sewellia albisuera

[Kajsa12]

Hi all,

 

I have a question about S. albisuera.

 

In the description (Freyhof, 2003) I can read: pelvic fins reaching anal fin origin , although the pictures in the same paper show a clear gap.

In the SF KnowledgeBase we differentiate S. albisuera and S. SEW01 by pattern and by a clear gap between pelvic fins and anal fin origin (S. albisuera) and pelvics reaching anal fin origin (S. SEW01)

 

Does anybody know more about this?

[torso]

Hi

Freyhof reported in 2005, that the cachting of S. albisurea was very difficult because of the very turbid water, even with electric fishing. Only five specimen resulting. The holotype is not the largest specimen (64 mm SL) but a smaller one (43 mm) with pectoral fins not  reaching the anal fin.

The onlyp pics he estimated to show “possibly S. albisurea” so far, were those of B. Newcomer. Large adult specimen which show pectorals reaching anal fin, in accord with the description. The pics of M. Hanselbauer show smaller specimen with the “gap”  as seen in the description too.

I would say that the description is right, pics with a “gap” show either younger specimen or a different species.

J. Freyhof wrote me in 2009 during a discussion about S. elongata, that he had remarked in his catch 2000 a specimen with longer pectoral fins, which would mean, that this feature wouldn’t be good for a difference to S. breviventralis as thought before. Different species but the same problem?

A revision should clear all these questions and make an end to the confusion created by Nguyen & Nguyen in 2005 where S. albisurea is Parasewellia monoloba (?),  S. spotted SEW 01 is Parasewellia polyloba or P. tetraloba (two specimen make two new species).

Two things are clear: S. spotted SEW 01 is not S. albisurea and both have pectorals reaching the anal fin.

Cheers Charles

[Kajsa12]

Thanks, Charles

So if I understand correctly, using a gap between pelvics and anal fin origin as characteristic can be a bit tricky especially when juvenile fish are involved.

Probably this is also the case in other gastromyzontids?

[torso]

@Kajsa12 said:
Thanks, Charles
So if I understand correctly, using a gap between pelvics and anal fin origin as characteristic can be a bit tricky especially when juvenile fish are involved.
Probably this is also the case in other gastromyzontids?

Hi

That’s right.

S. albisurea are rare in the hobby: highly polluted stream (makes them highly endangered), very turbid water. They are occasionally bycatch of S. lineolata from the same location.

I don’t know other species, where this differentiation is used.

Cheers Charles

[olly]

Hi all!

Very interesting, Charles, thanks.

@torso said:
Two things are clear: S. spotted SEW 01 is not S. albisurea and both have pectorals reaching the anal fin.
Cheers Charles

 Charles, what signs may be considered exact for proper separation of Sewellia albisuera and Sew01 to different species?

I have sewellias which I consider to be Sewellia albisuera only on the basis of their reticulated pattern. In a store tank among S.albisuera there was a big male of the size about 8 sm TL with a very rare reticulated pattern. My ones (6-7 sm TL) from this shipment have denser reticulated pattern. I am not sure that it is right to use the coloration pattern as a single feature to separate S.albisuera and Sew01 on two species. I watched for S.albisuera and Sew01 from different shipments in a one tank in a store. The pattern of Sew01 is looking like the most dense reticulate pattern of S.albisuera. If to use only this feature, S.albisuera and Sew01 look like color variations of a one species (as many color variations of Gastromyzon stellatus). Perhaps, they are geographically separated local populations of the one species.
Which other signs do exist to differ S.albisuera and Sew01? Or do they belong to a one species? It is not clear to me yet

Sewellia albisuera, female 7 sm TL

Sewellia albisuera, male 7sm TL

 

 The other one about 6sm TL

 

 Sewellia albisuera and Sew01 from different shipments in a one tank of the store

 Sew01 in a store tank

[torso]

Hi

I can’t see pattern variations within Sewellia sp. SEW 01 and I’ve seen some hundreds in the import. Adult specimen look definitivly different from S. albisurea – based on the pic in the description.Of course J. Freyhof knows Sewellia SEW 01 ver well, but never referred to S. albisurea. Which brings us back to the fact, that the description was made with just a small batch of specimen with only one adult. Looking at Sewellia lineolata with stunning different patterns I would say: it’s possibly one species but scientific input is needed.

What I can see is a change from dashed/patchy to spotted pattern on body in S. 01 with some reticulated parts on the head and dorsal from dorsal fin to caudal fin.

Pattern in adult S. albisurea is reticulated to coarsely netted.

Here some pics

 

 

 

 

 

 

 

 Cheers Charles

[olly]

Hi Charles,

Thank you and thanks for your fine photos. Cute young Sew01. In Sew01 dense spotted pattern appear in young age, in S.albisuera reticulated pattern are kept in adults. I saw young imported Sew01 and S.albisuera and they were looked different. What do you think about my sewellias that I consider S. albisuera. Am I right with their ID? Are they S.albisuera or it is a variation of Sew01? Excuse me please for bad additional pics, unfortunately I cannot take the qualitative pic from the side of their belly. Only these sewellias run along the frontal glass with the speed of cockroach and without stopping. These sewellias were imported for short period of time last year in a mix with S.lineolata or without them. And later again only Sew01 appeared in import.

 

[torso]

Hi

One pair of 7 cm, one male of 6 cm. I’m not shure about the smaller specimen in the LFS-tank.

We would know more as soon as you have bred them. All young Sewellias show diferent patterns.

Try to calm them down with a lot of hiding places/different water-flow direction to bring them to the front glass. So you could get better pics. Or try this: put a glass with algae in an angle of 50 degrees into the tank to get dorsal and ventral pics.

Cheers Charles

[olly]

Thank you very much Charles. Now I have no doubts.

These sewellias are the most shy as compared to S.lineolata, Sew03, S.marmorata.

[Author]

Posts