Noble Whitefish

description

Description. Shape: Slender body. Slender bodied with greatest body depth anterior of dorsal fin resulting in a slightly torpedo-like form. Dorsal and ventral profile similar and slightly arched. Dorsal and ventral profile from tip of snout to interorbital area mostly straight and then slightly convex to dorsal and pelvic fin origin respectively. Head moderately short. Mouth long and terminal or subtly sub-terminal. Lower jaw wide. Rostral plate equally wide as deep, quite pronounced with tip of snout fleshy and either roundish or blunt (square-like form). The eye is moderately large and that of historical specimens is larger than of contemporary specimens. Eye-socket thick and sickle cell-shaped. Pectoral fin moderately tapered and moderately long. Dorsal fin moderately long. Caudal peduncle narrow and elongated with caudal fin moderately forked and sometimes moderately to strongly asymmetrical. Meristics: Many and long gill rakers. Colour: Pigmentation of fins and body overall weak in live specimens. Pectoral and pelvic fin mostly transparent with yellowish ground colour, which is more pronounced in pectoral fin than pelvic fin. Pectoral fin rarely pigmented at distal part of fin

A taxonomic revision of ten whitefish species from the lakes Lucerne, Sarnen, Sempach and Zug, Switzerland, with descriptions of seven new species (Teleostei, Coregonidae)

diagnosis

Diagnosis. Coregonus nobilis is a medium-sized whitefish with weak pigmentation of the pectoral and pelvic fin and moderate pigmentation of the anal, caudal, adipose and dorsal fin and body; pectoral and pelvic fin with yellowish undertone; pale olive-brown colouration on the flanks above the lateral line with pale greenish undertone that is most pronounced on dorsal part of the head; moderate number of pigmented small dots on the scales on the flanks; slender, elongated, and slightly torpedo-like body; caudal peduncle elongated (12.4 - 15.3 % SL, mean = 13.9); tip of snout is fleshy and ranges from being square-like to roundish; large eye (eye diameter: 23.5 - 25.6 % HL, mean = 25.6) with a thick (4.6 - 5 % HL, mean = 4.7) and triangular eye socket; many and long gill rakers (longest gill raker: 15 % HL; total gill raker number = 41).

A taxonomic revision of ten whitefish species from the lakes Lucerne, Sarnen, Sempach and Zug, Switzerland, with descriptions of seven new species (Teleostei, Coregonidae)

distribution

Distribution and notes on biology. Coregonus nobilis occurs in all basins of Lake Lucerne (Fig. 2) except for Lake Alpnach (Nufer 1905). Since the species is endangered no commercial and recreational fisheries are permitted all year round (details on the decline of the population of C. nobilis and its putative extinction and its rediscovery is discussed in the Suppl. material 1: Paragraph 3). Hence, to understand the distribution of C. nobilis outside of the spawning season we can only consult historical catch records. These suggest that it was caught in large quantities and migrated heavily throughout the year within the basins of Lake Lucerne except for Lake Alpnach (Birrer and Schweizer 1936 a; Steinmann 1950). Specifically, it was caught in water depths of 5 - 25 m in the pelagic habitats in the basins ' Kreuztrichter', ' Gersauerbecken', ' Urnerbecken', ' Vitznauerbecken' and ' Kuessnachtersee' (Birrer and Schweizer 1936 a; Fig. 2). Coregonus nobilis feeds - depending on the time of the year - on different pelagic prey (i. e., variety of zooplankton such as Bythotrephes, Daphnia, Bosmina, Copepoda, Leptodora, and rarely Chironomidae) (Birrer and Schweizer 1936 a). It is a medi

A taxonomic revision of ten whitefish species from the lakes Lucerne, Sarnen, Sempach and Zug, Switzerland, with descriptions of seven new species (Teleostei, Coregonidae)

materials_examined

Material examined. Neotype. Historical specimen (year 1885): MHNG- 656.056, 207 mm SL, sex unknown; Switzerland: Lake Lucerne. Non-types. All from Switzerland, Lake Lucerne: Contemporary specimens (year 2005): NMBE- 1078053 - 1078063, NMBE- 1078065 - 1078074, N = 21, 253 - 315 mm SL. Historical specimens (years 1882, 1885): MHNG- 807.26, N = 2, 247 and 254 mm SL.

A taxonomic revision of ten whitefish species from the lakes Lucerne, Sarnen, Sempach and Zug, Switzerland, with descriptions of seven new species (Teleostei, Coregonidae)