Milnesium wrightae, Kaczmarek, Lukasz, Grobys, Daria, Kulpa, Adam, Bartylak, Tomasz, Kmita, Hanna, Kepel, Marta, Kepel, Andrzej & Roszkowska, Milena, 2019

Kaczmarek, Lukasz, Grobys, Daria, Kulpa, Adam, Bartylak, Tomasz, Kmita, Hanna, Kepel, Marta, Kepel, Andrzej & Roszkowska, Milena, 2019, Two new species of the genus Milnesium Doyere, 1840 (Tardigrada, Apochela, Milnesiidae) from Madagascar, ZooKeys 884, pp. 1-22: 1

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Milnesium wrightae

sp. nov.

Milnesium wrightae  sp. nov. Figures 6-8View Figures 6–8, 9-11View Figures 9–11, Table 7

Material examined.

Holotype and 28 paratypes, all from sample No 109: Ivohibory forest, Madagascar, moss sample from tree, coll. Marta Kepel and Andrzej Kepel.


Adult females ( Fig. 6View Figures 6–8, Table 7) with no modified claws I. Body light yellow before fixation and transparent afterwards, eyes present only in 39% of measured specimens. Dorsal cuticle sculptured with pseudopores not arranged in bands, sparsely distributed and not forming reticular design ( Fig. 7View Figures 6–8). Six peribuccal papillae and six peribuccal lamellae present around the mouth opening. Two cephalic papillae positioned laterally. Peribuccal papillae slightly longer than lateral papillae.

The buccal apparatus of the Milnesium  type ( Figs 6View Figures 6–8, 8View Figures 6–8). The buccal tube with standard width on average 62% of its length, and funnel-shaped, wider anteriorly (posterior diameter on average 91% of the anterior diameter) (Table 7). The pharyngeal bulb elongated, pear-shaped and without placoids or septulum.

Claws of the Milnesium  type, stout ( Figs 8View Figures 6–8 - 11View Figures 9–11). Primary branches on all legs with small, but distinct accessory points detaching from the branch at its greatest curvature ( Fig. 10View Figures 9–11, empty arrowhead). Secondary branches of claws similar in length to primary branches and sometimes even longer. Secondary branches with rounded basal thickenings ( Figs 9-11View Figures 9–11). Secondary branches on legs I–III with three points, secondary claws of anterior and posterior claws IV with four points (claw configuration: [3-3]-[4-4]). The fourth point on secondary branches is always very small and located near the base of the claw ( Figs 10-11View Figures 9–11, arrowheads). Single, long transverse, cuticular bars present under claws I–III ( Fig. 9View Figures 9–11, arrow).

Males unknown.

Eggs oval, smooth and deposited in the exuvium as in all other known Milnesium  species.

DNA sequences.

We obtained good quality sequences for the applied molecular markers: 28S rRNA sequence (GenBank: MN191504), 638 bp long; COI sequence (GenBank: MN187057), 638 bp long; ITS-2 sequence (GenBank: MN239907), 392 bp long.


The fourth points on secondary branches of posterior claws can be barely visible or not visible at all in some positions of the specimens.

Type locality.

Madagascar, 22°37'04.5"S, 46°43'14.1"E, ca. 1198 m asl, Fianarantsoa Province, Ivohibory forest.


This species is named after Patricia Chapple Wright, an American primatologist and conservationist, best known for her studies on lemurs. She contributed to the establishment of the Ranomafana National Park in Madagascar. She also organized and led the expedition to the Ivohibory forest, during which several new species of tardigrades were found, including this species.

Type depositories.

The holotype and 23 paratypes (slides: MAD109/1, MAD109/3, MAD109/4, MAD109/5, MAD109/7) are deposited at the Department of Animal Taxonomy and Ecology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, Poznań, Poland, five paratypes (slides: MAD109/2) are deposited at the Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9,30-387, Kraków, Poland.

Morphological differential diagnosis.

The new species, by the presence of four points on secondary branches of claws IV, is most similar to Mil. quadrifidum  Nederström, 1919, which is the only valid Milnesium  species with four points on secondary branches of all claws. However, Mil. wrightae  sp. nov. differs from Mil. quadrifidum  not only by claw configuration ([4-4]-[4-4] in Mil. quadrifidum  vs. [3-3]-[4-4] in Mil. wrightae  sp. nov.), but also by the position of fourth points on secondary branches of claws IV (located near the base of the claw in the new species vs. near the top of the claw in Mil. quadrifidum  ). Additionally, all secondary branch points have similar length in Mil. quadrifidum  , whereas the fourth points are very clearly smaller than the others in Mil. wrightae  sp. nov.

Genotypic differential diagnosis.

The ranges of uncorrected genetic p-distances between the Mil. wrightae  sp. nov. and species of the genus Milnesium  , for which molecular marker sequences are available from GenBank (see Table 6 for details), are as follows:

1. 28S rRNA: 5.7-8.0% (6.7% on average), with the most similar being Milnesium  sp. from North America (JX888585.1, JX888586.1, JX888587.1) (unpublished) and the least similar being Mil. t. tardigradum  from Poland (KC138808.1 and KC138809.1) (unpublished);

2. COI: 17.7-38.4% (22.0 % on average), with the most similar being Mil. variefidum  from UK (KT951663.1) ( Morek et al. 2016) and the least similar being Mil. t. tardigradum  from Spain (FJ435810.1) ( Guil and Giribet 2012);

3. ITS-2: 25.6-36.3% (31.5% on average), with the most similar being Mil. matheusi  sp. nov. (present studies) and the least similar being Mil. cf. granulatum  from USA (MK681879.1) ( Jackson and Meyer 2019).