Type: Acrocalanus longicornis Giesbrecht,1888. Total: 5 spp.
For Bowman (1958, p.121) the species of Acrocalanus are most conveniently distinguished by the shape of the cephalothorax in lateral view.

Diagnosis from Bradford-Grieve (1994, p.46) :
- As for the family definition.
- Rostrum with long slender filaments.
- Pegigerous segments 4 and 5 incompletely separated.
- A1 long .
- Basis of P1 with an inner-edge seta.
- Well developed ornamentation on the posterior surfaces of the swimming legs, all or some of the outer edges of the exopods of P2-P4 serrated, distal outer margin of the endopods endin a small spine.
- Male P5 present only on the left.

type: Bestiola zeylonica Andronov,1972. Total: 10 spp. + 1 undet.

Diagnosis from Bradford-Grieve (1994, p.51) :
- As for the family definition.
- Rostrum shortened in males and females.
- Male with dorsal cephalic hump.
- Basis of P1 with an inner edge seta.
- Endopod segment 3 of P3 and P4 with 6 setae.
- P5 rudimentary and knob-like in females.
- P5 male elongated on the left and a rudimentary knob on the right.
- Outer edges of exopod segments 2 and 3 of P2-P4 devoid of teeth and there are only 6 setae on endopod 3 of P3 and P4.

According Moon & al. (2010, p.39) the genus was separated from the other genera within the Paracalanidae based: 1- absence of serration on the outer margins of 2nd and 3rd exopodal segments of P2 to P4; 2 - female P5 reduced to 2 rounded lobes; 3- male P5 with reduced rounded lobe of right leg and 5-segmented left leg, with tiny non articulated process and relatively long terminal spine. Moon & al. (2010, p.39) suggest that the ornamentation on exopodal segment 2 of P2 to P4 may play an role in separating Bestiolina species.

After Suarez-Morales & Almeyda-Artigas (2016, p.307) , the species of Bestiolina are in general very much alike in terms of body shape and proportions, body segmentation and leg armature but they can be distinguished by subtle characters. The spinulation pattern on the anterior and posterior surfaces of the exopodal and endopodal segments of P2-P4 is the most relevant character used to separate species, but also there are differences in the presence or absence of minute spinules on the posterior corners of the 5th pedigerous somite, and the structure of the rostrum, among other characters.

Type: Calanus pavo Dana,1849; 1852. Total: 50 spp.

Diagnosis from Bradford-Grieve (1994, p.52) :
- As for the family definition.
- Head and pediger 1, and pedigers 4 and 5 fused or separated.
- Female urosome relatively short with 2-4 segments, often 2 setae on the caudal rami much thicker than the others, caudal rami sometimes asymmetrical.
- Female A1 often much longer than the body and segment 25 usually long, being at least twice as long as the preceding segment.
- Male A1 with segments 1-2, 3-6, and 24-25 fused.
- Basis of Mxp with an inner proximal row of conspicuous spines or teeth.
- Basis of P1 without seta, there may be fusion between exopodal and endopodal segments so that in a few species these rami may be both 1-segmented, endopod usually with 4 setae. The outer borders of the distal exopod segmenys not toothed.
- Female P5 symmetrical, uniramous of 3 or 4 segments.
- Male P5 asymmetrical, uniramous, 4-segmented on the right and 5-segmented on the left.

type: Paracalanus nudus Sewell,1929. Total: 2 spp.

Diagnosis from Bradford-Grieve (1994, p.66) As Delius :
- As for the family definition.
- Head and pediger 1 fused, pedigers 4 and 5 fused.
- Rostrum bifurcate, with its branches short and rather wide and not filiform.
- Cephalic dorsal hump absent in the male.
- Female urosome 4-segmented.
- Male urosome 5-segmented.
- A1 extends to the posterior border of the metasome.
- Mouthparts as for the family.
- Basis of P1 with 1 inner-edge seta.
- Outer edge of segments 2 and 3 of exopods of P2-P4 smooth.
- P5 reduced, being present only on the left ; of 2 segments in the female and 5 segments in the male.

Type: Mecynocera clausii I.C. Thompson,1888 . Total: 1 sp.

