Procaris chacei Hart & Manning, 1986
Procaris chacei: lateral view, after Hart & Manning, 1986
Taxonomic Characterization: Procaris chacei has a thin, fragile integument. The rostrum is short and acutely triangular, unarmed, reaching almost to the distal margin of the eyes. The carapace is unarmed. The abdomen with third somite produced posterodorsally as narrowly rounded cap hooding anterior half of fourth somite when abdomen extended. Telson, not including posterior spines, about 1.25 times as long as sixth somite. The eyestalk
splits into 2 blunt subtriangular lobes. The antennular peduncle is short and broad, reaching distal one-third of the antennal scale. The antennal scale is slightly less than 2.5 times as long as wide, with the distal margin rounded and a distolateral tooth. The mandible is massive, with a prominent 3-jointed palp, incisor and molar processes fused. All 5 pairs of pereiopods similar, each with large simple setae on flexor margins. The dactyls are short and stout, armed
with curved spines and long setae. All pleopods are similar, with short poorly developed endopods, none with appendices internae or masculinae (Hart & Manning, 1986).
Disposition of Specimens: Type specimens were deposited in the United States Museum of Natural History (USNM 195164, 195165).
Ecological Classification: Stygobitic
Size: Carapace length 10 mm.
Number of Species in Genus: Four, including one undescribed species; all stygobitic
Species Range: Known only from Green Bay Cave in Hamilton Parish, Bermuda.
Closest Related Species: Procaris chacei is very similar to both P. ascensionis and P. hawaiiana, though the species are different in that P. chacei has a lateral lobe longer than the median lobe in the eyes, whereas P. hawaiiana has equal lobes and P. ascensionis has a median lobe longer than the lateral lobe (Hart & Manning, 1986).
Habitat: Anchialine limestone caves
Ecology: P. chacei was collected from Green Bay Cave in Bermuda. Specimens were collected from more remote parts of this cave including the North Shore Passage and below the Air Bell Lake.
Life History: The sex was undetermined because secondary sexual characters appear to be lacking in P. chacei as in other Procaris species.
Evolutionary Origins: Hart and Manning (1986:416) note that the similarities between species and their highly anomalous distribution in marine caves indicate an extremely slow rate of evolution. They suggest that, "Procaris, or its predecessors, may, at one time, have been widely distributed throughout the oceans, surviving today only in cryptic habitats removed from some of the environmental pressures necessitating change."
Conservation Status: This species is listed as critically endangered (IUCN, 1996).
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