Two new tardigrade species from Romania (Eutardigrada: Milnesiidae, Macrobiotidae), with some remarks on secondary sex characters in Milnesium dornensis sp. nov.
Author
Roszkowska, Daniel Adrian Ciobanu Milena
Author
Kaczmarek, Łukasz
text
Zootaxa
2015
3941
4
542
564
journal article
41596
10.11646/zootaxa.3941.4.4
0e136add-c127-45be-bfe9-0987b523fb87
1175-5326
233659
66179A2D-14A6-4C5F-91F7-331E7922D1B0
Milnesium dornensis
sp. nov.
http://www.tardigrada.net/register/0018.htm (
Figs 1
–
14
,
Tables 1
–
2
)
Material examined:
Holotype
(female), 46
paratypes
(
36 females
and
10 males
) and five exuvia with 18 smooth eggs.
Description of the adults (
Figures 1
–
2
) (measurements in µm,
pt
ratios and statistics in
Tables 1
–
2
):
Body brownish (in live specimens) or transparent (after fixation in Hoyer’s medium). Eyes present or absent (visible before and after mounting; 68% of fixed specimens had eyes). Cuticle sculptured with pseudopores (0.5–0.7 Μm in diameter in females and 0.3–0.5 Μm in males), not arranged in bands, sparsely distributed and not forming a reticular design. Under PCM these pseudopores are visible as light spots, placing the species within the
granulatum
group (
Figs 4 and 6
). On the dorsal side, in the caudal region, an area similar to plate structures is visible (
Fig. 8
). These plates are visible only in a few females and at present it is hard to evaluate their taxonomic significance. Six peribuccal papillae and six peribuccal lamellae around the mouth opening present (
Figs 3 and 5
). Two cephalic papillae, positioned laterally.
Bucco-pharyngeal apparatus of the
Milnesium
type
(
Figs 3 and 5
). Buccal tube slightly funnel-shaped, wider anteriorly (posterior diameter on average 90% of the anterior diameter). Pharyngeal bulb elongated, pear-shaped and without placoids or septulum. Claws of the
Milnesium
type
, slender (
Figs 7, 9
and
11
–
13
). Primary claws on all legs are simple, unbranched with small accessory points detaching from the branch at its greatest curvature (
Figs 10
and
14
). Secondary claws on all legs with rounded basal thickenings (lunules) (sometimes barely visible) (
Figs 9
and
13
). Secondary claws on all legs with three branches (claw configuration: [3-3]-[3-3]) (
Figs 7, 9
and
12–13
), with the exception of the sexually dimorphic modified claws of the males of first pair of legs (
Fig. 11
). Single, long and transverse cuticular bars under claws I
–
III present (
Figs 7
and
12
). In males, the cuticular bars on first pair of legs distinctly wider than those on legs II–III.
Eggs:
Oval, smooth and deposited in exuvium as in all other known
Milnesium
species.
Locus typicus
:
47°20'13.7''N
,
25°19'38.8''E
;
968 m
asl:
Romania
, Suceava County, Vatra Dornei town, lichen (
Usnea
sp
.) from tree (
Picea abies
L., H. Karst.).
Etymology:
Milnesium dornensis
is named after Vatra Dornei, the town, where the species was found.
Type
depositories:
Holotype
(female; slide: VD-7), 36
paratypes
(
29 females
and seven males; slides VD1, VD2, VD10, VD11, VD13, VD14) and one exuvium with eggs (slide VD10) are preserved at the Department of Animal Taxonomy and Ecology, Adam Mickiewicz University in Poznań, Umultowska 89, 61–614 Poznań,
Poland
. Additionally, three
paratypes
(females) (slides: VD3, VD4, VD5) are deposited at the Natural History Museum of “Alexandru Ioan Cuza” University from Iaşi,
Romania
(Bd. Independenţei No.16, 700101) and eight
paratypes
(five females and three males; slides: VD6, VD8, VD9, VD12) are deposited at the Department of Zoology, Comenius University, Bratislava,
Slovakia
.
TABLE 1
. Measurements and
pt
values of selected morphological structures of fifteen females from the type population of
Milnesium dornensis
sp. nov.
mounted in Hoyer’s medium (N—number of specimens/ structures measured, RANGE refers to the smallest and the largest structure among all measured specimens; SD—standard deviation).
