List species and varieties by family
Clausocalanidae Giesbrecht, 1892 ( Clausocalanoidea )
(1) Clausocalanus Giesbrecht, 1888
Rem.: type: Calanus mastigophorus Claus,1863. The species identification before 1968 is often questionable and the geographical distributions are determined after Frost & Fleminger (1968), completed by later authors.
Total: 13 spp.
Frost & Fleminger (1968, p.17, 29, 44, 66) define 3 groups:
Groupe 1: C. mastigophorus, C. lividus, C. ingens and C. laticeps.
Groupe 2: C. arcuicornis, C. farrani, C. jobei, C. minor, C. paululus.
Groupe 3: C. pergens, C. brevipes, C. parapergens, C. furcatus.

Diagnosis from Frost & Fleminger (1968, p.15) :
- Cephalosome and pedigerous segment 1 fused, pedigerous segments 4 and 5 fused.
- Medial caudal seta short, located on dorsal surface of caudal ramus ; lateral-most caudal seta reduced to a short, lateral spine ; 2 apical and 2 subapical caudal setae long.
A1 segment 25 fused to distal posterior corner of segment 24.
- Exopod of A2 1.5 or more times as long as endopod.
- Exopod of P1-P4 trimemous ; endopod of P1 unimerous, of P2 biremous, of P3 and P4 trimerous.
- Basis (B2) of P2 and P3 broadening distally to about 1.5 or more times their width in region of attacment to coxa (B1) ; distal posterior margin with 3 or more spiniform processes.
Female :
- Urosome of 4 somites.
- Rostrum of 2 short, rigid spiniform processes.
- A1 23-segmented with segments 8-9 and 24-25 fused.
- Right and left P5 present, uniramus, trimerous, essentially symmetrical, distal segment produced distally into a short, pointed, bifid process.
Male :
- Urosome of 5 somites.
- Anal somite very short.
- Rostrum reduced to a single median, ventrally protruding knob or not well developed.
- A1 with segments 1-2, 8-9, 13-14, 15-16, 20-21 , and 24-25 completely fused, and with incomplete fusion of segments 4 to 8-9, 8-9 to 13-14, and 13-14 to 15-16.
- Right and left P5 present, uniramus, rami of very unequal length, longer ramus somewhat styliform, pentamerous, 5th segment short and attached subapically to 4th segment ; 1st segment more than twice as long as uni-, bi-, or trimerous shorter ramus of opposing leg.

Clausocalanus furcatus shows any differences among the other congeners.

[1] Clausocalanus arcuicornis  (Dana, 1849)   (F,M)    [Figs]

[2] Clausocalanus brevipes  Frost & Fleminger, 1968   (F,M)    [Figs]

Clausocalanus dubius    Brodsky, 1950   (M)
Ref.: Brodsky, 1950 (1967) (p.120, Descr.M, figs.M); Frost & Fleminger, 1968 (p.82, Rem.); Morioka, 1972 a (p.134); Brodsky & al., 1983 (p.234, figs.M)
Loc: Pacif. NW, off Hokkaido SE
Lg.: (22) M: 1,8
Rem.: Frost & Fleminger (1968) estiment que cette forme n'est pas un Clausocalanus. Cf. Groupe. inc. sed.

[3] Clausocalanus farrani  Sewell, 1929   (F,M)    [Figs]

[4] Clausocalanus furcatus  (Brady, 1883)   (F,M)    [Figs]

[5] Clausocalanus ingens  Frost & Fleminger, 1968   (F,M)    [Figs]

[6] Clausocalanus jobei  Frost & Fleminger, 1968   (F,M)    [Figs]

[7] Clausocalanus laticeps  Farran, 1929   (F,M)    [Figs]

Clausocalanus latipes    T. Scott, 1894   (juv. M)
Ref.: T. Scott, 1894 b (p.72, Descr.F, figs.F); Giesbrecht & Schmeil, 1898 (p.28); Frost & Fleminger, 1968 (p.82, Rem.)
Loc: G. de Guinée
Rem.: sp. inc. sedis. Cf. ? C. arcuicornis juv.M

[8] Clausocalanus lividus  Frost & Fleminger, 1968   (F,M)    [Figs]

[9] Clausocalanus mastigophorus  (Claus, 1863)   (F,M)    [Figs]

[10] Clausocalanus minor  Sewell, 1929   (F,M)    [Figs]

[11] Clausocalanus parapergens  Frost & Fleminger, 1968   (F,M)    [Figs]

[12] Clausocalanus paululus  Farran, 1926   (F,M)    [Figs]

[13] Clausocalanus pergens  Farran, 1926   (F,M)    [Figs]
(2) Ctenocalanus Giesbrecht, 1888
Rem.: Type poorly specified: Ctenocalanus vanus Giesbrecht,1888.
Total: 5 species.

