List species and varieties by family
Heterorhabdidae Sars, 1902 ( Arietelloidea )
Alrhabdus Grice, 1973
Rem.: Boxshall & Halsey (2004 (p.68, 126) transfer this genus to the Augaptilidae, however with some doubt as long as the male has not been encountered.
(1) Disseta Giesbrecht, 1889
Rem.: type: Disseta palumbii Giesbrecht, 1899. Total: 3 spp.
The species of this genus appear to feed mainly on particles by suspension feeding.

Diagnosis after Bradford-Grieve (1999 b, p.71) :
- As for the family definition.
- Female genital segment usually with a greatly protruding ventral process.
- A1 exceeding the body in length.
- A2 with subequal rami.
- Masticatory edge of Md without a large space between some teeth; there are 4 wide ventral teeth, and remaining dorsal teeth small.
- Mx1 in the form of a fan with long plumose setae; distally exopod and endopod arranged together at one level; outer lobe 1 with 9 setae, exopod with 10 setae, endopod with 11-12 setae.
- Mx2 with distal part greatly reduced, setae long, plumose, and of almost equal size.
- Mxp basipod 1 shorter than basipod 2 by 1/5 of its length and without large naked curved spines; endopod segments 1 and 2 not more than 1.5 times as long as wide.
- Male P5 with right exopod segment 2 with its inner edge swollen and with an inner edge protuberance.

Diagnosis after T. Park (2000, p.11) :
- All principal marginal setae of caudal rami except for 4th on left ramus armed with small spines in addition to normal setules.
- 1st segment of A1 with 1+3+3+3 setae/aesthetes.
- In A2, all 8 exopodal segments each with a well-developed inner marginal seta.
- In Md, masticatory edge with a basal spine, a group of 6-8 small, contiguous teeth, and 3 or 4 large, spiniform teeth: basis and 1st endopodal segment each with 4 setae, and 2nd endopodal segment with 8 terminal and 2 anterior appendicular setae.
- Mx1 with 2nd and 3rd inner lobes bearing setae; exopod reaching distal end of endopod.
- In Mx2, 5th and 6th lobes each with 1 spine, which is shorter than the long, normal setae of the lobe.
- Coxa of Mxp with 4 lobes bearing setae;
- Basis of P1 with outer seta;
- 3rd endopodal segment of P2 with 8 setae.
In female P5, outer spinule of 2nd rxopodal segment flanked by 2 large spiniform processes of the segment;
- In male left , geniculated A1, segments 19-21 fused as 1st post-geniculate complex with 1 proximal and 2 distal setae, which appear to belong to 19th and 21st segment, respectively.
) In male P5, 2nd segment of left endopod without seta; 2nd segment of right exopod with spiniform or toothlike medial projection.

For Park (2000, p.13), the genus Disseta is the most primitive genus in the Heterorhabdidae and can be distinguished from the other genera of the family by such primitive features as the inner marginal setae on all exopodal segments of A2, a large number of teeth and setae on Md, a relatively short endopod of Mx1, relatively unspecialized setae and spines of Mx2, a large number of setae on the coxa of Mxp, and an outer seta on the basis of P1.

For Park (2000) Disseta is a bathypelagic genus.

Disseta atlantica    Wolfenden, 1911   (F,M)
Ref.: Wolfenden, 1911 (p.313, Descr.F,M); Vervoort, 1965 (p.116)
Loc: Atlant.(équat.), Is. Cap Vert E & NE, off W Afr. S
Rem.: Cf. Disseta palumboi

Disseta coelebs    Heptner, 1972   (M)
Ref.: Heptner, 1972 (p.1645, Descr.M, figs.M)
Loc: Pacif. W (Fosse de Bougainville)
Rem.: Cf.: Disseta magna

Disseta grandis    Esterly, 1906   (F,M)
Ref.: Esterly, 1906 a (p.72, figs.F,M); Sewell, 1947 (p.185, 189: Rem.); Brodsky, 1950 (1967) (p.343, figs.F,M)
Loc: Californie (San Diego)
N: 1
Lg.: (17) F: 8,3; M: 7,6
Rem.: Cf. Disseta palumbii. Sewell (1947, p.189) estime que la femelle est synonyme de D. palumboi ce que ne confirme pas Vervoort (1965, p.116). Park (2000, p.13, 17-18) en fait un synonyme junior de D. palumbii.

[1] Disseta magna  Bradford, 1971   (F,M)    [Figs]

Disseta maxima    Esterly, 1911   (F)
Ref.: Esterly, 1911 (p.330, figs.F); Sewell, 1947 (Rem.: p.189); C.B. Wilson, 1950 (p.198);Tanaka, 1964 a (p.34, 37, Rem.)
Loc: San Diego
Lg.: (11) F: 9,4
Rem.: Cf. Disseta scopularis

Disseta minuta    Grice & Hulsemann, 1965   (F,M)
Ref.: Grice & Hulsemann, 1965 (p.245, figs.F,M); Heptner, 1972 a (p.60, Rem.)
Loc: Atlant. NE
Rem.: Cf. Microdisseta minuta

[2] Disseta palumbii  Giesbrecht, 1889   (F,M)    [Figs]

[3] Disseta scopularis  (Brady, 1883)   (F,M)    [Figs]

Disseta sp.    Esterly, 1911   (M)
Ref.: Esterly, 1911 (p.331, Descr.M, figs.M); Sewell, 1947 (p.185, 189, Rem.); Tanaka, 1964 a (p.32)
Loc: San Diego
Rem.: Cf. Disseta palumbii
(2) Hemirhabdus Wolfenden, 1911
Rem.: type: Heterochaeta grimaldii Richard, 1893 = Hemirhabdus grimaldii.
After Park (2000, p.143), the genus is bathypelagic.