CHARACTER |
N |
RANGE |
MEAN |
SD |
Holotype |
µm
pt
|
µm
pt
|
µm
pt
|
µm
pt
|
Body length |
15 |
384–874
1496–1986
|
679
1730
|
152
144
|
837
1816
|
Peribuccal papillae length |
11 |
5.7–12.0
22.0–28.3
|
9.9
25.2
|
1.9
1.9
|
11.5
24.9
|
Lateral papillae length |
14 |
4.2–9.2
15.0–23.7
|
7.2
18.7
|
1.2
2.4
|
6.9
15.0
|
Buccal tube |
Length |
15 |
24.5–46.1
-
|
39.0
–
|
6.7
–
|
46.1
–
|
Stylet support insertion point |
14 |
16.2–31.1
64.3–68.1
|
26.1
66.0
|
4.3
1.3
|
31.1
67.5
|
Anterior width |
15 |
10.7–24.0
42.5–54.5
|
18.1
46.3
|
3.8
3.3
|
22.9
49.7
|
Standard width |
15 |
9.4–22.7
37.8–51.6
|
17.3
44.1
|
3.8
3.9
|
22.7
49.2
|
Posterior width |
15 |
9.0–22.8
34.8–51.8
|
16.3
41.6
|
3.7
4.5
|
22.0
47.7
|
Standard width/length ratio |
15 |
38%–52%
-
|
44%
–
|
4%
–
|
49%
–
|
Posterior/anterior width ratio |
15 |
80%–98%
-
|
90%
–
|
6%
–
|
96%
–
|
Claw 1 lengths |
External primary branch |
14 |
11.6–22.0
40.1–50.4
|
18.1
46.7
|
3.5
3.1
|
20.8
45.1
|
External base + secondary branch |
14 |
9.2–18.3
34.2–40.9
|
15.3
38.5
|
2.8
2.3
|
17.7
38.4
|
External spur |
8 |
3.1–5.3
8.4–11.8
|
4.1
9.6
|
0.6
1.0
|
4.4
9.5
|
Internal primary branch |
14 |
10.8–21.0
36.9–47.7
|
16.7
43.0
|
3.4
3.0
|
20.0
43.4
|
Internal base + secondary branch |
14 |
8.8–17.2
33.0–38.6
|
14.4
36.3
|
2.5
1.8
|
16.6
36.0
|
Internal spur |
10 |
4.3–6.3
10.6–14.4
|
5.3
12.7
|
0.7
1.5
|
4.9
10.6
|
Claw 2 lengths |
External primary branch |
15 |
12.0–22.0
44.7–52.4
|
18.9
48.5
|
3.5
1.9
|
21.7
47.1
|
External base + secondary branch |
14 |
9.8–18.2
35.3–40.8
|
15.0
38.3
|
2.5
1.7
|
18.2
39.5
|
External spur |
7 |
2.9–5.8
7.6–14.1
|
4.3
10.6
|
1.1
2.1
|
4.7
10.2
|
Internal primary branch |
15 |
11.5–22.0
41.3–51.2
|
17.6
45.2
|
3.2
2.7
|
20.4
44.3
|
Internal base + secondary branch |
14 |
9.4–16.5
33.8–39.1
|
14.1
36.0
|
2.1
1.9
|
16.3
35.4
|
Internal spur |
9 |
4.1–6.5
10.3–14.6
|
5.4
13.1
|
0.9
1.5
|
6.5
14.1
|
Claw 3 lengths |
External primary branch |
15 |
13.2–23.7
47.0–54.4
|
19.6
50.4
|
3.4
2.6
|
23.0
49.9
|
External base + secondary branch |
13 |
10.0–17.8
36.7–43.7
|
15.2
39.5
|
2.3
2.2
|
17.0
36.9
|
External spur |
10 |
2.6–6.0
8.9–13.6
|
4.1
10.7
|
0.9
1.7
|
4.5
9.8
|
Internal primary branch |
14 |
12.4–21.8
42.2–50.6
|
18.3
47.3
|
3.3
2.3
|
21.1
45.8
|
Internal base + secondary branch |
13 |
9.0–17.3
33.3–41.7
|
14.3
37.1
|
2.3
2.6
|
16.6
36.0
|
Internal spur |
9 |
3.5–6.2
11.3–14.3
|
5.1
13.1
|
0.9
1.2
|
5.2
11. 3
|
Claw 4 lengths |
Anterior primary branch |
13 |
14.8–30.7
57.9–67.0
|
25.2
64.1
|
4.8
3.1
|
30.7
66.6
|
Anterior base + secondary branch |
12 |
10.3–21.4
40.9–50.3
|
18.0
45.5
|
3.0
3.3
|
21.2
46.0
|
Anterior spur |
12 |
3.5–6.6
12.1–17.9
|
5.6
14.2
|
0.9
1.5
|
5.6
12.1
|
Posterior primary branch |
13 |
16.1–30.4
58.0–69.1
|
24.9
63.7
|
4.2
3.5
|
29.0
62.9
|
Posterior base + secondary branch |
13 |
11.5–22.2
44.7–52.6
|
19.0
48.6
|
3.0
2.7
|
21.1
45.8
|
Posterior spur |
11 |
3.1–6.0
8.2–14.1
|
4.5
11.4
|
0.9
2.1
|
4.5 9.8 |
TABLE 2
. Measurements and
pt
values of selected morphological structures of ten males from the type population of
Milnesium dornensis
sp. nov.
