Gordius zwicki, 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 : 28-29

Gordius zwicki sp. nov.

( Fig. 10 C–F, 11C)

Type material: Holotype: 13, Zoological Museum Hamburg, ZMH V13275 .

Type locality. Russia, Russian Far East, small forest tributary in the upper course of Milogradovka River, 25 km NW of Milogradovo (coll. June 13, 1998 By Peter Zwick).

Other material examined. 13, Paratype from same location, same sample data: Zoological Museum Hamburg, ZMH V13276 . A further 43 and 6ƤƤ were found together with the paratype and holotype, these were not included in the detailed description (see under Remarks). These specimens are stored in the collection of A. Schmidt-Rhaesa as numbers 16–20, 22–23 and 25–27.

Etymology. The name honours the collector Peter Zwick for sending these and other specimens and for his continuing interest in gordiid biology.

Description. The body color is light brown; white spots are absent. The anterior end includes a white tip followed by a very weakly colored collar. Faintly darker ventral and dorsal median lines are visible. The holotype is 220 mm long, the paratype 270 mm. Their diameters are 0.5 and 0.6 mm, respectively.

The postcloacal crescent is very slightly parabolic and quite broad ( Fig. 10 D,E). It is directly at the point of bifurcation but extends slightly onto the tail lobes. The cloacal opening is round ( Fig. 10 D,E). The tail lobes are slightly shorter than twice their diameter, the inner side is not concave. Scattered tiny bristles are present only in the region around the cloacal opening, extending posteriorly not further than the posterior border of the postcloacal crescent ( Fig. 10 F, 11C). The tail lobes themselves are devoid of cuticular structures with the exception of a small region of minute spines posterior to the tips of the postcloacal crescent ( Fig. 10 F, 11C). These spines differ from bristles in being short and conical. Such spines are also present on the ventral cuticle in a broad region anterior of the cloacal opening.

The cuticle is smooth and no bristles were observed. On the terminal tip of the holotype, the cuticular surface appears to be abraded, resulting in a roughly structured surface (see Fig. 4 D).

Remarks. The distribution pattern of bristles and spines is unique to this species. The two specimens described in detail were found in a knot containing 12 specimens, 63 and 6ƤƤ. Females showed a smooth cuticle, but no further characters. The state of preservation of the other males was not sufficient to be included in the description.

Figures

FIGURE 4. Cuticular structures and artifacts. A. Scars on the surface of G. aquaticus from Germany (SR 952). B. The mixture of smooth and otherwise structured surface may be due to erostion (undetermined Gordius specimen from Italy; SR 1367). C. Cuticular surface structure in an undetermined Gordius specimen from Germany; SR 1031). D. Smooth and rough structure of the cuticle in G. z w i c k i sp. nov. (holotype ZMH V 13275). E. Cross section of the cuticle (cut) with layers of fibres. Below cuticle are epidermis (epi), longitudinal musculature (mus) and parenchyme (par) (G. helveticus sp. nov., paratype ZMH V 13277). F. “ Rhomboidal pattern ” on the cuticle created by the underlying arrangement of cuticular fibres (G. aquaticus from Germany, SR 995).

FIGURE 10. A, B. Gordius serratus sp. nov., C – F. G. z w i c k i sp. nov. A. Posterior end of holotype. B. Posterior end of paratype. C. Posterior end of paratype. D. Posterior end of holotype. E, F. Characteristic distribution of spines (arrow) posterior to the postcloacal crescent.