Echiniscus quitensis, Pilato, Giovanni, 2007

Pilato, Giovanni, 2007, Echiniscus quitensis, a new species of tardigrade from Ecuador (Heterotardigrada: Echiniscidae), Zootaxa 1389, pp. 55-60 : 56-59

Echiniscus quitensis sp. n.

Fig. 1 , Fig. 3 A , C

Type locality. Ecuador, Quito.

Material examined. Type specimen (slide N. 3577) and two paratypes.

Species diagnosis. Third median plate absent; terminal plate unfaceted; cirrus A short; other lateral and dorsal trunk appendages absent; cuticular plates with small dots, joined to one another by very thin stripes difficult to see, and light points; anterior portion of the paired plates II and III, anterior portion of the median plate 2 and the area corresponding to the median plate 3 with large polygonal points without joining stripes and without light points. Internal claws with a spur.

Description of the holotype. Body length 257 μm ( Fig. 1 A); the true body colour is not discernible since the specimen has decolorized, but, due to the fact that Maucci wrote Echiniscus rufoviridis on the label, it is probably similar to that of this species. Third median plate absent but the corresponding area is sculptured ( Fig. 1 C); terminal plate unfaceted and with two incisions. The cuticular sculpture is characteristic; cephalic plate, scapular plate, median plate 1 ( Fig. 1 B), posterior portion of paired plates II and III, posterior portion of median plate 2 and terminal plate ( Fig. 1 C, D) with a double ornamentation with many small, dark, almost star­shaped points joined to one another by very thin stripes very difficult to see, and less numerous, larger light points. Dots of the terminal plate slightly smaller than those of the other plates. Neck plate with only small points not joined to one another by stripes. Anterior portion of the paired plates II and III ( Fig. 1 C), anterior portion of the median plate 2 and area corresponding to the median plate 3 with a very different ornamentation with large (diameter up to 1.6 μm) polygonal points, without joining stripes and without light points. Cuticle between the scapular plate and the paired plates II, and between the paired plates II and III with only small dots. Ventral surface with many very small dots.

External and internal cephalic cirri ( Fig. 3 A ) 23.5 μm and 15.1 μm long respectively; cephalic papilla 8.4 μm long; clava 6.9 μm long; cirrus A 36.3 μm long. No other lateral or dorsal appendage present. First pair of legs with a spine 4.2 μm long ( Fig. 1 B); fourth pair of legs with a papilla 5.5 μm long and a dentate fringe with 8 unequal teeth ( Figs 1 C, 3 C).

Claws well developed; external and internal claws of the second pair of legs 15.3 μm and 16.3 μm long respectively; external and internal claws of the fourth pair of legs 18.2 μm and 19.1 μm long respectively. Internal claws with a straight spur turned downwards ( Fig. 3 C).

Etymology. The specific name refers to the type locality (Quito).

Remarks. Echiniscus quitensis sp. n. differs from E. rufoviridis in lacking the third median plate, in having the terminal plate unfaceted, shorter claws, a spur on the internal claws and in the characteristics of the plate ornamentation. As this characteristic is concerned, du Bois­Reymond Marcus in the description of E. rufoviridis (1944, pag. 3) wrote: “Escultura dupla: puntos finos uniformes, cerrados e sitos na profundidade da cuticula; covinhas maiores, irregulares e mais escassas, que parteneem à superficie da cuticula. Faltan covinhas nas metades anteriores das placas pares, na mesma da 2a placas intercalar, e na 2a intercalar inteira.” In E. quitensis sp. n. the anterior portion of the paired plates, the anterior portion of the median plates 2 and the area corresponding to the median plate 3 have large polygonal points ( Fig. 1 C) instead of small dots.

E. quitensis sp. n. is very similar to E. charrua Claps & Rossi, 1997 of which I examined 5 paratypes ( Figs 2 and 3 B, D). The cuticular sculpture of the new species is of the same type but some differences are evident: scapular plate with smaller and more numerous light points ( Figs 1 B and 2 A); dark dots more distant from each other and joining stripes more evident; anterior portion of the median plate 2, anterior portion of the paired plates II and III and the area corresponding to the median plate 3 ( Figs 1 C and 2 C) with larger and less numerous polygons (diameter up to 1.6 μm in the holotype of E. quitensis 257 μm long, up 1.1 μm in a paratype of E. charrua 270 μm long); light points on median plate 1 and posterior portion of the paired plates II and III ( Figs 1 C and 2 C) smaller and less numerous than in E. charrua . Cephalic papilla shorter ( Figs 3 A and 3 B); internal claws with a straight spur turned downwards absent in E. charrua ( Figs 3 C and D).

Figures

FIGURE 1. Echiniscus quitensis sp. n.: A, habitus (scale bar 30 μm). B, anterior portion of the body. C, posterior portion of the body; the polygons and the light points are in focus. D, sculpture of the terminal plate. In B, C and D, scale bar = 10 μm.

FIGURE 2. Echiniscus charrua: A, B, anterior portion of the body. C, posterior portion of the body; the polygons and the light points are in focus. D, claws of the second and third pairs of legs. Scale bar = 10 μm.

FIGURE 3. A, anterior portion of the body of Echiniscus quitensis sp. n.; B, idem of E. charrua: the buccal cirri and the cephalic papilla are in focus. C, claws of the fourth pair of legs of E. quitensis sp. n.; D, claws of the third pair of legs of E. charrua. Scale bar = 10 μm.