Doryphoribius picoensis, Fontoura, Paulo, Pilato, Giovanni & Lisi, Oscar, 2008

Fontoura, Paulo, Pilato, Giovanni & Lisi, Oscar, 2008, New records of eutardigrades (Tardigrada) from Faial and Pico Islands, the Azores, with the description of two new species, Zootaxa 1778, pp. 37-47 : 42-45

Doryphoribius picoensis sp. nov.

Fig. 3

Material examined: Holotype and 4 paratypes were collected from moss sample in Terras do Pico, Pico Island. Three paratypes were in molting stage with eggs in the exuviae.

Type repository: Holotype (slide No. 5230) is deposited in the collection of Binda & Pilato (Museo del Dipartimento di Biologia Animale “Marcello La Greca”, Università di Catania). 4 paratypes (slides BIII 27– BIII 29) are deposited in the collection of P. Fontoura (Department of Zoology and Anthropology, Faculty of Sciences, University of Porto).

Specific diagnosis: Cuticle with about 20 indistinct undulations and some small gibbosities (irregular in shape and more evident in caudal part of the body); tubercles and other cuticular designs absent; eyes present; buccal tube rigid and narrow with short ventral lamina; pharyngeal bulb with large apophyses and two macroplacoids; microplacoid and septulum absent; claws well developed with small accessory points on main branches; external claws with enlarged bases; claws of hind legs shorter than those of other legs; very small lunules at the base of claws present; other cuticular thickenings on legs absent.

Description of the holotype: Body length 312 μm, colorless; eyes present; cuticle with about 20 transversal undulations and some small, indistinct, and irregular in shape gibbosities (more evident in the caudal portion of the body) ( Fig. 3A ); other cuticular designs absent; gibbosities and tubercles on legs absent.

Mouth antero-ventral without peribuccal lamellae; peribuccal papulae not visible. Buccal armature simple consisting of two thin dorso-lateral and ventro-lateral ridges, large dorso-median round tooth and small and thin ventro-median triangular tooth ( Fig. 3B ). Buccal tube 38.3 μm long and 4.6 μm wide (pt = 12.0) externally, with thick walls ( Fig. 3B ) and ventral lamina 22.0 μm long (pt = 57.4). Stylet supports inserted on the buccal tube wall at 28.1 μm (pt = 73.4).

Pharyngeal bulb with well developed apophyses and two rod-shaped macroplacoids; microplacoid and septulum absent. Macroplacoids arranged in arcuate line. First macroplacoid 9.2 μm long (pt = 24.0) with central constriction and long, thin, anterior part ( Fig. 3C ). Second macroplacoid 5.3 μm long (pt = 13.8) with subterminal constriction. Ratio of first macroplacoid to second 1.7. Macroplacoid row 15.9 μm long (pt = 41.5).

Claws of Isohypsibius type, well developed ( Figs. 3D, E ). External claws with enlarged, smooth bases and with narrow lunules. Internal claws with short and thin bases ( Figs. 3D, E ) and with very small lunules. Other cuticular thickenings on legs absent. Main branches of claws with very thin accessory points ( Fig. 3D ); proximal portion of main and secondary branches of all claws swelled. Due to unfavourable orientation only anterior claws of hind legs were measured and were 14.5 µm long (pt = 37.9).

Eggs smooth with diameter of 65 to 69 µm, laid in the exuviae. Three paratypes in moulting stage have been examined ( Tab. 2 ; paratypes 2, 3 and 4) with 4, 2 and 7 eggs respectively.

Remarks: Paratypes are similar to holotype in both qualitative and morphometric characters. Presence or absence of eyes could be a variable character. Actually, in one paratype (paratype 2) eyes are not visible, in another one (paratype 4) they are very conspicuous.

Measurements of paratypes showed that the claws of the hind legs are slightly shorter than claws on the other legs ( Tab. 2 ).

Measurements of examined specimens are given in Table 2 .

Etymology: The name picoensis refers to the locus typicus: Pico Island.

