Macrobiotus insuetus Pilato, Sabella & Lisi, 2014, sp. nov.
Creators: name: Pilato, Giovanni
name: Sabella, Giorgio
name: Lisi, Oscar
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Tardigrada
Eutardigrada
Parachela
Macrobiotidae
Macrobiotus
Macrobiotus insuetus

description: Macrobiotus insuetus sp. nov.   
Figs 1, 2.  
 Material examined: Moss sample, Nelson Park, Maniace (Catania): holotype (slide No. 5520), 10 paratypes (slides Nos. 5521-5526) and 3 eggs (slides 5521, 5224 and 5225) (collected in November 2001 by Giovanni Pilato). Moss sample, Contrada Bauly, Palazzolo Acreide (Siracusa): 1 paratype (slide No. 1424) (collected by Angelo Zappalà in November 1985).   
 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: Colourless; cuticle smooth without pores; eye spots absent; buccal-pharyngeal apparatus of Macrobiotus type; pharyngeal bulb with three macroplacoids and microplacoid close to the third macroplacoid; claws of Macrobiotus hufelandi type but on the first three pairs of legs they have a short common tract, while on the hind legs primary and secondary branch are joined in an extended common tract and the secondary branch, markedly shorter than on legs I–III, forms a right angle with the main branch. Accessory points and lunules present. Eggs, freely laid, spherical with conical, reticulate processes; egg shell not areolated, with small dots around the base of the processes.   
 Description of the holotype: Body length 334 µm; colourless; cuticle smooth without pores; eye spots absent; Buccal-pharyngeal apparatus of Macrobiotus type (buccal tube rigid with ventral lamina); mouth terminal with 10 peribuccal lamellae (Fig. 1 A); buccal armature composed of an anterior band of small teeth, a posterior ring of triangular teeth and, more caudally, three dorsal and three ventral transverse ridges (Fig.1 A, B). Rigid buccal tube 35.8 µm long and 6.5 µm wide externally (pt = 18.2); stylet supports inserted on the buccal tube at 79.2 % of its length (pt = 79.2). Pharyngeal bulb with apophyses, three rod-shaped macroplacoids and microplacoid close to the third macroplacoid (Fig. 1 A); first macroplacoid 6.0 µm long (pt = 16.8); second 4.4 µm (pt = 12.3); third, with a preterminal constriction, 5.4 µm (pt = 15.1); microplacoid well developed 4.2 µm long (pt = 11.7); the entire placoid row 21.5 µm (pt = 60.1); the macroplacoid row 17.5 µm (pt = 48.9).   
 Claws well developed, of Macrobiotus hufelandi type but distinctive. Claws of the first three pairs of legs are typically formed with the primary and secondary branches joined along a short common basal tract and are clearly bifurcated, the external claws clearly longer than the internal (Table 1; Fig. 1 C). The claws of hind legs are markedly different as the primary and secondary branch of both posterior and anterior claws are joined for a much longer basal tract with the secondary branch bifurcating late, making it appear shorter, and forming a right angle with the main branch (Fig, 1D; Fig. 2 A-B). The claws of the hind legs are slightly shorter than those of legs II and III (Table 1), and the posterior claws slightly longer than the anterior, though the difference is less marked than that between external and internal claws of legs I–III. Basal portion of all claws with round lateral angles. Length of the external and internal claws of legs II = 12.9 µm (pt = 36.0) and 10.2 µm (pt = 28.5) respectively; on legs III = 12.8 µm (pt = 35.8) and 10.2 µm (pt = 28.5) respectively; posterior and anterior claws of legs IV = 11.9 µm (pt = 32.2) and 10.9 µm (pt = 30.4) respectively. All claw main branches with long, thin accessory points (Fig. 2B). Smooth lunules present on all legs (Fig.1 C), and a cuticular bar present under the lunules on legs I–III (Fig. 1 C).   
