Minibiotus xavieri, Fontoura, Paulo, Pilato, Giovanni, Morais, Paulo & Lisi, Oscar, 2009

Fontoura, Paulo, Pilato, Giovanni, Morais, Paulo & Lisi, Oscar, 2009, Minibiotus xavieri, a new species of tardigrade from the Parque Biológico de Gaia, Portugal (Eutardigrada: Macrobiotidae), Zootaxa 2267, pp. 55-64: 56-62

publication ID

http://doi.org/ 10.5281/zenodo.190870

DOI

http://doi.org/10.5281/zenodo.5626503

persistent identifier

http://treatment.plazi.org/id/038C7144-B367-3E68-1B81-CE4ACC4CF84C

treatment provided by

Plazi

scientific name

Minibiotus xavieri
status

sp. nov.

Minibiotus xavieri   sp. nov.

Figs. 1–2 View FIGURE 1. A – E View FIGURE 2. A – D

Material examined: 25 specimens and 15 eggs, one of them with fully developed embryo. Two specimens were mounted in polyvinyl lactophenol. All the other specimens and the eggs were mounted in Hoyer’s medium. One specimen was in simplex stage.

Type repository: The holotype (slide N. 5295), four paratypes and two eggs are deposited in the collection of Binda and Pilato (Museo del Dipartimento di Biologia Animale “Marcello La Greca”, Università di Catania); the other paratypes and eggs (slides CII- 28 to CII- 57) in the collection of P. Fontoura (Department of Zoology and Anthropology, Faculty of Sciences, University of Porto).

Specific diagnosis: Cuticle with variably shaped pores arranged in 9 wide transverse bands, the cephalic and caudal bands widest; granulation on legs absent. Eye spots present. Buccal tube narrow; buccal armature with peribuccal papulae as in all species of Minibiotus   ; bands of teeth seem to be absent but this feature needs to be confirmed; two very fine latero-ventral transverse ridges and a single transverse dorsal ridge present; medioventral ridge not visible. Pharyngeal bulb with apophyses, three small macroplacoids and microplacoid. Robust claws of hufelandi   type with well developed accessory points and smooth lunules. Eggs, freely laid, with long conical processes, with bifurcate apices and terminal filaments often broken; process surface and egg shell with widely spaced granulation.

Description of the holotype: Body length 369 µm, colorless; large eye spots consisting of a few pigment granules. Cuticle with small pores (longer diameter of elliptical pores up to about 2.0 µm long) arranged in 9 wide transverse bands, cephalic and caudal of which are widest; pores variable in shape: roundish, oval and, very few, trilobed ( Fig. 1 A View FIGURE 1. A – E ). Ventral surface of body with few roundish pores. Pores also present on legs ( Fig. 1 A View FIGURE 1. A – E ) where no granulation is present.

Mouth antero-ventral; buccal cavity very small ( Fig. 1 B, C View FIGURE 1. A – E ); buccal armature without peribuccal lamellae and with peribuccal papulae as in all species of Minibiotus   ; bands of teeth seem to be absent but this feature needs to be confirmed; two very fine latero-ventral transverse ridges and a single transverse dorsal ridge present; a medioventral ridge not visible.

Rigid buccal tube narrow, 32.7 µm long and 3.0 µm wide externally (pt = 9.2), with an unmarked anterior bend ( Fig. 1 C View FIGURE 1. A – E ). Slight thickening of buccal tube wall present caudal to stylet supports ( Fig. 1 B View FIGURE 1. A – E ). Ventral lamina not very long (pt = 55.7 measured in lateral view). Stout stylet supports inserted on buccal tube at 67.3 % of its length (pt = 67.3). Pharyngeal bulb with large triangular apophyses and three small macroplacoids and microplacoid ( Fig. 1 B, C View FIGURE 1. A – E ); first macroplacoid, pear shaped, partially lying under apophysis as in other species of the genus, 4.5 µm long (pt = 13.8); second macroplacoid, roundish, 3.6 µm (pt = 11 .0); third macroplacoid 3.9 µm long (pt = 11.9). Microplacoid 1.7 µm long (pt = 5.2). Macroplacoid row length, 12.6 µm long (pt = 38.5); entire row of placoids 13.9 µm long (pt = 42.5).

