Diphascon (Diphascon) dolomiticum, Pilato, Giovanni & Bertolani, Roberto, 2005

Pilato, Giovanni & Bertolani, Roberto, 2005, Diphascon (Diphascon) dolomiticum, a new species of Hypsibiidae (Eutardigrada) from Italy, Zootaxa 914, pp. 1-5 : 2-5

Diphascon (Diphascon) dolomiticum sp. n.

Material examined: Holotype (slide N. 5001) and one paratype; Italy, Dolomites Mts., Passo del Grostè (Trento), in an undetermined moss sample from soil.

Description of the holotype: Body length 215 µm, colourless, cuticle smooth, eyes absent. Bucco­pharyngeal apparatus of Diphascon type ( Fig. 1 A ); rigid buccal tube without ventral lamina; apophyses for insertion of the stylet muscles in shape of semilunar hooks symmetrical with respect to frontal plane; flexible pharyngeal tube with spiral thickening. Drop­shaped thickening present between buccal tube and pharyngeal tube. Buccopharyngeal tube 48.1 µm long; rigid buccal tube 24.8 long µm (pbf = 51.6) and 2.2 µm wide (ptd = 8.9). Peribuccal lamellae and peribuccal papulae absent. Stylet supports inserted on buccal tube at 61.9 % of its length (ptd = 61.9). Pharyngeal bulb (27.1 µm x 16.0 µm) with apophyses, three rod­shaped macroplacoids and microplacoid; septulum absent. First macroplacoid 4.5 µm long (ptd = 18.1), second 4.3 µm (ptd = 17.3), third 5.5 µm (ptd = 22.2), microplacoid 2.2 µm long (ptd = 8.9); entire placoid row (including microplacoid) 17.3 µm long (ptd = 69.8), macroplacoid row 14.8 µm (ptd = 59.7).

Claws, of Hypsibius type, short and stout (Fig. 2 B–E); basal portion of some claws seems to be subdivided into two portions by septum; this appearance is due to the presence of a more or less evident cavity in the claws. Basal margin of claws smooth on first three pairs of legs and indented on hind legs. Well developed accessory points present on main branches. Internal claws on first three pairs of legs almost as long as the external claws ( Tab. 1 ); on the hind legs, unlike the majority of species of eutardigrades, anterior claws longer than posterior claws ( Tab. 1 ). Lunules and other cuticular thickenings on legs absent.

Eggs not found.

Etymology: The name dolomiticum refers to the locus typicus: Dolomites Mts.

Remarks: The paratype is similar to the holotype in qualitative and quantitative characters.

In Table 1 dimensions of some structures of the two specimens found are indicated.

Discussion: Recently we have examined or reconsidered specimens similar to D. (D.) nobilei , understanding that in reality this name had been attributed to a group of related species ( Pilato et al., 2005). In spite of some resemblances, Diphascon (D.) dolomiticum cannot be considered as belonging to the nobilei group, as defined in Pilato et al. (2005). It differs from all species of this group in the following features: basal portion of hind legs not enlarged, shorter claws (particularly the external claws), posterior claws of hind legs shorter than anterior claws, higher value of the pbf index relative to the buccal tube length ( Tab. 1 ). Moreover, it also differs from D. (D.) serratum by having shorter placoids, and stylet supports inserted on the buccal tube in a more anterior position (ptd = 61.9–62.9 in D. (D.) dolomiticum sp. n., about 67 in D. (D.) serratum ). It also differs from D. (D.) nelsonae by having shorter placoids ( Tab. 1 ).

* The pharyngeal tube is slightly stretched and therefore the buccal tube, as %, appears slightly shorter.

In addition to the species of the nobilei group, some other species of the subgenus Diphascon have an indented basal portion of the claws, or of some claws, ( D. (D.) higginsi , D. (D.) greveni , D. (D.) mirabile and D. (D.) birklehofi ), but D. (D.) dolomiticum sp. n. mostly differs from all these species in claw shape, size of the external claws, lacking of septulum and cuticular bars on first three pairs of legs.