Diagnosis after Bradford-Grieve (1999b, p.76) :
As for the family with additional characteristics :
- Left Md with 4 teeth, right with 5 teeth ; with ventral capped teeth separated from the remaining tooth by a gap.
- Mx1 outer lobe 1 with 4 setae, endopod with 6 setaze.
- Mx2 lobe 1 with 4 fine setae, lobe 2 atrophied, lobes 3 and 4 with 2 setae each, lobes 5 and 6 each with a strong claw-like spine clophed on its concave surface with short, widely spaced spinules.
- Mxp first basipod 1.5 times shorter tann basipod 2.

Diagnosis after Park (2000, p.51) :
- 1st segment of A1 with 1+3+3+3 setae/aesthetes.
- 1st and 2nd exopodal segments of A2 each with a small inner marginal seta.
- Basis and 1st endopodal segment of Md with 1 and 2 setae, respectively; 2nd endopodal segment without appendicular setae; masticatory edge with a basal spine followed by 3 teeth in left Md and 4 teeth in right Md, which are separated by an extremely wide gap from last, ventralmost tooth. Posteriorly ventralmost tooth with longitudinal ridges resembling a reinforcement rib.
- In Mx1, 3rd inner lobe missing; endopod 1-segmented, relatively well-developed; exopod elongate, accupying at distal end of appendage.
- In Mx2, 2nd lobe missing, 5th and 6th each with a large, coarely serrated saberlike spine in addition to 2 small setae; endopod with 2 long setae.
- Coxa of Mxp with a middle seta and 2 or 3 distal setae.
) 3rd endopodal segment of P2 with 7 setae.
- 3rd exopodal segment of P3 broad, with small terminal spine.
- In male P5, 2nd endopodal segment in broad legs with an inner marginal seta; 2nd exopodal segment of right leg with toothlike or fingerlike medial projection close to proximal end

The genus Hemirhabdus can be distinguished from Disseta, Mesorhabdus, Heterostyles by 1- Body massive; 2- masticatory edge of Md with ventralmost tooth separated from the other teeth by an extremely wide gap; 3- Mx2 with 2nd lobe missing, 3rd and 4th lobes with only small and unarmed setae, and endopod with only 2 setae; 4- Ledt A1 male with first 2 segments only partially fused and last 5 (21st to 25th) segments all separate.
Hemirhabdus shares with Heterostylites: 1- Mx1 with 3rd inner lobe missing; 2- masticatory edge of Md without a group of small, contiguous teeth next to basal spine; 3- coxa of Mxp with only 2 distal lobes bearing 1 seta on the 1st and 2or 3 setae on 2nd; 4- 3rd endopodal segment of P2 with 7 setae.

Hemirhabdus falciformis    Wolfenden, 1911   (F)
Ref.: Wolfenden, 1911 (p.310, Descr.F, figs.F); Heptner, 1972 a (p.59)
Loc: Atlant. tropical S
Rem.: Cf. Neorhabdus falciformis

[1] Hemirhabdus amplus  Park, 2000   (F,M)    [Figs]

[2] Hemirhabdus grimaldii  (Richard, 1893)   (F,M)    [Figs]

Hemirhabdus latus    Sars, 1905   (F,M)
Syn.: Heterorhabdus latus Sars, 1905 c (p.9, Rem.F); 1920 c (p.11)
Ref.: Sars, 1925 (p.232, figs.F,M); Sewell, 1932 (p.306, 307, Rem.); C.B. Wilson, 1950 (p.238, Rem.); Heptner, 1972 a (p.58)
Loc: Canaries
Rem.: Cf. Neorhabdus latus

Hemirhabdus truncatus    A. Scott, 1909   (F)
Syn.: Mesorhabdus truncatus A. Scott, 1909 (p.132, Descr.F, figs.F); ? Heterorhabdus latus Sars, 1905 c (p.9); 1920 c (p.11)
Ref.: Heptner, 1972 a (p.58)
Loc: Mer des Moluques
Rem.: Cf. Neorhabdus latus
(3) Heterorhabdus Giesbrecht, 1898
Rem.: type: Heterochaeta spinifrons Claus, 1863.
For Vervoort, 1951 (p.140) the genus Alloiorhabdus is based exclusively on the number of setae on the various segments of the swimming legs. It appears, however, that wolfenden’s observations are inaccurate as no differences in this respect exists between Heterorhabdus stricto sensu and the proposed genus Alloiorhabdus. The structure of the oral appendages in these genera too does not justify such a distinction.
Brodsky , 1950 (1967, p.345) establishes the 2 subgenera : Heterorhabdus (type: H. robustus) et Euheterorhabdus (types : H. papilliger & H. norvegicus).
Park establishes 4 groups ("spinifrons", "papilliger", "fistulosus", "abyssalis".
Type: Heterochaeta spinifrons Claus, 1863. Total: 31 spp. (+ 4 doubtful).
The species of this genus appear typical carnivores preying upon copepodids, polychaetes, and othe rmacrozooplanktoners (see litt. in Ohtsuka & al., 1997).