Diagnosis from Bradford-Grieve (1994, p.95) :
- As for the family definition.
- Head and pediger segment 1 fused, pediger segments 4 and 5 fused.
- Rostrum of 2 fine filaments in both sexes.
- A1 female with segments 1 and 2, 9 and 10, and 24 and 25 usually separate ; of the male usually with segments 1 and 2, 8 to 10, and 23 to 25 fused.
- A2 exopodal segments 2 and 3 fused.
- Male P1 exopodal segments 1 and 2 without outer-edge spines.
- Basis of P2 and P3 not enlarged posterodistally but have posterodistal spinules which are very small in female but larger in the male.
- External spines on exopodal segment 3 of P3 and P4 finely toothed.
- Female P5 asymmetrical, present on left.
- Male P5 asymmetrical, uniramous on left, very reduced on right.

[1] Ctenocalanus campaneri  Prado-Por, 1984   (F,M)    [Figs]

[2] Ctenocalanus citer  Heron & Bowman, 1971       [Figs]

[3] Ctenocalanus heronae  Vega-Perez & Bowman, 1992   (F)    [Figs]

Ctenocalanus longicornis    Mori, 1937   (F)
Ref.: Mori, 1937 (1964) (p.37, Descr.F, figs.F)
Loc: Japon S, Mer Rouge
Lg.: (91) F: 1,23
Rem.: ? Cf. Ctenocalanus vanus

[4] Ctenocalanus tageae  Prado-Por, 1984   (F,M)    [Figs]

[5] Ctenocalanus vanus  Giesbrecht, 1888   (F,M)    [Figs]
Drepanopsis Wolfenden, 1911
Rem.: type: Drepanopsis frigidus Wolfenden,1911. nom. préoc. Cf. Farrania
Drepanopsis frigidus    Wolfenden, 1911   (F)
Ref.: Wolfenden, 1911 (p.245, Descr.F, figs.F); Tanaka, 1956 c (p.399, figs.F, Rem.)
Rem.: Cf. Farrania frigida
Drepanopsis lyra    Rose, 1937   (F)
Ref.: Rose, 1937 (p.157, Descr.F, figs.F)
Loc: Alger
Rem.: Cf. Farrania lyra
Drepanopsis pacificus    Brodsky, 1950   (F)
Ref.: Brodsky, 1950 (1967) (p.141, Descr.F, figs.F); Brodsky & al., 1983 (p.241, figs.F, Rem.)
Rem.: Cf. Farrania pacifica
(3) Drepanopus Brady, 1883 (part.)
Rem.: type: Drepanopus pectinatus Brady,1883.
Total: 4 species.

Diagnosis from Bradford-Grieve (1994, p.95) :
- As for the family definition.
- Head and pediger segment 1, pediger segments 4 and 5 fused or separate.
- Male rostrum with 2 filaments;
- A1 female 23- or 24-segmented.
- Male A1 slightly asymmetrical, 21- to 23-segmented on the left and 20- to 22-segmented on the right.
- Female genital segment long with distinct anteroventral swelling.
- Both male and female P1 exopods with 3 external spines;
- Endopods of P2 1- or 2-segmented, of P3 2- or 3-segmented.
- Basis of P2 and P3 not widened and without dentiform processes.
- Exopodal segment 3 of P2-P4 with 2 (D. bispinosus) or 3 outer-edge spines.
- Posterior surfaces of P2 and P3 may carry spinules in the female.
- Female P5 symmetrical, 2-segmented with a large curved terminal spine, pectinated along its distal outer half.
- Male P5 prehensile, asymmetrical, exopods 2- or 3-segmented on right ending in a long curved claw, 3-segmented and much shorter on the left; endopods rudimentary or absent.

[1] Drepanopus bispinosus  Bayly, 1982   (F,M)    [Figs]

[2] Drepanopus bungei  Sars, 1898   (F,M)    [Figs]

[3] Drepanopus forcipatus  Giesbrecht, 1888   (F,M)    [Figs]

Drepanopus furcatus    Brady, 1883   (F)
Ref.: Brady, 1883 (p.77, Descr.F, figs.F)
Rem.: Cf. Clausocalanus furcatus

[4] Drepanopus pectinatus  Brady, 1883   (F,M)    [Figs]
(4) Farrania Sars, 1920
Rem.: Type: Farrania oblonga Sars,1920. 5 spp. (of which 1 doubtful) + 1 unidentified.