Figures

FIGURE 1, A – E. Diphascon (Diphascon) dolomiticum sp. n. A, Bucco­pharyngeal apparatus of the holotype; B, claws of the third pair of legs of the holotype; C, anterior claw of the hind legs of the holotype; D, claws of the third pair of legs of the paratype; E, claws of the hind legs of the paratype.

Tables

TABLE 1. Length (in µm) of some structures of D. (D.) dolomiticum n. sp., D (D.) nobilei Binda 1969, D. (D.) serratum Pilato et al., 2005, D. (D.) nelsonae Pilato et al., 2005., D. (D.) platyugue Pilato et al, 2005, and D. (D.) hydrophilum Pilato et al., 2005.

	dolomiticum	nobilei	serratum nelsonae	platyungue	hydrophilum
Body	203.0–215.0	370.0	217.0 231.0–310.0	194.0–238.0	213.0–307.0
Buccal tube	24.8–24.8	25.7	21.6 21.0–24.3	20.8–23.2	20.9–23.3
Bucco­pharynegal tube	49.7–48.1	59.5	49.9 46.4 – 57.3	45.2 – 53.1*	46.0 – 49.4
pbf	49.9–51.6	43.2	43.3 45.2 – 42.4	46.0–43.7*	45.4–47.2
Tube diameter	2.5–2.2	2.7	2.5 2.0–2.6	1.7–2.3	1.8–2.2
ptd	10.1–8.9	10.5	11.6 9.5–10.7	8.2–9.9	8.6–9.4
ptd stylet supports insertion point	62.9–61.9	60.7	67.2 63.7–61.8	62.9–62.7	64.4–63.1
Placoid row	16.6–17.3	18.6	18.5 17.7–21.2	16.1–17.3	14.5–18.1
ptd Macroplacoid row	66.9–69.8 14.0–14.8	72.3 16.1	85.6 84.3–87.2 16.5 15.5–18.9	77.4–74.6 14.1–15.6	69.4–77.7 11.9–15.8
ptd	56.5–59.7	62.6	76.4 73.8–77.8	67.8–67.2	56.9–67.8
First macroplacoid	4.3–4.5	5.4	4.9 4.3–5.3	3.8 – 4.2	3.8–4.9
ptd	17.3–18.1	21.0	22.7 20.5–21.8	18.3–18.1	18.2–21.0
Second macroplacoid	3.8–4.3	4.1	4.6 4.0–5.2	3.6–4.0	3.7–4.6
ptd	15.3–17.3	15.9	21.3 19.0–21.4	17.3–17.2	17.7–19.7
Third macroplacoid	5.5–5.5	6.3	6.9 6.5–7.4	5.7–7.0	4.5–5.8
ptd	22.2–22.2	24.5	31.9 30.9–30.4	27.4–30.2	21.5–24.9
Microplacoid	2.2–2.2	2.1	1.8 1.6 – 1.7	1.7 –?	1.8–1.7
ptd	8­9–8.9	8.2	8.3 7.6 – 7.0	8.2 –?	8.6–7.3
II, III internal claw	5.5–6.5	10.2	6.4 7.0–9.7	6.1–6.9	?–?
ptd	22.2–26.2	39.7	29.6 33.3–39.9	29.3–29.7	?–?
II, III external claw	5.8–6.7	15.8	8.6 10.5–13.7	? – 8.6	4.8–16.1
ptd	23.4–27.0	61.5	9.8 50.0–56.4	? –37.1	70.8–69.1
IV anterior claw	7.7–8.3	12.4	7.3 7.9–9.8	6.5–7.1	8.9–10.4
ptd	31.6–33.5	48.2	33.8 37.6–40.3	31.2–30.6	42.6–44.6
IV posterior claw	7.5–7.3	16.0	9.2 11.5 –?	8.5–9.8	14.5–15.8
ptd	30.2–29.4	62.2	42.6 54.8 –?	40.9–42.2	69.4–67.8