Robust claws of hufelandi   type, with well-developed accessory points on main branches ( Fig. 1 D, E View FIGURE 1. A – E ) particularly prominent on hind legs. External and internal claws of legs II and III 10.5 µm long (pt = 32.1) and 10.0 µm long (pt = 30.6) respectively, including accessory points and peduncle. Posterior and anterior claws of fourth pair of legs 13.0 µm long (pt = 39.8) and 12.0 µm long (pt = 36.7) respectively.

Smooth lunules, better developed on fourth pair of legs (about 3.0 µm longer diameter), present. Two small, faint cuticular bars, difficult to see, present below lunules on first three pairs of legs.

The measurements of some structures of holotype and four paratypes are shown in Table 1 View TABLE 1 .

Minibiotus xavieri   sp. nov.

Eggs: Eggs, freely laid, spherical or slightly oval, with dotted shell and long conical processes with bifurcate apices and two or more terminal filaments (often broken) ( Fig. 2 View FIGURE 2. A – D , black arrows); some processes forked in a more proximal position ( Fig. 2 A–C View FIGURE 2. A – D white arrows). Diameter 56.0–79.0 µm excluding processes, 80 and 99.2 µm, including these structures. Processes, 20–23 around circumference, 75–95 in hemisphere, 10.6 –19.0 µm high and basal diameter of 3.7–6.6 µm. Egg processes 3.3–5.8 µm apart. Egg process surface and egg shell with obvious, well-spaced granulation ( Fig. 2 C, D View FIGURE 2. A – D ).

*) Unfortunately, due to a qui pro quo, Binda and Pilato, in the paper of 1992, wrote that the pt value relative to the buccal tube in M. furcatus   is 7.94.

The paratypes are similar to the holotype in both qualitative and metric characters. The smallest measured specimen is 275 µm long (structures not measured) and the largest specimen 410 µm.

Etymology: The new species is dedicated in honor of Alberto Xavier da Cunha, pioneer in the study of Portuguese tardigrades.

Differential diagnosis: We compared Minibiotus xavieri   sp. nov. with the species of the genus having cuticular pores of variable shape (also trilobate) arranged in more or less defined transverse bands, buccal tube with an anterior bend and no posterior bend, and pharyngeal bulb with three macroplacoids and microplacoid. These characters considered, the most similar species are: Minibiotus eichorni Michalczyk & Kaczmarek, 2004   , M. orthofasciatus   , M. vinciguerrae   , and M. furcatus   ; the new species differs from them in some qualitative and quantitative characters of both animals and eggs.

The eggs of Minibiotus eichorni   are not known but the specimens of Minibiotus xavieri   sp. nov. differ from M. eichorni   in the distribution of the cuticular pores (9 transverse bands instead of 8); in having smaller cuticular pores (longer diameter of elliptical pores up to 2 µm long in the holotype of Minibiotus xavieri   sp. nov. 369 µm long, up to 3.5 µm in specimens of M. eichorni   318 µm long); in lacking pores with 4 or 5 arms; in lacking granulation on the legs and in having claws with more prominent accessory points.

The new species differs from Minibiotus orthofasciatus   in the distribution and size of the cuticular pores: Minibiotus xavieri   sp. nov. has a lower number of transverse bands (9 instead of 11) each with a higher number of pores; the diameter of pores is the same but in specimens of very different body length; in having longer microplacoid ( Table 2 View TABLE 2 ); in having slightly longer claws ( Table 2 View TABLE 2 and Figs. 1 D, E View FIGURE 1. A – E and 3 A View FIGURE 3. A – C ) and in producing quite different eggs ( Figs. 2 View FIGURE 2. A – D and 3 B, C View FIGURE 3. A – C ).