Diagnosis after Bradford-Grieve (1999 b, p.76) :
As for the family definition with the additional characteristics :
- Left Md with 3 teeth, right with 4 teeth.
- Mx1 is drawn out, the axis of exopod is of equal height to the remaining part which is aligned with exopod ; endopod reduced with 1-5 setae and sometimes atrophied.
- Mx2 lobe 1 with 2 setae, lobe 2 atrophied and replaced by 1 seta or spine, lobe 3 with 2 setae, lobe 4 with 3 long claw-like setae, the proximal parts of which have a partial comb of secondary spines or teeth, the distal part is smooth and sometimes flexed relative to proximal part.
- Mxp basipod 1 1.5 times shorter than basipod 2, proximal seta is often thickened, stronger, and noticeably longer than its segment (subgenus Heterorhabdus see Brodsky, 1950 as Euheterorhabdus) or the proximal seta is thin, plumose, and not longer than its segment (subgenus Paraheterorhabdus Brodsky, 1950).
- In some species P1 basipod 2 with a relatively large posteriorly-directed hook, visible in lateral view of whole copepod.

Diagnosis after Park (2000, p.89) :
- Dorsally, forehead with a midanterior tubercular process, which extends ventrad inyo tostrum.
- Sternite of the 1st pedigerous somite with a spiny papilla.
- Left caudal ramus fused with anal somite and distinctly longer than right.
- In 1st segment of A1, 1st lobe with a small seta, 2nd with 1 long and 1 very short setae and 1 aesthete, 3rd with 1 small and 2 medium-sized setae, 4th with 1 medium-sized and 1 long setae and 1 aesthete.
- Left geniculate A1 of male with segments 22 and 23 fused.
- In A2, first 2 exopodal segments without setae, last exopodal segment with a normally developed inner marginal seta, inner and outer lobes of 2nd endopodal segment with 8 (marginal) + 1 (posterior appendicular) and 6+1 setae, respectively.
- In Md, basis with 1 seta, 1st endopodal segment with 1 very small and 2 well-developed setae, 2nd with 8 terminal and 1 anterior appendicular setae; masticatory edge with basal spine followed by 2 teeth in left side and by 3 teeth in right side; ventralmost tooth separated from remaining teeth by a wide, flat gap. Ventralmost teeth of both Md symmetrical, large, falciform, each extending proximad, in the form of a reinforcement rib attached to the tooth, along ventral margin of mandibular blade to a distance about equal to length of tooth protruding beyond masticatory edge.
- Mx1 wit exopod greatly elongated and 2nd inner lobe (= coxal endite) bearing a relatively short seta.
- In Mx2, 1st segment greatly elongated; 1st lobe small, papillate, with 2 unequal setae; 2nd represented by a short, stout spine attached directly to segment; 3rd represented by a small seta and a medium-sized stout spine, both arising directly from segment; 4th elongate, with a small posterior subterminal spine and 2 long, saberlike terminal spines of similar length; 5th lobe elongate, with a relatively short saberlike spine and a long falcate spine; 6th with a very small anterior seta and a long falcate terminal spine serrated with short spinules along proximal section of medial margin; endopd small, with 7 relatively short setae;
- Coxa odf Mxp with middle marginal spine developed into a long, saberlike spine reaching to distal end of basis; anterior distal spine large and stout and 2 posterior distal spines greatly reduced in size.
3rd exopodal segment of P3 broad, with small terminal spine.

For Park (2000, p.90), the most important characters shared by all species of this genus are a spiny papilla of the sternite of the 1st pedigerous somite and a saberlike of falciform spine on the coxa of Mxp. Also important for identification of this genus are Mx1, which has a small endopod bearing 3 or fewer setae and an elongate exopod, and Mx2 in which the 5th lobe has 2 large, saberlike or falciform spines. The male P5 are characteristic in having elongate exopods and the terminal spine of the left exopod greatly elongated and completely fused with the segment.

1 er Groupe: Spinifrons
Ref.: Park, 2000 (p.90, Déf., clé des spp.)
Rem.: 7 spp.:

[1] Heterorhabdus ankylocolus  Park, 2000   (F,M)    [Figs]

[2] Heterorhabdus caribbeanensis  Park, 1970   (F,M)    [Figs]

[3] Heterorhabdus heterolobus  Park, 2000   (F,M)    [Figs]

[4] Heterorhabdus insukae  Park, 2000   (F,M)    [Figs]

[5] Heterorhabdus quadrilobus  Park, 2000   (F,M)    [Figs]

[6] Heterorhabdus spinifrons  (Claus, 1863)   (F,M)    [Figs]

[7] Heterorhabdus subspinifrons  Tanaka, 1964   (F,M)    [Figs]

2 ème Groupe: Papilliger
Ref.: Park, 2000 (p.102, Déf., clé spp.)
Rem.: 5 spp.:

[1] Heterorhabdus guineanensis  Park, 2000   (F,M)    [Figs]

[2] Heterorhabdus lobatus  Bradford, 1971   (F,M)    [Figs]

[3] Heterorhabdus papilliger  Claus, 1863   (F,M)    [Figs]

[4] Heterorhabdus prolatus  Park, 2000   (F,M)    [Figs]

[5] Heterorhabdus spinifer  Park, 1970   (F,M)    [Figs]

3 ème Groupe: Fistulosus
Ref.: Park, 2000 (p.110, Déf., clé spp.)
Rem.: 2 spp.:

[1] Heterorhabdus egregius  Heptner, 1972   (F,M)    [Figs]

[2] Heterorhabdus fistulosus  Tanaka, 1964   (F,M)    [Figs]

4 ème Groupe: Abyssalis
Ref.: Park, 2000 (p.114, Déf., clé spp.)
Rem.: 17 spp.:

[1] Heterorhabdus abyssalis  (Giesbrecht, 1889)   (F,M)    [Figs]

[2] Heterorhabdus americanus  Park, 2000   (F,M)    [Figs]

[3] Heterorhabdus austrinus  Giesbrecht, 1902   (F,M)    [Figs]

Heterorhabdus austrinus var.    Farran, 1929   (F,M)
Ref.: Farran, 1929 (p.265: petites formes); Vervoort, 1957 (p.132, Rem.)
Loc: Antarct., sub-Antarct., off Nouvelle-Zélande E
Lg.: (35) F: 3,18-2,97; M: 2,88-2,84
Rem.: Pour Vervoort (1957) on n’observe pas de différence structurelle entre cette variété et l’espèce précédente.

