The Anatomy of the Kidney of the Soleidae (Teleostei: Pleuronectiformes): the Importance of Plastination and Interest for the Phylogeny of Flatfishes

Abstract

Pleuronectiformes or flatfishes are teleostean fishes well known for their external asymmetry, with the two eyes on one side of the body, right or left according to the species. Their internal asymmetry has not been studied in detail in various species and we report here some original observation and manipulation on the kidney of some flatfishes. In most flatfishes, the kidney is an uneven and symmetrical organ present in the dorsal part of the abdominal cavity, lying on the ventral side of the vertebral column, between the haemal arches. Dorsally, the kidney bends ventrally and the whole organ is boomerang‐shaped. However, in two flatfish families, the structure of the kidney appears to be different. Kobelkowsky (2000) shows that the kidney of the American soles (family Achiridae) is asymmetrical with a more developed right posterior part extending backwards between the haemal spines and the right epaxial musculature. Such an asymmetry has been mentioned in the common sole (Solea solea [Soleidae]) by Audigé (1910) and forgotten in the subsequent literature. However, it is the left side posterior part that is more developed in the common sole. This peculiar structure has been observed in dissected and plastinated specimens of several soleid species. This anatomical feature seems to be unique to flatfish species belonging to the Soleidae, a more developed left posterior of the kidney appears to be a synapomorphy of the animals belonging to this family and confirms the monophyly of this group. We hope to specify this point in a near future. The anatomy of kidney should then be taken in account in future works dedicated to flatfishes systematics. Conclusions:(1) The anatomy of soft organs is mostly unknown for flatfishes, even for those of economic importance, and examination of the structures of these species is highly needed. (2) The study of the soft anatomy reveals a new set of data for the research of flatfish phylogeny. (3) In order to make a better comparison between the different species, a process of good conservation, like plastination, is needed for preservation of the structures (Grondin and Olry, 2000; Dieckwisch, 1990). In fish, plastination is well known to preserve the internal organs (Asadi, 1998).References Asadi, M.H., 1998: Plastination of Sturgeons with the S10 technique in Iran: the first Trials. J. Int. Soc. Plastination, 13: 15–16.Audigé, J., 1910: Contribution à l’étude des reins des poissons téléostéens. Arch. Zool. Expér., 5 sér. 4: 275‐624.Dieckwisch, B., 1996: Plastination of fishes. 5th Int. Conf. Plast., Heidelberg, Germany.Grondin, G. and R. Olry, 2000: Current Plastination Index 2000, Publication of the International Society for Plastination, Université du Québec à Trois‐Rivières ed., 66 p.Kobelkowsky, A., 2000: Sistema urogenital de los lenguados de la familia Achiridae (Pisces : Pleuronectiformes) del Golfo de México. Hidrobiológica, 10: 51–60.