Phylum Arthropoda
Subphylum Crustacea
Class Remipedia
Order Nectiopoda
Family Speleonectidae

Speleonectes benjamini Yager, 1987


Taxonomic Characterization: No eyes. Antenna 1 very long, extending from 1/2 to 2/3 the length of the body. Trunk appendages with many small, serrate, spine-like comb setae along distal margins of predistal segments. Body elongate, slender, with tiny setae dispersed over surface. Without pigment. Cephalic shield small, tapered slightly at anterior end. Trunk segment numbers vary with age, with a maximum number of 27. The terminal fang is quite long and slender. Raptorial life-style (Yager, 1987).

Ecological Classification: Stygobitic

Size: Maximum length of examined specimens is 16.8 mm.

Number of Species in Genus: Nine, all stygobitic

Genus Range:

Species Range: Known from Asgard Cave and Sagittarius Cave, Sweeting's Cay, Grand Bahama Island and from Dan's Cave, Abaco Island, Bahamas.

Closest Related Species: S. benjamini is morphologically similar to S. lucayensis Yager, 1981 and S. ondinae (Garcia-Valdecasas, 1985).

Habitat: Anchialine limestone caves

Ecology: Found below the density interface in low oxygen, polyhaline waters. Associated fauna include the remipedes S. lucayensis, Cryptocorynetes haptodiscus, and Godzillius robustus, amphipods, isopods, thermosbaenaceans, ostracods, mysids and the blind cave fish Lucifuga spelaeotes.

Life History: Five adult specimens have been collected. According to Yager (1994):
"Remipedes are simultaneous hermaphrodites. The ovary originates in the posterior portion of the head and lies dorsal to the midgut. The oviducts extend ventrally to the 7th swimming or trunk appendages where the female gonopores are located. The female gonopore is a semicircular structure on the posterior base of the protopod.
The testes are paired organs which originate in the 7th trunk segment and extend posteriorly until about the 10th trunk segment. At this position there is a transition from testes to vas deferens. The vas deferens extends to the male gonopores located at the base of the 14th swimming or trunk appendages. Spermatids are flagellate with a 9 + 2 microtubular arrangement. As they mature and move posteriorly they are packages into spermatophores.
To date, nothing is known about remipede development. Small juveniles have been collected which resemble adults. They are about one-third or less the length of adults."


Evolutionary Origins: The large number of trunk segments, each with similar, laterally directed, biramous, swimming appendages, plus a combination of the other characteristics necessitated the erection of a new crustacean class, the Remipedia (Yager, 1981). Remipedes are believed to be the most primitive of living crustaceans. The fossil species Tesnusocaris goldichi Brooks from Late Mississippian deposits in Texas has been placed in this class. The recent discovery of remipedes from anchialine caves in Western Australia is further evidence for a Tethyan distribution (Yager & Humphreys, 1996).

Conservation Status: Restricted to one anchialine cave on Abaco and two on Grand Bahama Island.

References:

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Contributor: Jill Yager, Antioch College, Yellow Springs, OH