[4] Heterorhabdus clausi  (Giesbrecht, 1889)   (F,M)    [Figs]

[5] Heterorhabdus cohibilis  Park, 2000   (F,M)    [Figs]

[6] Heterorhabdus confusibilis  Park, 2000   (F,M)    [Figs]

[7] Heterorhabdus habrosomus  Park, 2000   (F,M)    [Figs]

[8] Heterorhabdus longisegmentus  Park, 2000   (F,M)    [Figs]

[9] Heterorhabdus norvegicus  (Boeck, 1872)   (F,M)    [Figs]

[10] Heterorhabdus oikoumenikis  Park, 2000   (F,M)    [Figs]

[11] Heterorhabdus pacificus  Brodsky, 1950   (F,M)    [Figs]

[12] Heterorhabdus paraspinosus  Park, 2000   (F,M)    [Figs]

[13] Heterorhabdus prolixus  Park, 2000   (F,M)    [Figs]

[14] Heterorhabdus pustulifer  Farran, 1929   (F,M)    [Figs]

[15] Heterorhabdus spinosus  Bradford, 1971   (F,M)    [Figs]

[16] Heterorhabdus tanneri  (Giesbrecht, 1895)   (F,M)    [Figs]

[17] Heterorhabdus tuberculus  Park, 2000   (F,M)    [Figs]

Espèces citées comme Heterorhabdus en synonymie ou douteuses

[1] Heterorhabdus atlanticus  Wolfenden, 1905   (M)

Heterorhabdus brevicaudatus    Wolfenden, 1905   (F)
Ref.: Wolfenden, 1905 a (p.12, Descr.F, fig.F)
Rem.: Cf. Mesorhabdus brevicaudatus

[2] Heterorhabdus brevicornis  (F. Dahl, 1894)   (F)

Heterorhabdus compactoides    Heptner, 1971   (F,M)
Ref.: Heptner, 1971 (p.152, figs.F,M); 1972 a (p.59)
Rem.: Cf. Paraheterorhabdus (Paraheterorhabdus) compactoides

Heterorhabdus compactus    Sars, 1900   (F,M)
Ref.: Heterochaeta compacta Sars, 1900 (p.83, Descr.F, figs.F)
Rem.: Cf. Paraheterorhabdus (Antirhabdus) compactus

Heterorhabdus farrani    Brady, 1918   (F,M)
Ref.: Brady, 1918 (p.27, figs.F,M)
Rem.: Cf. Paraheterorhabdus (Paraheterorhabdus) farrani

Heterorhabdus fistulosus tuberculata    Heptner, 1971   (F)
Ref.: Heptner, 1971 (p.149, figs.F)
Rem.: Cf. Heterorhabdus fistulosus

Heterorhabdus fistulosus typica    Heptner, 1971   (F,M)
Ref.: Heptner, 1971 (p.149, figs.F,M)
Rem.: Cf. Heterorhabdus fistulosus

Heterorhabdus grandis    Wolfenden, 1904   (F,M)
Ref.: Wolfenden, 1904 (p.120, fig.F); 1905 a (p.8, Descr.F,M, fig.M)
Loc: Atlant. NE
Rem.: Cf. Disseta palumbii

Heterorhabdus grimaldii    Richard, 1893   (F,M)
Syn.: Heterochaeta grimaldii Richard, 1893 a (p.151, Descr.F)
Ref.: Giesbrecht & Schmeil, 1898 (p.117, Rem.); Wolfenden,1905 a (p.10, Rem.F,M); Sewell, 1913 (p.354)
Loc: Canaries, Açores N, Irlande, Indien (G. du Bengale)
Rem.: Cf. Hemirhabdus grimaldii

Heterorhabdus latus    Sars, 1905   (F)
Ref.: Sars, 1905 c (p.9, Rem.F); Heptner, 1972 a (p.58)
Loc: Canaries
Rem.: Cf. Neorhabdus latus

Heterorhabdus longicornis    Giesbrecht, 1889   (F,M)
Syn.: Heterochäta longicornis Giesbrecht,1889; 1892 (p.373, figs.F)
Ref.: Giesbrecht & Schmeil, 1898 (p.116)
Rem.: Cf. Heterostylites longicornis

Heterorhabdus longispinus    Davis, 1949   (M)
Ref.: Davis, 1949 (p.58, Descr.M, figs.M)
Loc: Pacif. NE (off C. Flattery)
Rem.: Cf. Paraheterorhabdus (Paraheterorhabdus) longispinus

Heterorhabdus major    F. Dahl, 1894   (M)
Syn.: Heterochaeta major F. Dahl,1894
Ref.: Giesbrecht & Schmeil, 1898 (p.117)
Rem.: Cf. Heterostylites major

Heterorhabdus medianus    Park, 1970   (F,M)
Ref.: Park, 1970 (p.477, 525, figs.F, non M)
Rem.: Cf. Paraheterorhabdus (Paraheterorhabdus) medianus

Heterorhabdus nigrotinctus    Brady, 1918   (M)
Ref.: Brady, 1918 (p.27, Rem.M, figs.M)
Rem.: Cf. Heterostylites nigrotinctus.

