Isohypsibius saltursus Schuster, Toftner & Grigarick, 1978

(Figs 1 –7)

Material examined: 28 specimens: holotype (Pope Beach, Lake Tahoe, CA, X-10-75, sublittoral, RO Schuster, EC Toftner) and 27 paratypes (1–3. Pope Beach, Lake Tahoe, CA, X-10-75, sublittoral, RO Schuster, EC Toftner; 4–9. Pope Beach, L. Tahoe, CA, X-10-75, sublittoral, RO Schuster, EC Toftner; 10–11. Pope Beach, Lake Tahoe, Calif., VIII-15-75, sublittoral, RO Schuster, EC Toftner; 12. Pope Beach, Lake Tahoe, Calif., VIII-23-69, sand in stream, RO Schuster; 13. Pope Beach, Lake Tahoe, Calif., VIII-28-75, sublittoral, RO Schuster, EC Toftner; 14–15. Lake Tahoe, Pope Beach, Cal., IX-1-1974, RO Schuster, EC Toftner, Colrs.; 16. Pope Beach, Lake Tahoe, Calif., VIII-29-69, in sand, RO Schuster; 17–19. Pope Beach, Lake Tahoe, VIII-3-75, RO Schuster, sublittoral; 20. L. Tahoe, Pope Beach, Cal., IX-1-74, RO Schuster, EC Toftner; 21. Pope Beach, Lake Tahoe, III-17-1974, sublittoral, RO Schuster, EC Toftner, Colrs; 22. Pope Beach, Lake Tahoe, VIII-28-75, sublittoral Roschwater, RO Schuster, EC Toftner; 23. Pope Beach, Lake Tahoe, X-10-1975, sublittoral, RO Schuster, EC Toftner Colrs; 24. X-10-1975, sublittoral Roschwater, EC Toftner; 25. Pope Beach, Lake Tahoe, XI-7-1975, sublittoral, RO Schuster, EC Toftner; 26. Pope Beach, Lake Tahoe, XI-7-1975, sublittoral Roschwater, RO Schuster, EC Toftner; 27. Pope Beach, Lake Tahoe, XI-7-75, sublittoral Roshwater, EC Toftner.

Type locality: longitude 120°01’30” and latitude 38°56’20”, 1899 m. asl, Pope Beach, Lake Tahoe, California (USA)

Distribution: Known only from two localities in USA (Lake Tahoe, California; Lake Erie, Ohio).

CHARACTER N RANGE MEAN SD Holotype Redescription: Adult (for measurements see Table 1): Body white/transparent, eyes absent. Cuticle smooth or slightly wrinkled, without gibbosities, spines or defined sculpture (Fig. 2).

Buccal-pharyngeal apparatus with twelve peribuccal lamellae. Peribuccal papulae absent. Mouth anteroventral. Oral cavity armature composed of second and third band of teeth (first band of teeth absent). Second band composed of a number of irregular rows of small teeth and the third band composed of one row of larger teeth situated just under the second band of teeth (Figs 3–4, see also Fig. 25 (SEM microphotographs) in Schuster et al. 1978).

At the posterior end of the buccal tube, rod-shaped pharyngeal apophyses present. Pharyngeal bulb spherical with three rod-shaped macroplacoids (Fig. 4). The first macroplacoid longest, second shortest (i.e. macroplacoid length configuration is 1-3-2). Microplacoid and septulum absent.

Claws of the Isohypsibius type (configuration 2-1-2-1), similar in size and shape. Basal portions on all claws normally developed and slender (Figs 5 –7). Primary branches of claws with distinct knob and accessory points (Figs 5 –7, black arrows). Additionally, a clearly visible septum is present between the primary branch and the rest of the claw (Figs 5 –7). Lunules present only on external claws I–III and posterior IV (Figs 6 –7). Two long and straight bars present only under claws on legs I–III, no other cuticular bars are present on legs (Fig. 6). Claws I–III and anterior IV similar in length, but posterior IV clearly larger.

Eggs: oval deposited in exuvium (for more details see Schuster et al., 1978)

Remarks. Only ten specimens (including holotype) of all examined paratypes were measured (the remaining individuals are either in the simplex stage or the orientation of their structures was unsuitable for measurements).

In the original description, Schuster et al. (1978) drew lunules on the posterior claws IV and divided cuticular bars although these characters were not mentioned in the text. We also observed the lunules only under external claws I–III and posterior IV. The bases of the internal claws were slightly expanded. In most of the specimens two separate cuticular bars were visible (one bar under each claw), but in some specimens it was difficult to see this separation.

Differential diagnosis. Thulinius saltursus comb. nov. differs from:

T. augusti by: presence of lunules under the external and posterior claws, cuticular bars on legs divided, shorter and slightly broader basal claws, absence of subdivided lobes around the mouth.

T. itoi by: absence of lunules under the internal and anterior claws, cuticular bars on legs more robust and divided, lower pt of stylet insertion point (71.3–74.7 in T. saltursus and more than 80.0 in T. itoi).

T ruffoi by: absence of lunules under the internal and anterior claws, cuticular bars on legs divided.

T. stephaniae by: presence of lunules under the external and posterior claws, cuticular bars on legs less strong and divided.