Minibiotus continuus, Pilato, Giovanni & Lisi, Oscar, 2006

Pilato, Giovanni & Lisi, Oscar, 2006, Notes on some tardigrades from southern Mexico with description of three new species, Zootaxa 1236, pp. 53-68 : 64-66

Minibiotus continuus sp.n.

( Fig. 4 A–F)

Type locality

Southern Mexico, Chiapas, Selva El Ocote.

Species diagnosis

Cuticle smooth without pores; eye spots absent; pharyngeal bulb with apophyses, three granular macroplacoids and a small microplacoid; eggs with processes (21–22 around the circumference, 78–80 in the hemisphere) similar to those of M. intermedius but all included in a continuous hyaline layer.

Description of the holotype

Body length about 180 m ( Fig. 4 A); colourless, cuticle smooth without pores, small dots present on the hind legs; eye spots absent. Mouth without peribuccal lamellae; buccal tube rigid, with two bends ( Fig. 4 A), 20.6 m long and 1.3 m wide (pt = 6.3); ventral lamina short (7.4 m, pt = 35.9); stylet supports inserted on the buccal tube at 56.1% of its length (pt = 56.1). Pharyngeal bulb (18.9 m x 16.6 m) with apophyses, three granular macroplacoids and a small microplacoid. Each macroplacoid 1.9 m long (pt = 9.2); microplacoid 0.9 m long (pt = 4.4); entire placoid row 7.1 m long (pt = 34.5); macroplacoid row 6.1 m long (pt = 29.6).

Claws of hufelandi type ( Fig. 4 B,C) 5.0 m long (pt = 24.3) on the second and third pairs of legs, anterior and posterior claws of the hind legs 5.8 m (pt = 28.2) and 5.9 m (pt = 28.6) long respectively. Accessory points on the main branches and smooth lunules present. No other cuticular thickenings seem to be present near the lunules on the legs.

Eggs, free laid, spherical, with processes similar to those of M. intermedius but all included in a continuous hyaline layer ( Fig. 4 D–F). Diameter 46.2 m excluding the processes, 52.2 m including them; 21–22 processes are present around the circumference, 78–80 in the hemisphere; each process is 3.6 m high, basal diameter 1.8 m, diameter of the distal extremity 2.5–2.7 m.

Remarks

Minibiotus continuus sp. n., due to some characteristics of the eggs, appears to be related to Macrobiotus acontistus De Barros, 1942 b (and that species, in our opinion, must be transferred to the genus Minibiotus ), and to Minibiotus taiti . The type material of M. acontistus is lost but its description allows us to think that our specimens belong to a different species due to the absence of eye spots, the presence of microplacoid and to some differences in the eggs (diameter without processes 46.2 m in M. continuus sp. n., up 59 m in M. acontistus ), with smaller processes (3.6 m high in M. continuus sp. n., 5 m in M. acontistus ).

The new species is also similar to M. taiti ; but it differs from it in the following features: cuticular dots present only on the hind legs; stylet supports inserted on the buccal tube in a slightly more cephalic position (pt = 54.9–56.1 in M. continuus sp. n., 60–61 in M. taiti ); shorter claws; and some characters of the eggs: smaller dimensions (diameter without processes about 46.2 m in M.continuus sp. n., 54 m in M. taiti ), only 21–22 processes around the circumference (about 48 in M. taiti ), only 78–80 processes in the hemisphere (about 160 in M. taiti ).

Also Macrobiotus spertii Ramazzotti, 1957 has eggs with processes immersed in a hyaline membrane, but the dimensions of the animals and of the eggs and the characters of the processes clearly indicate that Minibiotus continuus sp. n. is a different species.

Figures

FIGURE 4. Minibiotus continuus sp. n. A. Habitus and bucco­pharyngeal apparatus of the holotype (scale bar = 20 m). B. Claws of the third pair of legs of a paratype. C. Claws of the fourth pair of legs of a paratype. D. egg. E – F. Detail of the eggs where the hyaline layer is evident. Scale bar = 10 m.