During recent helminthological investigations of some marine fishes in the Bay of Bengal, India, nematode specimens of the genus
Fish were caught by trawl nets by local fishermen in the Bay of Bengal and were obtained in the landing centres Cuddalore (11°42’N, 74°46’E), Parangipettai (11°29’N, 79°46’E) and Pazhayar (11 °21’N, 79°50’E) on the eastern coast of India. The nematodes collected from fish were washed in physiological saline and were then fixed and preserved in 4 % formalin. Philometrid males were dissected out from formalin-fixed fish ovaries. For light microscopy examination, the nematodes were cleared with glycerine.
Drawings were made with the aid of a Zeiss drawing attachment. Specimens used for scanning electron microscopy were postfixed in 1 % osmium tetroxide (in phosphate buffer), dehydrated through a graded acetone series, critical-point-dried and sputter-coated with gold; they were examined using a JEOL JSM-7401F scanning electron microscope at an accelerating voltage of 4 kV (GB low mode). All measurements are in micrometres unless otherwise indicated. The fish nomenclature adopted follows FishBase (Froese & Pauly, 2015).
Family Philometridae Baylis et Daubney, 1926
Description: Male (10 specimens; measurements of holotype in parentheses): Body filiform, whitish, 2.73 – 3.37 (3.02) mm long, maximum width at middle of body 48 – 60 (51); anterior part of body somewhat narrowed just posterior to cephalic end (Figs. 1E, 3C); body width at this narrowed part 27 – 33 (27). Maximum width/body length ratio 1:51 – 62 (1:59). Cuticle smooth. Cephalic end rounded, 39 – 45 (42) wide. Oral aperture small, triangular, surrounded by small circular elevation. 14 minute cephalic papillae arranged in two circles present: external circle formed by four submedian pairs of papillae (each pair consisting of one larger and one smaller papilla); internal circle by four submedian and two lateral papillae. Small lateral amphidsjust posterior to lateral papillae of internal circle, followed by fairly large lateral crescent-shaped formations of slightly elevated cuticle; additional short lateral rod-like cuticular elevations present just posterior to inner lateral papillae (Figs. 1C,D, 2C,E). Oesophagus 396 – 516 (516) long, comprising 13 – 17 % (17 %) of body length, with inflation at anterior end measuring 39 – 48 × 24 – 30 (48 × 24); posterior part of muscular oesophagus overlapped by well-developed oesophageal gland with large cell nucleus; maximum width of gland 18 – 24 (24). Nerve ring and oesophageal nucleus 147 – 180 (180) and 315 – 409 (360) from anterior extremity, respectively. Excretory pore 195 – 228 (225) from anterior end. Testis extending anteriorly to short distance posterior to level of excretory pore, overlapping thus posterior portion of oesophagus (Fig. 1E). Posterior end of body blunt, 36 – 42 (39) wide, provided with broad V-shaped mound situated laterally and dorsally to cloacal opening; anterior part of each arm of mound separated from posterior part by transverse groove (Figs. 1G,L,M, 2D,F, 3A). Four adanal pairs of very flat, hardly visible caudal papillae present on anterior parts of caudal mound; additional pair of larger subdorsal papillae situated posterior to cloacal aperture. Phasmids small, located at approximately middle of each of posterior arm of caudal mound, followed by pair of small shallow cuticular depressions situated more dorsally (Figs. 1G, 2D,F, 3A,B). Spicules slender, needle-like, equally long, with somewhat expanded proximal and sharply pointed distal tips (Figs. 1L,M, 2D,F, 3D,E); length of spicules 96 – 120 (111), representing 3 – 4 % (4 %) of body length. Gubernaculum 75 – 90 (87) long, with anterior portion somewhat dorsally bent; length of anterior bent part 42 – 51 (45), representing 50 – 61 % (52 %) of entire gubernaculum length (Fig. 1K – M); posterior portion of gubernaculum markedly broad at anterior end, forming ventral tooth in lateral view; distal end of gubernaculum narrow, with 12 – 14 dorsal, transverse lamella-like structures forming distinct dorsal protuberance in lateral view (Figs. 1I – M, 2D,F, 3D,E). Length ratio of gubernaculum and spicules 1:1.21 – 1.39 (1:1.29). Spicules and gubernaculum well sclerotized; spicules and gubernaculum yellowish, anterior part of gubernaculum colourless.
