Ramazzottius libycus, Pilato & D’Urso & Lisi, 2013

Pilato, Giovanni, D’Urso, Vera & Lisi, Oscar, 2013, Ramazzottius thulini (Pilato, 1970) bona species and description of Ramazzottius libycus sp. nov. (Eutardigrada, Ramazzottidae), Zootaxa 3681 (3), pp. 270-280 : 274-279

Ramazzottius libycus sp. nov.

( Figs. 5B – D , 6 )

Material examined. Libya, Barce (32°29'17"N; 20°50'19"E), in the neighbourhood of the town; moss sample: holotype (slide No. 2754), 7 paratypes (slides No. 2753 and 2754), and three eggs (slides No. 2731 and 2752) collected in 1975 by the colleagues Francesco Furnari and Salvatore Brullo ( University of Catania ) .

Type repository. Holotype and paratypes are deposited in the Binda & Pilato collection ( Museum of the Department of Animal Biology “ Marcello La Greca ”, University of Catania, Italy) .

Specific diagnosis. Cuticle ornamentation and colour (5 longitudinal and 9 transverse pigmented bands) as usually in R. oberhaeuseri ; eye spots absent; a pair of elliptical cephalic organs present; buccal-pharyngeal apparatus of Hypsibius type ( Ramazzottius variant), pharyngeal bulb with two macroplacoids; microplacoid and septulum absent; claws of Ramazzottius type; small lunules, difficult to see, present. Eggs, laid free, with hemispherical and, very rarely, trunco-conical and conical processes.

Description of the holotype. Body length 286 µm; colour (5 longitudinal and 9 transverse reddish bands separated by unpigmented bands) and cuticular ornamentation as usually in R. oberhaeuseri ; polygonal tubercles, less visible in the anterior portion of the body and more visible in the posterior portion, are present having diameter up to 2.6 µm ( Fig. 5B ); eye spots absent; a paired of cephalic, elliptical, organs present as ascertained in most species of the genus; buccal-pharyngeal apparatus of Hypsibius type ( Ramazzottius variant) i.e. with rigid buccal tube without ventral lamina, dorsal and ventral apophyses for the insertion of the stylet muscles in shape of blunt hooks, asymmetrical with respect to the frontal plane; peribuccal lamellae and peribuccal papulae absent ( Pilato & Binda, 2010). Buccal tube, 29 µm long (with a slightly thicker tube wall immediately caudally to the insertion of the stylet supports) ( Fig. 5C ), and 1.5 µm wide internally (pt = 5.2). Stylet supports inserted on the buccal tube at 60 % of its length (pt = 60.0). Pharyngeal bulb with apophyses and two short macroplacoids; microplacoid and septulum absent ( Fig. 5C ); first macroplacoid 3.9 µm long (pt = 13.4), second 3.1 µm long (pt = 10.7); entire placoid row 7.6 µm long (pt = 26.2).

Claws, of Ramazzottius type ( Fig. 5C, D and 6A, B ), well developed; length of external and internal claws of the third pair of legs 19.1 µm (pt = 65.9) and 11.2 µm (pt = 38.6), respectively; length of posterior and anterior claws of the hind legs 24.6 µm (pt = 84.8) and 12.2 µm (pt = 42.1), respectively. Due to the difficulty in measuring the total length of the external claws, we provided the separate lengths of the sclerified portions of the main branches and the basal portion + secondary branch in Table 1. Thin accessory points present on the main branches of all claws. Small, difficult to see, lunules present on all legs ( Fig. 6A, B ). Other cuticular thickening on the legs, absent.

Eggs laid freely ( Fig. 6C,D ); we found three eggs but only one is measurable; its the diameter is 60.0 µm excluding and 64.0 µm including processes; there are 16 processes in the circumference and 48 in the hemisphere. Most processes are hemispherical, 3.0 – 3.4 µm high, with the basal diameter 8.0 – 8.6 µm. Few processes are truncoconical or conical in shape ( Fig. 6D ).

Remarks. Paratypes similar to the holotype in both qualitative and metric characters: Measurements of some structures are given in Table 1.