Heterorhabdus pilosus    Tanaka, 1953   
Ref.: Tanaka, 1953 (p.134, nom.nud.); 1964 a (p.11)
Rem.: Cf. Heterorhabdus tanneri

[3] Heterorhabdus profundus  (F. Dahl, 1894)   (F,M)    [Figs]

Heterorhabdus proximus    Davis, 1949   (F,M)
Ref.: Davis, 1949 (p.57, figs.F,M); non Bradford, 1971 a (p.126, figs.F,M)
Rem.: Cf. Heterorhabdus tanneri

Heterorhabdus robustoides    Brodsky, 1950   (F,M)
Ref.: Brodsky, 1950 (1967) (p.346, figs.F,M); Tanaka, 1964 a (p.20, Rem.); Vervoort, 1965 (p.118, Rem.); Heptner, 1971 (p.156, 158, Rem.); Gardner & Szabo, 1982 (p.368, figs.F,M)
Loc: Pacif. NW, Mer de Béring
Rem.: Cf. Heterorhabdus robustus

Heterorhabdus robustus    Farran, 1908   (F,M)
Ref.: Farran, 1908 b (p.65, figs.F,M, Rem.)
Rem.: Cf.: Paraheterorhabdus (Paraheterorhabdus) robustus.

Heterorhabdus tenuis    Tanaka, 1964   (M)
Ref.: Tanaka, 1964 a (p.20, Descr.M, figs.M)
Rem.: Cf. Paraheterorhabdus (Paraheterorhabdus) vipera

[4] Heterorhabdus tropicus  (F. Dahl, 1894)   (F,M)

Heterorhabdus vipera    Giesbrecht, 1889   (F,M)
Syn.: Heterochäta vipera Giesbrecht,1889; 1892 (p.373, 383, figs.F, non M);
Ref.: Giesbrecht & Schmeil, 1898 (p.116)
Rem.: Cf. Paraheterorhabdus (Paraheterorhabdus) vipera

Heterorhabdus zetesios    Wolfenden, 1902   (M)
Syn.: Heterochaeta zetesios Wolfenden, 1902 (p.367, Descr.M); Fowler, 1903 (p.124)
Ref.: Vervoort, 1957 (p.135)
Loc: Féroé
Rem.: Cf. Heterostylites major
(4) Heterostylites Sars, 1920
Rem.: Type: Heterochaeta longicornis Giesbrecht, 1889. Total: 6 spp.
The species of this genus appear to feed mainly on particles by suspension feeding, additionally feeding on zooplankters, such as copepods (see in Harding, 1974 and Ohtsuka & al., 1997). For Park (2000, p.143), This genus is meso-bathypelagic, occurring widely in the world's oceans. Of the 6 species found by Park (2000), H. major and H. longicornis have the widest ranges, occurring throughout the Pacific, Atlantic, and Indian Oceans, except for Arctic and Antarctic waters. The most common of the six species found were the the two Pacific species, H. longioperculis and H. echinatus, each representing 30 % of the specimens found for the genus, followed by H. longicornis and H. major accounting for 20 % and 16 %, respectively

Diagnosis after Bradford-Grieve (1999 b, p.88) :
- As for the family definition.
- Genital segment with a protruding ventral process with a large genital valve.
- A1 much longer than the body.
- Masticatory edge of Md with 3 teeth on the left and 4 teeth on the right; without a wide space between 1 tooth and the rest.
- Mx1 with 1 thick plumose spine on the proximal border of inner lobe 1 some distance from the terminal broup of finer spines; endopod with 5 setae.
- Mx2 lobes 5 and 6 each with 1 smooth, thickened hook-like seta; lobe 4 is the largest; the distal part of the limb is reduced, without large spines.
- Mxp basipod 1 is 1.5 times shorter than basipod 2.
- Female P5 with a complex crest of fused spines near the base of outer spine of exopod segment 2.
- Male P5 right exopod segment 2 inflated on inner border but without a definitr process.

Diagnosis after Park (2000, p.37) :
- None of marginal setae of caudal rami armed with conspicuous spines in addition to normal setules.
- 1st segment of A1 with 4 lobes bearing 1, 3, 2, 2 setae/aesthetes.
- In exopod of A2, first 2 exopodal segments without setae.
- In Md, masticatory edge with a basal spine and 3 or 4 long spiniform teeth, without a group of short contiguous teeth next to basal spine; basis with a long seta; 1st endopodal segment with 2 setae; 2nd endopodal segment with only 8 terminal setae, witout appendicular setae.
- mx1 with 3rd inner lobe missing; exopod greatly elongated, making up distal half of appendage.
- In Mx2, 5th and 6th lobes each with a large saberlike spine; 1 of 3 setae on 4th lobe reansformed into a long spine.
- Coxa of Mxp with 1 middle and 3 distal marginal setae ( 1 anterior and 2 posterior; first posterior distal seta greatly elongated).
- Basis of P1 without outer seta.
- 3rd endopodal segment of P2 with 7 setae.
- Anteriorly, 2nd exopodal segment of female P5 with distal margin extended distad into a serrated lappet.
- Left geniculated A1 of male with 2 setae belonging to 20th segment. Both right and left endopods of male pair of legs with inner marginal seta on 2nd segment. 2nd exopodal segment of right P5 much wider than long, with short medial projection normally divided distally into 2 processes (a spiny and a plumose process).

