Changes to Rivulus genus

[Shi Xuan]

Hi,

My perceived information is quite late but nonetheless, beneficial to those who are still unaware of it. It seems that as of October 2011, the Rivulus genus will only cover but not limited to the current better known & described species, R.cylindraceus & R.insulaepinorum. The new classification Dr. Costa has done, include genus; Anablepsoides, Atlantirivulus, Cynodonichthys, Laimosemion & Melanorivulus.
http://www.itrainsfishes.net/content/

Best regards,
Shi Xuan

[stormhawk]

Costa wants to follow in the footsteps of Sven O. Kullander. Subgenus of the Rivulus have been around for the past few years, and only this year did he upgrade them to full genus status. In the past he split Megalebias from Austrolebias, only to reverse his decision at a later date. I don't think those genus names will stick with hobbyists, because there's people who still follow the old system, purely for convenience.

Besides, Cynodonichthys, Laimosemion, Anablepsoides? The Anablepsoides don't even look like the Anableps aka 4-Eye Livebearer, except in body form. He could have called them something+rivulus in the name. Cynodonichthys? Dog-Tooth Fish

[Shi Xuan]

Like you, I was initially astounded & rather perplexed with the genus name, Anablepsoides, because it spells a lot identical to the name of the four-eyed livebearer though.

As for convenience sake, You will be surprised that many killi keepers update themselves on the latest changes in taxonomy & classifications of their fishes though, that's why I find myself a bit late for the news.

[stormhawk]

If the ads on Aquabid are anything to go by, some prefer using Rivulus. Others follow Costa and use the new names. To me, no difference, since they're so rare. Rivulus cylindraceus was my first Rivulus, and very nice fish too. At least it remained in Rivulus.

[kim m]

I think the tricky part is figuring out where the undescribed species belongs. I have some Rivulis sp. COL 09/28 but have no idea where they would fit into the new system...it will be a lot easier when the big Cory-revision comes at least I think it is easier to see where a new species belong there.

These new names will take some time to get used to. Personally I think I'll go with (Riv.) after the genus name when putting eggs on Aquabid. For instance Anablepsoides (Riv.) ornatus.

[Shi Xuan]

Hi all,

I must admit, Rivulus are rare, in fact it applies very well to all the killies sp. Re-classification of zoological taxonomy is not a big issue for fishes afterall, because many species are on the pending list of being named as well.

I can't think of any better way to find Cory classification as easy. Take Corydoras orcesi for example, it looks like a hybrid between a Corydoras & Aspidoras or maybe Scleromystax but still classified as a Corydoras sp.

Nonetheless, of all Rivulus sp, I still like Rivulus sp. Rio Itaya but it's so rare no one keeps this sp. Btw, if there's any researchers working in the field of African annuals, I was thinking if they might eventually upgrade sub-genus for Nothobranchius too.

Best regards,
Shi Xuan

[kim m]

Hi all,

I must admit, Rivulus are rare, in fact it applies very well to all the killies sp. Re-classification of zoological taxonomy is not a big issue for fishes afterall, because many species are on the pending list of being named as well.

I can't think of any better way to find Cory classification as easy. Take Corydoras orcesi for example, it looks like a hybrid between a Corydoras & Aspidoras or maybe Scleromystax but still classified as a Corydoras sp.

Nonetheless, of all Rivulus sp, I still like Rivulus sp. Rio Itaya but it's so rare no one keeps this sp. Btw, if there's any researchers working in the field of African annuals, I was thinking if they might eventually upgrade sub-genus for Nothobranchius too.

Best regards,
Shi Xuan

To me orcesi looks like a typical saddle-snout. In fact this group (saddle snouts like semiaquilus, orcesi, fowleri, acutus etc.) will be the only Corydoras after the revision, as C. geoffroy (also a saddle snout) is the type-species for Corydoras. Everything else will need new genus names (old ones like Hoplosoma, Gastrodermus etc. will probalbly be used again). It is really interesting. I've been supplying specimens and tissues samples for DNA-analysis for the project. There's a chapter from the scientists about it in the back of Fuller/Evers supplement for their ID-book: http://www.corydorasworld.com/books/...h_supplement_1

[stormhawk]

The Nothobranchius species have been grouped in their respective subgenera, also in the past decade or so. But to date, none of the researchers have elected to raise them to full genus status. Either they feel that splitting the genus is not necessary, or this decision has been shelved till a later date.

Too much splitting going on these days. I wonder what else these scientists will do next. Costa has reversed his decisions before, in the case of Megalebias that I stated earlier. So it remains to be seen whether his decision this time, will stay this way, or change again at a later date...

[Shi Xuan]

Well, I wouldn't be surprise if there's so much of the "do's" & the "un-do's", fishes has always been the least understood group of organisms of the animal kingdom. For example, some species of the Nothos & Rivulus has only been discovered in recent times but very little published papers has been written about them. Rivulus might have been a long overdue genus yet to be revised, perhaps because of the small number of biologists involved in the work. I think it's time credits should be given to Dr Costa for his efforts in this field of aspect.

[stormhawk]

Credit is given where it is due, but Costa is not without controversy. He considers Hypsolebias antenori to be valid, but Jean Huber believes it should be Simp. heloplites. Another case involves Riv. duckensis/kirovskyi, of which now R. kirovskyi should be correct.

His description of kirovskyi was submitted in Jan 2004, publish in March 2004.
Description of Riv. duckensis was submitted on 15 Nov 2003, published 24 April 2004.

Lucky for him, the rules dictate that whichever was published earlier is valid. See also entries regarding Plesiolebias glaucopterus/pantanalensis.

Rivulus as a whole is a huge group, much like our native anabantoids to the region. They occupy the same ecological niche. Puddles in the rainforest littered with rotting vegetation and other gunk. While this group is varied, living in all sorts of environments, you can't keep up with all the names. Some look nearly the same save for a few differences.

The world of taxonomy is fraught with debate, disagreements and ultimately, confusion for lay hobbyists.

[Shi Xuan]

Hmm...taxonomy changes are always attested by debates, controversies among taxonomists, so yes, it can be confusing for non-practitioners of this field, in this case, mere hobbyists. Take Centromochlus perugiae for example, it used to be Tatia perugiae but many of websites still keep the old genus name. I guess as long as evident pictures are provided, it doesn't really matter.