Synodontis grandiops & S. multipunctatus
Posted: 05 Jan 2007, 22:59
Hello all.
I was mixed as to where to put this post. It relates to a topic dealing with the recently published revision of the Lake Tanganyikan Synodontis species. The initial post on this topic has grown long and I felt it better to maybe start a new string or two to address separate topics relating to this. If the moderators feel that this should be somewhere else please feel free to move it. I will add that if you have not read that thread it might be good to do so.
In the revision noted above, a new species, Synodontis grandiops, is described. It is very close to S. multipunctatus and in fact the color descriptions of the two species, with only very minimal differences having nothing to do with the color, are identical. There are a number of features noted that differentiate the two species and the most notable (from our, or at least my, point of view) among these is the size of the eye. The eye size in S. grandiops is larger that that of S. multipunctatus. The way the eye size is stated is as a percent of snout length. In S. grandiops this is noted to range from 64.2 to 81% of the snout length. In S. multipunctatus it is 44.9 to 62.0%. At the extremes these differences would be, and are, quite noticable. But, reality must also be taken into account.
To explore this aspect of the two species I downloaded and printed out some selected pictures from the S. multipunctatus section of the Cat-elog on this site (these were basically lateral views having reasonable resolution). As a control, I also downloaded Erwin Schraml's photo of the type specimen of S. multipunctatus from the All Catfish Species Inventory website (by using this I had a picture of a fish in which the specific measurements were presented in the revision). I won't go to crazy here with all of the details (unless someone really wants to know), but basically following the same measurement standards that were used in the revision I measured the size of the eye and the lengths of the snouts from the photos. From there, using a little math I came up with the percentage size of the eyes in the snout lengths.
It was not possible to do all photos, so as noted, I selected certain ones. For now, I would like to make note of two of these.
Photo, or image, number one - In just looking at this picture it is easy to note the large eye. My measurements (admittedly rough based on a number of considerations), show this specific fish to have an eye size that is approximately 78% of the snout length. So, as far as I am concerned this particular fish is easily diagnosable as S. grandiops.
Photo, or image, number sixteen - Visually, compared to the length of the snout, this fish has a smaller eye. My measurements on this place the eye at about 48% of snout length. So this fish would fit nicely into the measurements that were provided for S. multipunctatus and I consider it as such.
So, there is a little start to try to straighten out the situation with these two species which are among us in the hobby. I also pulled out some photos that I had taken in 1977 and subjected them to the same measurements and (son of a gun) found out to my interest (and satisfaction) that I had S. grandiops way back then.
One addtional note: in the revision it is stated that it is not known whether S. grandiops has a cuckoo style of reproduction as is known in S. multipunctatus. If my methods of measurements are correct it can be said that both species practice a similar style of reproduction. This is based on doing the same type of measurements on a limited number of existing spawning act photos that I looked at. I shall be doing more of these for further confirmation.
As copies of the revision get into more hands we will hopefully see additional thoughts and comments regarding the various covered species posted on PC. I know that Steve Grant has a copy heading his way and I will look forward to some of his analysis on the topic.
Lee
I was mixed as to where to put this post. It relates to a topic dealing with the recently published revision of the Lake Tanganyikan Synodontis species. The initial post on this topic has grown long and I felt it better to maybe start a new string or two to address separate topics relating to this. If the moderators feel that this should be somewhere else please feel free to move it. I will add that if you have not read that thread it might be good to do so.
In the revision noted above, a new species, Synodontis grandiops, is described. It is very close to S. multipunctatus and in fact the color descriptions of the two species, with only very minimal differences having nothing to do with the color, are identical. There are a number of features noted that differentiate the two species and the most notable (from our, or at least my, point of view) among these is the size of the eye. The eye size in S. grandiops is larger that that of S. multipunctatus. The way the eye size is stated is as a percent of snout length. In S. grandiops this is noted to range from 64.2 to 81% of the snout length. In S. multipunctatus it is 44.9 to 62.0%. At the extremes these differences would be, and are, quite noticable. But, reality must also be taken into account.
To explore this aspect of the two species I downloaded and printed out some selected pictures from the S. multipunctatus section of the Cat-elog on this site (these were basically lateral views having reasonable resolution). As a control, I also downloaded Erwin Schraml's photo of the type specimen of S. multipunctatus from the All Catfish Species Inventory website (by using this I had a picture of a fish in which the specific measurements were presented in the revision). I won't go to crazy here with all of the details (unless someone really wants to know), but basically following the same measurement standards that were used in the revision I measured the size of the eye and the lengths of the snouts from the photos. From there, using a little math I came up with the percentage size of the eyes in the snout lengths.
It was not possible to do all photos, so as noted, I selected certain ones. For now, I would like to make note of two of these.
Photo, or image, number one - In just looking at this picture it is easy to note the large eye. My measurements (admittedly rough based on a number of considerations), show this specific fish to have an eye size that is approximately 78% of the snout length. So, as far as I am concerned this particular fish is easily diagnosable as S. grandiops.
Photo, or image, number sixteen - Visually, compared to the length of the snout, this fish has a smaller eye. My measurements on this place the eye at about 48% of snout length. So this fish would fit nicely into the measurements that were provided for S. multipunctatus and I consider it as such.
So, there is a little start to try to straighten out the situation with these two species which are among us in the hobby. I also pulled out some photos that I had taken in 1977 and subjected them to the same measurements and (son of a gun) found out to my interest (and satisfaction) that I had S. grandiops way back then.
One addtional note: in the revision it is stated that it is not known whether S. grandiops has a cuckoo style of reproduction as is known in S. multipunctatus. If my methods of measurements are correct it can be said that both species practice a similar style of reproduction. This is based on doing the same type of measurements on a limited number of existing spawning act photos that I looked at. I shall be doing more of these for further confirmation.
As copies of the revision get into more hands we will hopefully see additional thoughts and comments regarding the various covered species posted on PC. I know that Steve Grant has a copy heading his way and I will look forward to some of his analysis on the topic.
Lee