Etymology. The name refers to the geographic area ( Libya) of the locus typicus (Barce).

Differential diagnosis. For many characters of the adults and the eggs, Ramazzottius libycus sp. nov. is very similar to R. oberhaeuseri and R. thulini . However, it differs from R. oberhaeuseri in having slightly shorter buccal tube with respect to the body length (% ratio = 10.0 – 10.1 in R. libycus sp. nov.,11.5 – 12.0 in R. oberhaeuseri ); more slender internal claws I – III and anterior claws IV ( Figs. 5D , 6A, B and 3C – E ) with higher values of the pt index ( Table 1); higher pt values of the sclerified portion of both the main branches and basal portion + secondary branch in the external claws; the percent ratio between these portions of the claw is the same in the legs I – III but higher in the hind legs ( Table 1). The eggs have a lower number of processes in the hemisphere (48 in R. libycus sp. nov., 57 – 60 in R. oberhaeuseri ), but the number of eggs we examined is too low for us to know the range of individual variability of this character and therefore whether or not this is a significant difference.

R. libycus sp. nov., differs from R. thulini in having polygonal tubercles also in the anterior extremity of the body, slightly shorter buccal tube with respect to the body length (% ratio = 10.0 – 10.1 in R. libycus sp. nov., 11.6 – 12.0 in R. thulini ); stylet supports inserted on the buccal tube in a slightly more caudal position (pt = 59.6 – 61.7 in R. libycus sp. nov., 57.3 – 57.9 in R. thulini : Table 1); different shape of the internal claws: the main branches of R. libycus sp. nov. are longer and more slender, and the secondary branches are longer and taper gradually, whereas in R. thulini the secondary branches taper more abruptly ( Figs. 5D , 6A, B and 2C, D, E ); higher pt index values relative to internal claws I – III and anterior claws IV ( Table 1); in the external claws the pt values of both the sclerified portion of the main branches and the basal portion + secondary branches length are higher; in legs I – III the percent ratio between the length of these structures is the same but it is clearly higher in the hind legs ( Table 1). The eggs have a lower number of processes in the hemisphere (about 48 in R. libycus sp. nov., 57 – 60 in R. thulini ), but the limited number of eggs we examined for R. libycus sp. nov. has not provided the range of the individual variability and we cannot say this is a significant difference.

Ramazzottius libycus sp. nov. is clearly different from the Swedish smooth specimens, which Durante Pasa & Maucci (1979) attributed to R. oberhaeuseri , in having ornamented cuticle; higher pt index values relative to the internal claws ( Table 1); external claws with larger pt values relative to the basal portion + secondary branch ( Figs. 5C , 6A, B and 5A ; Table 1) and different percent ratio between the main branch and the basal portion + secondary branch ( Table 1). We have no eggs produced by the specimens with smooth cuticle for comparison.

Figures

FIGURE 2. A–E, Ramazzottius thulini (holotype). A, Buccal-pharyngeal apparatus. B, Claws of the second and third pairs of legs. C, Claws of the second pair of legs. D, Claws of the third pair of legs. E, Claws of the hind legs. Scale bar = 10 µm.

FIGURE 3. A–E, Ramazzotius specimens from the locus typicus of R. oberhaeuseri. A, Buccal-pharyngeal apparatus. B, Claws of the first and second pairs of legs. C, Internal claw of the first pair of legs. D, Internal claw of the third pair of legs. E, Claws of the second pair of legs. Arrow indicates a visible lunule. Scale bar = 10 µm.

FIGURE 5. A, Ramazzottius sp. with smooth cuticle from Sweden. Claws of the second pair of legs. B–D, Ramazzottius libycus sp. nov. B, Cuticle ornamentation (paratype). C, Buccal-pharyngeal apparatus of the holotype. D, Claws of the second pair of legs of the holotype. Scale bar = 10 µm.

FIGURE 6. A–D, Ramazzottius libycus sp. nov. A, claws of the hind legs of the holotype. Arrow indicates a visible lunule. B, Claws of the hind legs of a paratype. Arrows indicate visible lunules. C, D, Eggs. Arrows indicate some conical or truncoconical processes. Scale bar = 10 µm.