Diagnosis from Bradford-Grieve (1994, p.95) :
- As for the family definition.
- Rostrum or rostral filaments absent.
- Head and pediger segment 1 fused or separate, pediger segments 4 and 5 separate, usually extended into points.
- A1 24-segmented, segments 8-9 fused, all segments with very long setae.
- A2 endopod longer than or equal to the exopod which is 7-segmented.
- Md with a very small endopod.
- Posterior surfaces of coxa and basis and endopods of P2 and P3 may be ornamented with spinules.
- Female P5 3-segmented with 2 or 3 terminal spines.
- Male P5 biramous and styliform and asymmetrical; endopods 1-segmented, exopods 3-segmented, left exopod shorter than the right, terminated by an elongate spine.

[1] Farrania frigida  (Wolfenden, 1911)   (F,M)    [Figs]

[2] Farrania lyra  Rose, 1937   (F)    [Figs]

[3] Farrania oblonga  Sars, 1920   (F)    [Figs]

[4] Farrania orba  (Tanaka, 1956)   (F,M)    [Figs]

[5] Farrania pacifica  (Brodsky, 1950)   (F)    [Figs]

[6] Farrania sp.  Séret, 1979   (F)    [Figs]
(5) Microcalanus Sars, 1901
Rem.: type: Pseudocalanus pygmaeus Sars,1900.
Total: 1 species (with 2 varieties) or 2 species (according to the authors) + 2 unidentified.
Only a genetic analysis could clearly define the extent of the variability, and the validity of two species or more.

Diagnosis from Bradford-Grieve (1994, p.95) :
- As for the family definition.
- Head and pediger segment 1 fused, pediger segments 4 and 5 fused.
- Female A1 24-segmented with segments 8 and 9 fused.
- Male A1 20-segmented, segments 1-2, 8-11, and 24-25 fused.
- A2 exopod longer than the endopod, exopod segments 2-3 fused.
- P1 exopodal segment 1 without 1 external edge spine, endopod with 4 setae.
- Female P5 absent.
- Male P5 small, asymmetrical, left leg slender, 6-segmented, right leg very small 3-segmented, last segment not styliform.

[1] Microcalanus pusillus  Sars, 1903   (F,M)    [Figs]

[2] Microcalanus pygmaeus  (Sars, 1900)   (F,M)    [Figs]

Microcalanus pygmaeus pusillus    Sars, 1903   (F,M)
Syn.: M. pusillus Sars,1903
Ref.: Farran & Vervoort, 1951 e (p.3, figs.F); Falconetti & Seguin, 1977 (p.188); Gardner & Szabo, 1982 (p.176, figs.F,M); Bradford-Grieve, 1994 (p.130: figs.M)
Loc: Norvège (fjords), baie de Lübeck
Rem.: Cf. Micocalanus pusillus.

Microcalanus pygmaeus pygmaeus    Sars, 1900   (F,M)
Syn.: Pseudocalanus pygmaeus Sars, 1900 (p.73)
Ref.: Farran & Vervoort, 1951 e (p.3, figs.F); Vervoort, 1957 (p.36); Tanaka, 1960 (p.35); Bradford-Grieve, 1994 (p.130, figs.F)
Loc: Antarct., Arct. (Archipel de Nouvelle-Sibérie)
Rem.: Cf. Cf. Microcalanus pygmaeus

[3] Microcalanus sp. A  Vidal, 1971   (F,M)    [Figs]

[4] Microcalanus sp. B  Vidal, 1971   (F,M)    [Figs]
(6) Peniculoides Markhaseva & Renz, 2015
Rem.: Diagnosis of genus after Markhaseva & Renz (2015, p.1033) :
- Rostrum as small round-triangular projection bearing 2 filaments.
- Cephalosome and pediger 1, pedigers 4 and 5 separate.- A1 of 24 free segments.
- A2 endopod segment 1 with 1 seta; exopod with 1,1-1-1,1,1,1,1,0 and 3 setae.
- Md gnathobase strong, heavily sclerotisede; basis with 3 setae; endopod segment 1 with 2 setae, segment 2 with 9 setae.
Mx1 praecoxal arthrite larger than the remaining part of the limb, heavily sclerotized, with 9 terminal and 2 posterior setae; coxal epipodite without setae; coxal, proximal basal and distal endites with 2 setae each; endopod with 4 setae: exopod with 4 or 5 setae.
- Mx2 praecoxal to basal endites with distal part flat and round, in coxal and basal endites its surface is densely covered by short spinules, brush-like, setal formula 4, 3, 2, 1 +1, 2; endopod with 3 setae;
- Mxp praecoxal endites setal formula 1, 2 a,d 3, coxal endite with 3 setae; 5 free endopod segments with 4, 4, 3, 3, and 4 setae.
- P1 to P4 segmentation and setation typical of the superfamily Clausocalanodea.
- P5 uniramous, 3-segmented; left leg with 3, right leg with 2 terminal spines.
- Male unknown.

