Macrobiotus contii, 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 : 61-63

Macrobiotus contii sp. n.

( Fig. 3 A–D)

Locus typicus

Southern Mexico, Chiapas, Selva El Ocote.

Material examined

Holotype (slide N. 5096), one paratype and two eggs (one of which in the ovary of the paratype) from an undetermined moss sample developing on a tree.

Species diagnosis

Cuticle with very small dots; eye spots absent; pharyngeal bulb with three rod­shaped macroplacoids and a microplacoid as long as the second macroplacoid; eggs with long, conical processes, smooth (only a trace of roughness is visible on the terminal portion); egg shell dotted.

Description of the holotype

Body length 315 m, colourless, eye spots absent, cuticle with very small dots difficult to see; pores absent. Mouth terminal; buccal tube rigid, with ventral lamina. Mouth ( Fig. 3 A) with ten peribuccal lamellae, an anterior band of fine teeth, a posterior ring of triangular teeth and a system of three dorsal and three ventral transverse ridges. Buccal tube 41.9 m long and 7.3 m wide (pt = 17.4); stylet supports inserted on the buccal tube at 75.0 % of its length (pt = 74.5). Pharyngeal bulb (34.7 m x 32.3 m) with apophyses, three rod­shaped macroplacoids and well developed microplacoid as long as the second macroplacoid ( Fig. 3 A). First macroplacoid 5.2 m long (pt = 12.4), second 4.7 m (pt = 11.2) (the anterior portion is thin, therefore in some focus positions the second macroplacoid may appear shorter); third macroplacoid, with a preterminal narrowing, 5.3 m long (pt = 12.6), microplacoid 4.6 m (pt = 11.0). Entire placoid row 22 m long (pt = 52.5); macroplacoid row 17.2 m (pt = 41.3).

Claws of hufelandi type ( Fig. 3 B) with thin accessory points on the main branches. Anterior and posterior claws of the hind legs 10.4 m (pt = 24.8) and 10.9 m long (pt = 26.0) respectively. The unfavourable orientation of the other claws does not allow the correct measurement. Small lunules with smooth margins are present. A cuticular thickening, slightly visible, is present near the lunules on the first three pairs of legs.

The eggs, laid freely, are spherical and provided with long, conical processes ( Fig.3 C, D). We found one egg without embryo but fortunately the paratype has one mature, recognizable egg in the ovary. Diameter is 69 m without processes, 96 m including these structures. The processes, 22–23 around the circumference and about 82 in the hemisphere, are long, conical, very sharpened at the apex; the terminal portion is flexible and never forked. They are 16.5–17.3 m high; basal diameter 8.0– 8.8 m. The surface of processes is smooth, without traces of reticular sculpture; only a trace of roughness is visible on the terminal portion. The egg shell is dotted; some dots are contiguous to one another and seem to give an irregular reticular design.

The paratype has the same qualitative characteristics of the holotype; the dimensions of some structures of the two specimens are indicated in Table 3 .

Remarks

Macrobiotus contii sp. n. belongs to the harmworthi group and differs from most species of the group by having smooth egg processes. In particular it differs from M. australis in the following features: eye spots absent, buccal cavity with an anterior band of small teeth (absent in M. australis ) and a ring of triangular teeth in the posterior portion (in M. australis a band of small teeth is present), egg processes longer (16.5–17.3 m in M. contii , 10–11 m in M. australis ).

M. contii sp. n. is similar to M. armatus , the eggs of which are unknown, but it differs from it by lacking eye spots, and by lacking a spur on the claws.

M. contii sp. n. differs from M. kovalevi in the following features: eye spots absent; buccal cavity with an anterior band of teeth and a posterior ring of teeth (both absent in M. kovalevi ), microplacoid more developed; and in some characters of the eggs (egg processes more regular in shape, never forked, without small spines but with a trace of roughness only in the terminal portion, egg shell dotted without a true regular reticular ornamentation).

Iharos, 1973 did not specify whether M. wauensis Iharos , has smooth or sculptured egg processes, but M. contii sp. n. differs from this species in having a more developed microplacoid, egg processes more numerous and spaced, egg shell dotted and without tubercles.

Macrobiotus contii sp. n.

paratype holotype

Figures

FIGURE 3. Macrobiotus contii sp. n. A. Bucco­pharyngeal apparatus of the holotype. B. Claws of third and fourth pairs of legs. C – D. Egg. Scale bar = 10 m.