Miljutin, D. M.; Gad, G.; Miljutina, M. M.; Mokievsky, V. O.; Fonseca-Genevois, V.; Esteves, A. M. (2010). The state of knowledge on deep-sea nematode taxonomy: how many valid species are known down there?. Marine Biodiversity. 40(3): 143-159.
Miljutin, D. M.; Gad, G.; Miljutina, M. M.; Mokievsky, V. O.; Fonseca-Genevois, V.; Esteves, A. M.
The state of knowledge on deep-sea nematode taxonomy: how many valid species are known down there?
Available for editors
All available information from literature sources
dealing with deep-sea nematode species was analyzed, in
order to obtain an overview of the state of knowledge in
deep-sea nematode taxonomy and answer the question of
how many valid nematode species are known from the deep
sea so far. One hundred and twenty-seven taxonomic and
ecological literature sources reported a total of 638 valid
species belonging to 175 genera and 44 families, from 474
deep-sea stations at depths of 400–8,380 m. This number is
less than 16% of all known marine nematode species,
whereas the deep sea comprises about 91% of the ocean
bottom. Of these species, 71% were initially described from
the deep sea. Most of the valid species have been reported
from the North Atlantic, including the Mediterranean. The
rest of the World Ocean, including the Pacific, Indian,
Arctic and Antarctic oceans, is considerably less studied.
The largest numbers of valid species were reported from the
continental slope and the abyssal plains, while information
on valid species from trenches, deep-sea canyons, and
seamounts is extremely scanty. Some deep-sea families are
much more investigated than others in proportion to their
relative species abundances in the deep sea, i.e., the
percentage of valid species from these families among all
valid deep-sea species is much higher than the real
percentage of species from these families reported in
faunistic studies (e.g., Desmoscolecidae, Comesomatidae,
Sphaerolaimidae, Benthimermithidae, Leptosomatidae, and
Draconematidae). On the other hand, the families Xyalidae,
Oxystominidae, and Monhysteridae were recognized as the
most “underinvestigated,” as, in spite of their high species
abundance in the deep sea, there are quite a few taxonomic
studies on these taxa. Some deep-sea nematode species
were reported from two or three oceans, and can be
considered probable cosmopolitan species. Some number
of probable eurybathic species were also found (the
difference between minimum and maximum depth was
from 1 km to more than 5 km).