 In the sample studied we found only Macrobiotus insuetus sp. nov. and three eggs, which we believe belong to this species. The eggs, freely laid, are spherical with conical processes (Fig. 2C, D). We were able to measure two eggs (Table 2) and, despite a marked difference in diameter (59 and 72.6 µm), the number of processes to the circumference (11 and 13), the number of processes per hemisphere (31 for both) and the process height and basal diameter were all similar (Table 2). The processes have a short, flexible terminal portion, sometimes forked and often broken (Fig. 2C), while the surface has a reticular design with small, almost isodiametric mesh (Fig.2D). Unfortunately, observation of the egg surface was difficult, but it is clearly not areolated and though the egg shell seemed to be smooth, small dots and some thin radial striae around the base of the processes are present. The eggs are most similar to three other harmsworthi type species, M. diffusus, M. dimentmani and M. wuzhishanensis Yin, Wang, & Li, 2011.   
 Macrobiotus insuetus sp. nov.   
Slide No. 5526 5520 5523  
Paratype Holotype Paratype  
 µm (pt) µm (pt) µm (pt)   
Body length 293 334?  
Buccal tube length 33.1 35.8 41.1  
 External buccal tube width 6.3 (19.0) 6.5 (18.2) 8.1 (19.7) Style supports insertion point (79.0) (79.2) (79.4) First macroplacoid 5.1 (15.4) 6.0 (16.8) 6.6 (16.1) Second macroplacoid 4.2 (12.7) 4.4 (12.3) 5.6 (13.6) Third macroplacoid 5.2 (15.7) 5.4 (15.1) 6.3 (15.3) Microplacoid 3.9 (11. 8) 4.2 (11. 7) 4.6 (11. 2) Placoid row 19.6 (59.2) 21.5 (60.1) 23.9 (58.2) Macroplacoid row 15.3 (46.2) 17.5 (48.9) 19.4 (47.2) External claw II 11.0 (33.2) 12.9 (36.0) 13.1 (31.9) Internal claw II 9.2 (27.8) 10.2 (28.5) 10.5 (25.5) External claw III 11.5 (34.7) 12.8 (35.8) 13.2 (32.1) Internal claw III 9.5 (28.7) 10.2 (28.5) 11.0 (26.8) Posterior claw IV?? 11.9 (33.2) 12.6 (30.7) Anterior claw IV?? 10.9 (30.4) 11.3 (27.5) Remarks: The paratypes are similar to the holotype in both morphological and metric characters; morphometric charaters of the holotype and two paratypes with measurable characters are reported in Table 1. Etymology: The name insuetus (Latin: unusual) refers to the uniqueness of the very different hind leg claw shape from those of the legs I–III   
 Differential diagnosis: Based on the egg structure and the claw shapes of legs I-III, Macrobiotus insuetus sp. nov. is similar to three other known harmsworthi type species: Macrobiotus wuhzishanensis, Macrobiotus diffusus and Macrobiotus dimentmani. It differs from Macrobiotus wuhzishanensis in: lacking eye spots, having wider buccal tube, higher pt index values relative to placoids and claws, differently shaped hind leg claws from those of legs I–III and the posterior hind leg claws shorter than the external claws of legs II–III (in Macrobiotus wuhzishanensis they all the same length) (Table 3). The eggs of the two species are very similar but those of the new species are: smaller, with shorter processes, fewer processes in the circumference and less evident ring of basal dots (Table 2).   
 Macrobiotus insuetus sp. nov. is also similar to Macrobiotus dimentmani but differs in: lacking eye spots, a slightly narrower buccal tube (pt index values 18.2–19.7 in M. insuetus sp. nov., 19.3–23.2 in M. dimentmani), stylet supports inserted on the buccal tube at a slightly more caudal position (pt index value = 79.0– 79.4 in M. insuetus sp. nov., 75.8–77.5 in M. dimentmani); both anterior and posterior claws of legs IV with a long common basal tract and short secondary branches, while in M. dimentmani only the posterior claws have this characteristic (Figs. 2 A-B and 3A). Characters of the eggs differ in: smaller dimensions, fewer processes, shorter processes and more rarely forked (Figs 2C, D and 3B; Table 2), and less visible dots on the egg shell.   
