Gordius paranensis, Camerano, 1892

Schmidt-Rhaesa, A., Thomas, F. & Poulin, R., 2000, Redescription of Gordius paranensis Camerano, 1892 (Nematomorpha), a species new for New Zealand, Journal of Natural History 34 (3), pp. 333-340 : 334-336

Gordius paranensis from New Zealand

The length of 19 specimens measured varies between 7.5 and 22 cm with 7.5 cm being an unusually short male, because the length of all other specimens varies between 13 and 22 cm, with an average length of 17.6 cm. The maximal diameter varies between 0.3 and 0.7 mm with longer specimens being thicker than shorter ones. The anterior end is not distinctly tapered. The body colour varies from a very light creamy brown to darker chestnut brown. The anterior end (calotte) is white in some specimens, followed by a brown pigmentation that is slightly darker than the remaining body (collar). Other specimens lack the white calotte and have a completely brown body. The mouth opening is not closed by cuticle and is situated terminally on the anterior end (fi gure 2A). In the posterior end the cuticle around the cloacal opening and of the postcloacal crescent is pigmented darker than the surrounding cuticle, indicating a stronger cuticularization. This is especially evident in lightly coloured specimens. Some specimens have white spots on their cuticle.

The cuticle of the whole animal is generally smooth and unstructured. The exception is a hexagonal or polygonal cuticular pattern (areolation) that is visible in a small region anterior of the precloacal row of bristles (see below). This region is a few micrometres broad and areoles disappear anteriorwards (fi gure 1C).

The posterior end of the males is bilobed, the tail lobes are shorter than the diameter of the animals (in an average-sized specimen with a diameter of 0.5 mm the tail lobes were 0.35 mm long and 0.22 mm in diameter). Posterior of the round cloacal opening is a semicircular cuticular structure called the postcloacal crescent which is present in all Gordius species (fi gure 1A). Anterior of the cloacal opening is a parabolic or semicircular row of bristles (fi gure 1A). This row ends at about the level of the postcloacal crescent. The bristles are longest in the ventral region anterior of the cloacal opening and become shorter towards the posterior ends of the row. They are not furcated apically. The cuticular surface that is enclosed by the parabolic row of bristles is very smooth, smoother than the cuticle of the remaining body. Only in one specimen investigated were there short spiny structures present in this area (fi gure 1D).

One of the specimens investigated ultrastructurally showed a peculiar structure on the anterior end that was not present in the other specimens. The region around the terminal mouth opening is surrounded by knob-like structures (fi gure 2A, B). In a distance of about 110 μm from the mouth opening, these structures are replaced by short spines. These spines form a circle of about 70 μm (figure 2A). Halfway between mouth opening and the circle of spines there is an irregular line that likely represents the separation of two cuticular layers (fi gure 2B).

The host of Gordius paranensis in New Zealand is the Cave Weta Pleioplectron simplex Hutton, 1897 ( Rhaphidophoridae , Orthoptera ) (fi gure 3).

Gordius paranensis from Chile

The three complete animals of the museum collection were 24, 30.5 and 34.5 cm long with a diameter between 0.8 and 1.3 mm. The colour of the body is dark brown, white spots are present on the cuticle. A white calotte and a dark collar are not present, in one specimen only the anterior end was slightly lighter than the remaining body. The anterior end is not distinctly tapered. The cuticle is smooth, but the preservation of the specimen investigated was not good enough to observe further details, e.g. if a local areolation similar to that of the New Zealand species is present or not.

The tail lobes of the male posterior end are shorter than the diameter of the animals. The postcloacal crescent is semicircular, as is the precloacal row of bristles (fi gure 1B). The bristles of the precloacal row are not furcated apically. The cloacal opening is round.