Notahypsibius pallidoides ( Pilato, Kiosya, Lisi, Inshina & Biserov, 2011 ) Tumanov, 2020

Tumanov, Denis V., 2020, Integrative redescription of Hypsibius pallidoides Pilato et al., 2011 (Eutardigrada: Hypsibioidea) with the erection of a new genus and discussion on the phylogeny of Hypsibiidae, European Journal of Taxonomy 681, pp. 1-37 : 22-23

Notahypsibius pallidoides ( Pilato, Kiosya, Lisi, Inshina & Biserov, 2011) gen. et comb. nov. Figs 1–7 , Tab. 2, 3

Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011: 13–15 , fig. 7a–d (description).

Geographical distribution

This species was described from Kherson Oblast, South Ukraine ( Pilato et al. 2011). Later it was recorded for the Minsk Oblast, Central Belarus ( Pilato et al. 2012) and Sicily ( Lisi 2015). My observations extend the distribution of this species to North-West Russia (St Petersburg and Karelia), Croatia and Austria (Carinthia). It should be noted that Dastych (1988) observed a configuration of the bucco-pharyngeal apparatus similar to N. pallidoides gen. et comb. nov. in some Polish specimens attributed by him to H. convergens ( Dastych 1988: 147, pl. XXIa, c). Also, some of the microphotographs of the claws of Dastych’s specimens of H. convergens show a similarity to those described for N. pallidoides gen. et comb. nov. ( Dastych 1988: pl. XXIi). So, it is very likely that the latter species is present among the tardigrade fauna of Poland. The species attributed to as “ H. convergens ” by Guil & Giribet (2012) is nearly identical to N. pallidoides gen. et comb. nov. in 18S and 28S gene sequences (see Genotypic differential diagnosis). In my opinion, this is evidence for the presence of N. pallidoides gen. et comb. nov. in Spain, but it was recently shown ( Guidetti et al. 2019a) that closely related species can share an identical 18S rRNA haplotype. Thus, without analyses of the more sensitive barcode genes (particularly COI and ITS-2), and in the absence of morphological data, the possibility of the presence of another species similar to N. pallidoides gen. et comb. nov. in Spain cannot be excluded.

Figures

Fig. 1. Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011, total view. A. Phase contrast (SPbU 251(82)). B. Dorsal view in SEM. C. Ventral view in SEM. Scale bars = 50 µm.

Fig. 2. Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011, dorsal sculpture. A. Type series specimen (KNU Чер-9 II), PhC. B. Type series specimen (KNU Чер-9 II), DIC. C. Specimen from Austria (SPbU 251(82)), PhC. D. Specimen from Russia (SPbU 113(3)). Scale bars = 5 µm.

Fig. 3. Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011. A. Dorsal view of the caudal body end, white arrowheads indicate the dorsal inflations of the hind legs, SEM. B. Dorsal sculpture of the caudal body region, SEM. C. Dorsal surface of the head region, black arrowheads indicate the elliptical sensory organs, white arrowhead indicates the central concavity on the dorsal surface of the head, SEM. D. Dorsal surface of the head region, black arrowheads indicate the elliptical sensory organs (SPbU 251(89)), PhC. Scale bars = 5 µm.

Fig. 4. Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011. A. Lateral view of the head region, white arrowhead indicates the anterior porous area, black arrowhead indicates the elliptical sensory organ, SEM. B. Enlarged view of the lateral surface of the head, white arrowhead indicates the anterior porous area, white arrow indicates the muscle attachment zone, SEM. C. Mouth opening with peribuccal lobes, SEM. D. Mouth opening with anterior ring of teeth, SEM. E. Dorsal sculpture of the juvenile, SEM. F. Bucco-pharyngeal apparatus (SPbU 251(82)), PhC. G. Dorsal view of the buccal cavity, black arrowhead indicates the circumoral elliptical structures (SPbU 251(82)), PhC. H. Ventral view of the buccal cavity, black arrowhead indicates the circumoral elliptical structures (SPbU 251(82)), PhC. Scale bars: A, F–H = 5 µm; B–C = 2 µm; D = 1 µm; E = 10 µm.

Fig. 5. Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011, bucco-pharyngeal apparatus. A. Lateral view of the bucco-pharyngeal apparatus, black arrowheads indicate the thickenings of the buccal tube, white arrow indicates the septulum (SPbU 251(109)), PhC. B. Dorsal AISM (SPbU 251(82)), DIC. C. Ventral AISM (SPbU 251(82)), DIC. D. Pharyngeal bulb, black arrowhead indicates the pharynx outline, black arrow indicates the cuticular line connecting second macroplacoid with septulum, white arrow indicates the septulum, white arrowhead indicates the “pseudoseptulum” (SPbU 251(89)), PhC. E. Macroplacoids, black arrowhead indicates the constriction of the first macroplacoid (SPbU 251(89)), DIC. F. Cuticular structures of the pharynx, black arrowhead indicates the constriction of the first macroplacoid, black arrow indicates the constriction of the second macroplacoid, SEM. Scale bars: A–E = 5 µm; F = 2 µm.

Fig. 6 (opposite page). Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011, claws. Specimens SPbU 251(82) (A, C, E) and KNU Чер-9 II (B, D, F). A. Claws of leg I, black arrowhead indicates the flexible part of the external claw main branch, black arrows indicates the lunule of the internal claw, PhC. B. Claws of leg III, type series specimen, black arrowhead indicates the flexible part of the external claw main branch, PhC. C. Claws of leg II, white arrow indicates the elongated bulge near the base of the internal claw, white asterisk – pulvilla on the inner side of the leg, PhC. D. Claws of leg IV, type series specimen, black arrow indicates the filamentous structure connecting the external claw main branch with the claw base, PhC. E. Claws of leg IV, black arrow indicates the thickened region on the lunule margin, PhC. F. Claws of leg IV, type series specimen, black arrow indicates the thickened region on the lunule margin, PhC. G. Claws of leg II, white arrowhead indicates the lateral crest of the claw base, SEM. H. Claws of leg III, white arrow indicates the elongated bulge near the base of the internal claw, white asterisk – pulvilla on the inner side of the leg, SEM. I. Claws of leg IV, white arrowhead indicates the lateral crest of the claw base, SEM

Fig. 7. A–G. Hypsibius pallidoides Pilato, Kiosya, Lisi, Inshina & Biserov, 2011 eggs. A–D, specimen KNU Чер-9 II. A. Type series specimen mounted during the egg laying process, PhC. B. Type series egg shell, PhC. C. Type series egg shell, DIC. D. Type series egg shell structure with numerous internal pillars visible, DIC. E. Austrian population egg shell (SPbU 251(3)), PhC. F. Karelian population egg shell (SPbU 113(2)), PhC. G. Pushkin population egg shell (SPbU 235(28)), PhC. – H. Pilatobius recamieri (Richters, 1911), egg shell (SPbU 203(7)), PhC. Scale bars: A = 50 µm; B–H = 5 µm.