new subspecies
• Guyanancistrus brevispinis
  orientalis, new subspecies
• Guyanancistrus nassauensis
  Mol, Fisch-Muller & Covain, new species
• Guyanancistrus brownsbergensis
  Mol, Fisch-Muller & Covain, new species
• Guyanancistrus teretirostris
  , new species
• Guyanancistrus tenuis
  , new species
• Guyanancistrus megastictus
  , new species
• Cryptancistrus new genus
• Cryptancistrus similis
  , new species

Key to species of Guyanancistrus.

1. • Presence of distinct spots on body and fins, all spots roundish and smaller than size of a lateral dermal plate; pectoral-fin spine length 31.9–45.5% of SL. .....2
   • Absence of distinct spots on body and fins, or presence of spots at least as large as a dermal plate, or coalescing, or forming bands on posterior part of body and fins; pectoral-fin spine length 22.2–34.4% of SL. .....3
2. • Body and fins covered with small roundish yellow spots; odontodes on dorsolateral margin of the upper lip minute; dorsal-fin base length 29.0–32.0% of SL. .....
     Guyanancistrus longispinis
   • Body and fins covered with minute white dots; odontodes on dorsolateral margin of the upper lip elongated (Fig 7D); dorsal-fin base length 24.8–28.8% of SL. .....
     Guyanancistrus niger
3. • Anal fin with 4 branched rays; dentary tooth cup 24.2–31.9% of head length. .....
     Guyanancistrus nassauensis
   • Anal fin with 5 branched rays; dentary tooth cup 23.6% or less of head length. .....4
4. • Longest evertible cheek odontodes reaching the first half of the opercle (except in some large specimens surpassing 70 mm SL reaching the third quarter but not reaching its last quarter). .....
     Guyanancistrus brevispinis
   • Longest evertible cheek odontodesreaching the last quarter of opercle or beyond its posterior end (except in very small specimens). .....5
5. • Pelvic-fin spine not reaching origin of anal fin. .....
     Guyanancistrus teretirostris
   • Pelvic-fin spine reaching beyond origin of anal fin. .....6
6. • Orbital diameter 1.7–2.1 times in interorbital width; depth of caudal peduncle 3.1–3.6 times in its length. .....
     Guyanancistrus tenuis
   • Orbital diameter 2.2–2.4 times in interorbital width; depth of caudal peduncle 2.5–3.0 times in its length. .....7
7. • Pelvic-fin spine reaching beyond end of anal fin base; depth of caudal peduncle 2.5 times in its length. .....
     Guyanancistrus brownsbergensis
   • Pelvic-fin spine not reaching beyond end of anal fin base; depth of caudal peduncle 2.9–3.0 times in its length. .....
     Guyanancistrus megastictus

[bekateen]

For what it's worth, I have not yet added any of the new species because I do not know if they correspond to preexisting L numbers. If someone with knowledge of the L numbers and familiarity with this group can check that issue and let me know, then I'll go ahead and create new CLOG entries.

[Karsten S.]

Hi Erik,

as you can see from the key to the genus there are no new species with distinct spots on body and fins. The L numbers known for Guyanancistrus from the affected areas all have distinct spots.
- L 221/L 223 from Rio Paru
- L 317 from Rio Jari

There are two more numbers:
- L 56 from Rio Araguarí has only some pale spots but with a completely different distribution
- L 490 from Rio Jatapu again has clear spots

So I'm very sure that we are not talking about L numbers.

But, it's indeed interesting that we do already know exactly from the same rivers L numbers. However, the newly described species are from the very upper part of the river and the L numbers L 221/L 223 from the lower part of Rio Paru and L 317 most probably as well from the lower Rio Jari.
In Suriname & French Guyana we also have species of the lower parts (G. brevispinis) and of the upper parts in the mountains (Nassau & Brownsberg, Mitaraka).

Cheers,

[Jools]

Thanks for adding the species and images - look forward to hearing more about these species as Raphael Covain presents at the CSG convention in England in a couple of months time. Eh, @CoryWally?

Jools

[bekateen]

You're welcome, Jools.

As for subspecies, I wasn't quite sure how to handle them. For now, I simply added photos of subspecies. I considered using the "variant" tool on the CLOG page to create subspecies, but I thought better about it and decided against that for two reasons: (1) in case the subspecies get disentangled at a later date as unique species in their own right, and (2) given the issues described elsewhere with regard to the forgetfulness of the variant selections for photos, I thought it might just unnecessarily complicate matters.

Would you prefer I use the variant tool and create a variant for each subspecies? Or just leave everything as is?

Cheers, Eric

[Jools]

I would give it a while; if you feel a strong desire to add them then you need to add them as distinct species entries.

Jools

[bekateen]

I'll leave them be as is for now.

Cheers, Eric