Differential diagnosis: 14 of 23 known species of the genus Doryphoribius have two macroplacoids. But only D. macrodon and D. maranguensis , by their dorsal cuticle with undulations as well as without any reticular sculpture and very distinct gibbosities ( D. maranguensis has indistinct gibbosities), are the species most similar to D. picoensis sp. nov.

The new species differs from D. maranguensis ( Figs. 4A, C ) in the absence of small cuticular tubercles, in having claws of the fourth pair of legs slightly shorter than those of the other pairs of legs and presence of lunules.

D. picoensis sp. nov. differs from D. macrodon ( Figs. 4 D, F) in having no color (yellowish in D. macrodon ), in having some indistinct gibbosities and clearly different buccal armature (thin dorso-lateral and ventro-lateral transversal ridges, one dorso-medial tooth, and one ventro-medial tooth are present in D. picoensis sp. nov., while in D. macrodon also an irregular ring of teeth anterior to the median teeth are present); the new species differs from D. macrodon also in having claws of the hind legs slightly shorter than those on other pairs of legs.

Including the present study, 17 species of tardigrades are known for the Azores ( Tab. 3). Five species (29.4 %) are endemic according to current knowledge: Diphascon faialense Fontoura and Pilato, 2007 ; Bryodelphax atlantis Fontoura et al. 2008 , Echiniscus azoricus Fontoura et al. 2008 ; Macrobiotus almadai sp. nov. and Doryphoribius picoensis sp. nov. Up to now only three of the nine islands of the Archipelago have been poorly examined and it is very probably that the number of speciess of tardigrades on these islands will be much higher.

Figures

FIGURE 3. A – E, Doryphoribius picoensis sp. nov.: A, habitus of a paratype (Scale bar = 20 µm); B and C, bucco-pharyngeal apparatus of a paratype (in C the shape of the first macroplacoid is shown) (scale bar = 10 µm); D, claws of the third pair of legs of a paratype; E, claws of the hind legs of the holotype (Scale bar = 10 µm).

FIGURE 4. A – C, Doryphoribius maranguensis (holotype): A, bucco-pharyngeal apparatus; B, claws of the third pair of legs; C, cuticular ornamentation of the posterior portion of the body (Scale bar = 10 µm). D – F, Doryphoribius macrodon (holotype): D, bucco-pharyngeal apparatus; E, claws of the first pair of legs; F, claws of the third pair of legs (Scale bar = 10 µm).

Tables

TABLE 2. Dimensions in µm and pt values of some structures of the studied specimens of Doryphoribius picoensis sp. nov.

Characters	Holotype	Paratype 1 Paratype 2 Paratype 3 Paratype 4
Body length	312	269?? 403
Buccal tube length	38.3	33.0 37.3 37.7 42.8
Buccal tube external width pt	4.6 12.0	3.8 4.5 4.3 4.8 11.5 12.1 11.4 11.2
Stylets support insertion pt	73.4	72.4 72.7 73.2 71.9
Ventral strengthening bar length pt	22.0 57.4	18.8 20.4 21.4 24.1 57.0 54.7 56.8 56.3
First macroplacoid length pt	9.2 24.0	8.2 9.1 9.1 10.4 24.8 24.4 24.1 24.5
Second macroplacoid length pt	5.3 13.8	4.6 5.0 5.0 5.7 13.9 13.4 13.3 12.6
Ratio first/second macroplacoid	1.74	1.78 1.82 1.82 1.82
Placoid row length pt	15.9 41.5	13.8 15.3 16.1 18.2 41.8 41.0 42.7 42.5
Exterenal claw II pt	??	15.2? 15.3 22.0 46.1? 40.6 51.4
Internal claw II pt	??	12.1? 12.1 16.5 36.7? 32.1 38.6
External claw III pt	??	14.3? 14.2? 43.3? 37.7?
Internal claw III pt	??	11.8 12.9 12.6 16.5 35.8 34.6 33.4 38.6
Anterior claw IV pt	14.5 37.9	10.8? 11.0? 32.7? 29.2?
Posterior claw IV pt	??	13.2? 14.0? 40.0? 37.1?
Conclusions