Erebonectes nesioticus Fosshagen, 1985
Erebonectes nesioticus: dorsal view, after Fosshagen & Iliffe, 1985
Taxonomic Characterization: E. nesioticus is characterized by a 27-segmented 1st antenna of the female, an 8-segmented exopod of the 2nd antenna, essentially unmodified mouthparts and 3-segmented rami of all legs of both sexes with strongly modified exopods of the 5th legs of the male. The male differs from the female in its 5-segmented urosome and the geniculate right 1st antenna. The female body is robust with the prosome being about 3 times longer than the urosome. The rostrum is directed downward, bifurcate and with filaments. The male endopods are similar to the female except for a dense hairy patch along the outer side of the 2nd segment of the left leg (Fosshagen & Iliffe, 1985).
Disposition of Specimens: All type specimens were deposited in the American Museum of Natural History; male holotype from Christie's Cave (AMNH Cat. No. 11 312), one female paratype from Christie's Cave and one female paratype from Devonshire Cave (AMNH Cat. No. 11 313).
Ecological Classification: Stygobitic
Size: Total body length of male was 1.75 mm, females were 1.73 and 1.90 mm.
Number of Species in Genus: One
Species Range: Reported originally from Christie's and Devonshire Caves, Hamilton Parish, Bermuda (Fosshagen & Iliffe, 1985).
Later found in Jane's, Church and Bitumen Caves (Fosshagen et al., 2001).
Closest Related Species: Erebonectes nesioticus is most closely related to Erebonectoides macrochaetus from the Caicos Islands. It also shows many similarities to Enantiosis and Epacteriscus. Erebonectes and Enantiosis have in common modified setae in the proximal part of the 1st antenna and extra long setae on the corresponding segments, a reduced endopod and similar teeth of the mandible, and an elongate endopod of the 1st maxilla and spinous setae of the 2nd maxilla and maxilliped.
Habitat: Anchialine limestone caves
Ecology: E. nesioticus inhabits Christie's and Devonshire Caves of Bermuda, both located c. 50 m inland from open water. Both caves have clear water and lack normal littoral fauna due to their remote connection with the sea; they are separated from each another by 5 km. The male specimen from Christie's Cave was taken at a depth of c. 4 m and the female specimen from Devonshire Cave was taken at a depth between 6 and 10 m. The specimens were collected on sight or accidentally when dragging a fine-meshed net, less than 100 microns. In the laboratory, the male specimen was observed using maxillae and maxillipeds to form a basket-like structure, probably used for prey capture. It was also observed swimming with the dorsal side down (Fosshagen & Iliffe, 1985).
Life History: Original specimens included 1 male and 2 females. Later collections included copepodid stage I and V and two females.
Evolutionary Origins: Erebonectes may be considered one of the most primitive calanoids with its 27-segmented 1st antenna, 8-segmented exopod of 2nd antenna, and the 3-segmented swimming legs (Fosshagen & Iliffe, 1985).
Conservation Status: E. nesioticus is considered to be critically endangered (IUCN, 1996). It is restricted to five caves in Bermuda.
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