Hypsibius valentinae, Pilato, Giovanni, Kiosya, Yevgen, Lisi, Oscar & Sabella, Giorgio, 2012

Pilato, Giovanni, Kiosya, Yevgen, Lisi, Oscar & Sabella, Giorgio, 2012, New records of Eutardigrada from Belarus with the description of three new species, Zootaxa 3179, pp. 39-60 : 54-57

Hypsibius valentinae sp. nov.

( Fig. 9 )

Type material. Minsk Oblast, vicinity of Zhodino, pine forest (approximately 54°6ʹ N, 28°21ʹ E), moss on soil collected (November 2008) by S.A. Dobrovolsky: holotype and 55 paratypes; moss on wood collected (November 2008) by S.A. Dobrovolsky: 19 paratypes. Vitebsk Oblast, Sennensky district, Spruce forest, Vicinity of Margoitsy village (54°40'19"N, 29°37'27"E); moss sample collected (June 2002) by G.O. Mazepa: 1 specimen.

Type repository. Holotype (slide No. 5436) and 21 paratypes (slides No. 5426, 5427 and 5429) are deposited in the collection of Binda & Pilato (Museum of the Department of Animal Biology “Marcello La Greca”, University of Catania, Italy). Other specimens and exuvia are deposited in the collection of Kiosya (Kharkiv National University, Ukraine).

Specific diagnosis. Cuticle smooth; eye spots present; two macroplacoids and a small septulum present; claws of the Hypsibius type with slightly enlarged bases and accessory points on the main branches; small, smooth, flexible lunules present; a short cuticular bar was present between the bases of the claws of the hind legs; no cuticular bar on the first three pairs of legs.

Description of the holotype. Body length 315 µm; colourless, cuticle smooth; cuticular pores and dots not visible. Eye spots present. Bucco-pharyngeal apparatus of the Hypsibius - type ( Fig. 9 A). Mouth subterminal without peribuccal lamellae; buccal cavity small without rings of teeth. Rigid buccal tube, without ventral lamina, 27.2 µm long and 2.0 µm wide (pt = 7.4); apophyses for the insertion of the stylet muscles hook-shaped; stylet supports inserted on the buccal tube at 62.2% of its length (pt = 62.2). Pharyngeal bulb with apophyses, two macroplacoids and a small septulum. Length of first macroplacoid 6.0 µm (pt = 22.1), second 4.4 µm (pt = 16.2), and septulum 1.4µm (pt = 5.1); entire placoid+septulum row 12.1 µm long (pt = 44.5); macroplacoid row length 10.9 µm (pt = 40.1).

Claws of the Hypsibius - type, well developed ( Fig. 9 B–E) with slightly enlarged base and accessory points present on the main branches. Due to the orientation, only some of the claws were measurable; external claws on the first and second pairs of legs 14.9 µm (pt = 54.8) and 16.4 µm long (pt = 60.3) respectively; posterior and anterior claws on the hind legs 17.2 µm (pt = 63.2) and 11.5 µm long (pt = 42.3) respectively. Small, smooth, flexible lunules, present but difficult to see ( Fig. 9 C, arrow; Fig 9 E, arrow a); a short cuticular bar was present between the bases of the claws of the hind legs ( Fig. 9 E, arrow b); no cuticular bar on the first three pairs of legs. Smooth eggs laid in the exuvia.

Remarks. The paratypes were similar to the holotype in qualitative and metric characters. (we referred to the pt index values when the specimens had different body length). The measurements of three specimens are presented in Table 4.

Etymology. The specific name refers to the zoologist Valentina Schevchenko , our colleague from the Chernihiv National University ( Ukraine).

Differential diagnosis. Prior to this description of Hypsibius valentinae sp. nov., six species of Hypsibius were described with smooth cuticle, two macroplacoids and septulum: H. iskandarovi , H. septulatus , H. heardensis Miller, W.R., McInnes, & Bergstrom, 2005 , H. seychellensis , H. dujardini , and H. pallidoides . Comparing adults of, where possible, comparable size the new species can be from the other species (Table 4) as follows:

The new species differed from H. iskandarovi , H. septulatus and H. heardensis in lacking cuticular bars on the first three pairs of legs; in addition, it differed from H. iskandarovi in having eye spots; lacking a pseudoseptulum ( Figs. 9 A, B and 10A), and had shorter claws (the pt index relative to the posterior claws of the hind legs about 63 in Hypsibius valentinae sp. nov., 75.4–95.3 in H. iskandarovi according to Tumanov, 1997).

The new species also differed from H. septulatus in lacking cuticular undulations; having a slightly narrower buccal tube; smaller septulum (Table 4; Figs. 9 A and 10C), and in having lunules.

It also differed from H. heardensis in having eye spots and lunules.

The new species differed from H. pallidoides by having stylet supports inserted on the buccal tube in a more caudal position (pt = 61.3–62.5 in H. valentinae sp. nov., 54.2–55.2 in H. pallidoides ); slightly longer placoids and septulum; external claws very different in shape as the claws of H. pallidoides were of the pallidus type (i.e. with the main branches inserted on the internal branches more distant from the base) ( Figs 9 C–D and 11A); and in having lunules.

Hypsibius valentinae sp. nov. differed from H. seychellensis in having slightly wider buccal tube (Table 4); smaller septulum; longer claws (Table 4), and in having lunules ( Figs. 9 C, arrow, ad 11B).

The new species differed from H. dujardini in having the buccal tube of the same width in the anterior and posterior portion, while in H. dujardini the width of the buccal tube gradually increases; smaller septulum (Table 4; Figs. 9 A and 11D), and in having lunules.

Hypsibius valentinae sp. nov. had a small septulum, Hypsibius allisoni had a very small microplacoid; considering the dimensions of these structures and, sometimes, the difficulty in distinguishing between a microplacoid and a septulum in these species, we think it opportune to stress that H. valentinae sp. nov. also differed from H. allisoni in having different claw shape as the main branch of external claws was inserted on the secondary branch in a more distal position ( Figs. 9 B–E and 11C); in having small lunules and a cuticular bar between the bases of the claws on the hind legs.

Very probably Hypsibius convergens sensu stricto lacks both microplacoid and septulum, but some authors attributed to this species specimens that have a small microplacoid and, due to the possibility of confusion between microplacoid and septulum, it cannot be excluded that at least some of those specimens will have a septulum. In this case, it would be necessary to ascertain whether they belong to H. valentinae sp. nov. as, in our opinion, such specimens cannot be attributed to H. convergens . In any case, Hypsibius valentinae sp. nov. differed from H. convergens in having lunules and the common portion of the claws longer, slender and with the basal extremity less expanded.

Figures

FIGURE 9. Hypsibius valentinae sp. nov. A, bucco-pharyngeal apparatus of the holotype (slide No. 5426). The arrow indicates the small septulum. B, Claws of the first pair of legs of the holotype. C, Claws of the second pair of legs of a paratype (slide No. 5426) (arrow indicates the small lunula of the external claw). D, Claws of the third pair of legs of the same paratype. E. Claws of the hind legs of a paratype (slide No. 5426) (arrow ‘ a’ indicates the lunula of the anterior claw; arrow ‘ b’ indicates the cuticular bar between the claws). (Scale bars = 10 µm).