mounted in Hoyer’s medium (N—number of specimens/ structures measured, RANGE refers to the smallest and the largest structure among all measured specimens; SD—standard deviation).
CHARACTER |
N |
RANGE |
MEAN |
SD |
µm
pt
|
µm
pt
|
µm
pt
|
Body length |
10 |
448–498
1500–1938
|
474
1647
|
18
121
|
Peribuccal papillae length |
10 |
4.1–4.9
12.5–19.1
|
4.5
15.8
|
0.3
1.9
|
Lateral papillae length |
10 |
5.1–5.9
16.5–21.5
|
5.6
19.5
|
0.2
1.7
|
Buccal tube |
Length |
10 |
25.7–32.7
-
|
28.9
–
|
2.1
–
|
Stylet support insertion point |
10 |
15.8–21.0
61.5–64.7
|
18.3
63.4
|
1.5
1.1
|
Anterior width |
10 |
10.6–12.9
36.5–44.7
|
11.3
39.2
|
0.8
2.4
|
Standard width |
10 |
9.0–10.4
30.6–38.9
|
9.8
33.9
|
0.5
2.5
|
Posterior width |
10 |
8.7–10.8
30.4–37.0
|
9.7
33.6
|
0.6
1.8
|
Standard width/length ratio |
10 |
31%–39%
-
|
34%
–
|
3%
–
|
Posterior/anterior width ratio |
10 |
80%–90%
-
|
86%
–
|
3%
–
|
Claw 1 lengths |
External primary branch |
4 |
15.0–18.1
53.6–69.3
|
17.1
62.5
|
1.4
6.5
|
External base + secondary branch |
5 |
15.1–18.2
53.9–63.3
|
16.7
59.2
|
1.3
3.4
|
External spur |
0 |
?
?
|
?
?
|
?
?
|
Internal primary branch |
5 |
14.1–20.4
50.4–65.8
|
17.1
60.6
|
2.4
5.9
|
Internal base + secondary branch |
6 |
15.0–19.0
53.6–68.1
|
17.3
61.5
|
1.7
5.4
|
Internal spur |
0 |
?
?
|
?
?
|
?
?
|
Claw 2 lengths |
External primary branch |
10 |
17.7–20.0
60.3–71.2
|
19.2
66.5
|
0.7
3.7
|
External base + secondary branch |
10 |
13.1–15.8
47.1–56.0
|
15.0
51.9
|
0.7
2.5
|
External spur |
6 |
3.1–4.0
11.3–15.6
|
3.6
12.5
|
0.4
1.7
|
Internal primary branch |
9 |
16.6–19.4
51.7–66.5
|
18.1
62.0
|
0.9
4.7
|
Internal base + secondary branch |
10 |
11.9–15.3
45.6–54.4
|
14.3
49.4
|
1.0
3.1
|
Internal spur |
7 |
4.1–4.9
13.2–17.1
|
4.5
15.2
|
0.3
1.6
|
Claw 3 lengths |
External primary branch |
9 |
17.3–20.0
61.2–72.0
|
19.0
65.6
|
0.9
3.7
|
External base + secondary branch |
8 |
13.1–15.4
47.1–53.2
|
14.6
50.1
|
0.8
1.9
|
External spur |
2 |
2.6–2.8
9.0–9.3
|
2.7
9.1
|
0.1
0.2
|
Internal primary branch |
9 |
16.5–19.3
55.0–66.4
|
17.9
61.8
|
1.0
3.9
|
Internal base + secondary branch |
8 |
13.1–15.1
45.9–54.5
|
14.3
49.2
|
0.7
2.7
|
Internal spur |
6 |
4.0–5.7
12.9–21.4
|
4.8
16.4
|
0.7
3.5
|
Claw 4 lengths |
Anterior primary branch |
10 |
20.9–24.4
71.0–88.7
|
22.7
78.9
|
1.1
6.1
|
Anterior base + secondary branch |
10 |
14.4–17.0
50.6–61.5
|
15.7
54.5
|
0.8
3.6
|
Anterior spur |
9 |
3.7–5.1
11.9–18.2
|
4.4
15.3
|
0.6
2.7
|
Posterior primary branch |
9 |
21.3–25.0
76.1–89.5
|
23.2
80.4
|
1.1
4.7
|
Posterior base + secondary branch |
9 |
15.0–16.6
51.3–61.1
|
15.8
55.6
|
0.5
3.1
|
Posterior spur |
8 |
2.9–3.4
9.7–12.2
|
3.1
11.0
|
0.2 0.9 |
FIGURES 1–2
.