For Park (2000, p.38), the genus Heterostylites differs from Mesorhabdus and Disseta by: 1 - 1st segment of A1 with 1+3+2+2 setae/aesthetes, instead of 1+3+3+3 setae/aesthetes. 2 - first 2 exopodal segments of A2 witout setae. 3 - masticatory edge of Md without a group of short, contiguous teeth next to basal spine and 2nd endopodal segment with only 8 terminal setae; 4 - Mx1 with 3rd inner lobe missing; exopod greatly elongated, making up distal half of appendage. 5 - In Mx2, 1 or 3 setae on 4th lobe transformed into a long spine. 6 - coxa of Mxp with 4 setae, 3 on distalmost lobe and 1 seta on penultimate lobe; 1st pposterior seta of distalmost lobe much longer than the others. 7 - in basis of P1, outer seta missing as in Mesorhabdus. 8 - in P2, 3rd endopodal segment with 7 setae, instead of 8. 9 - anteriorly, distal margin of 2nd exopodal segment of female P5 extending distad into a serrated lappet; 10 - in male P5, 2nd endopodal segment in both legs with an inner marginal seta. 11 - in right P5 male, 2nd endopodal segment greatly enlarged, with a small but hugkly specialized medial projection.

The females of Heterostylites can be distinguished from those of the other calanoid copepods by a unique feature of P5: the serrated distal lappet of the 2nd exopodal segment. The male can be distinguished from those of the other heterorhabdid genera by the greatly enlarged 2nd exopodal segment of the right P5.

[1] Heterostylites echinatus  Park, 2000   (F,M)    [Figs]

[2] Heterostylites longicornis  (Giesbrecht, 1889)   (F,M)    [Figs]

[3] Heterostylites longioperculis  Park, 2000   (F,M)    [Figs]

[4] Heterostylites major  (F. Dahl, 1894)   (F,M)    [Figs]

[5] Heterostylites nigrotinctus  (Brady, 1918)   (F,M)    [Figs]

[6] Heterostylites submajor  Park, 2000   (F,M)    [Figs]
(5) Mesorhabdus Sars, 1905
Rem.: type: Mesorhabdus annectens (= Heterorhabdus brevicaudatus). Total: 5 spp.
After park (2000, p.143), Mesorhabdus is a meso-bathypelagic genus.

Diagnosis after Bradford-Grieve (1999 b, p.90) :
- As for the family definition.
- Left mandibular blade with 6 teeth, right blade with 7 teeth; teeth are distributed in 2 groups not separated by a space, there are 3 wide teeth on left and 4 wide teeth on right; remaining teeth are small and merge together.
- Mx1 outer lobe 1 and endopod with 5-6 and 3-4 setae respectively; exopod with 5-11 setae.
- Mx2 with 2 proximal endopod segments each with a strong claw-like spine bordered on all sides with fine difficult-to-observe hairs; proximal spine is longer, distal spine is stronger.
- Mxp basipod 1 more than 1.5 times (up to 2 times) shorter than basipod 3.

Diagnosis after T. Park (2000, p.23) :
- 3rd marginal seta of left caudal ramus and 3rd and 4th marginal setae of right caudal ramus armed with small spines in addition to normal setules.
- 1st segment of A1 with 1+3+3+3 setae/aesthetes.
- Masticatory edge with a basal spine, a group of 2 or 3 short, contiguous teeth, and 3 or 4 long spiniform teeth ; 2nd endopodal segment with 8 terminal setae plus 2 appendicular setae.
- Mx1 with 1 of setae on 1st inner lobe developed into a conspicuously large spine; 3rd inner lobe with 1 or 2 setae; exopod extending beyond distal end of endopod by 1/2 its length.
- In Mx2, 5th and 6th lobes each with a large, saber-like spine.
- Coxa of Mxp with 3 lobes bearing setae.
- Basis of P1 without outer seta.
- P2 with 8 setae on 3rd endopodal segment.
- Left A1 male with 0 or 1 seta belonging to 20th segment.
- 2nd endopodal segment of male left P5 without seta. 2nd exopodal segment of male right P5 with a large toothlike medial projection.

For Park (2000, p.24), male's geniculated A1 and P5 are basically the same as those of the Disseta male, but the male can be distinguished from that of Disseta by the medial projection of the 2nd exopod of the right P5, which is relatively long and extends at right angle to the longitudinal axis of the appendage.

[1] Mesorhabdus angustus  Sars, 1907   (F,M)    [Figs]

Mesorhabdus annectens    Sars, 1905   (F)
Ref.: Sars, 1905 c (p.9, Rem.F)
Loc: Açores
Rem.: Cf. Mesorhabdus brevicaudatus

[2] Mesorhabdus brevicaudatus  (Wolfenden, 1905)   (F,M)    [Figs]

[3] Mesorhabdus gracilis  Sars, 1907   (F,M)    [Figs]

[4] Mesorhabdus paragracilis  Park, 2000   (F,M)    [Figs]

[5] Mesorhabdus poriphorus  Park, 2000   (F,M)    [Figs]

Mesorhabdus truncatus    A. Scott, 1909   (F)
Ref.: A. Scott, 1909 (p.132, Descr.F, figs.F); Heptner, 1972 a (p.58)
Loc: Mer des Moluques
Rem.: Cf. Neorhabdus latus
(6) Microdisseta Heptner, 1972
Rem.: Type: Disseta minuta Grice & Hulsemann, 1965. Total: 1 sp.
Boxshall & Halsey (2004, p.126) do not follow the opinion of Park on the uncertainty of the place of this genus within this family. Total: 1 species.
The feeding habits of species are still enigmatic, but probably mainly employs suspension feeding on the basis of their similarities in the mouthpart structures to those of Disseta and Heterostylites (see the fine structures of Md and labrums in Ohtsuka & al., 1997).

