Phylum Arthropoda
Subphylum Crustacea
Subclass Copepoda
Order Cyclopoida
Family Cyclopidae
Subfamily Halicyclopinae

Halicylops bowmani Rocha & Iliffe, 1993

	Halicylops bowmani: habitus, dorsal, after Rocha & Iliffe, 1993

Taxonomic Characterization: Female: Posterior borders of all prosomites smooth. Genital double somite 1.2 times longer than broad, and with slight lateral protrusion at halflength. Hyaline frill of posterior border of genital double somite and urosomite 3 with ventral denticles longer and more slender than dorsal ones. Caudal rami 1.3 times longer than wide. Outer apical seta twice longer than ramus and about 4 times longer than inner apical seta. Dorsal seta 1.5 times longer than outer apical seta. Antennule of 6 segments. Antenna of 3 segments. Inner spine of leg 1 basis reaching insertion level of seta of endopod segment 2. Leg 2 and leg 3 similar to each other; distal endopod segment of these legs with spiniform proximal seta being plumose basally and spinulose distally. Leg 4 inner setae about equal in length, plumose at basal 1/4 and serrate along remaining 3/4. Leg 5 exopod 1.6 times longer than wide. Male: Leg 4 endopod differing from female in having proximal seta on second segment modified as setae on terminal segment. Proximal seta on endopod segment 3 also shorter. Leg 5 exopod 1.6 times longer than broad, bearing 3 spines and 2 setae. Leg 6 represented by serrate inner spine, and 2 setae. Antennae, mouthparts, and legs 1-3 as is female (Rocha & Iliffe, 1993).

Disposition of Specimens: Type specimens were deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM 257021 and 257023) and in the Museu de Zoologia da Universidade de São Paulo (11380).

Ecological Classification: Stygobitic or stygophilic

Size: Female 500-530 microns, prosome:urosome ratio = 1.5-1.69 : 1. Male 410-430 microns, prosome:urosome ratio = 1.4-1.8 : 1.

Number of Species in Genus: Numerous

Species Range: Known only from Deep Blue Cave in Hamilton Parish, Bermuda.

Closest Related Species: Halicyclops bowmani resembles H. herbsti in the structure of the terminal segment of leg 4 endopod. The two species also share the same ornamentation of the posterior borders of the genital double somite and following urosomite. They differ by the presence of a well-developed anal pseudoperculum in H. bowmani. Other differences include the proportions of the caudal rami, the shape of the leg 5 exopod, and the armature of the last antennal segment (Rocha & Iliffe, 1993).

Habitat: Anchialine limestone caves

Ecology: Found in 0-2 m depths in the cave water column and on algae covered rocks of shaded cave entrance pools.

Life History: Collected specimens included 7 females, 8 males and 3 copepodids.

Evolutionary Origins: Halicyclops is a cosmopolitan genus found mainly in coastal brackish waters such as estuaries, lagoons, ponds. marshes, wells, interstitial water in sandy beaches, and cave (Rocha & Iliffe, 1993).

Conservation Status: Restricted to Deep Blue Cave in Hamilton Parish, Bermuda.

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Contributor: Carlos Eduardo F. da Rocha, Universidade de São Paulo, Brazil