Semitobrilus andrassyi, Gagarin, Vladimir G. & Gusakov, Vladimir A., 2013

Gagarin, Vladimir G. & Gusakov, Vladimir A., 2013, Neotripyla vulgaris gen. n., sp. n. and Semitobrilus andrassyi sp. n. (Nematoda, Triplonchida) from freshwater bodies of Vietnam, Zootaxa 3716 (4), pp. 565-576 : 571-575

Semitobrilus andrassyi sp. n.

( Figs 4 , 5 ; Table 2 )

Type material. Holotype male, slide reference number 102/19, deposited in the helminthological museum of the Russian Academy of Sciences (RAS), Institute of Ecology and Evolution, Center for Parasitology, RAS (Moscow, Russia).

Paratypes. Two males deposited in the helminthological museum of the Russian Academy of Sciences, Institute of Ecology and Evolution, Center for Parasitology, RAS (Moscow, Russia).

Measurements. Table 2 .

Type locality. Vietnam, Khánh Hòa Province, Cam Ranh Peninsula, small man-made temporary pond near a road (N 12°00.222, E 109°12.535), altitude 8 m, depth 0.15 m, water temperature 34.9 °С, рН 6.6, conductivity 190 ΜS/sm, white sand with a thin layer of silt, 0 7 October 2010 (leg. V.A. Gusakov).

Etymology. The species is named in honour of the outstanding Hungarian nematologist Dr. Istvan Andrássy.

Description. Male. Body cylindrical, tapering toward both extremities. Cuticle finely annulated, about 1 µm thick at mid-body. Crystalloids numerous. Somatic setae short and scarce anteriorly, becoming longer and denser in the posterior part of the body, at level with supplements and on the tail. Lips well developed. Inner labial sensillae papilliform. Outer labial sensillae and cephalic sensillae in the shape of comparatively thick setae arranged in a single circle. Six outer labial sensillae 9.5–11.7 µm long, about 27–36 % of labial region width. Cephalic sensillae 4.7–5.3 µm long. Cheilostom comparatively narrow; buccal cavity cup-shaped, 10.7–13.7 µm long. Dorsal pocket and dorsal tooth not visible. Both subventral pockets separate, located far apart, at distance of 7.5–9.5 µm from each other. Teeth in pockets are comparatively small. Stoma 26–30 µm long, 0.8–0.9 labial region width. Amphidial fovea cup-shaped, amphid aperture located at the level of buccal cavity. Cervical setae absent. Pharynx muscular, comparatively long, expanding gradually towards its base. Nerve ring encircles pharynx at 45–48 % of pharyngeal length. Cardia small, surrounded by 3 oval glands. Renette, renette canal, ampulla and excretory pore not observed. Testes paired, opposed, situated to the left of intestine; anterior testis outstretched, posterior testis reflexed. Vas deferens well developed. Spicules 1.6–1.8 times as long as the cloacal body diameter, comparatively long and slender. Distal part of spicules strongly bent at a right angle and bearing keel-like projection and two (one on each of the sides) lateral ribs (fig. 5E). Distal end of spicules bifurcate. Gubernaculum short, 19–20 µm long, with short dorsal appendix. Precloacal supplementary organs vesiculate, small, 6 in number. The four supplements nearest to the cloaca arranged in 2 groups, with two supplements in each group. The others are located separately (1+1+2+2). Supplement pads absent. Supplements completely submerged under cuticle, with only a short thorn protruding beyond cuticle. Row of supplements 163–191 µm long. Tail slender, long, with conical proximal and cylindrical distal portions, gradually merging into one another. Distal portion 2.4–2.5 times longer than proximal portion. Three caudal glands present, opening through short spinneret. Tail terminus without subventral setae.

Female. Not found.

Diagnosis. Mail body 2224–2389 µm long. Cuticle finely annulated. Crystalloids numerous. Outer labial setae and cephalic setae arranged in single circle. Outer labial setae longer than cephalic setae and as long as 27–36 % of labial region width. Cheilostom comparatively small. Buccal cavity cup-shaped. Dorsal pocket absent. Subventral pockets separate, with small teeth. Spicules comparatively long and slender. Distal part of spicules strongly bent at a right angle and bearing keel-like projection and lateral ribs. Gubernaculum small, with short dorsal appendix. Precloacal supplementary organs vesiculate, small, 6 in number. They completely submerged under cuticle besides a short thorn protruding beyond cuticle. The four supplements nearest to the cloaca arranged in 2 groups, with two supplements in each group (1+1+2+2). Tail slender, long, without subventral setae.

Differential diagnosis. Semitobrilus andrassyi sp. n. similar to S. gagarini (Ebsary, 1982) in body size and length of outer labial setae, but differs from it in the longer spicules (71–80 µm long vs. 65 µm long in S. gagarini ) and presence of a keel-like projection and lateral ribs at distal part of spicules (Ebsary, 1982).

Distribution. To date the species has not been found outside of the type locality.

Discussion. S. Tsalolikhin (2000) revised the genus Semitobrilus and included the following four valid species in this genus: S. pellucidus (Bastian, 1865) , S. closlongicaudatus (Gagarin, 1971) , S. parapellucidus (Ebsary, 1982) , S. ebsaryi Tsalolikhin, 2000 . He synonymized the species S. gagarini (Ebsary, 1982) with the species S. pellucidus (Bastian, 1865) . But S. gagarini differs from S. pellucidus in a number of morphological characters. It has crystalloids (crystalloids absent in S. pellucidus ), shorter outer labial setae (9.5–10.0 µm long, 40 % of labial region width vs. 10–13 µm long, 60 % of labial region width in S. pellucidus ) and shorter spicules (spicules 65 µm long vs. spicules 68–97 µm long in S. pellucidus ) (Gagarin, 1971; Ebsary, 1982; Table 3). We consider the species S. gagarini (Ebsary, 1982) a valid species of the genus Semitobrilus . Thus at present the genus Semitobrilus contains 6 valid species: S. pellucidus (Bastian, 1865) Tsalolikhin, 2000 , S. closlongicaudatus (Gagarin, 1971) Tsalolikhin, 2000 , S. parapellucidus (Ebsary, 1982) Tsalolikhin, 2000 , S. gagarini (Ebsary, 1982) Tsalolikhin, 2000 , S. ebsaryi Tsalolikhin, 2000 , and S. andrassyi sp. n.

Figures

FIGURE 4. Semitobrilus andrassyi sp. n., hololype male. A: entire body; B: head; C: spicules and gubernaculum; D: posterior body end; E: supplement. Scale bars: A = 120 µm; D = 100 µm; B, C = 20 µm: E = 10 µm.

FIGURE 5. Semitobrilus andrassyi sp. n., holotype and paratype males. A: entire body; B: anterior body end; C: head with labial papillae; D: posterior body end with supplements (S 1 - S 6); E: cloaca region. Scale bars: A = 100 µm; B, D, E = 20 µm; C = 10 µm.

Tables

TABLE 2. Morphometrics of Semitobrilus andrassyi sp. n. (all measurements are given in µm, except for the ratios a, b, c, c’).

Character	Holotype male	Paratype males (n = 2)
L	2224	2389 2238
a	34	34 36
b	6.3	6.5 5.9
c	7.6	8.3 8.0
c’	6.7	6.5 6.1
diam.c.s.	33	36 34
diam.midb.	66	71 63
a.d.	44	44 46
o.l.s.	11.7	9.5 11.7
c.s.	4.8	4.7 5.3
ph.l.	352	370 379
dis.ph.cl.	1579	1732 1580
spic.	71	80 71
t.l.	293	287 279