Macrobiotus aradasi Binda, Pilato & Lisi, 2005, sp. nov.

Macrobiotus aradasi sp. nov. (Fig. 2)

Material examined. King George Island, Admiralty Bay; 30 specimens (holotype and paratypes) and 14 eggs, one of which with fully developed embryo, from moss samples.

Type repository. Zoologisches Institut und Zoologisches Museum der Universität Hamburg.

Description of the holotype. Body length 432 m; colourless, cuticle smooth, eyes present. Buccopharyngeal apparatus of Macrobiotus type (Fig. 2 A, B); mouth terminal with ten peribuccal lamellae; buccal cavity without an anterior band of fine teeth, with a posterior ring of very fine triangular teeth and three dorsal and three ventral delicate transverse ridges. Also some very fine ventral supplementary teeth are present. The buccal tube 43.6 m long and 5.3 m wide (pt = 12.2); the stylet supports are inserted on the buccal tube at 72.2 % of its length (pt = 72.2). The pharyngeal bulb has apophyses, 3 short macroplacoids without narrowings, microplacoid present; first macroplacoid 6.0 m long (pt = 13.8) second 4.7 m (pt = 10.8), third 5.1 m (pt =11.7), microplacoid 3.3 m (pt = 7.6.); entire placoid row 21.8 m long (pt = 50.0); macroplacoid row 17.7 m long (pt = 40.6).

The claws, of the hufelandi type, have very developed accessory points on main branches (Fig. 2 C). The internal claw on the third pair of legs 12.6 m long (pt = 28.9) accessory points and peduncle included, the external claw of the same pair 12.8 m long (pt = 29.4). Small lunules are present. A cuticular thickening is also present near the lunules on the first three pair of legs.

The eggs, laid freely, are spherical and provided with processes (Fig. 2 D, E). The diameter is 83.5–90.5 m excluding the processes, 97.5–100 m including them. Egg processes (21–23 in the circumference) twice (rarely once) divided from half process length; terminal branches blunt. Each subdivision may be dichotomic or multiple, i.e., two or more branches may be formed. Process surface smooth without refracting areas. Processes of the largest measured egg 8.69 m high, their basal diameter 8.4–9.5 m; base of each process with some projections forming a ring of basal dots (Fig. 2 D, E). The egg shell has many small refracting points and therefore it has a reticular sculpture with very small meshes (Fig. 2 E).

The paratypes are similar to the holotype for both qualitative and quantitative characters. In Table 1 the dimensions of some structures of the smallest and the largest measured specimens are indicated.

Etymology. The name aradasi is in honour of Prof. Andrea Aradas, malacologist of the nineteenth century, of the University of Catania.

Remarks. The new species differs from M. furciger in the following features: caudal portion of buccal cavity narrower, anterior band of teeth absent; stylet supports inserted on the buccal tube in a more cephalic position (pt = 72.0– 72.8 in M. aradasi sp. nov., 76.2– 77.1 in M. furciger); third macroplacoid shorter (it is about as long as the first one); microplacoid shorter (Table 1); and in some characters of the eggs (slightly smaller dimensions; processes smaller, without refracting areas, generally twice (rarely once, never thrice) divided, with terminal branches blunt; reticular sculpture of egg shell more delicate).

Macrobiotus aradasi sp. nov. has been found by Dastych (1984) but named M. furciger. This author also drew the buccopharyngeal tube (Dastych, 1984, p. 391, Fig.7 b, c; p. 392, Fig. 8 f). It is not easy to understand whether other records of M. furciger refer to M. aradasi sp. nov.