Corydoras filamentosus & CW143

[Karsten S.]

Hi,

Corydoras filamentosus belongs to acutus group, lineage 1.
Similar story as with C. spilurus, the tissue sample used within the framework of the phylogeny of Alexandrou et al. 2010 belonged to the sympatric CW143 which belongs to lineage 8. I have discussed this with Raphael Covain and he only realised after the publication that the tissue samples he sent (MHNG 2707.015-SU07-625) belong to the mimic species,
see pictures here: Corydoras filamentosus and Corydoras sp. "CW143".
So you have it swapped, whether your pictures are are correctly assigned is IMHO impossible to tell with the given picture quality. The body shape is nearly identical, the bets criterion to differentiate is the pectoral spine serration.

Cheers,

[bekateen]

Hi Karsten, yes C. filamentosus belongs in Lineage 1. I've made that taxonomic correction in the CLOG.

Coincidentally, I have a jar full of preserved filamentosus, from the first shipment received by Mike Downey 2-3 years ago. Sadly, when his shipment arrived, all of these fish had died in transit. Because they were dead on arrival, their preservation state is not good (probably not for photos, but I'll take another look), but still good enough for me to dissect for the presence/absence of post-axillary venom glands.

Looking at pics of CW143 on L-welse and on CW (so independent of whether or not the PCF pics are correctly ID'd), I am challenged to imagine that the fish shown as CW143 on those other websites are Lineage 8, subgroup 4 (any lineage 8 for that matter). The body shape seems inconsistent with any lineage 8 cory. Are we sure it's not lineage 1?

Cheers, Eric

Cheers, Eric

[Karsten S.]

Hi Eric,

in Corantijne river system (Sipaliwini river) we have three Corydoras with similar colour pattern:
- Cordoras filamentosus: lineage 1
- Corydoras sipaliwini: lineage 9 (= CW114)
- Corydoras sp. "CW143": lineage 8

The picture from Raphael Covain in the link (MHNG 2707.015-SU07-625) was the source of the tissue sample that Alexandrou et al. used in their phylogeny 2010. In "Evolution, Ecology and Taxonomy of the Corydoradinae revisited" from Alexandrou & Talor this species is placed in lineage 8, subclade 2 (consistently with the phylogenetic tree in their previous paper)
This was my starting point some years back because this was obviously wrong for C. filamentosus. I contacted Martin Taylor to find the source of the tissue sample and finally received this picture from Raphael Covain and he confirmed that he considered this specimen collected in Sipaliwini river being C. filamentosus before DNA analysis and only realised that it was not afterwards.
I was still surprised that this specimen was not ending up in subclade 4 in which I would have put it, that's why I was not more specific than "lineage 8"...

The imports that came in 2017 were mixed ones of Cordoras filamentosus and CW143, the body shape is nearly identical. The easiest way to distinguish them is the pectoral spine, heavily serrated in Cordoras filamentosus, in CW143 short spines/serrations directed to spine insertion point.

So, yes, CW143 does look pretty much like lineage 1 at the first sight and without knowing of the existence of that sibling anyone would have assumed that the fish Raphael caught was Cordoras filamentosus...
I have even asked Raphael a second time (as the pectoral spine is not sharp enough on the picture) if there it is absolutely sure that this depicted Corydoras was the source of the tissue sample and he confirmed this again.

Cheers,