Gravid female (2 complete larvigerous specimens; measurements of allotype in parentheses): Body of fixed specimens grey-white, with distinct dark-brown intestine visible through cuticle; body ends rounded. Posterior part of body narrower than anterior part; maximum width in region posterior to oesophagus. Cuticle smooth. Body length 145 (171) mm, maximum width 1.06 mm (1.29 mm); maximum width/body length ratio 1:137 (1:161). Cephalic end rounded, with two small lateral elevations (Figs. 1A,B,); width of cephalic end 299 (340). Cephalic papillae small, indistinct when viewed laterally. Oral aperture oval, surrounded by four pairs of submedian cephalic papillae of external circle (each pair formed by one circular and one more elongate papilla) and six single papillae (two lateral and four submedian) of internal circle (Figs. 1B, 2A,B). Amphids indistinct. Two small lateral triangular cuticular elevations present somewhat posterior to inner lateral papillae. Oesophagus including anterior bulbous inflation 1.25 mm (1.16) mm long, comprising 0.9 % (0.6 %) of body length; anterior inflation 136 (109) long and 136 (109) wide; maximum width of oesophagus including gland 136 (163). Oesophageal gland relatively narrow, opening into oesophagus just posterior to nerve ring, with large cell nucleus in middle (Fig. 1A). Nerve ring and oesophageal nucleus 381 (340) and 884 (843) from anterior extremity, respectively. Small ventriculus 41 (41) long and 109 (109) wide. Oesophagus opening into intestine through distinct valve. Intestine narrow at anterior end; its posterior end narrow, attached by ligament ventrally to body wall near caudal end (Fig. 1H); ligament 408 (1,238) long. Vulva and anus absent. Ovaries reflected, situated near body ends (Fig. 1 A,H). Uterus occupying most space of body, filled with numerous larvae with long, slender tail (Fig. 1F); larvae (n=5) from paratype 480 – 528 long and 18 wide; length of oesophagus 147 – 180, of tail 114–150, representing 31 – 34 % and 22 – 31 %, respectively, of entire body length of larva. Posterior end of female rounded, 408 (272) wide, without any caudal projections (Fig. 1H).
Subgravid female (2 complete and 4 incomplete ovigerous specimens): Body length 30 – 72 mm, maximum width 598 – 911; maximum width/body length ratio 1:50 – 79. Width of cephalic end 199 – 299. Cephalic papillae small, indistinct when viewed laterally.
Oesophagus including anterior bulbous inflation 830 – 843 long, comprising 1.2 – 2.8 % of body length; anterior inflation 82 – 126 long and 82 – 122 wide; maximum width of oesophagus including gland 95 – 136. Nerve ring and oesophageal nucleus 218 – 299 and 571 – 666 from anterior extremity, respectively. Small ventriculus 27 long, 68 – 82 wide. Length of intestinal ligament 299 – 517. Uterus filled with spherical eggs. Posterior end of body rounded, 163 – 258 wide, without any caudal projections.
Nongravid female (1 mature specimen): Length of body 4.28 mm, maximum width 84; maximum width/body length ratio 1:51. Width of anterior end 57. Entire oesophagus 517 long and 36 wide. Anterior oesophageal bulb 48 long, 33 wide; ventriculus 27 long, 36 wide. Nerve ring and oesophageal nucleus 177 and 351 from anterior extremity, respectively. Vulva and incompletely developed vagina present; former situated 2.92 mm from anterior extremity (at 68 % of body length). Uterus empty. Posterior end rounded, without caudal projections.
Type host: Belanger’s croaker
Type locality: Bay of Bengal, off eastern coast of India (collected in January – December 2013).
Prevalence and intensity: 20 % (4 fish infected/20 fish examined); mean intensity 24 nematode specimens per fish. A single fixed fish ovary contained 58 males and 2 gravid, 7 subgravid and 1 nongravid female nematodes.
Type specimens: Holotype, allotype and paratypes in the Helminthological Collection of the Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, České Budějovice (Cat. No. N – 1108).
Etymology: The specific name of this nematode
At present, 67 gonad-infecting species of
To date, the following six nominal gonad-infecting species of
Moreover,
All of the above-mentioned valid species are easily distinguishable from
The new species differs from
It has been mentioned above that
Moravec & Diggles (2014b) reported
Gonad-infecting philometrids (only females) from J.
Description: Gravid female (3 body fragments of 2 specimens): Body grey-white with brown-coloured intestine visible through cuticle. Available fragment of anterior portion of body 140 mm long, maximum width 2.41 mm. Width of cephalic end 680. Cephalic end rounded, cephalic papillae very small, indistinct when viewed laterally. Oesophagus 2.58 mm long, 326 wide including oesophageal gland; anterior bulbous inflation markedly broad, 163 long and 286 wide. Ventriculus small, 54 long, 122 wide. Nerve ring and oesophageal nucleus 286 and 1.306, respectively, from anterior extremity. Uterus filled with larvae 498 – 510 long, maximum width 18 – 21; length of their oesophagus 156 – 171, representing 31 – 34 % of body length; sharply pointed tail 144 – 150 long, representing 28 – 30 % of body length. Posterior end of female rounded, 680 – 748 wide, without any caudal projections.
Host: Atlantic tripletail
Locality: Bay of Bengal, off eastern coast of India (collected in January – May 2013).
Prevalence and intensity: 10 % (10 fish infected/100 fish examined); mean intensity 2 nematode specimens per fish. Voucher specimens: Helminthological Collection of the Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice (Cat. No. N–984).
Although only female body fragments were available, the species identification as
Description: Gravid female (1 larvigerous specimen without body ends): Available body fragment 93 mm long, maximum width 1.29 mm. Body grey-brown, with dark brown intestine visible through cuticle. Uterus filled with numerous larvae with long, slender tail; larvae (n=5) from 420 – 441 long and 12 – 15 wide; length of oesophagus 123 – 135, of tail 126 – 141, representing 28 – 31 %and 30 – 32 %, respectively, of entire body length of larva.
Host: Bartail flathead,
Locality: Bay of Bengal, off eastern coast of India (collected in January – December 2013).
Prevalence and intensity: 5 % (2 fish infected/10 fish examined); 1 nematode specimen.
Voucher specimen: Helminthological Collection, Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice (Cat. No. N–1100).
Moravec et al. (2016a) reported
According to Moravec et al. (2016a),