Apomorphies for the genus are: 1- Md gnathobase strong and heavily sclerotized; 2 - Mx1 praecoxal arthrite large and heavily sclerotized; 3 - Mx1 exopod with 4-5 setae, coxal epipodite lacking setae; 4 - Mx2 coxal and basal endites surface densely covered by short spinules, brush-like.

For Markhaseva & Renz (2015, p.1044) The morphology of its mandible gnathobase, maxillule praecoxal arthrite and its specialized maxilla all of which strongly deviate from typical oral limbs of other Clausocalanidae and from those described for the superfamily Clausocalanoidea as a whole. The only other genus in the superfamily with highly specialized oral parts is Chiridiella Sars, 1907 (Aetideidae). The brush-like surfaces of the maxilla endites, which are densely covered by short spinules and provide a large surface for attaching or holding prey, suggest its feeding mode would probably point more towards a carnivorous than detrivorous life style. The maxilla structure might also serve for brushing or cleaning the food of unwanted particles.

[1] Peniculoides secundus  Markhaseva & Renz, 2015   (F)    [Figs]
(7) Pseudocalanus Boeck, 1872
Rem.: Type: Clausia elongata Boeck,1872.
This genus comprises 7 species that have often been confused because of their weak morphological differentiation; there are confined to high latitudes in the northern hemisphere (Cf. Frost, 1989, p.529) + 1 unidentified.
I have restricted the distribution to the most reliable.

Diagnosis from Bradford-Grieve (1994, p.95) :
- As for the family definition.
- Head and pediger segment 1 fused, pediger segments 4 and 5 fused.
- Last metasomal segment with rounded corners.
- Rostrum in male consisting of 2 filaments.
- A1 does not extend beyond the caudal rami, 24-segmented in female (segments 8-9 fused), in male usually 19-segmented.
- Female P5 absent.
- Male P5 uniramous, left slightly longer than the right; terminal segment of left leg much shorter than the preceding segment and bearing a row of spinules and 1 long, slender terminal spine, segments of the right leg taper distally with the terminal segment about as long as the preceding segments and styliform.

Holmborn & al. (2011, p.514) point to when studying the geographic distribution of all Pseudocalanus species, Frost (1989) found that two or more species of this genus commonly co-occur. Therefore, due to the difficulty of visually discriminating between Pseudocalanus species, the reported biology and ecology of single species is fairly unreliable in the litterature. In ecosystems containing multiple species of Pseudocalanus, the use of genetic methods, such as the RFLP protocol and DNA sequencing described by the authors will greatly improve our understanding of the ecological significance of individual species. Protocol of this kind are easy to develop and provide an excellent tool for discriminating between morphologically indistinguishable species.

Questel & al. (2016, p.611) underline that the genus is comprised of 7 species that co-occur as differing assemblages within their geographic ranges; They are herbivorous epipelagic filter-feeders that target a wide size range of food particles, such as diatoms, flagellates and coccolithophores, and opportunistically feed on sea-ice algae in Arctic regions. The species display only very subtle morphological differences in the adult stage with diagnostic features dependent upon the shape of the urosomal segment containing the genital pore as well as the shape of the seminal receptacle ir-tself (Frost, 1989). However, species show typical levels of interspecific genetic divergence for COI sequences of copepods (10-23%) (Bucklin & al., 2003). These extremely subtle morphological differences have created difficulties in accurate species identification and have resulted in a general lack of detailed species-specific distribution data, with co-occuring species typically treated as a species complex and reported simply as Pseudocalanus spp.
P. newmani and P. mimus are considered as temperate species. P. acuspes and P. minutus are Arctic species. Within the northern Gulf of Alaska, the predominant species are P. mimus and P. newmani with P. minutus present in low numbers in both the shelf region and within Prince William Sound (See Napp & al., 2005), and is also found to numerically dominate the outer domains of the Bering Sea (See Bailey & al., 2015).
P. acuspes and P. minutus, P. newmani numerically dominate the species complex in the shallow Chukchi and Beaufort Sea.
In the Pacific, the geographical distribution of P. acuspes is primarily restricted to the North Pacific Ocean and Pacific Arctic Region, and extends south into the Bering Sea (Bailey & al., 2015), an ecosystem heavily influenced by seasonal ice cover.