 Macrobiotus insuetus sp. nov. differs from the third similar species, Macrobotus diffusus, in some claw and egg characters. In the new species, both the anterior and posterior claws of leg IV have a long common basal tract (in Macrobiotus diffusus only the posterior claws have this characteristic) (Figs. 2A, and 3 C); the secondary branches are clearly shorter (Figs. 2 A-B and 3C); the claws of legs I–III (particularly the external) have higher pt index values (Table 3); leg IV posterior claws are slightly shorter than the external claws of legs II–III, while in M. diffusus they are longer or of similar length (Table 3). The eggs of M. insuetus sp. nov. differ from M. diffusus in: having fewer processes in both circumference and hemisphere (Table 2), and processes terminal portions that are thin and flexible, not true filaments (Figs. 2C, D, and 3 D). Although the egg shell characters of the new species are not clearly visible, it does appear similar to M. diffusus in lacking areolation and with few, small dots and some thin radial striae around the base of the processes.   
 M. insuetus M.wuzhishanensis * M. diffusus M. dimentmani   
 sp. nov.   
Slide No. 5520 3471 5359 5359  
Holotype Holotype Holotype Paratype Paratype  
 µm (pt) µm (pt) µm (pt) µm (pt) µm (pt) Body length 334 420 303 333 333   
Buccal tube length 35.8 44.2 35.8 39.0 39.9  
 External buccal tube width 6.5 (18.2) 5.3 (12.0) 7.6 (21.2) 8.0 (20.5) 8.1 (20.3) Stylet supports insertion point (79.2) (78.7) (78.3) (77.5) (77.0) First macroplacoid 6.0 (16.8) 5.5 (12.4) 5.1 (14.3) 5.5 (14.1) 5.6 (14.0) Second macroplacoid 4.4 (12.3) 4.4 (10.0) 4.9 (13.7) 5.0 (12.8) 5.3 (13.3) Third macroplacoid 5.4 (15.1) 5.7 (12.9) 5.5 (15.4) 5.1 (13.1) 6.0 (15.0) Microplacoid 4.2 (11.7) 4.9 (11. 1) 4.0 (11.2) 4.5 (11.5) 5.0 (12.5) Placoid row 21.5 (60.1)?? 21.2 (59.2) 23.1 (59.2) 22.9 (57.4) Macroplacoid row 17.5 (48.9) 18.2 (41.2) 16.4 (45.8) 18.2 (46.7) 18.9 (47.4) External claw II 12.9 (36.0) 13.0 (29.4) 9.9 (27.7) 14.5 (37.2) 14.5 (36.3) Internal claw II 10.2 (28.5) 9.1 (20.6) 9.1 (25.4) 10.9 (27.9) 11.4 (28.6) External claw III 12.8 (35.8) 13.0 (29.4) 9.9 (27.7) 14.5 (37.2) 14.5 (36.3) Internal claw III 10.2 (28.5) 9.1 (20.6) 9.1 (25.4) 10.9 (27.9) 11.4 (28.6) Posterior claw IV 11.9 (33.2) 13.0 (29.4) 11.2 (31.3) 13.7 (35.1) 14.0 (35.1) Anterior claw IV 10.9 (30.4) 10.4 (23.5) 10.0 (27.9) 13.2 (33.8) 13.5 (33.8)   
 *) According to Yin et al. (2011).
description: Published as part of Pilato, Giovanni, Sabella, Giorgio & Lisi, Oscar, 2014, Two new tardigrade species from Sicily, pp. 173-184 in Zootaxa 3754 (2) on pages 174-179, DOI: 10.11646/zootaxa.3754.2.6, http://zenodo.org/record/227398