Milnesium dornensis
sp. nov.
habitus: 1—female (ventral view); 2—male (ventral view).
FIGURES 3–6
.
Milnesium dornensis
sp. nov.
female: 3—buccal apparatus (ventral view); 4—sculpture on dorsal cuticle; male: 5—buccal apparatus; 6—sculpture on dorsal cuticle (ventral view).
FIGURES 7–10
.
Milnesium dornensis
sp. nov.
female: 7—claws I; 8—dorsal plates on caudal end; 9—claws IV; 10—accessory point on main branch of claw.
Differential diagnosis (for adult females).
Based on having a sculptured dorsal cuticle,
Milnesium dornensis
sp. nov.
belongs to the
granulatum
group (Michalczyk
et al.
2012a,b). The new species is most similar to
M. alabamae
Wallendorf & Miller, 2009
,
M. beasleyi
Kaczmarek
et al
., 2012
a,
M. granulatum
(
Ramazzotti, 1962
)
,
M. katarzynae
Kaczmarek
et al
., 2004
,
M. krzysztofi
Kaczmarek & Michalczyk, 2007
,
M. lagniappe
Meyer
et al
., 2013
and
M. reticulatum
Pilato
et al
., 2002
, but it differs from:
M. alabamae
by: different dorsal sculpture (pseudopores not arranged in bands, sparsely distributed and not forming a reticular design in
M. dornensis
sp. nov.
vs
pseudopores arranged in bands (especially in caudal region), densely distributed and forming a reticular design in
M. alabamae
), the presence of accessory points on primary branches of claws and a larger
pt
of the body length ([
1,496–1,986
] in
M. dornensis
sp. nov.
vs
[
821–1,388
] in
M
.
alabamae
).
M. beasleyi
by: a different claw configuration ([3-3]-[3-3] in
M. dornensis
sp. nov.
vs
[2-3]-[3-2] in
M. beasleyi
), the presence of rounded basal thickenings under secondary branches of claws (sometimes poorly visible), larger
pt
of peribuccal papillae length ([
22.0–28.3
] in
M. dornensis
sp. nov.
vs
[
19.6–21.3
] in
M
.
beasleyi
), larger
pt
of the anterior buccal tube width ([
42.5–54.5
] in
M. dornensis
sp. nov.
vs
[
35.3–41.8
] in
M
.
beasleyi
) larger
pt
of the anterior primary branch of the claw IV ([
57.9–67.0
] in
M. dornensis
sp. nov.
vs
[
53.1–57.4
] in
M
.
beasleyi
).
M. granulatum
by: a different dorsal sculpture (pseudopores not arranged in bands, sparsely distributed and not forming reticular design in
M. dornensis
sp. nov.
vs
pseudopores densely distributed and forming a reticular design in
M. granulatum
) different lengths of claws on legs IV (see
Table 1
below and
Table
2
in
Bartels
et al.
(2014)
for the exact differences in dimensions of the claws).
FIGURES 11–14
.
Milnesium dornensis
sp. nov.
male: 11—modified claws I; 12—claws III; 13—claws IV; 14—accessory point on main branch of claw.
