Hypsibius microps Thulin, 1928

Kaczmarek, Łukasz & Michalczyk, Łukasz, 2009, Redescription of Hypsibius microps Thulin, 1928 and H. pallidus Thulin, 1911 (Eutardigrada: Hypsibiidae) based on the type material from the Thulin collection, Zootaxa 2275, pp. 60-68 : 61-62

Hypsibius microps Thulin, 1928

( Figs.1–3 , 7–9 , 13 , 15–17 )

Redescription. Adult (measurements in Table 1 ): Body white/transparent ( Fig. 13 ). Large eyes present.

Cuticle smooth, without pores. Bucco-pharyngeal apparatus of the Hypsibius type ( Figs.7 , 15 ). Mouth anteroventral, without lamellae or papulae.

Oral cavity armature absent or not detectable under DIC. Buccal tube rigid and with one bend in posterior part (visible in lateral view). Ventral buccal lamina absent. Pharyngeal bulb almost spherical with distinct triangular apophyses, two macroplacoids and without the microplacoid. Macroplacoids in the shape of small granules (almost as wide as long), without constrictions. The first microplacoid only slightly longer than the second ( Figs.7 , 15 ).

Claws of the Hypsibius - type, small and stout ( Figs.8–9 , 16–17 ). Internal claws much smaller and in a different shape than the external ones.

External claws with slender primary branches connected with the rest of the claw by a thinner, lightrefracting part. Secondary branches equal or longer than base claws (i.e., primary branches seem to be attached low, near the claw base), secondary branches relative lengths vary between 50.0% and 62.9% (mean ± SD: 57.3 ± 3.2%, calculated from all measurable claws, n=20).

Internal claws smaller and more robust with primary branches connected to the rest of the claw without a thinner, light-refracting part ( Fig. 9 ). Primary branches of external and internal claws with distinct accessory points. Lunules and other cuticular structures on legs absent.

Eggs: White/transparent, smooth, oval, deposited in exuvium (1–4 per exuvium).

Remarks: Measurements and pt values of selected morphological structures for 5 specimens are provided in Table 1 . Among 5 analysed specimens, three had eyes (60%).

Material examined: Holotype and 8 paratypes (see Material and Methods for details).

Figures

FIGURES 1 – 6. The type material of Hypsibius microps and Hypsibius pallidus from the Thulin collection: 1 – 3, H. microps; 4 – 6, H. pallidus.

FIGURES 7 – 12. Thulin’s original drawings of H. microps and H. pallidus: 7 – 9, H. microps (7, buccal apparatus; 8, external claw III; 9, claws IV); 10 – 12, H. pallidus (10, buccal apparatus; 11, external claw III; 12, claws IV). (7 – 11 from Thulin 1928, 12 from Thulin 1911, not scaled)

FIGURES 13 – 14. The type material of Hypsibius microps and Hypsibius pallidus from the Thulin collection: 13, H. microps, habitus (holotype); 14, H. pallidus, habitus (paratype). (scale on 14 same as on 13)

FIGURES 15 – 20. The type material of Hypsibius microps and Hypsibius pallidus from the Thulin collection: 15 – 17, H. microps (15, buccal apparatus (holotype); 16, claws III (holotype); 17, claws IV (holotype )); 18 – 20, H. pallidus (18, buccal apparatus (paratype); 19, claws III (holotype); 20, claws IV (paratype )). (scale on 18 same as on 15, and on 17, 19 - 20 same as on 16)