Species Card of Copepod
Calanoida ( Order )
    Arietelloidea ( Superfamily )
        Heterorhabdidae ( Family )
            Heterorhabdus ( Genus )
Heterorhabdus americanus  Park, 2000   (F,M)
Park, 2000 (p.127, figs.F,M, Rem.)
Species Heterorhabdus americanus - Plate 1 of morphological figuresissued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 2000, 31. [p.249, Fig.97].
Female: a, habitus (left side); b, c, urosome (dorsal, left, respectively); d, forehead (left); e, f, genital somite (ventral, left, respectively); g, genital somite from different specimen (left); h, left Mx2 (posterior).

- Cephalosome 46 % length of prosome
- Prosome 70 % length of body and approximately 2.2 times length of urosome.
- Urosome 31 % length of body.
- Length ratios of 4 urosomal somites and left caudal ramus 39.6 : 18.0 : 13.4 : 8.1 : 20.9 = 100.
- Mx2: Posterior subterminal spine of 4th lobe 46 % as long as 2nd saberlike spine; falcate spine of 5th lobe with proximal 56 % of medial margin serrated with spinules; falcate spine of 6th lobe with proximal 70 % of medial margin serrated with spinules.

Species Heterorhabdus americanus - Plate 2 of morphological figuresissued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 2000, 31. [p.250, Fig.98].
Female: a, exopod of P1 (anterior); b, P5 (posterior).

Male: c, P5 (anterior); d, distal end of exopod of right P5 (lateral); e, basipods of P5 (anterior); f, g, basipod of right P5 (anterior, tilted clockwise, respectively); h, i, second exopodalsegment of right P5 (anterior, posterior, respectively); j, exopod of left P5 (anterior).

- Prosome 72 % length of body and about 2.5 times length of urosome.
- Urosome 28 % length of body.
- Caudal rami and setation as in female
- left geniculate A1 similar in morphology to that of H. spinifrons
- All other cephalosomal appendages and P1-P4 as in female

Species Heterorhabdus americanus - Plate 3 of morphological figuresHeterorhabdus americanus female:
1 - See key to species groups of Heterorhabdus: ''abyssalis'' Group (p.90, 114).
2 - Genital somite without a conical projection mediodorsally (Fig.97- a, f).
3 - Laterally, genital somite without a tubercular outgrowth posteriorly on dorsal margin (Fig.97-f).
4 - Laterally, genital operculum far short of reaching posterior end of somite (Fig.97-c).
5 - Laterally, right and left genital flanges symmetrical.
6 - Laterally, genital prominence distinctly separate from ventral wall of somite (Fig.97-f).
7 - Dorsally, as well as ventrally, lateral swellings of genital somite reaching posterior end of somite (Fig.97-b).
8 - Laterally, genital prominence far short of extending to posterior end of somite; genital somite with a low dorsal hump.
9 - Laterally, genital operculum reaching posterior end of genital prominence (Fig.97-c).

Species Heterorhabdus americanus - Plate 4 of morphological figuresHeterorhabdus americanus male:
1 - See key to species groups of Heterorhabdus: ''abyssalis'' Group (p.90, 114).
2 - Basis of left P5 without a well-developed inner lobe (Fig.98-c, e).
3 - Basal inner lobe of right P5 armed with normal bristles (Fig.98-c, e).
4 - 3rd exopodal segment of right P5 with a short terminal lobe, less than 1/3 length of terminal spine (Fig.98-c, d).
5 - Basal lobe of right P5 arising from anteromedial side of segment (Fig.98-a).
6 - 2nd exopodal segment of left P5 with outer spine not borne on a conical process (Fig.98-c, j).
7 - 3rd exopodal segment of right P5 with terminal spine longer than 1/2 length of segment (Fig.98-c).
8 - Anteriorly and when tilted clockwise, basal lobe of right P5 recurved by folding.
9 - Anteriorly, basal lobe of right P5 slightly folded (Fig.98-e).
10 - Basal lobe of right P5 conspicuously inflated distally (Fig.98-e).

Compl. Ref.:
Park & Ferrari, 2009 (p.143, Table 8, biogeography).
NZ: 3

Distribution map of Heterorhabdus americanus by geographical zones
E Pacif. (20° S - 31° N; America westward to 119°W)

Type locality: 16°09'S, 75°42'W.

For Park (2000, p.128) the species is taken in the east Pacific between 20°20' S and 31°38' N and from the west coast of the Americas westward to 118°53' W. This findings seem to indicate that the species is endemic to the coastal area of the eastern tropical Pacific.
N: 1
(824) F: 3,52-3,12; M: 3,36-2,96; {F: 3,12-3,52; M: 2,96-3,36}
Rem.: "Abyssalis" Group.
For Park (2000, p.129) this species is very close to H. cohibilis.
After Park (2000, p.128), the female genital somite is characteristic in having a moderately sigmoid dorsal margin, a strongly ventral margin formed by the genital flange together with the posterior ventral wall and a long genital operculum reaching the junction between the genital flange and the posterior ventral wall.
Last update : 17/10/2017
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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2021. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed January 23, 2021]

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