Contributions to Zoology, 70 (3) (2001)Carlos Neira*; Gunnar Gad; Nina L. Arroyo; Wilfrida Decraemer: Glochinema bathyperuvensis sp. n. (Nematoda, Epsilonematidae): A new species from Peruvian bathyal sediments, SE Pacific Ocean
Systematic description

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Remarks.

– The number of dorsal-subdorsal pharyngeal thorns varies individually not only in number but also in their distribution, however, independently of sex or developmental stage (fourth juvenile stage). They can be paired in one annule or asymmetrically set on different annuli. Moreover, some of these thorns are accompanied by somatic setae and some appear bifurcated either at their base or at the tip. Only the pair of thorns which in the holotype is situated in annule 10 (Figs. 2A, 2B, 2F) seems to be constant and accompanied by a seta. The blade-like cuticular protrusions forming a palisade surrounding the anterior pharyngeal region can also vary in number (10 to 13 at each side) and disposition. Sometimes, two of them originate on the same annule and sometimes single ones are bifurcated. Paratype 1 illustrates most of these differences (Fig. 2B). This specimen shows a second dorsal thorn in annule 19, together with 3 small lumps in the preceeding annuli. Intraspecific variability in the disposition of ambulatory setae and of cuticular structures has already been pointed out for Glochinema chilense and G. agile (Lorenzen, 1974) and for Metaglochinema globicephalum (Gourbault & Decraemer, 1986).

The determination of the number of ambulatory setae of the outer subventral rows is not always evident. The posteriormost ambulatory setae without distinct bending are not always clearly differentiated from the anteriormost supporting setae. Data on more juvenile stages could elucidate this problem.