Two new species of trouts, resident and migratory, sympatric in streams of northern anatolia (Salmoniformes: Salmonidae)

Abstract

Sahno rizeensis, new species, is described from the upper part of streams and rivers draining to the south and southeastern Black Sea, and S. coruhensis, new species, from the lower and the middle part of the streams and rivers of the same area. Salmo rizeensis is distinguished by a small size (maximum known size 250 mm SL); a single conspicuous black spot behind eye; black spots on the back and upper part of flank; no black spot on the middle part of body in specimens larger than 200 mm SL; red spots few, organised in three or four irregular rows on middle part of body, distinctly ocellated; maxilla long and narrow. Salino coruhensis is distinguished by a large size (maximum size up to at least 800 mm SL); 4-17 black spots behind eye (cheek and preopercle) in large adult males; black spots on back, flank and middle part of body in males larger than 200 mm, very few in females smaller than 300 mm SL; number of black and red spots increasing with increasing size (not increasing in S. rizeensis); red spots in median part of body, surrounded by irregularly shaped white ring; maxilla short and narrow. The two species occur in sympatry in several streams, and occasionally in syntopy. Molecular analyses (nuclear [ITS1] and mitochondrial genes [cytochrome b]) show that they belong to distinct lineages and support their specific distinctness. In our study, the resident trouts of different drainages are more closely related to each other than to the migratory ones in the same drainages, and vice versa. This contradicts the credo that resident and migratory trouts in a given stream are only 'forms' of the same species with different life histories. We do not extrapolate this to be the case in other drainages and for other species, but this calls for a more cautious treatment of the taxonomy, diversity and conservation of trouts at a local level. © 2009 by Verlag Dr. Friedrich Pfeil, München, Germany.