Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Aetideidae ( Family )
            Bradyidius ( Genus )
Bradyidius arnoldi  Fleminger, 1957   (F,M)
Fleminger, 1957 b (p.355, figs.F,M); Park, 1966 (p.810); Bradford, 1976 a (p.6: Rem.); Othman & Greenwood, 1987 (p.1137); Markhaseva, 1996 (p.70, figs.F,M); Markhaseva & al., 2008 (p.2433: Rem.)
Species Bradyidius arnoldi - Plate 1 of morphological figuresissued from : A. Fleminger in Fish. Bull. Fish Wildl. Serv., 1957, 57 (117). [p.357, Pl. 1].
Female (from G. of Mexico): 1-2, habitus (lateral and dorsal, respectively); 6 b, Md (cutting edge); 7, P2; 8, P1; 9, endopod of P4; 10, endopod of P3; 11, genital segment (ventral); 13, Mx2; b, Md (cutting edge.
Nota: A1 24-segmented, as long as cephalothorax less spiniform processes of last segment.
Md with dentition differing from that in B. armatus; teeth more numerous, those on ventral half of of gnathal lobe overlapping.
Mx2 with short seta on lobes 2-4, each with closely spaced row of spinules on proximal portion; falcate spine on lobe 5 with closely spaced rowof short hairs.
Remaining cephalic appendages similar to those in B. armatus.
Proportional lengths of urosomal segments (caudal rami included; segments 4 and 5 taken together) 39 : 19: 20: 22 = 100.

Male: 3-4, lateral and dorsal); 5, rostrum; 6, Md (cutting edge);12, P5.
Nota: Differs from B. pacificus and B. similis chiefly in details of P5.
Proportional lengths of urosomal segments (segments 4 and 5 taken together) 15: 29: 21: 19: 16 = 100. A1 extending to caudal rami, right A1 20-segmented (primitive segments 8-10, 12-13, 20-21, 24-25 fused).

Stage V Male: 6 a, Md (cutting edge).
Nota: Mandibular gnathal lobe (fig.6a) apparently similar to that in B. armatus

Species Bradyidius arnoldi - Plate 2 of morphological figuresBradyidius arnoldi female:
1 - Rostrum with nondivergent and parallel rami.
2 - Points of last thoracic segment long, reaching nearly posterior third of genital segment.

Species Bradyidius arnoldi - Plate 3 of morphological figuresBradyidius arnoldi male:
1 - P5 biramous.
2 - Endopod of left P5 2-segmented. A1 reaching caudal rami.

Compl. Ref.:
Suarez-Morales & Gasca, 1998 a (p.107); Markhaseva, 1998 (p.250, Fig.2)
NZ: 1

Distribution map of Bradyidius arnoldi by geographical zones
Gulf of Mexico
N: 2
(553) F: 1,67; M: 1,23; 1,19; {F: 1,67; M: 1,19-1,23}
Rem.: epipelagic (in night samples).
According to Fleminger (1957 b, p.355) the female appears to differ slightly from B. armatus (vide Sars, 1902) and pacificus (vide Brodsky, 1950). Despite the limited degree of morphological characterization and the lack of data on variability, it is proposed that this Gulf of Mexico form be given specific status because: 1- the most outstanding character occurs in a sexual structure (P5 male), 2- It appears to be geographically as well as ecologically separated (temperature range) from other forms of Bradyidius.
Last update : 30/12/2014
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 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 25, 2024]

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