Diphascon (D.) platyungue, Pilato & Binda & Bertolani & Lisi, 2005

Pilato, Giovanni, Binda, Maria Grazia, Bertolani, Roberto & Lisi, Oscar, 2005, Four new species of the Diphascon nobilei group (Eutardigrada, Hypsibiidae), Journal of Natural History 39 (14), pp. 1029-1041 : 1036-1037

Diphascon (D.) platyungue sp. n.

( Figure 4 ; Table I)

Material examined

Marche: Mt Vettore (Ascoli): Shelter Zilioli (2250 m): holotype (slide N. 4926) and three paratypes in meadow; Zilioli cross (2150 m) (three specimens in meadow) ; Latium: Sabaudia (Latina) (three specimens from mosses on sand dunes in pine-wood) .

Description of the holotype

Body length 194 M m, colourless, eyes absent, cuticle smooth without pearls. Buccopharyngeal apparatus shown in Figure 4A . The bucco-pharyngeal tube, measured as indicated in the description of D. serratum , is 45.2 M m long; the rigid buccal tube 20.8 M m long (pbf 546) and 1.7 M m wide (ptd 58.2). The stylet supports are inserted on the bucal tube at 62.9% of its length (ptd 562.9). The pharyngeal bulb (27.4 M m × 19 M m) has small apophyses, three rod-shaped macroplacoids and microplacoid, the septulum is absent. The entire placoid row is 16.1 M m in length (ptd 577.4) including the microplacoid, 14.1 M m (ptd 567.8) excluding it. The first macroplacoid is 3.8 M m in length (ptd 518.3), the second 3.6 M m (ptd 517.3), the third 5.7 M m (ptd 527.4), microplacoid 1.7 M m (ptd 58.2).

The claws ( Figure 4B–D ) have accessory points on the main branches. The claws of the hind legs ( Figure 4C ), particularly of the posterior claws, have the basal portion extremely enlarged; their branches are short; the indented basal margin of both internal and external claws appear prolonged in one medial and one lateral thickening. On the first three pairs of legs ( Figure 4B, D ) the external claws have an indented basal margin, the internal claws have a smooth basal margin. The internal claws are 6.1 M m long (ptd 529.3) on the second and third pairs of legs, the external claws of the same pairs of legs are not measurable due to their unfavourable orientation (in other specimens the value of the ptd index relative to these claws is 36–39.3); on the hind legs the anterior claws are 6.5 M m long (ptd 531.2) and the posterior claws 8.5 M m long (ptd 540.9). A cuticular bar is present near the internal claws on the first three pairs of legs.

Eggs not found.

The paratypes are similar to the holotype. In Table I the dimensions of some structures of the smallest and of the largest measured specimens are indicated.

Etymology

The name platyungue refers to the shape of the basal portion of the hind legs.

Remarks

Diphascon platyungue sp. n. differs from D. nobilei in having claws shorter with respect to the buccal tube length ( Table I), claws of the hind legs with a wider basal portion, internal claws on the first three pairs of legs without basal spines.

The new species differs from D. serratum in having the stylet supports inserted on the buccal tube in a more cephalic position ( Table I), narrower buccal tube, shorter placoids ( Table I), claws of the hind legs with a wider basal portion.

The new species differs from D. nelsonae in the following features: slightly longer buccal tube and, as a consequence, lower values of the ptd index relative to placoid row and to the claw length ( Table I); claws shorter and less slender with shorter secondary branches, claws of the hind legs with a clearly larger basal portion ( Figures 3 , 4 ).

Figures

Figure 3. Diphascon (D.) nelsonae sp. n. (A) Bucco-pharyngeal apparatus; (B) claws of the second pair of legs; (C) claws of the fourth pair of legs. Scale bar: 10 Mm.

Figure 4. Diphascon (D.) platyungue sp. n. (A) Bucco-pharyngeal apparatus; (B) claws of the third pair of legs; (C) claws of the fourth pair of legs; (D) claws of the second pair of legs of a paratype. Scale bar: 10 Mm.