M. katarzynae
by: a different claw configuration ([3-3]-[3-3] in
M. dornensis
sp. nov.
vs
[2-2]-[2-2] in
M. katarzynae
), different dorsal sculpture (pseudopores not arranged in bands, sparsely distributed and not forming a reticular design in
M. dornensis
sp. nov.
vs
pseudopores densely distributed and forming a reticular design in
M. katarzynae
), a larger body size (384
–
874 µm in
M. dornensis
sp. nov.
vs
285.0
–
294.5 µm in
M. katarzynae
), the stylet supports inserted in a more anterior position ([
64.3–68.1
] in
M. dornensis
sp. nov.
vs
[
73.3–78.3
] in
M. katarzynae
), a different buccal tube standard width (9.4–22.7 Μm in
M. dornensis
sp. nov.
vs
6.6–7.6 Μm in
M. katarzynae
) and a different
pt
of buccal tube standard width ([
37.8–51.6
] in
M. dornensis
sp. nov.
vs
[
21.7–26.6
] in
M. katarzynae
).
M. krzysztofi
by: a different claw configuration ([3-3]-[3-3] in
M. dornensis
sp. nov.
vs
[2-3]-[3-2] in
M. krzysztofi
), a different dorsal sculpture (pseudopores not arranged in bands, sparsely distributed and not forming a reticular design in
M. dornensis
sp. nov.
vs
pseudopores densely distributed and forming a reticular design in
M. krzysztofi
), larger
pt
of the body length ([
1,496–1,968
] in
M. dornensis
sp. nov.
vs
[
1,262–1,425
] in
M. krzysztofi
) larger internal/anterior spurs of claws I
–
IV (I: 4.3
–
6.3 Μm [
10.6–14.4
]; II: 4.1
–
6.5 Μm [
10.3–14.6
]; III: 3.5
–
6.2 Μm [
11.3–14.3
]; IV: 3.5
–
6.6 Μm claws [
12.1–17.9
] in
M. dornensis
sp. nov.
vs
I: 2.5
–
2.5Μm [
10.1–10.1
]; II: 2.5
–
2.8 Μm [?
–9.8
];
ca.
III: 3.4 Μm [
ca. 10.8
]; IV: 2.7–3.2 Μm [
8.0–10.1
] in
M. krzysztofi
).
M. lagniappe
by: a different claw configuration ([3-3]-[3-3] in
M. dornensis
sp. nov.
vs
[2-3]-[3-2] in
M. lagniappe
), a different dorsal sculpture (pseudopores not arranged in bands, sparsely distributed and not forming a reticular design in
M. dornensis
sp. nov.
vs
nine dorsal and lateral sculptured bands bearing a reticulated pattern of polygons in
M. lagniappe
), having six peribuccal lamellae (four in
M. lagniappe
), the stylet supports inserted in a more anterior position ([
64.3–68.1
] in
M. dornensis
sp. nov.
vs
[
69.7–73.4
] in
M. lagniappe
), smaller
pt
of width of the buccal tube ([
42.5–54.5
], [
37.8–51.6
], [
34.8–51.8
] anterior, standard and posterior respectively in
M. dornensis
sp. nov.
vs
[
68.0–77.5
], [
63.4–77.9
], [
61.8–70.8
] anterior, standard and posterior respectively in
M. lagniappe
), a smaller buccal tube standard width/length ratio (38%
–
52% in
M. dornensis
sp. nov.
vs
63%
–
78% in
M. lagniappe
) and a smaller
pt
of the external base+secondary branch of claws I ([
34.2–40.9
] in
M. dornensis
sp. nov.
vs
[
41.6–51.0
] in
M. lagniappe
).
M. reticulatum
by: a different claw configuration ([3-3]-[3-3] in
M. dornensis
sp. nov.
vs
[2-3]-[3-2] in
M. reticulatum
), a different dorsal sculpture (pseudopores not arranged in bands, sparsely distributed and not forming a reticular design in
M. dornensis
sp. nov.
vs
pseudopores arranged in nine sculptured bands, forming a reticular design in
M. reticulatum
), absence of cuticular gibbosities, having six peribuccal lamellae (four in
M. reticulatum
), the stylet supports inserted in a more anterior position ([
64.3–68.1
] in
M. dornensis
sp. nov.
vs
[
68.5–69.8
] in
M. reticulatum
) and larger claws I
–
IV (see
Table 1
below and
Table
2
in
Pilato
et al.
(2002)
for the exact differences in dimensions of the claws).