Speleonectes parabenjamini Koenemann, Iliffe & van der Ham, 2003
Speleonectes parabenjamini after Koenemann et al., 2003
Taxonomic Characterization: A relatively small species composed of 24
postcephalic segments; pleural tergites well developed, broadly rounded,
becoming increasingly pointed in posterior part of trunk; trunk sternites with
pointed posterolateral corners; sternal bars heteromorphic; frontal filaments
with short, stout processes; antennules with long dorsal flagella; segment 4 of
maxillule subrectangular, bearing 1 very long, serrate spine and several slender
setae; maxillulary claw very long; maxilla and maxilliped slender, without
distinct tagmosis (segments on either side of the elbow are subequal in width
and length), setation sparse; arc of horseshoe-type claw composed of 7-8
small denticles; anal somite longer than wide; caudal rami shorter than anal
somite (Koenemann et al., 2003).
Ecological Classification: Stygobitic
Size: Adult length extends to 13 mm.
Number of Species in Genus: Nine, all stygobitic
Species Range: Know only from Basil Minns Blue Hole, Great Exuma Island,
Exuma Cays, Bahamas.
Closest Related Species: As the name implies, S. parabenjamini is morphologically closely allied with S. benjamini from Abaco.
Habitat: Anchialine limestone caves
Ecology: S. parabenjamini was collected from below a hydrogen sulfide layer in 33-43 m depths of an isolated, collapse, dome room located several hundred meters into the cave from the surface entrance. In the depth range in which remipedes were collected, salinity was about 34 ppt, temperature 25oC, pH 7.4 and dissolved oxygen 3 mg/l. Three new species of Speleonectes were collected from this cave including S. tanumekes, S. parabenjamini and S. minnsi. However, the sympatry of these three species is not exceptional for remipedes as several other instances of 2-3 sympatric species have been observed. Sympatric remipedes are likely to be subjected to strong competition, which could lead either to niche differentiation or competitive exclusion. S. tanumekes appears to be the most abundant remipede in this cave. Other stygobitic fauna from this cave includes copepods, ostracods, leptostracans, bochusaceans, amphipods, thermosbaenaceans, mysids, and polychaetes (Koenemann et al., 2003).
Life History: The fact that remipedes are hermaphrodites may point towards an adaptation to small population size (Koenemann et al., 2003).
Evolutionary Origins: Remipedes are an ancient group of crustaceans sharing several well defined features with Tesnusocaris goldichi from the Carboniferous. The current distribution of remipedes consists of a prominent cluster in the northern Caribbean including the Bahamas. Whether this cluster is an ancient center of origin and the disjunct taxa in the Canary Islands and Western Australia are isolated relicts remains to be seen (Koenemann et al., 2003).
Conservation Status: Known only from one anchialine cave on Great Exuma Island.
Contributor: Stefan Koenemann, University of Amsterdam, The Netherlands.
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