Minibiotus xavieri, a new species of tardigrade from the Parque Biológico de Gaia, Portugal (Eutardigrada: Macrobiotidae)
Author
Fontoura, Paulo
Author
Pilato, Giovanni
Author
Morais, Paulo
Author
Lisi, Oscar
text
Zootaxa
2009
2267
55
64
journal article
40463
10.5281/zenodo.190870
d45ecd47-ec83-484b-9093-42acbf19d3ab
1175-5326
190870
Minibiotus xavieri
sp. nov.
Figs. 1–2
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. 1A
). Ventral surface of body with few roundish pores. Pores also present on legs (
Fig. 1A
) where no granulation is present.
Mouth antero-ventral; buccal cavity very small (
Fig. 1B, C
); 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. 1C
). Slight thickening of buccal tube wall present caudal to stylet supports (
Fig. 1B
). 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. 1B, C
); 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. 1D, 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
.
TABLE 1.
Measurements (in µm) of some structures of the holotype and four paratypes of
Minibiotus xavieri
sp. nov.
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 |
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
, black arrows); some processes forked in a more proximal position (
Fig. 2A–C
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. 2C, D
).
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 |
? |
*) 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
); in having slightly longer claws (
Table 2
and
Figs. 1D, E
and
3A
) and in producing quite different eggs (
Figs. 2
and
3B, C
).
FIGURE 1.
A–E,
Minibiotus xavieri
sp. nov.
: A, posterior portion of the body of a paratype showing the dorsal bands of pores; B, bucco-pharyngeal apparatus of the holotype, arrow indicates a thickening of the buccal tube caudal to the stylet supports (not very visible in the figure due to the orientation of the specimen); C, bucco-pharyngeal apparatus of a paratype; D, claws of the first pair of legs of the holotype, arrow indicates the faint cuticular thickenings below the lunules; E, claws of the fourth pair of legs of a paratype. (Scale bars = 10 µm)
FIGURE 2
. A–D, details of the eggs of
Minibiotus xavieri
sp. nov.
: A, the terminal filaments of the egg processes are broken one case excluded (black arrow), one process is forked in the proximal position (white arrow); B, one process is forked in the preterminal position and has terminal filaments (black arrow), another process is forked in a more proximal position (white arrow); C, one process is forked in the preterminal position and has terminal filaments (black arrow), another process is forked in a more proximal position (white arrow), the well-spaced granulation of the egg shell is visible; D, the terminal filaments, the well-spaced granulation of a process (black arrow) and of the egg shell are visible. (Scale bars = 10 µm)
FIGURE 3.
A–C,
Minibiotus orthofasciatus
: A, claws of the first and second pair of legs; B, details of the eggs, the shape of the processes and the covering membrane are shown; C, details of the egg, the ornamentation of the egg shell is shown (arrow); D–F,
Minibiotus vinciguerrae
: D, details of the egg, the process surface and the egg shell are smooth; E, claws of the second pair of legs; F, claws of the fourth pair of legs. (Scale bars = 10 µm)
FIGURE 4.
A, claws of
Macrobiotus lazzaroi
.
B–D,
Macrobiotus pseudofurcatus
: B, claws of the first pair of legs; C, claws of the fourth pair of legs; D, details of the egg, some long terminal filaments of the egg processes are shown (arrow), the process surface is smooth. (Scale bars = 10 µm)
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. 1D, E
and
3
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
and
3
D).
The new species differs from
Minibiotus furcatus
in having few trilobate cuticular pores and no quadrilobate ones; narrower buccal tube (
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. 1A
and
4A
), narrower buccal tube (
Table 2
), and quite different eggs.
Minibiotus xavieri
sp. nov.
differs from
Macrobiotus pseudofurcatus
in having narrower buccal tube (
Table 2
), claws shorter (
Table 2
) and different in shape (
Figs. 1D, E
and
4
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. 2C, D
and
4
D); the proximal portion of the processes, below the bifurcation, is generally longer than in the eggs of
Macrobiotus pseudofurcatus
(
Figs. 2
and
4
D); the egg shell has a more evident granulation in
M. xavieri
.
Maucci & Durante-Pasa (1984a)
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.
TABLE 3.
Checklist of Tardigrada known from the “Parque Biológico de Gaia”. SPECIES
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