Diagnosis after Bradford-Grieve (1999 b, p.91) :
- As for the family definition.
- Md with 6 conical, ungrouped teeth of one type.
- The body of Mx1 is drawn out so that the distal part of the exopod only extends as far as the proximal part of the endopod; outer lobe 1 with 6 setae, exopod with 7 setae, endopod with 9 setae.
- Mx2 lobes 1-4 with one type of long plumose setae; lobe 5 with a strong, slightly shorter, crescent-shaped spine.
- Mxp basipod 1 noticeably longer than basipod 2; endopod segment 1 equal to segment 2, twice as long as wide and more than half the length of basipod 2.

After Boxshall & Halsey (2004, p.127) the genus Microdisseta is doistinguished from Disseta by the basal endite of Mx2 with claw-like element plus 1 seta in the former and without claw-like element, armed with 3 setae in the latter.

[1] Microdisseta minuta  (Grice & Hulsemann, 1965)   (F,M)    [Figs]
(7) Neorhabdus Heptner, 1972
Rem.: type: Heterorhabdus latus Sars, 1905. Total: 5 spp.
After Park (2000, p.143), the genus is bathypelagic occurring mainly in the low latitudes. Of the 5 species found by the author, N. latus and N. brevicornis were commonly found throughout the low latitudes of the world's oceans and represented 61 % and 20 %, respectively of the specimens found for the genus. N. falciformis and N. capitaneus were found in all three major oceans but they were very rare, each representing only 8 % of the total found for the genus. N. subcapitaneus was represented by only 3 specimens found in the northwestern Atlantic and southeastern Pacific.

Diagnosis after Bradford-Grieve (1999 b, p.92) :
- As for the family definition.
- Left mandibular blade with 4 teeth, right blade with 5 teeth; ventral capped teeth separated from remaining tooth by a gap.
- Mx1 outer lobe 1 with 3 setae.
- Mx2 with lobes 1-4 developed, with setae, part of which is thickened basally, sometimes they are claw-like, abruptly tapering distally, densely covered in fine hairs; 1-2 of these setae on every lobe is curved in the direction of the distal part of limb; lobes 5 and 6 relatively short, each with a strong claw-like spine with a row of spinules on the concave border.
- Mxp basipods 1 and 2 are more or less equal.

Diagnosis after Park (2000, p.57) :
- Body massive.
- In 1st segment of A1, 1st lobe with 1 seta, 2nd with 2 setae + 1 aesthete, 3rd with 2 setae + 1 or more aesthetes, 4th with 2 setae and 2 or more aesthetes.
- 1st and 2nd exopodal segments of A2 without appendicular setae.
- In Md, basis without seta, 1st endopodal segment with 2 setae, 2nd endopodal segment with 7 terminal setae and without appendicular seta; masticatory edge with a basal spine followed by 3 teeth in left sideb and 4 teeth in right side, which are separated from last, ventralmost tooth by a wide gap.
- 2nd inner lobe of Mx1 with or without a seta, 3rd inner lobe without seta; endopod 1-segmented and small; exopod elongate, occupying at distal end of appendage.
- Mx2, all setae on 1st to 4th lobes modified into spines, either unarmed or armed with short spinules only; 5th and 6th lobes of equal length, each with a large saberlike, serrated spine in addition to a small spine; endopod vestigial , with 2 setae of equal length.
- Coxa of Mxp with 1 middle seta and 2 or 3 distal setae.
- 3rd endopodal segment of P2 with 7 setae.
- In male, P5, 2nd endopodal segment with 1 seta in both legs; 2nd exopodal segment of right leg of P5 with a digitiform medial projection.

The species of this genus had been referred to Hemirhabdus until Hepner (1972a) recognized their differences from the latter and placed them in a new genus, Neorhabdus. However, neorhabdus is most closely related to hemirhabdus and they share common features: 1- dorsally, forehead without midanterior tubercular process extending from rostral base; 2- caudal rami wide; left ramus only a little longer than right; 3- on masticatory edge, basal spine is followede by 3 teeth in left side and 4 in right side, which are separated from last, ventralmost tooth by an extremely wide gap; 4- ventralmost tooth with longitudinal ridges resembling a reinforcement rib; 5- in Mx1, 1st inner lobe elongate, with 9 or fewer setae, 3rd inner lobe without seta; 6- in Mx2, large spines of 5th and 6th lobes well developed, saberlike and conspicuously serrated with large teeth; endopod vestigial, with only 2 setae; 7- coxa of Mxp with 1 middle and 2 or 3 distal setae; 8- in male P5, each endopod with 1 inner seta on 2nd segment; 2nd segment of right exopod with digitiform medial projection.
The differences between the two genera can be distinguished from each other in Mx2, which in Neorhabdus has all setae on the first 4 lobes modified into spines and the 5th and 6th lobes of similar length. In Mx2 of Hemirhabdus the 2nd lobe is missing, none of the setae of the first 3 remaining lobes modified into spines, and the 5th lobe is much larger and longer than the 6th.
Additional differences between the genera are: 1- cephalosome in lateral view with a cervical groove in Hemirhabdus but without it in Neorhabdus; 2- A2 with a small inner marginal seta on 1st and 2nd exopodal segments and 1 posterior appendicular seta on inner and outer lobes of 2nd endopofal segment in Hemirhabdus; they are absent in Neorhabdus; 3- Md with 1 seta on basis and 8 terminal setae on 2nd endopodal segment in Hemirhabdus, but no seta on basis and 7 terminal setae on 2nd endopodal segment in neorhabdus; 4- Mx1 with 9 setae on 1st inner lobe, 1 seta on basis, and 5 long lateral and 3 small medial setae on exopod in Hemirhabdus, but 6 or 7 setae on 1st inner lobe, 2 or 3 setae on basis, and only 3 or 4 long lateral setae on exopod in Neorhabdus: 5- in P1, each outer exopodal spine is attached in a socket formed by spiniform processes of segment in Neorhabdus, but no such sockets in P1 of Hemirhabdus; 6- exopodal terminal spine of P3 is much smaller than that of P4 in Hemirhabdus, but the same spine of P3 is slightly larger than that of P4 in Hemirhabdus, but the same spine of P3 is slightly larger than of P4 in Neorhabdus; 7- in geniculate A1 male, 19-20th segments fused in Hemirhabdus, but 19th-21st segments fused in Neorhabdus.