Minibiotus xavieri   sp. nov. differs from Minibiotus vinciguerrae   in having shorter body length, in lacking granulation on the legs; in having the cuticular pores (never quadrilobate) clearly arranged in transverse bands; in having less slender claws ( Figs. 1 D, E View FIGURE 1. A – E and 3 View FIGURE 3. A – C E, F), and in characters of the eggs (the processes are less numerous, 20–23 in the circumference, 75–95 in the hemisphere in M. xavieri   sp. nov., 26 and 110 respectively in M. vinciguerrae   ; they are longer, 10.6–19 µm in the new species, 8–9 µm in M. vinciguerrae   ; the process surface and the egg shell are clearly dotted while they are smooth in M. vinciguerrae   ) ( Figs. 2 View FIGURE 2. A – D and 3 View FIGURE 3. A – C D).

The new species differs from Minibiotus furcatus   in having few trilobate cuticular pores and no quadrilobate ones; narrower buccal tube ( Table 2 View TABLE 2 ), and very different eggs (the egg processes are up to 19 µm long, with a well-spaced granulation and bifurcate apex in M. xavieri   sp. nov., while in M. furcatus   they are up to 6 µm long, smooth and never bifurcate; in addition the egg shell is clearly dotted in M. xavieri   sp. nov. and smooth in M. furcatus   ).

As stressed by Pilato & Lisi (2006), by Guidetti et al. (2007) and by Fontoura et al. (2009), some species described as belonging to the genus Macrobiotus   should be transferred to the genus Minibiotus   . For this reason we think that it is appropriate to compare Minibiotus xavieri   sp. nov. with three species of Macrobiotus   ( M. pustulaus Ramazzotti, 1959   , M. lazzaroi   and M. pseudofurcatus   ) which are similar to the new species, and whose systematic position needs to be analyzed because the examination of the type material did not confirm the presence of peribuccal lamellae (a generic character of Macrobiotus   ).

Minibiotus xavieri   sp. nov. differs from Macrobiotus pustulatus Ramazzott   i, 1959 in having eye spots, clearly smaller cuticular pores (diameter of largest pores in M. xavieri   sp. nov. about 2 µm, in M. pustulatus   up 6-7 µm), longer placoid row, and different eggs.

Minibiotus xavieri   sp. nov. differs from Macrobitous lazzaroi   in having slightly smaller and more numerous cuticular pores ( Figs. 1 A View FIGURE 1. A – E and 4 A View FIGURE 4. A ), narrower buccal tube ( Table 2 View TABLE 2 ), and quite different eggs.

Minibiotus xavieri   sp. nov. differs from Macrobiotus pseudofurcatus   in having narrower buccal tube ( Table 2 View TABLE 2 ), claws shorter ( Table 2 View TABLE 2 ) and different in shape ( Figs. 1 D, E View FIGURE 1. A – E and 4 View FIGURE 4. A B, C), (the difference in length between main and secondary branches is lower than in M. pseudofurcatus   ), and in some characters of the eggs: they are slightly smaller (diameter 56–79 µm without processes in the new species, 83–90 µm in M. pseudofurcatus   ); the processes are less numerous (20–23 in the circumference and 75–95 in the hemisphere in Minibiotus xavieri   , 30–31 and about 130 respectively in M. pseudofurcatus   ); the process surface has a wellspaced granulation while it is smooth in M. pseudofurcatus   ( Figs. 2 C, D View FIGURE 2. A – D and 4 View FIGURE 4. A D); the proximal portion of the processes, below the bifurcation, is generally longer than in the eggs of Macrobiotus pseudofurcatus   ( Figs. 2 View FIGURE 2. A – D and 4 View FIGURE 4. A D); the egg shell has a more evident granulation in M. xavieri   .

