Diversity and Geographic Distribution of Pelagic Copepoda > Cosmopolitanism and endemism

Abstract | Introduction | Presentation | Diversity | Main marine currents | The different oceanic zones : Summary of the species - Marine currents and other maps | Cosmopolitanism and endemism | Species indicative of continental drift | Species whose localization is difficult to explain | Anthropic mechanisms | Conclusion


Cosmopolitanism and endemism :

Of the 2693 recorded forms taking all orders together, the number of cosmopolitan and endemic species has been established. A total of 1255 species, i.e. 46.6 %, are known in only one of the 25 zones, and 71 (2.6 %) are cosmopolitan with the occasional exception of regions where they have not been identified (polar or other) and are present in at least 20 zones. One species, Oithona similis, has been reported in all zones;5 in 24 zones: Aetideus armatus, Euchirella rostrata, Paracalanus parvus, Pleuromamma xiphias, Rhincalanus nasutus; 5 in 23 zones: Haloptilus longicornis, Nannocalanus minor, Oncaea venusta, Pleuromamma robusta, Undeuchaeta major; and 20 in 22 zones: Calocalanus pavo, Gaetanus brevispinus, Gaetanus tenuispinus, Heterorhabdus papilliger, Heterorhabdus spinifrons, Heterostylites longicornis, Mecynocera clausi, Megacalanus princeps, Mesocalanus tenuicornis, Metridia lucens, Microsetella rosea, Neocalanus gracilis, Oithona atlantica, Oithona plumifera, Pleuromamma abdominalis, Pleuromamma gracilis, Pseudoamallothrix ovata, Scaphocalanus magnus, Scolecithricella minor, Undeuchaeta plumosa.

So contrary to general ideas about ancient forms, tributary to the exchange mechanisms between the various oceans, the number of cosmopolitan species seems relatively low. It is true that the distribution of many meso- and bathypelagic forms, often poorly represented in catches, is still badly documented, as is that of many podopleans because of their small size and the fact that they are not taken into consideration when samples are analysed. Hyperbenthic species are underestimated because sampling techniques are not adapted to their way of life.

The table below presents in two columns the numbers of endemic and cosmopolitan species (present in at least 20 zones) for each of the 25 zones (with the access to the lists of species with hyperlink under each number) :

Number of endemic species
Number of cosmopolitan species
Sub-Antarctic (zone 3)
Antarctic (zone 4)
South Africa (E & W), Namibia (zone 5)
Gulf of Guinea (sensu lato): Angola-Liberia (zone 6)
Venezuela, Caribbean Sea, Gulf of Mexico, Caribbean, Florida, Sargasso Sea (zone 7)
Cape Verde Is., Canary Is., Madeira Is., Azores, Bay of Biscay, Ibero-Moroccan Bay (zone 8)
Ireland, English Channel, Faroe, Norway, North Sea, Baltic Sea (zone 9)
Southern Iceland, southern Greenland (E & W), Strait of Davis, Labrador Sea (zone 10)
Cape Cod, Nova Scotia, Island of Newfoundland (zone 11)
Central South-Atlantic (Tristan da Cunha-Trinidad-St Helena-N Ascension) (zone 12)
Brazil-Argentina (zone 13)
Mediterranean Sea, Black Sea (zone 14)
Red Sea (zone 15)
Indian Ocean (zone 16)
Gulf of Thailand, Malaysia-Indonesia-Philippines (zone 17)
Australia (E), Great Barrier Reef, Tasman Sea, New Zealand, New Caledonia (zone 18)
Central Tropical Pacific (zone 19)
Eastern Tropical Pacific (Central America, Galapagos, Northern Peru) (zone 20)
China Seas, Vietnam (zone 21)
Japan Sea, Japan (zone 22)
North West Pacific (Sea of Okhotsk-Kuril Islands-Kamtchatka-Sea of Bering) (zone 23)
North East Pacific (Gulf of Alaska, "P" station, British Columbia) (zone 24)
California-Gulf of California (zone 25)
Chile (sensu lato) (zone 26)
Arctic Ocean (zone 27)

It may be noted that the zone 7 includes a large number of endemic species (144). A wide area as Indian Ocean (zone 16), has a high number of endemic species (176). However, the zone 19, as wide but little explored, includes a small number of endemic species (28).

Polar areas are those where the presence of cosmopolitan species is among the least important (40 for the zone 4 and 28 for the zone 27). A small zone rather close as the Red Sea (zone 15), and recently opened to the Mediterranean through the Suez Canal, has a relatively small number of cosmopolitan species (43).

Fig. C1B : Distribution of the number of species of pelagic Copepoda depending on their number of quotations (N)The graph opposite shows the distribution of the number of species of pelagic Copepoda with the factor N (numbers of quotations of the concerned species in the consulted publications).
940 species have been only once quoted (logically close to 1255 known species in only one of the 25 zones). And only 764 species (28.4 %) have more than 10 quotations.
Some species of the Heterorhabdus genus (belonging to the "Abyssalis" Group established by Park, 2000) show a wide distribution for only one quotation.

Below is the table of 20 most often quoted species :

 Species Number of quotations Number of zones
 Euchaeta marina 2120 ? (any confusion with E. rimana in the Indian Ocean and probably in the East tropical Pacific) 17
 Oithona similis-Group 694 (??: see in remarks). 25
 Paracalanus parvus 665 ? 24
 Acartia (Acartiura) clausi 547 ? (some being confused) 16
 Calanus finmarchicus 526 6
 Oncaea venusta 512 ? (probably less because inadequacy précision with O. venella, if it is maintened) 23
 Pareucalanus sewelli 510 ? 13
 Acartia (Acanthacartia) tonsa 480 16
 Oithona plumifera 449 22
 Nannocalanus minor 443 23
 Temora stylifera 428 ? 14
 Euterpina acutifrons 419 17
 Pleuromamma gracilis 397 22
 Clausocalanus furcatus 390 20
 Lucicutia flavicornis 386 21
 Rhincalanus nasutus 385 24
 Calocalanus pavo 376 22
 Centropages typicus 368 (SE Pacif.: 1, S Atlant.: 3; N Atlant.: 191; Sub-Arct.: 2; Medit.: 162; Black Sea: 2; Red Sea: 1) 9
 Oithona nana 367 21
 Calanus helgolandicus 352 6

The numbers of quotations followeb by the ? character indicate serious doubts about the concerned species (possible confusion with other species).
The number of quotations is strongly linked to fishing effort in each zone. However, in most cases, it changes proportionally with the number of distribution zones of the species .


 Any use of this site for a publication will be mentioned with the following reference :

Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2024. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed May 27, 2024]

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