Milnesium granulatum Ramazzotti, 1962

Michalczyk, Łukasz, Wełnicz, Weronika, Frohme, Marcus & Kaczmarek, Łukasz, 2012, Redescriptions of three Milnesium Doyère, 1840 taxa (Tardigrada: Eutardigrada: Milnesiidae), including the nominal species for the genus, Zootaxa 3154, pp. 1-20 : 9-11

Milnesium granulatum Ramazzotti, 1962 , bona species

( Figs 7–11 , Table 2 )

Material examined. One paratype, female, slide labelled as follows: “Tipo 145. 1 H. baumanni, 1 M. tardigradum granulatum Ramazzotti; Fray Jorge ( Cile) a m 620, 22.5.62, Lichene su parmo (Polivinil).”

Description (measurements in Table 2 ). Body colour unknown, eyes present according to the original description ( Ramazzotti 1962), but now are no longer visible ( Fig. 7 ). Dorso-lateral cuticle or only caudo-dorsal cuticle covered with a reticular design (diameter of polygons 0.5–1.5 μm) ( Fig. 8 ). The design better developed on the caudal cuticle. Ventral cuticle smooth. Granulation or pores in cuticle absent. Two lateral and six peribuccal papillae present(ventral papilla smaller than other papillae).

Buccal apparatus of the Milnesium type ( Fig. 9 ). Six peribuccal lamellae around the mouth opening present. Buccal tube slightly funnel-shaped, wider anteriorly (posterior diameter 87% of the anterior diameter). Pharyngeal bulb elongated, pear-shaped and without placoids or septulum.

Claws of the Milnesium type, slender ( Figs 10–11 ). Primary branches on all legs with small, but distinct accessory points detaching from the branch near its end. Secondary branches with rounded basal thickenings. All secondary branches on all legs with three points (i.e. claw configuration: [3-3]-[3-3]). Single, long transversal, cuticular bars under claws I–III present ( Fig. 10 ).

Although eggs were not described by Ramazzotti (1962), we should probably expect them to be oval, smooth and deposited in exuvium as in all other known Milnesium species.

Remarks. Maucci (1973–74) reported M. tardigradum granulatum also from the Trieste Kras, but we have not had an occasion to examine those animals. However, given the locus typicus of M. granulatum lies on a different continent and in a different zoogeographical region, we hypothesise that Maucci could have found a different species of the Milnesium granulatum group. Until the record is re-examined, we suggest this report should be considered dubious.

Locus typicus. Coquimbo Region, Bosque de Fray Jorge National Park, Ovalle, ca. 420 km to the North from Santiago de Chile, ca. 30°40'S and 71°40'W, ca. 600 m asl, temperate hygrophilous forest surrounded by steppe, mosses and lichens growing on shrubs.

Distribution. Currently confirmed is only the type locality in Chile (but see also Remarks above).

Etymology. Giuseppe Ramazzotti named the species ‘ granulatum ’ most likely because he interpreted the reticular design on the cuticle as granulation. In fact, ‘granules’ are shallow depression in the shape of rounded polygons (see Fig. 8 ).

Type depositories. The type material is preserved at the Natural History Museum of Verona, Italy.

Differential diagnosis. Apart from M. granulatum there are four other described Milnesium species with sculptured cuticle (see Table 1 ). M. granulatum differs specifically from:

M. alabamae Wallendorf & Miller, 2009 by having accessory points on the primary branches.

M. katarzynae Kaczmarek, Michalczyk & Beasley, 2004 by a different claw configuration ([3-3]-[3-3] in M. granulatum and [2-2]-[2-2] in M. katarzynae ), a wider buccal tube (pt ca. 39 % in M. granulatum and pt ca. 21– 26% in M. katarzynae ) and stylet supports inserted in more anterior position (pt ca. 66% in M. granulatum and pt. ca. 73–78% in M. katarzynae ).

M. krzysztofi Kaczmarek & Michalczyk, 2007 by a different claw configuration ([3-3]-[3-3] in M. granulatum and [2-3]-[3-2] in M. krzysztofi ).

M. reticulatum Pilato, Binda & Lisi, 2002 by the absence of gibbosities, having six peribuccal lamellae (four in M. reticulatum ) and a different claw configuration ([3-3]-[3-3] in M. granulatum and [2-3]-[3-2] in M. reticulatum ).

Figures

FIGURES 7 – 9. Milnesium granulatum Ramazzotti, 1962. 7 — habitus (dorso-ventral view, paratype); 8 — dorso-caudal cuticle (paratype); 9 — buccal tube (dorso-ventral section, paratype). [All PCM].

FIGURES 10 – 11. Milnesium granulatum Ramazzotti, 1962. 10 — claws III (paratype); 11 — claws IV (paratype). [All PCM].