[1] Neorhabdus brevicornis  Park, 2000   (F,M)    [Figs]

[2] Neorhabdus capitaneus  Park, 2000   (F,M)    [Figs]

[3] Neorhabdus falciformis  (Wolfenden, 1911)   (F,M)    [Figs]

[4] Neorhabdus latus  (Sars, 1905)   (F,M)    [Figs]

[5] Neorhabdus subcapitaneus  Park, 2000   (F)    [Figs]

Neorhabdus truncatus    A. Scott, 1909   (F)
Syn.: Mesorhabdus truncatus A. Scott, 1909 (p.132, Descr.F, figs.F); ? Hemirhabdus latus Sars, 1925 (p.232, figs.F,M); C.B. Wilson, 1950 (p.238); non Hemirhabdus truncatus : Sewell, 1932 (p.306, figs.F, Rem.); 1947 (p.181); 1948 (p.330, 530, 533, 547)
Ref.: Heptner,1972 a (p.58); Park, 1999 (p.58: Rem., 59)
Loc: Mer Arabe, Is. Laquedives, Inde S, Mer des Moluques
N: 3
Lg.: (5) F: 7; (11) F: 9,667; (44) F: 7,44
Rem.: Cf. Neorhabdus latus
(8) Paraheterorhabdus Brodsky, 1950
Rem.: After Park (2000, p.72) Paraheterorhabdus is a valid taxon chearly distinguishable of the genus Heterorhabdus and other genera of the family Heterorhabdidae in morphological details mainly of Mx2 and Mxp.
In Mx2, 1st segment elongate, about as long as the rest of the appendage, first 3 lobes with 2, 1 and 2 relatively small setae/spines, respectively ; 5th highly elongated, with a small seta and a long spine ; 6th lobe with 2 small setae and a long spine ; long spines of 5th and 6th lobes saberlike, slender, gradually tapering into sharp points, finely serrated along medial margins except for distal sections.
Coxa of Mxp with well-developed middle and distal spines ; middle spine elongate ; anterior distal spine thicker but shorter than 1st posterior distal spine ; 2nd posterior distal spine thinnest and shortest.
Paraheterorhabdus compactus (Sars, 1900) differs from the other species of the genus and a new subgenus is erected for it.
Total: 8 spp.
For Park (2000, p.143), the subgenus comprising 6 species seems to be mesopelagic, occurring widely in the world's oceans. P. robustus, P. illgi, P. medianus, P. vipera all have a similar range of distribution, occurring widely in the low and midlatitudes of all three major oceans. P. robustus was the most common, representing 26 % of the specimens found for the subgenus, followed in orfer by P. illgi, P. medianus, P. vipera accounting for 14 %, 10 % and 8 %, respectively. P. longispinus is endemic to the northern Pacific, where it seems to be quite common. P. farrani is distributed exclusively in the Southern Ocean, accounting for26 % of the total found for the subgenus, and one of the samples, taken in the Drake Passage, contaned as many as 61 specimens.

[1] Paraheterorhabdus (Antirhabdus) compactus  (Sars, 1900)   (F,M)    [Figs]

[2] Paraheterorhabdus (Paraheterorhabdus) compactoides  (Heptner, 1971)   (F,M)    [Figs]

[3] Paraheterorhabdus (Paraheterorhabdus) farrani  (Brady, 1918)   (F,M)    [Figs]

[4] Paraheterorhabdus (Paraheterorhabdus) illgi  Park, 2000   (F,M)    [Figs]

[5] Paraheterorhabdus (Paraheterorhabdus) longispinus  (Davis, 1949)   (F,M)    [Figs]

[6] Paraheterorhabdus (Paraheterorhabdus) medianus  (Park, 1970)   (F,M)    [Figs]

[7] Paraheterorhabdus (Paraheterorhabdus) robustus  (Farran, 1908)   (F,M)    [Figs]

[8] Paraheterorhabdus (Paraheterorhabdus) vipera  (Giesbrecht, 1889)   (F,M)    [Figs]

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Razouls C., de Bovée F., Kouwenberg J. et Desreumaux N., 2005-2019. - Diversity and Geographic Distribution of Marine Planktonic Copepods. Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed February 22, 2019]

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