Maucci & Durante-Pasa (1984 a) reported M. pseudofurcatus   from Portugal. Keeping in mind the similarities between Minibiotus xavieri   sp. nov. and Macrobiotus pseudofurcatus   , we examined one specimen from Portugal attributed by those authors to M. pseudofurcatus   . We can exclude the proposition that the Portuguese specimens recorded by Maucci belong to this species and state that they very probably belong to Minibiotus xavieri   sp. nov.

Macrobiotidae Thulin, 1928  

Calcarobiotus   ( Calcarobiotus   ) sp. Dastych, 1993 Macrobiotus cf. harmsworthi Murray, 1907   Macrobiotus hufelandi Schultze, 1834  

Macrobiotus lusitanicus Maucci & Durante Pasa, 1984   b Macrobiotus recens Cuénot, 1932  

Macrobiotus cf. richtersi Murray, 1911  

Minibiotus cf. intermedius ( Plate, 1889)  

Minibiotus orthofasciatus Fontoura, Pilato, Lisi & Morais, 2009   Minibiotus xavieri   sp. nov.

Eohypsibiidae Bertolani & Kristensen, 1987   (nomen novum for Amphibolidae Bertolani, 1981   ) Bertolanius weglarskae ( Dastych, 1972)  

Hypsibiidae Pilato, 1969  

Hypsibius seychellensis Pilato, Binda & Lisi, 2006   Isohypsibius josephi ( Iharos, 1964)  

Isohypsibius prosostomus ( Thulin, 1928)  

Isohypsibius sattleri ( Richters, 1902)  

Diphascon (Diphascon) patanei Binda & Pilato, 1971   Diphascon (Diphascon) pingue ( Marcus, 1936)   Astatumen trinacriae ( Arcidiacono, 1962)  

Milnesiidae Ramazzotti, 1962  

Milnesium tardigradum Doyère, 1840  

TABLE 1. Measurements (in µm) of some structures of the holotype and four paratypes of Minibiotus xavieri sp. nov.

  paratype paratype paratype holotype paratype
Body length 275 305 335 369 410
Buccal tube 27.5 28.9 32.2 32.7 32.1
Buccal tube external width 2.7 2.4 2.8 3.0 3.1
pt 9.8 8.3 8.7 9.2 9.7
Stylet supports pt 66.1 67.9 67.6 67.3 66.7
Ventral lamina pt 56.8 57.4 55.2 55.7 56.9
First macroplacoid 3.6 ? 4.1 4.5 4.3
pt 13.1 ? 12.7 13.8 13.4
Second macroplacoid 2.9 3.2 3.5 3.6 3.3
pt 10.6 11.1 10.9 11.0 10.3
Third macroplacoid 3.0 3.2 3.6 3.9 3.6
pt 10.9 11.1 11.2 11.9 11.2
Microplacoid 1.5 ? 1.6 1.7 2.0
pt 5.5 ? 5.0 5.2 6.2
Placoid row 10.9 ? 13.0 13.9 13.9
pt 39.6 ? 40.4 42.5 43.3
Macroplacoid row 9.8 ? 11.7 12.6 11.7
pt 35.6 ? 36.3 38.5 36.5
External claws II, III 8.8 9.4 11.4 10.5 10.9
pt 32.0 32.5 35.4 32.1 34.0
Internal claws II, III 8.3 9.1 10.1 10.0 10.5
pt 30.2 31.5 31.4 30.6 32.7
Posterior claws IV 10.3 11.3 13.2 13.0 13.1
pt 37.5 39.1 41.0 39.8 40.8
Anterior claws IV 9.9 11.1 13.0 12.0 12.9
pt 36.0 38.4 40.4 36.7 40.2

TABLE 2. Measurements (in µm) of some structures of Minibiotus xavieri sp. nov., Minibiotus orthofasciatus, Minibiotus furcatus, Macrobiotus lazzaroi and Macrobiotus pseudofurcatus.

