Prehendocyclops abbreviatus Rocha, 2000
Prehendocyclops abbreviatus: after Rocha et al., 2000
Taxonomic Characterization: Characteristic of the genera
Prehendocyclops is an antennal prehensile device formed by a stout curved
spine on the third segment, and the three proximalmost appendages of the
terminal segment modified into stout, heavily serrate spines; the distalmost
spine of these is claw-shaped. Additionally, on the praecoxal arthrite of the
maxillule the two outermost apical spines are curved towards a strong, straight,
pointed spine inserted on the inner surface of the arthrite. P. abbreviatus
differs from other species of Prehendocyclops in having a more elongated
prosome, a pair of integumental windows only on the pedigerous somite 2, a
genital double somite as well as the 2 subsequent somites without integumental
sensilla, a seminal receptacle with almost straight ducts leading to the genital
antra, a remarkably reduced outer middle apical caudal seta, a short inner
apical spine of the praecoxal arthrite, the ventral surface of the labrum
smooth, the setae of the praecoxal endite of the maxilla very different in
length, the maxilliped with the terminal segment reduced to a small knob, 2
outer spines on expod 3 leg 1, and legs 1-4 with only 1 integumental pore on the
outer corner of the basis (Rocha et al., 2000).
Disposition of Specimen: National Museum of Natural History, Smithsonian Institution, catalog number USNM 287100.
Ecological Classification: Stygobitic
Size: Female body length, excluding caudal setae, measures 0.665 mm
Number of Species in Genus: Three
Species Range: Known only from Cenote Chan-Hoch, Homun, in the State
of Yucatan, Mexico.
Closest Related Species: Sister species P. monchenkoi and P. boxshalli, although these two species are morphologically more similar to each other than to P. abbreviatus.
Habitat: Anchialine limestone caves
Ecology: Found free-swimming and near submerged tree roots at depths of 0-8 m. Prehendocyclops has modified mouthparts and antenna like its sister genera Colpocyclops and Smirnoviella, which enable the genera to externally parasitize a host. Thus, Rocha et al. assumed that Prehendocyclops is probably also parasitic, although the possible host is unknown.
Life History: Not known, only a single adult female has been identified.
Evolutionary Origins: Prehendocyclops and sister genera Smirnoviella and Colpocyclops, which evolved in esturaries connected to the Caspian and Black Sea, were linked in the past as part of the Tethys Sea. Considering that the three genera have similar mouthparts and antenna, they may be derived from one or more ectoparasitic Halicyclops-like ancestral forms (Rocha et al., 2000).
Conservation Status: Restricted to a single cave in Yucatan.
Contributor: Carlos Eduardo F. da Rocha, Universidade de São Paulo,
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