Sarnen Whitefish

description

Description. Shape: Body elongated and slender. Greatest body depth anterior of dorsal fin resulting in a slightly torpedo-like form. Ventral profile and dorsal profile similar and slightly arched. Dorsal and ventral profile from tip of snout to interorbital mostly straight and then slightly convex to dorsal and pelvic fin origin respectively. Head moderately long. Snout often has an ~ 40 - 50 ° angle to body axis anterior of eye, such that profile from tip of snout to vertical projection where anterior part of eye crosses dorsal profile is straight and afterwards slightly convex. Tip of snout if often roundish and seldomly fleshy resulting in a not strongly pronounced rostral plate. Mouth thick (i. e., width of upper and lower jaw), long and often terminal and only rarely slightly sub-terminal. Large eye with a variable eye-socket shape ranging from sickle cell-shaped to roundish. Pectoral fin moderately long and tapered. Anterior unbranched ray of erected dorsal fin ranges from almost vertically straight to an ~ 70 - 80 ° angle to body axis and only bent slightly posteriorly at end of ray. Caudal peduncle often narrow and elongated (seldomly stout) with caudal fin forked. Unbranc

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 sarnensis is a medium-sized whitefish (standard length at 3 years of age: range = 188 - 223, mean = 211) with weak pigmentation of the pectoral and pelvic fin and moderate pigmentation of the anal, caudal, adipose and dorsal fin and body; pale green to pale olive-brown colouration on the flanks above the lateral line; moderate number of pigmented small dots on the scales on the flanks; slender, elongated body; caudal peduncle mostly elongated (caudal peduncle depth: 7.1 - 8.6 % SL, mean = 7.7; caudal peduncle length: 11.5 - 14.1 % SL, mean = 12.6); tip of snout is fleshy, roundish, and often has an ~ 40 - 50 ° angle to the body axis anterior of the eye, such that the profile from the tip of the snout to the vertical projection where the anterior part of the eye crosses the dorsal profile is straight and afterwards slightly convex; large eye (eye diameter: 22.2 - 27.1 % HL, mean = 23.9); many and long gill rakers (longest gill raker: 10.6 - 15.8 % HL, mean = 13; total gill raker number: 33 - 40).

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 sarnensis occurs in Lake Sarnen. It has further been identified by genetic assignments to be present in Lake Alpnach (Suppl. material 1: figs S 2, S 3), which it most likely colonised naturally over the River Sarner Aa. It has also been shown to be present south of the alps in Lake Maggiore. The ' Bondella' (local name of the population) of Lake Maggiore derives from translocations and has been shown to group in a neighbour-joining tree with C. sarnensis from Lake Sarnen (Hudson et al. 2011). Lake Sarnen was once part of Lake Lucerne (connected through Lake Alpnach respectively) and got disconnected by amassing of sediments from the rivers Grosse Schlieren, Kleine Schlieren, and Grosse Melchaa several thousand years ago (Steinmann 1950; Pfiffner 2021). The occurrence of whitefish scales in sediment cores from Lake Sarnen that predate (scales found in the sediment layer of 1861 - 1857 (Suppl. material 1: fig. S 1 )) the earliest allochthonous whitefish introductions (1888) and independent genetic grouping of the Lake Sarnen population (AFLP data: Hudson et al. 2011; Microsattelite data: Suppl. material 1: figs S 2, S 3) from the lakes tha

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

etymology

Etymology. The specific name sarnensis refers to Sarnen, a village on the shores of the lake to which it gave its name. An adjective.

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