Macrobiotus polonicus, Pilato & Kaczmarek & Michalczyk & Lisi, 2003

Pilato, Giovanni, Kaczmarek, Łukasz, Michalczyk, Łukasz & Lisi, Oscar, 2003, Macrobiotus polonicus, a new species of Tardigrada from Poland (Eutardigrada: Macrobiotidae, ‘ hufelandi group’), Zootaxa 258 (1), pp. 1-8 : 2-7

Macrobiotus polonicus sp. nov.

( Figures 1­15 )

Description

Holotype: Body length 325.0 ( Fig. 1 ). Body colourless, posterior eyes present. Cuticle smooth, without any granulation but with small, circular or elliptical pores (1.0 x 2.0) ( Figs 6­7 ). Two lateral hemispherical gibbosities are present on the hind legs ( Figs 1 , 5 ). Bucco­pharyngeal apparatus of Macrobiotus type ( Fig. 2 ). Buccal tube 34.4 long and 4.6 [13.4] wide; stylet supports inserted on the buccal tube at 78.8% of its length; mouth terminal with ten peribuccal lamellae. Fine anterior band of teeth almost invisible, posterior band of small teeth and a system of three dorsal and three ventral transversal ridge­shaped teeth (ventralo­median ridge shorter than the dorsalo­median ridge). Pharyngeal bulb oval (31.9 x 25.6) with two rod­shaped macroplacoids clearly different in length and microplacoid. First macroplacoid 9.4 [27.3] long with central constriction, second 6.2 [18.0] long, microplacoid 3.2 [9.3] long. Macroplacoid row 16.2 [47.1] long, placoid row 18.7 long [54.4].

Claws of hufelandi type, well developed ( Figs 3 , 8­11 ). Due to the unfavourable orientation, only external claws of second and third pairs of legs and the claws of the hind legs were measured. External claws of second and third pairs of legs 10.3 [29.9] and 10.6 long [30.8] respectively; external and internal claws of the hind legs 9.9 [28.8] and 11.4 long [33.1] respectively. Well developed accessory points on main branches of claws. Lunules present; more developed and with indented margin on the hind legs. Two sclerotised areas are present near the lunules on each of the first three pairs of legs.

Eggs: White, laid freely, spherical, with spaced processes in shape of short truncated cones terminated with disc ( Figs 4 , 12­15 ). Processes in number of 20 ­ 26 on circumference of egg, with large, strongly indented (7 ­ 12 teeth on circumference of disc) terminal disc. Teeth on terminal disc blunt so it may resemble cogwheel. Diameter of egg without processes 72.6 ­ 76.2 and 82.6 ­ 87.1 including them. Processes 5.1 ­ 6.1 high, basal diameter 5.2 ­ 6.7; diameter (including teeth) of terminal disc 4.9 ­ 6.3 – almost as long as the basal diameter of the process. Surface between processes without reticular pattern, visible as smooth in Light Microscopy and wrinkled in SEM.

Remarks

Paratypes are similar to the holotype. In Table 1 the length of some structures of the smallest and largest measured specimens are given. As regards the value of the pt index relative to the insertion point of the stylet supports on the buccal tube, we measured 14 specimens and found values ranging from 77.0 to 78.9.

Type locality

Wielkopolski National Park, near Poznañ (North­Western Poland); 03. 2002.; moss from concrete wall on railway bank; leg. Ł. Kaczmarek.

Material examined

The holotype, 15 paratypes and 6 eggs are deposited in the collection of Binda and Pilato ( Department of Animal Biology “ Marcello La Greca ”, University of Catania, Italy) , 62 paratypes and 22 eggs are deposited in the Department of Animal Taxonomy and Ecology (A. Mickiewicz University, Poland) , 50 and 17 eggs paratypes are preserved in the collection of Ł. Michalczyk ( Jagiellonian University , Poland) .

Etymology The name ‘ polonicus ’ refers to the country where the new species has been found. Differential diagnosis

Macrobiotus polonicus sp. nov. belongs to the ‘ hufelandi group’; due to some characters it is similar to Macrobiotus persimilis Binda & Pilato, 1972 (first macroplacoid clearly longer than the second and with a central constriction, lunules of the hind legs markedly larger than those of the first three pairs of legs and with an indented margin, similar values of the pt index relative to the insertion point of the stylet supports on the buccal tube, egg shell smooth), but differs from it in the following features: cuticular pores smaller and less evident, hind legs with two evident lateral gibbosities, narrower buccal tube (specimens about 400 long: 7.9 in M. persimilis and 5.6 in M. polonicus ), lunules of the hind legs less developed and with a less evident indentation, eggs with a fewer processes (24 ­ 32 on the circumference of egg in M. persimilis and 20 ­ 26 in M. polonicus ) – the egg processes are more spaced, the terminal discs are larger and with a more evident indentation.

The new species differs also from Macrobiotus patagonicus Maucci, 1988 in the following features: hind legs with two evident lateral gibbosities, fine anterior band of small teeth present in the buccal cavity, first macroplacoid with a central constriction, claws more slender, lunules of hind legs larger and with an indented margin, egg processes less slender (in M. patagonicus their height is about twice larger as the width of the base).

Figures

FIGURE 1. Macrobiotus polonicus sp. nov. habitus (arrows indicate two lateral hemispherical gibbosities on the hind legs).

FIGURES 2­4. Macrobiotus polonicus sp. nov. 2, buccal apparatus; 3, claws of the IV pair of legs (note the larger lunulae on the internal claws); 4, details of the egg.

FIGURES 5­6. Macrobiotus polonicus sp. nov. 5, two lateral hemispherical gibbosities on the IV pair of legs (arrows); 6, pores in the dorso­lateral cuticle (PC).

FIGURES 7­8. Macrobiotus polonicus sp. nov. 7, pores in the cuticle; 6, claws of the IV pair of legs, (SEM).

FIGURES 9­11. Macrobiotus polonicus sp. nov. 9­10, claws of the II pairs of legs; 11, claws of the IV pair of legs (note the larger lunulae on the internal claws) (PC).

FIGURES 12­15. Macrobiotus polonicus sp. nov. 12, the egg; 13­15, series of the closer looks at the egg (SEM).