Milnesium reductum, Tumanov, Denis V., 2006

Tumanov, Denis V., 2006, Five new species of the genus Milnesium (Tardigrada, Eutardigrada, Milnesiidae), Zootaxa 1122, pp. 1-23: 15-18

publication ID

http://doi.org/ 10.5281/zenodo.171737

publication LSID

lsid:zoobank.org:pub:920D938D-F578-47BE-B7E7-50DD7864703D

persistent identifier

http://treatment.plazi.org/id/B32287EE-281C-C830-FEBD-FDBF8ECFD44F

treatment provided by

Plazi

scientific name

Milnesium reductum
status

sp. nov.

Milnesium reductum  sp. nov. ( Figs. 6, 7View FIGURES 2 – 9, 30–36View FIGURES 30 – 36, Table 5)

Type Material. Holotype: sex indeterminate, slide number 192 (1). Collected by Dr. I. G. Danylov (Zoological Institute of the Russian Academy of Sciences, St. Petersburg) 20.06. 1998, Kirghizia. Paratypes: slide’s numbers 192 (2, 3, 5) from the same locality. Type locality: Kirghizia, Jalal­Abad Area, vicinity of Tashkumyr, Sarakamyshsai, near 2000 m a.s.l., moss from sandstone rock. 10 adult and juvenile specimens were found.

Etymology. This species is named after its typical characters—reduced basal spurs and accessory points on claws.

Description. Body length up to 758.1 µm; colour of living specimens slightly reddish or white, cuticle smooth, eyes present in most specimens (among 6 adult specimens only one lack eyes). Six peribuccal and two lateral papillae present. The mouth with 6 peribuccal lamellae longitudinally striped in their basal portion.

Claws long, slender. Main branch of each claw lacks accessory points. Complex basal claw+secondary branch with a rounded basal thickening. Outer claws on all legs lacks basal spurs. First three pairs of legs with elongated cuticular thickening near the claw bases. All dimensions are given in Table 5.

No eggs and mature males were found.

Remarks. In one specimen the abnormal development of claws was found. It has an additional branching of the main branch of one claw on the leg of the 3 rd pair ( Fig. 35View FIGURES 30 – 36) and a small lateral spine on the base of one claw on the leg of the 4 th pair, which is possibly the rudimentary basal spur ( Fig. 36View FIGURES 30 – 36).

Differential Diagnosis. Milnesium reductum  sp. nov. differs from M. reticulatum  by having smooth cuticle without gibbosities, larger body length of adult specimens (578– 758 µm in M. reductum  sp. nov. and 270–405 µm in M. reticulatum  ), longer buccal tube (42.2–43.7 µm in M. reductum  sp. nov. and 25.0– 38.8 µm in M. reticulatum  ) and longer claws without accessory points (pt value of the length of main branches of the claws of the IV pair of legs is 59.3–70.7 in M. reductum  sp. nov. and 41.7–44.3 in M. reticulatum  ).

Milnesium reductum  sp. nov. differs from M. katarzynae  by having smooth cuticle, more cephalic position of the insertion point of the stylet supports (pt value 65.3–69.3 in M. reductum  sp. nov. and 73.3–78.3 in M. katarzynae  ) and longer claws without accessory points and with basal spurs on the inner claws of all legs (pt value of the length of main branches of the claws of the IV pair of legs is 59.3–70.7 in M. reductum  sp. nov. and 43.5– 43.8 in M. reticulatum  ).

Milnesium reductum  sp. nov. differs from M. dujiangensis  by having main claw branches on all legs.

Milnesium reductum  sp. nov. differs from M. tardigradum  by having more slender claws, larger pt ratio of the claws of the IV pair of legs and reduced accessory points on all claws and basal spurs on the outer claws (for comparison see Tables 1 and 5).

Milnesium reductum  sp. nov. differs from M. almatyense  sp. nov. by having slightly longer buccal tube, completely reduced accessory points on all claws and reduced basal spurs on outer claws only (for comparison see Tables 3 and 5).

Milnesium reductum  sp. nov. differs from M. antarcticum  sp. nov. by having larger pt ratio of the length of the claws of the IV pair of legs, smaller buccal tube dimensions, more cephalic position of the insertion point of the stylet supports and more slender claws with reduced accessory points on all claws and basal spurs on outer claws (for comparison see Tables 2 and 5).

Milnesium reductum  sp. nov. differs from M. asiaticum  sp. nov. by having shorter buccal tube, shorter claws (especially on the IV pair of legs), reduced accessory points on all claws and basal spurs on outer claws (for comparison see Tables 4 and 5).

Milnesium reductum  sp. nov. differs from M. tetralamellatum  by having 6 peribuccal lamellae, smaller buccal tube dimensions, more caudal position of the insertion point of the stylet supports (pt value 65.3–69.3 in M. reductum  sp. nov. and 63.9 in M. tetralamellatum  ), reduced accessory points on all claws and larger pt ratio of the length of the main branch of the IV pair of legs (59.3–70.7 in M. reductum  sp. nov. and 54.7 in M. tetralamellatum  ).

Milnesium reductum  sp. nov. differs from M. brachyungue  by having larger pt ratio of the length of the claws of the IV pair of legs (pt value of the length of main branches of the claws of the IV pair of legs is 59.3–70.7 in M. reductum  sp. nov. and 33.1 in M. brachyungue  ) and longer claws.

Milnesium reductum  sp. nov. differs from M. eurystomum  by having typical configuration of buccal apparatus.

TABLE 5. Summary of morphometric data for Milnesium reductum sp. nov. (n = 6).

Claw base+sec. branch length, leg IV (µm)