Recognition and Distribution of Two North Atlantic Gadiculus Species, G. argenteus and G. thori (Gadidae), Based on Otolith Morphology, Larval Pigmentation, Molecular Evidence, Morphometrics and Meristics

Abstract

Abstract:The silvery pout genus Gadiculus consists of small aberrant codfishes with several extinct and currently only one recognized extant species. The oldest representatives of a Gadiculus lineage known from otoliths are Early Miocene in age. Fossil evidence has showed Gadiculus to originate from older genera diverging early from other true cods of the family Gadidae. As adult specimens of different species have been found to be highly similar and difficult to distinguish based on meristic and morphometric data, the number of species in this gadid genus has been controversial since different larval morphotypes were first discovered some 100 years ago. For almost 70 years, Gadiculus thori and Gadiculus argenteus have been considered subspecies only, with a distribution in the Northeast Atlantic Ocean including the Mediterranean. In this study, we resolve the long-standing issue of extant Gadiculus not being monotypic. New results in the form of distinct adult otoliths and molecular data unambiguously show two species of Gadiculus present-in agreement with larval morphotypes. Morphometric, meristic and molecular characters, as well as larval pigmentation are discussed in addition to present and past geographic distributions of the two taxa from distributions of fossil otoliths. At present, the cold-water species Gadiculus thori (northern silvery pout) is distributed in cold-temperate and subarctic latitudes in the Northeast Atlantic, including a new range extension off Southeast Greenland. Gadiculus argenteus (southern silvery pout) occurs in warmer waters and is distributed in the warm-temperate East Atlantic and Mediterranean. Fossil otoliths show that both species often co-existed in the Mediterranean from the Late Pliocene to the Middle Pleistocene.

Taxonomy, Distribution and Evolution of Trisopterine Gadidae by Means of Otoliths and Other Characteristics

“…Micromesistius, Boreogadus and Arctogadus must be excluded from this tribe. Although the genus Micromesistius is not so distant from the trisopterines [21], it is more closely related to Gadiculus [7,94], and might be included in the tribe Gadiculini. The genus Boreogadus belongs to the tribe Gadini based on morphology and genetic data [7], and according to morphological characteristics Arctogadus should also be placed in the Gadini.…”

Metagenomic Shotgun Analyses Reveal Complex Patterns of Intra- and Interspecific Variation in the Intestinal Microbiomes of Codfishes

“…Norway pout is benthopelagic, distributed from the English Channel, around Iceland, and up to the Southwest Barents Sea. It is mostly found at depths between 100 and 200 m. Poor cod is also benthopelagic, distributed from the Trondheim Fjord in Norway to the Mediterranean Sea, and mostly found between 15 and 200 m. Northern silvery pout (Gadiculus thori) is meso-to bathypelagic (36), distributed in the North Atlantic Ocean, along the coast of Norway, and around Iceland and Greenland. It forms large schools that are usually found between 200 and 400 m (34,36,37).…”

“…It is mostly found at depths between 100 and 200 m. Poor cod is also benthopelagic, distributed from the Trondheim Fjord in Norway to the Mediterranean Sea, and mostly found between 15 and 200 m. Northern silvery pout (Gadiculus thori) is meso-to bathypelagic (36), distributed in the North Atlantic Ocean, along the coast of Norway, and around Iceland and Greenland. It forms large schools that are usually found between 200 and 400 m (34,36,37). Finally, Atlantic cod has a trans-Atlantic distribution, from the Bay of Biscay to the Barents Sea, the Baltic Sea, around Iceland and Greenland, in the Hudson Bay, and along the North American coast (34,(38)(39)(40)(41)(42).…”

New observations and ontogenetic transformation of photogenic tissues in the tubeshoulder Sagamichthys schnakenbecki (Platytroctidae, Alepocephaliformes)

“…No coI data of S. schnakenbecki are available except for Greenland specimens (Table ), which precludes molecular comparisons in relation to distribution. The distribution of S. schnakenbecki in the eastern Atlantic Ocean is reminiscent of the distributions of some gadids, such as the genera Gadiculus Guichenot 1850 and Micromesistius Gill 1863 (Gaemers & Poulsen, ; Halvorsen et al ., ). However, contrary to these gadid genera, S. schnakenbecki does not show an anti‐tropical distribution.…”