Gordius helveticus, Schmidt-Rhaesa, Andreas, 2010

Schmidt-Rhaesa, Andreas, 2010, Considerations on the genus Gordius (Nematomorpha, horsehair worms), with the description of seven new species, Zootaxa 2533, pp. 1-35 : 24

Gordius helveticus sp. nov.

( Fig. 8 , 11 A)

Type material: 13, Holotype: Zoological Museum Hamburg, ZMH V13272 .

Type locality. Swizerland, Meiringen (Berner Oberland), altitude 793m. (coll. July 18, 2008 by Axel Groenveld).

Other material examined. 13, Paratype from same location, same sample data: Zoological Museum Hamburg, ZMH V13277 .

Etymology. The name refers to the sampling location in Swizerland ( Helvetia).

Description. The body color is medium brown; white spots are present; one dark median line is slightly visible. The anterior end includes a white tip followed by a very weakly darker colored collar. The holotype is 160 mm long and has a diameter of 0.6 mm, the paratype measures 135 mm in length and 0.55 mm in diameter.

The postcloacal crescent is semicircular ( Fig. 8 A,D). It is directly at the point of bifurcation; the arms extend slightly onto the tail lobes. The tail lobes are a bit shorter than their double diameter, the inner side is not concave. The cloacal opening is round ( Fig. 8 D). Bristles occur in the posterior end in a particular distribution pattern. In the holotype, the bristles appear a bit more prominent than in the paratype, but the distribution pattern is the same. Scattered bristles occur on the ventral side of the posterior end at the level of the cloacal opening, but the region immediately around the cloacal opening is free of bristles ( Fig. 8 A). Scattered bristles are also found on the tail lobes, they concentrate in one region on the inner side of the tail lobes. This region is a patch of dense bristles posterior to the tips of the postcloacal crescent ( Fig. 8 A,B, 11A). The cuticular surface of the remaining body contains several scattered bristles ( Fig. 8 C).

Remarks. The distribution of bristles in the posterior end of this species must be compared to G. borisphaenicus Spiridonov, 1984 from the Ukraine ( Spiridonov 1984) and G. karwendeli (see below), which also have peculiar distribution patterns. Gordius borisphaenicus has one concentration of spines (not bristles) on the inner side of the tail lobes, about halfway between the point of bifurcation and the tips. Gordius karwendeli has a smaller, row-like concentration of bristles posterior to the postcloacal crescent. Because the distribution pattern is observed in two specimens (with only some differences in the density), and because clear differences are present to the two other species mentioned, G. helveticus is regarded as a new species.

Figures

FIGURE 8. Gordius helveticus sp. nov. A. Posterior end of holotype, arrows indicate characteristic accumulation of bristles posterior of the postcloacal crescent. B. Magnification of bristles marked by arrow in A. C. Body cuticle of paratype showing scattered bristles. D. Posterior end of paratype.

FIGURE 11. Schematic drawing indicating the differences in the distribution of bristles and spines in the posterior end of A. G. helveticus, B. G. karwendeli and C. G. zwicki.