Diphascon (Diphascon) procerum, Pilato, Giovanni, Sabella, Giorgio & Lisi, Oscar, 2014

Pilato, Giovanni, Sabella, Giorgio & Lisi, Oscar, 2014, Two new tardigrade species from Sicily, Zootaxa 3754 (2), pp. 173-184: 179-182

publication ID

http://dx.doi.org/10.11646/zootaxa.3754.2.6

publication LSID

lsid:zoobank.org:pub:995C32F3-15B0-4616-A69C-EA8FAA9BB6AC

DOI

http://doi.org/10.5281/zenodo.5623121

persistent identifier

http://treatment.plazi.org/id/1F5E505C-F21D-A327-94DD-F94209B54FC8

treatment provided by

Plazi

scientific name

Diphascon (Diphascon) procerum
status

sp. nov.

Diphascon (Diphascon) procerum   sp. nov.

Figs. 4 View FIGURE 4 , 5 View FIGURE 5 .

Material examined: Cava San Giovanni Lo vecchio: Noto (Siracusa), holotype (slide No. 3171) and 9 paratypes (slides Nos. 3168 -3170, 3172; 3253 - 3154 and 3266) (moss sample collected by Sebastiano Distefano in January 1980).

Type repository: Holotype and paratypes are deposited in the Binda & Pilato collection, Department of Biological, Geological and Environmental Sciences, Section of Animal Biology, University of Catania.

Specific diagnosis: Cuticle without gibbosities, with extremely fine tubercles that viewed vertically appear as dots; eye spots present; pharyngeal tube (measured from the caudal extremity of the drop-shaped thickening) slightly shorter than the pharyngeal bulb; two rod-shaped macroplacoids and septulum present; lunules absent; accessory points present; a cuticular bar present near the internal claw on legs I–III; two short cuticular bars present on legs IV, one near the base of the anterior claw and one between the anterior and posterior claws.

Description of the holotype: Body length 358 µm; colourless; eye spots present; cuticle with extremely small tubercles (visible as dots) ( Fig. 4 View FIGURE 4 A), also present on the legs. Buccal-pharyngeal apparatus of Diphascon   type (rigid buccal tube, without ventral lamina, and flexible, spirally thickened pharyngeal tube); drop shaped thickening is present between the buccal and the pharyngeal tube ( Fig. 4 View FIGURE 4 B); mouth without peribuccal lamellae or papulae; no teeth visible in the buccal cavity; buccal tube with dorsal and ventral apophyses for the insertion of the stylet muscles in the shape of hooks symmetrical with the respect to the frontal plane.

Buccal-pharyngeal tube length (measured from the anterior margin of the stylet sheaths to the caudal end, excluding pharyngeal apophyses), 64.8 µm; buccal tube length (measured from the anterior margin of the stylet sheaths to the caudal end of the drop-shaped thickening), 27.3 µm; expressed as a ratio of the total length of the bucco-pharyngeal tube, 42.1 % (pbf = 42.1); buccal tube external width 2.2 µm (ptd = 8.1); stylet supports inserted at 61.1 % of the buccal tube length (ptd = 61.1); pharyngeal tube length 37.6 µm.

Pharyngeal bulb with apophyses, two rod-shaped macroplacoids and septulum ( Fig. 4 View FIGURE 4 B), microplacoid absent. First macroplacoid, with central constriction, 7.3 µm long (ptd = 26.7); second macroplacoid, with a preterminal constriction (see more clearly in Fig 5 View FIGURE 5 A paratype), 6.9 µm long (ptd = 25.3); septulum length 2.8 µm (ptd = 10.3); entire placoid + septulum row length 17.3 µm (ptd = 63.4); entire macroplacoid row 14.5 µm (ptd = 53.1).

Hypsibius   type claws ( Fig. 4 View FIGURE 4 B–D), well developed with a short basal tract, broader in the external claws and particularly the posterior claws of legs IV (see more clearly in Fig. 5 View FIGURE 5 B, C paratype); leg I external claw length, 11.6 µm (ptd = 42.5); internal claws on same leg 7.7 µm (ptd = 28.2); leg IV posterior claw length, 14 µm (ptd = 51.3) with indented basal margin; anterior claw on same leg 9.7 µm long (ptd = 35.5). Additional measurements are given in Table 4 View TABLE 4 . Thin accessory points present on all main claw branches ( Fig. 5 View FIGURE 5 B); lunules absent; obvious cuticular bar present near the internal claws of legs I–III ( Figs. 4 View FIGURE 4 C and 5 C); two clearly visible, short cuticular bars are present on the hind legs, one near the base of the anterior claw and the second between the anterior and the posterior claws ( Figs. 4 View FIGURE 4 D and 5 B). Eggs not found.

Remarks: The paratypes are similar to the holotype in both qualitative and metric characters; measurable characters of the holotype and two paratypes are reported in Table 4 View TABLE 4 .

Etymolog y: The name procerum   refers to the claw shape (the main branches are long with respect to the total claw length, and for this reason the claws appear slender; Latin: proceru s = long and slender).

