Echiniscus azoricus, Fontoura, Paulo, Pilato, Giovanni & Lisi, Oscar, 2008

Fontoura, Paulo, Pilato, Giovanni & Lisi, Oscar, 2008, Echiniscidae (Tardigrada, Heterotardigrada) from Faial and Pico Islands, the Azores, with the description of two new species, Zootaxa 1693, pp. 49-61 : 50-54

Echiniscus azoricus sp. nov.

Fig. 1 A–E, Tables 1 & 2

Material examined: Holotype (female) and six paratypes (4 females and 2 specimens of unknown sex) from a moss sample collected in Terras do Pico, Pico Island. All the specimens were mounted in Hoyer’s medium with a small amount of potassium iodide.

Type repository: The holotype (slide N. 5200) is preserved at the Museum of the Dipartimento di Biologia Animale “Marcello La Greca”, Università di Catania in the collection of Binda & Pilato. The six paratypes (BII-6 to BII-11) are preserved in the collection of P. Fontoura at the Department of Zoology and Anthropology, Faculty of Sciences, University of Porto.

Specific diagnosis: Small Echiniscus with unpaired plate 3 present; dorsal plates sculptured with dark knobs surrounded by a ring of small pores. Anterior portion of the median plate 2, anterior portion of paired plates II and III, and median plate 3 with very few or no pores. Apart from the cirrus A, all lateral appendages (B, C, D, E) and dorsal appendages present (C d and D d) are spines.

Description of the holotype: Adult female. Body length about 180 µm. Eyes absent in living specimens. Body reddish-brown. Median plate 3 present.

The dorsal plates’ sculpture consists of large dark knobs surrounded by a ring of small pores, generally six or seven pores ( Fig. 1 A–D). Cephalic plate with knobs and pores ( Fig. 1 A & B), notch on cephalic plate not visible due to the unsuitable orientation of the holotype (the notch is visible on paratype BII-8). Neck plate ( Fig. 1 A & B) thin and sculptured with small knobs (about 1.2 µm in diameter) and few pores (about 0.7 µm in diameter). Scapular plate unfaceted, without smooth transversal or longitudinal bands but with two lateral folds forming two small shoulder plates. The sculpture of the shoulder plates consists only of small knobs (about 1.2 µm in diameter), pores are lacking. Large knobs (2.7 µm in diameter) and pores (1.7 µm in diameter) are present in the central portion of the scapular plate ( Fig. 1 A & B). Paired plates II and III divided into an anterior and a posterior portion by a single and thin transversal band without sculpture ( Fig. 1 D). Posterior portion of the paired plates with large dark knobs (diameter 2.7 µm) surrounded by pores (diameter about 1.0 µm); the diameter of these knobs decreases gradually laterally and anteriorly ( Fig. 1 B & D). In the anterior portions of the paired plates the knobs are also smaller (about 1.4 µm in diameter) and the pores are very scarce ( Fig.1 B & D). Median plates 1, 2 and 3 present ( Fig. 1 A, C & D). Median plates 1 and 3 undivided with the same pattern of ornamentation as the scapular plate with knobs (diameter 2.0 µm) and pores (diameter 1.2 µm). Median plate 2 with a thin transversal and smooth band ( Fig. 1 D); the posterior portion of this plate has knobs larger than those of the anterior portion (respectively 2.4 and 1.4 µm in diameter) and also larger and more numerous pores (respectively 1.2 and 0.8 µm in diameter). Intersegmental areas ornamented only with small dark knobs with a diameter of about 0.7 µm. Terminal plate unfaceted (but gently faceted in some paratypes), with the two usual postero-lateral indentations (19.5 µm long) and with the same pattern of sculpture as the scapular plate with large knobs (about 3.2 µm diameter) and pores (1.6 µm in diameter) ( Fig. 1 C). No smooth longitudinal or transversal band on terminal plate is present. The ventral cuticle has a very fine granulation.

Leg plates with fine granulation except on leg IV where they present a sculpture with very small knobs and some small pores. A spine (2.4 µm long) is present on legs I; hind legs with a papilla (3.9 µm long) and a dentate fringe with about 13 sharp, triangular teeth 2.6 µm long ( Fig. 1 E).

Cephalic cirri with cirrophore; internal cirrus 10.6 µm long; external cirrus 16.2 µm long; cephalic papilla 7.0 µm long; clava 5.4 µm long ( Fig. 1 A,B). Apart from cirrus A (filament 52.6 µm long), all other lateral and dorsal appendages are spines: spine B, 16.9 µm long; C, 22.0 µm long; D, 20.6 µm long and E, 13.7 µm long. Dorsal appendages C d and D d are short spines: C d, 2.4 µm long and D d, 2.3 µm long.

External claws smooth, internal claws of all legs with a straight and thin spur directed downwards. Internal claws of legs IV 12.9 µm long with a spur 3.3 µm long inserted at about 3.7 µm from base (28.7%) ( Fig. 1 E). External and internal claws IV 11.5 µm and 12.9 µm long respectively; claws I–III slightly shorter ( Table 1 ).

In Table 1 the measurements of the smallest and the largest (the holotype) specimens are recorded.

Eggs unknown.

Variability: The combination of lateral and dorsal spines was similar in all the seven specimens examined and, besides some differences in length ( Table 2 ), no asymmetry has been found. Spine C is the longest, followed by D. The length of spine E, in contrast with B, is very variable ( Table 2 ). The dorsal appendages can be very short spines less than 3 µm long as in the holotype, or relatively long spines (about 15 µm in BII-7 and BII-11, cf. Table 2 ).

Etymology: The name azoricus refers to the Archipelago of the Azores that includes the Island of Pico, the locus typicus of the new species; azoricus = from the Azores.

