Parascon nichollsae, Pilato, Giovanni & Lisi, Oscar, 2004

Pilato, Giovanni & Lisi, Oscar, 2004, Doryphoribius neglectus sp. n. and Parascon nichollsae sp. n., new species of eutardigrades from Australia, Zootaxa 545, pp. 1-7 : 4-7

Parascon nichollsae n. sp. ( Fig. 2. A –D)

Description of the holotype: Body length 220.0 µm, colorless, cuticle smooth without pores, eye spots absent. Bucco­pharyngeal apparatus of Parascon type ( Fig. 2 A ); buccal tube rigid without ventral lamina, pharyngeal tube rigid without spiral thickening; apophyses for the insertion of the stylet muscles shaped like flat ridges; their caudal processes (very thin and pointing laterally in the genus) not visible due to the orientation of the specimen. No cuticular drop­like thickening present between buccal and pharyngeal tube. Stylet furcae very small, with very short branches, not swollen. Stylet supports present. Total length of the bucco­pharyngeal tube 20.8 µm; buccal tube 15.5 µm long (pbf = 74.5) and 1.5 µm wide (pt = 9.7). Pharyngeal bulb without apophyses and placoids ( Fig. 2 A , C). Claws of Hypsibius type ( Fig. 2 C); main branches with thin accessory points. On all legs the external claws have, as the other species of genera Parascon , Itaquascon and Astatumen , a slightly forked base. Due to the orientation, we were able to measure only the external claws of the first pair of legs (12.7 µm long: pt = 81.9), the external claws of the second pair of legs (13.4 µm long: pt = 86.5), and the internal claws of the second pair of legs (5.7 µm: pt = 36.8). Lunules and other cuticular thickenings on the legs absent.

Differential diagnosis: Up to now only one species of genus Parascon is known: Parascon schusteri Pilato & Binda 1987 ( Fig. 2 B) from Tanzania. The new species differs from it in the following features: shorter pharyngeal tube length in relation to the total length of the bucco­pharyngeal tube (see Fig. 2 and the values of the pbf index in table 1), shorter claws with lower values of the pt index (table 1).

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Figures

FIGURE 2. A, Bucco­pharyngeal apparatus of Parascon nichollsae sp. n.; B, bucco­pharyngeal apparatus of Parascon schusteri; C, claws of the first three pairs of legs of Parascon nichollsae sp. n.; D, claws of the first three pairs of legs of Parascon schusteri. (Scale bar = 20 µm).