Diphascon (D.) procerum   sp. nov. D. (D.) ramazzottii  

Slide No. 3253 3171 3170 1404

Paratype Holotype Paratype Paratype Differential diagnosis: Six species within the subgenus Diphascon   ( Diphascon   ) are reported to have an ornamented cuticle that is without gibbosities or reticular design, 2 macroplacoids and septulum. These are: D, (D) oculatum   Murray, 1906, D. (D.) rugocaudatum   ((Rodriguez Roda, 1952), D. (D.) nodulosum ( Ramazzotti, 1957)   , D. (D.) ramazzottii ( Robotti, 1970)   , D. (D.) granifer Greven, 1972   and D. (D.) burti   Nelson, 1991.

Diphascon (D.) procerum   sp. nov. differs from D. (D.) oculatum   and D. (D.) rugocaudatum   in having cuticular tubercles on the entire dorsal body surface and not limited to the caudal region; in addition, it differs from D. (D.) oculatum   in having shorter pharyngeal tube and longer macroplacoids.

From D. (D.) nodulosum   the new species differs in the markedly smaller size of the cuticular tubercles, and from D. (D.) burti   in lacking the pseudoseptulum and in having obvious cuticular bars on the legs.

Diphascon (D.) procerum   sp. nov., differs from D. (D.) granifer   in: having clearer cuticular tubercules or dots, eye spots present, and having obvious cuticular bars on the legs.

The new species differs from D. ramazzottii   in having: smaller and more wide-spaced cuticular tubercles (visible as dots) (in D. ramazzottii   the cuticular tubercles are near neighbour polygonals with the appearance of a reticular design (Pilato & Binda, 1977 )). In addition, the new species has: slightly more caudally positioned stylet supports ( Table 4 View TABLE 4 ), longer second placoid and, as a consequence, longer placoid row ( Table 4 View TABLE 4 ), clearly longer claws ( Table 4 View TABLE 4 ); main branch of each claw longer with respect to the total claw length ( Table 4 View TABLE 4 ; Figs. 5 View FIGURE 5 B, C and 5 D).

Conclusions. The tardigrade fauna of the relatively small region encompassed by Sicily and the associated archipelegos could be considered well known with 24 papers spaced over 50 years and a current species list of 96 species. However, this study has described new species, Macrobiotus insuetus   sp. nov. and Diphascon (D.) procerum   sp. nov., from separate Sicilian localities, which indicates there are still a large number of microenvironments in this area waiting to be studied.

TABLE 4. Measurements (in µm), and other morphological parameters, for Diphascon (D.) procerum sp. nov. holotype and two paratypes, compared with a similar sized paratype of Diphascon (D.) ramazzottii. (ptd index values in brackets).

µm (ptd) µm (ptd) µm (ptd) µm (ptd)
Body length 346   358   369   346  
Buccal-pharyngeal tube length 61.8   64.8   68.8   71.5  
Buccal tube length 28.4   27.3   29.1   30.9  
pbf ratio 46.0   42.1   42.3   43.2  
Pharyngeal tube 33.7   37.6   39.9   40.3  
External buccal tube width 2.5 (8.8) 2.2 (8.1) 2.3 (7.9) 2.4 (7.8)
Stylet supports insertion point (61.8)   (61.1)   (62.4)   (59.2)
First macroplacoid 8.2 (28.8) 7.3 (26.7) 9.2 (31.6) 8.3 (26.9)
Second macroplacoid 6.2 (21.8) 6.9 (25.3) 6.8 (23.4) 6.1 (19.7)
Septulum 3.0 (10.5) 2.8 (10.3) 3.2 (11.1) 3.1 (10.0)
Placoids + septulum 18.1 (63.5) 17.3 (63.4) 19.1 (65.6) 18.2 (58.9)
Macroplacoid row 14.9 (52.3) 14.5 (53.1) 15.7 (54.0) 14.6 (47.2)
External claw I? ? 11.6 (42.5) ? ? ? ?
% main branch/ total claw length? ? 9.3 (80.2) ? ? ? ?
Internal claw I 8.3 (29.1) 7.7 (28.2) ? ? ? ?
% main branch/ total claw length 7.6 91.6 6.7 87.0 ? ? ? ?
External claw II? ? ? ? 12.2 (41.9) 10.9 (35.2)
% main branch/ total claw length? ? ? ? 10.5 86.1 8.3 76.1
Internal claw II 8.9 (31.2) 9.1 (33.3) ? ? 8.2 (26.5)
% main branch/ total claw length 7.9 88.8 8.1 89.0 ? ? 6.2 75.6
External claw III? ? ? ? ? ? 10.3 (33.3)
% main branch/ total claw length? ? ? ? ? ? 8.1 78.6
Internal caw III 9.4 (33.0) ? ? 10.6 (36.7) 8.9 (28.8)
% main branch/ total claw length 8.5 90.4 ? ? 9.5 89.6 6.9 77.5
Posterior claw IV 15.2 (53.3) 14.0 (51.3) ? ? 13.4 (43.4)
% main branch/ total claw length 12.4 81.6 11.7 83.6 ? ? 10.5 78.4
Anterior claw IV 10.7 (37.5) 9.7 (35.5) 11.5 (39.5) ? ?
% main branch/ total claw length 8.9 83.2 8.3 85.6 9.8 85.2 ? ?