Body length Minibiotus xavieri   sp. nov. holotype 369 Minibiotus orthofasciatus   holotype 186 Minibiotus furcatus   280 Macrobiotus lazzaroi   paratype 235 Macrobiotus pseudofurcatus   holotype 342
Buccal tube 32.7 22.6 30.1 28.1 36.8
Buccal tube external width 3.0 1.8 3.4 3.0 3.9
pt 9.2 8.0 11.2* 10.7 10.6
Stylet supports pt Ventral lamina pt 67.3 55.7 66.8 58.4 64.1 62.0 65.3 55.4 67.7 56.5
First macroplacoid 4.5 3.1 4.2 4.1 6.0
pt Second macroplacoid 13.8 3.6 13.7 2.4 13.8 2.9 14.6 3.3 16.3 3.6
pt 11.0 10.6 9.8 11.7 9.8
Third macroplacoid pt 3.9 11.9 2.4 10.6 3.1 10.2 3.6 12.8 4.4 12.0
Microplacoid 1.7 0.9 1.5 1.2 1.8
pt Placoid row 5.2 13.9 4.0 8.3 4.8 12.0 4.3 12.1 4.9 16.9
pt 42.5 36.7 39.9 43.1 45.9
Macroplacoid row pt 12.6 38.5 7.4 32.7 11.0 36.5 10.9 38.8 15.2 41.3
External claw II, III 10.5 6.8 9.4 8.2 13.8
pt Internal claw II, III 32.1 10.0 30.1 6.3 31.3? 29.2 8.0 37.5 12.6
pt 30.6 27.9 ? 28.5 34.2
Posterior claw IV 13.0 6.8 ? 9.8 18.2
pt Anterior claw IV 39.8 12.0 30.1 6.9 ? 11.6 34.9 9.6 49.5?
pt 36.7 30.5 38.6 34.2 ?

Kingdom

Animalia

Phylum

Tardigrada

Class

Eutardigrada

Order

Parachela

Family

Macrobiotidae

Genus

Minibiotus

Loc

Minibiotus xavieri

Fontoura, Paulo, Pilato, Giovanni, Morais, Paulo & Lisi, Oscar 2009
2009
Loc

Minibiotus orthofasciatus

Fontoura, Pilato, Lisi & Morais 2009
2009
Loc

Hypsibius seychellensis

Pilato, Binda & Lisi 2006
2006
Loc

Eohypsibiidae

Bertolani & Kristensen 1987
1987
Loc

Macrobiotus lusitanicus

Maucci & Durante Pasa 1984
1984
Loc

Amphibolidae

Bertolani 1981
1981
Loc

Bertolanius weglarskae (

Dastych 1972
1972
Loc

Diphascon (Diphascon) patanei

Binda & Pilato 1971
1971
Loc

Hypsibiidae

Pilato 1969
1969
Loc

Isohypsibius josephi (

Iharos 1964
1964
Loc

Astatumen trinacriae (

Arcidiacono 1962
1962
Loc

Milnesiidae

Ramazzotti 1962
1962
Loc

Diphascon (Diphascon) pingue (

Marcus 1936
1936
Loc

Macrobiotus recens Cuénot, 1932

Cuenot 1932
1932
Loc

Macrobiotidae

Thulin 1928
1928
Loc

Isohypsibius prosostomus (

Thulin 1928
1928
Loc

Macrobiotus cf. richtersi

Murray 1911
1911
Loc

Macrobiotus cf. harmsworthi

Murray 1907
1907
Loc

Isohypsibius sattleri (

Richters 1902
1902
Loc

Minibiotus cf. intermedius (

Plate 1889
1889
Loc

Milnesium tardigradum Doyère, 1840

Doyere 1840
1840
Loc

Macrobiotus hufelandi

Schultze 1834
1834