Contributions to Zoology, 69 (1/2) (2000)S. Bell; J.E. Bron; C. Sommerville: The distribution of exocrine glands in Lepeophtheirus salmonis and Caligus elongatus (Copepoda: Caligidae)

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Caligus elongatus

The nauplius and copepodid larvae of C. elongatus showed the same pattern of DAB-positive gland distribution found in the corresponding stages of L. salmonis.

Both adult male and female C. elongatus possessed all of the main DAB-positive regions seen in L. salmonis adults. Some differences were noted i.e. the ‘swellings’ (Boxshall, 1974) on the ventral cuticle between thI and thII always stained heavily with DAB and a slight structural difference of the frontal gland complex was noted.

Specimens of C. elongatus had considerably more dorsal surface regions than their L. salmonis counterparts with adult males having »280 distinct regions while females had »160 (Fig. 6). A sexual dimorphism of these regions was evident, at least in the genital segment. These regions again showed a bilateral symmetry in their distribution, with the greatest proportion found around the extreme margins of the cephalothorax, close to the point of marginal membrane attachment.


Fig. 6. Dorsal view of DAB-stained adult female C. elongatus. Note stained muscle attachment points on dorsal cuticle (x). dsr dorsal surface regions; agc anterior gland complex; fgc frontal gland complex. Scale bar 500 µm.