See the ex-family Mecynoceridae for the morphologic chharacters.

Type: Calanus parvus Claus,1863. Total: 14 spp. + 1 variety + 2 unident.

Diagnosis from Bradford-Grieve (1994, p.66) :
- As in the family definition.
- Head and pediger segment 1 and pedigers 4 and 5 separate or fused.
- Rostrum with fine filaments.
- Urosome female 4-segmented.
- Urosome male 5-segmented.
- Genital segment and caudal rami symmetrical without outer-edge seta.
- A1 25-segmented in female.
- A1 strongly swollen at its base in the male, with segments 1-6, 7-8 fused, and the terminal segment small but free ; sensory organs well-developed and numerous in the male.
- A2 endopod shorter than exopod.
- Md with a large blade.
- Mx1 endopod with indistinct segmentation, outer lobe 2 with a very reduced seta.
- Mxp basis with a prosximal row of very fine spinules along its inner border.
- Male mouth parts very reduced. : A2 with proximal segments elongated at the expense of the terminal segment, the 3 terminal setae present in the female, absent in the male ; Mx1 very reduced with inner lobes atrophied and only a few setaze on the remains of the outer parts of this limb ; Mx2 represented by a knob ; Mxp terminal part hardly segmented with 3 enlarged plumose outer setae and atrophied inner setae.
- P1 coxa and basis with 1 inner-edge setae, endopod 2-segmented.
- External border of P4 exopodal segment 3 divided by a spine into 2 parts of which the distal part is less than half the proximal part.. External border of exopodal segment 2 not toothed ; external border of exopodal segment 3 of some or all of P2-P4 toothed.
- Endopod segment 3 of P1 with 5 setae ; endopod segment 3 of P2 with 7 setae.
- P5 short, uniramous, symmetrical, 2-segmented in the female.
- P5 male uniramous, asymmetrical, 5-segmented on the left, 2-segmented on right.

Diagnosis from K.S. Kesarkar & A.C. Anil (2010, p.407) :
1 - Basis 2 of P1 usually with inner edge seta.
2 - P1 with endopod 2-segmented.
3 - P1 with endopod segment 2 with 5 setae.

Type: Paracalanus crassirostris Dahl,1894. Total: 8 spp. (if the genus is maintained).

Diagnosis from Bradford-Grieve (1994, p.69) :
- As in the family definition.
- The fusion line between pedigers 4 and 5 usually conspicuous.
- Rostrum bifurcated, short and solid.
- Cephalic dorsal hump absent in the male.
- Female urosome 4-segmented.
- A1 25-segmented.
- Basis of P1 without inner-edge seta, endopod with 1- or 2-segmented.
- Posterior and lateral surfaces of P2-P4 may be ornamented with spines.
P5 2)segmented, symmetrical in femalewith short terminal spines.
- P5 male asymmetrical, left leg 5-segmented, right leg 2- or 3-segmented.
For S.Y. Moon & al. (2014, p.41) the genus Parvocalanus shows many similarities with Paracalanus, but differs by: 1- rostrum short, broad and bifurcated in both sexes; 2- distal segment of P5 terminal spines short in female; 3- absence of a medial keel-like dorsal hump on the cephalosome of male. However, 5 species of Parvocalanus have been described and/or illustrated as having 1 inner seta on the basis of P1 ( arabiensis, dubia, leei, scotti, serratipes). The authors slightly modifye the generic diagnosis of Parvocalanus : basis of P1 with or without inner seta and endopod of P1 unsegmented or 2-segmented (to accommodate P. arabiensis).
A molecular phylogeny discriminates the genera Parvocalanus and Paracalanus, with Parvocalanus placed as sister to the rest of paracalanid genera (Cornils & Blanco-Bercial, 2013). But the morphological phylogeny assessed in parallel by the same authors failed to separate the two genera, although it should be remarked that the morthological dataset used was extremely poor due to the poorness of the original species descriptions.

Diagnosis from K.S. Kesarkar & A.C. Anil (2010, p.407) :
1 - Basis 2 of P1 usually without inner edge seta.
2 - Endopod of P1 with 1 or 2-segmented.
3 - P1 with endopodal segment 2 with 6 setae.