[1] Pseudocalanus acuspes  (Giesbrecht, 1881)   (F,M)    [Figs]

Pseudocalanus armatus    Boeck, 1872   (F,M)
Ref.: Brady, 1878 (p.46, figs.F,M, Rem.)
Rem.: Cf. Aetideus armatus

Pseudocalanus clausii    Brady, 1865   
Syn.: P. elongatus Brady,1865
Ref.: Corkett & McLaren, 1978 (p.5); Frost, 1989 (p.535)
Loc: Mer du Nord.
Rem.: Cf. Pseudocalanus elongatus

[2] Pseudocalanus elongatus  (Boeck, 1865)   (F,M)    [Figs]

Pseudocalanus feildeni    Norman, 1878   
Ref.: Giesbrecht, 1892 (p.302)
Rem.: genre douteux. Cf. ?

Pseudocalanus gracilis    Sars, 1903   (F,M)
Syn.: P. minutus Geletin,1977
Ref.: Sars, 1903 (p.154, figs.F,M); With, 1915 (p.57, Rem.); Corkett & McLaren, 1978 (p.6); Brodsky & al., 1983 (p.222, figs.F,M)
Loc: Finmark-Bear Island
Rem.: Cf. Pseudocalanus minutus

[3] Pseudocalanus major  Sars, 1900   (F,M)    [Figs]

[4] Pseudocalanus mimus  Frost, 1989   (F,M)    [Figs]

[5] Pseudocalanus minutus  (Kröyer, 1845)   (F,M)    [Figs]

Pseudocalanus minutus elongatus    Boeck, 1864   (F,M)
Ref.: Marques,1966 (p.3); Frost, 1989 (p.535)
Rem.: Cf. P. elongatus

Pseudocalanus minutus gracilis    Sars, 1903   (F,M)
Syn.: P. gracilis Sars,1903 (p.154); P. minutus Geletin, 1977
Ref.: Frost, 1989 (p.530)
Rem.: Cf. Pseudocalanus minutus

Pseudocalanus minutus major    Sars, 1900   
Syn.: P. major Sars,1900
Ref.: Frost, 1989 (p.539)
Rem.: Cf. Pseudocalanus major

[6] Pseudocalanus moultoni  Frost, 1989   (F,M)    [Figs]

[7] Pseudocalanus newmani  Frost, 1989   (F,M)    [Figs]

Pseudocalanus pygmaeus    Sars, 1900   (F)
Ref.: Sars, 1900 (p.73, Descr.F, figs.F); Mrazek, 1902 (p.508, figs.F,M, Rem.: G. douteux); Giesbrecht,1902 (p.20, figs.F)
Loc: Archipel de Nouvelle-Sibérie
Rem.: Cf.: Microcalanus pygmaeus

[8] Pseudocalanus sp.  Vidal, 1971   (F,M)    [Figs]
(8) Spicipes Grice & Hulsemann, 1965
Rem.: type: Spicipes nanseni Grice & Hulsemann,1965.
Total: 1 species.

Diagnosis from Bradford-Grieve (1994, p.95) :
- As for the family definition.
- Head and pediger segment 1 separate, pediger segments 4 and 5 separate.
- Rostrum small and rounded.
- A1 23-segmented, extending to the end of the caudal rami, segments 8 and 9, 24 and 25 fused.
- Exopod of A2 longer than endopod, segments 1 to 3 apparently fused.
- Endopod and exopod of Md subequal, blade with small uniform teeth.
- Mx1 and Mx2 appear to have a reduced compliment of setae.
- Exopod of P1 1-segmented, of P2-P4 3-segmented.
- Endopod of P1-P4 1-segmented.
- Exopodal segment 3 of P2-P4 with 2 outer edge spines and 4 inner setae.
- The terminal spines of P2 and P3 with outer margins serrate (P4 damaged ?).
- P5 female 3-segmented, the terminal segment bearing a single spiniform seta.
- Male unknown in 2015.

After Bradford-Grieve (1994, p.131) this genus should be close to Farrania in spite of the 1-segmented endopods and exopodal segment 3 of P2 and P3 at least having 2 outer-edge spines. The discovery of Drepanopus bispinosus which also has 2 outer-edge spines on the exopodal segment 3 of P2-P4 indicates that Spicipes is not alone in the Clausocalanidae in blurring the distinction between it and the Paracalanidae (see Bayly, 1982). The apparent reduction in the female mouthparts is not typical for the Clausocalanidae so the position of this genus must remain provisional until more specimens and males are discovered.

[1] Spicipes nanseni  Grice & Hulseman, 1965   (F)    [Figs]

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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2023. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at [Accessed November 28, 2023]

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