Differential diagnosis: Taking into consideration the pattern of the cuticle ornamentation, the lateral and dorsal appendages present and the characters of these appendages, Echiniscus azoricus sp. nov. appears different from all the known species of the genus. A few species have a pattern of cuticular ornamentation somewhat similar to that of Echinicus azoricus sp. nov.: E. bisculptus Maucci, 1983 , E. vinculus , E. ehrenbergi , E. curiosus , E. zetotrymus (according to Pilato et al., 2005) and E. laterospinosus Rudescu, 1964 , but the new species differs from them.

It differs from E. bisculptus in having lateral appendages A, B, C, D, E and dorsal appendages C d and D d while in E. bisculptus the filament A is the only appendage present.

E. azoricus sp. nov. differs from E. vinculus in having lateral appendages A, B, C, D and E and dorsal appendages C d and D d while in E. vinculus only the appendage A is present. In addition, E. vinculus has very evident smooth areas on the scapular and the terminal plates absent in E. azoricus sp. nov.

The new species differ from E. curiosus and E. zetotrymus in having cuticular dark knobs less dense; this is particularly evident on the scapular plate, where the pores are larger and forming a ring around each dark knob ( Figs. 1 A, B & D; 2A & B). The smooth transversal band on the paired plates II and III is less evident than in E. curiosus and E. zetotrymus ( Figs. 1 D, 2A, B & C); in addition, in these species the anterior portion of the median plate 2 is sculptured only on its anterior margin ( Figs. 2A & C ), and the appendage B is lacking.

E. azoricus sp. nov. differs from E. eherenbergi in having more scattered dark knobs, larger and more numerous pores. In E. ehrenbergi the knobs are often contiguous or fused to one another, and the pores, very small, do not form a true ring around each knob. In addition, in this species the lateral appendages are filaments and the dorsal appendage C d is lacking.

E. laterospinosus is a nomen inquirendum believed to be composed of two different species ( Ramazzotti & Maucci, 1983). E. azoricus sp. nov. differs from it in the presence of the median plate 3 and in having lateral and dorsal appendages with a normal base not enlarged.

Figures

FIGURE 1. Echiniscus azoricus sp. nov. A (holotype), B, C, D (paratype), details of the plate sculpture and appendages; E, claws of the fourth pair of legs of the holotype, the dentate collar, and the spur on one internal claw are visible (arrows). Scale bar = 10 µm.

FIGURE 2. A, E. curiosus, cuticular ornamentation (paratype); B, C, E. zetotrymus, cuticular ornamentation of the anterior portion (B) and the posterior portion (C) of the body of a paratype. Scale bar = 10 µm.

Tables

TABLE 1. Measurements (in µm) of some structures of the smallest and the largest (the holotype) specimens of E. azoricus sp. nov. (% bo = percentage of body length; % sc = percentage of scapular plate length).

Character	Smallest specimen		Largest specimen
	µm %bo	%sc	µm %bo	%sc
Body length	129 -	-	180 -	-
Scapular plate length	29.5 22.9	-	39.5 21.9	-
Internal cephalic cirrus	10.0 7.8	33.9	13.8 7.7	34.9
External cephalic cirrus	14.8 11.5	50.2	17.9 9.9	45.3
Cephalic papilla	5.4 4.2	18.3	7.0 3.9	17.7
Clava	3.6 2.8	12.2	4.9 2.7	12.4
Lateral appendage A	43.1 33.4	146.1	52.6 29.2	133.2
Lateral appendage B	12.9 10.0	43.7	16.9 9.4	42.8
Lateral appendage C	21.8 16.9	73.9	22.0 12.2	55.7
Lateral appendage D	17.0 13.2	57.6	20.6 11.4	52.2
Lateral appendage E	14.2 11.0	48.1	13.7 7.6	34.7
Dorsal appendage C d	10.0 7.8	33.9	2.4 1.3	6.1
Dorsal appendage D d	10.8 8.4	36.6	2.3 1.3	5.8
Spine on legs I	1.6 1.2	5.4	2.4 1.3	6.1
Internal claws I	8.9 6.9	30.2	10.6 5.9	26.8
External claws I	8.5 6.6	28.8	10.2 5.7	25.8
Internal claws II/III	9.3 7.2	31.5	10.4 5.8	26.3
External claws II/III	8.2 6.4	27.8	9.7 5.4	24.6
Internal claws IV	10.2 7.9	34.6	12.9 7.2	32.7
External claws IV	9.2 5.1	31.2	11.5 6.4	29.1
Papilla on legs IV	3.2 2.5	10.8	3.9 2.2	10.0
Spur on claws IV	??	?	3.3 1.8	8.4

TABLE 2. Measurements (in µm) of the lateral and dorsal appendages of the examined specimens of E. azoricus sp. nov. (Htype = holotype; BII- 6 – BII- 11 = paratypes).

Character	Htype	BII-6	BII-7	BII-8	BII-9	BII-10	BII-11
Body length	180	129	?	167	179	145	?
Lateral appendage A	52.6	43.1	39.3	51.9	52.4	48.4	50.9
Lateral appendage B	16.9	12.9	14.4	13.8	13.5	11.5	16.4
Lateral appendage C	22.0	21.8	20.1	25.2	19.4	19.4	25.4
Lateral appendage D	20.6	17.0	18.2	21.3	16.6	16.8	21.2
Lateral appendage E	13.7	14.2	14.9	10.4	7.5	13.6	22.5
Dorsal appendage C d	2.4	10.0	15.2	10.9	6.0	9.2	7.1
Dorsal appendage D d	2.3	10.8	4.2	10.5	3.4	8.7	14.9