Benthic-Intermediate Whitefish

description

Description. Shape: Only slightly deep bodied with greatest body depth anterior of dorsal fin. Dorsal profile from tip of snout to anterior origin of dorsal fin and ventral profile from interorbital area to pelvic fin origin are moderately convex. Head moderately short. Mouth moderately long and mostly sub-terminal and rarely terminal. Lower jaw moderately wide. Rostral plate equally wide as deep, not strongly pronounced with tip of the snout often more pointed than blunt. Eye-socket thick and sickle cell-shaped. Pectoral fin moderately tapered and moderately short. Dorsal fin rather short with anterior unbranched ray of erected dorsal fin mostly 70 - 80 ° angle to body axis, almost straight and only very slightly bent posteriorly at end of the ray. Dorsal fin longest anteriorly and progressively shortening posteriorly with outer margin of dorsal fin mostly straight and rarely concave. Caudal peduncle stout and moderately short with caudal fin moderately forked. Unbranched rays of anal fin slightly bent posteriorly. Anal fin longest anteriorly and progressively shortening posteriorly with outer margin of anal fin mostly straight and only rarely slightly concave. Meristics: Moderate

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 intermundia is a medium-sized whitefish (standard length at 3 years of age: range = 243 - 300 mm, mean = 273) with moderate pigmentation of all fins and the body; greenish blue colour on the flanks above the lateral line; moderate number of pigmented small dots on the scales along the flank; short head (19.1 - 21.5 % SL, mean = 20.3); sub-terminal mouth; thick (3.4 - 5.7 % HL, mean = 4.4) and triangular-shaped eye socket; rather short and stout caudal peduncle (caudal peduncle depth: 7 - 8.3 % SL, mean = 7.5; caudal peduncle length: 11.6 - 14.4 % SL, mean = 12.9).

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 intermundia occurs in all basins of Lake Lucerne (Fig. 2) except possibly in Lake Alpnach. It has been caught during the spawning season in all basins except for Lake Alpnach, where no nets were set by Hudson et al. (2016). There is no isotopic or stomach content data available for C. intermundia to infer the prey spectrum of this species. Coregonus intermundia is a medium-sized whitefish species and the size (i. e., standard length) at 3 years of age of C. intermundia is smaller than that of C. litoralis, considerably larger than that of C. muelleri and almost equal to that of C. suspensus (Suppl. material 1: table S 3). We cannot compare its size to C. nobilis since only older individuals of the latter species have been caught (Hudson et al. 2016). Coregonus intermundia has most likely a short spawning season in winter around the month of December. The spawning season lasts for approximately two weeks and the spawning depth is mostly in shallow waters (10 - 30 m, rarely 40 m; Hudson et al. 2016). The spawning depth of C. intermundia overlaps partially with that of C. litoralis, with the former spawning deeper than the latter (Hudson et

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 intermundia means in Latin ' spaces between the worlds'. It refers to the observation that this species is intermediate to C. litoralis and C. suspensus in its ecology and in some morphological characters. A noun in apposition.

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