Truttaedacnitis pybusae Anderson, 1992

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 153-155

** Truttaedacnitis pybusae Anderson, 1992

Synonym: Truttaedacnitis stelmioides of Pybus, Uhazy & Anderson, 1978 Description (after Pybus et al. 1978a). With characteristics of the genus. Slender worms with blunt anterior end and pointed, conical tail with small mucron. Cuticle smooth or with fine transverse striations. Lateral alae extend from level of nerve ring to posterior border of pre-cloacal sucker. Deirids behind nerve ring either directly opposite each either or one slightly anterior to the other. Excretory pore behind nerve ring, at same level as, or anterior to, at least one deirid. Mouth opening slit-like or triangular, dorso-ventral in position, surrounded by thin collarette containing 100 to 120 conspicuous cuticular ”teeth”. Cephalic papillae comprise four prominent double submedian papillae. Fused papillae of unequal size; larger papilla containing central cuticular rod. Amphids lateral. Six small papillae located near oral margin. Oesophagus clavate and muscular, expanding anteriorly around conical pseudobuccal capsule. Dorsal oesophageal gland nucleus prominent near posterior end oesophagus; gland opens in dorsal angle of mouth opening. Subventral oesophageal gland nuclei inconspicuous, opening at nerve ring level. Cuticle lining each angle of triradiate oesophagus thickened into paired longitudinal rods extending from near oral margin to anterior oesophago-intestinal valve. Oesophageal rods diverge anteriorly to form pseudobuccal cavity. Cuticle lining capsule thickened to form cephalic plates separated by thin sutures ( Fig. 86 D). Two to four coelomocytes in body cavity.

Males: 10.2 (8.1–12.9) long; maximum width 0.31 (0.26–0.37). Nerve ring 0.370 (0.324–0.465) from anterior end. Oesophagus 0.97 (0.86–1.15) long. Tail 0.287 (0.237–0.367) long. Single testis in posterior third of body, looping anteriorly then reversing. Muscular pre-cloacal sucker lacks cuticularized rim, 8.8 (7.1–11.3) from anterior end. Spicules equal or sub-equal, 0.502 (0.382–0.650) long; cross section of spicules shows three longitudinal hollow areas running entire length. Arrangement of caudal papillae similar to that of T. clitellarius above ( Fig. 87 B). Gubernaculum Y-shaped, 0.087 (0.074–0.104) long.

Females: 11.6 (9.5–14.3) long; maximum width 0.34 (0.26–0.44). Nerve ring 0.397 (0.350–0.470) from anterior end. Oesophagus 1.040 (0.937–1.200) long. Anterior ovary in middle third of body, the posterior one in posterior third. Oviducts looping beyond vulva, then reversing and expanding into uteri. Vulva located behind midbody, anterior lip larger than posterior. Eggs near vagina in morula stage, 0.063–0.087 x 0.051–0.068. Tail bears one pair lateral papilliform phasmids ( Fig. 88 ).

Larvae: Pybus et al. (1978b) and Anderson (1996) discussed the transmission of T. pybusae , including the morphometry of larvae in lamprey ammocoetes and “transformers”. The biology of the nematode appears to be closely linked to the metamorphosis and maturation of lampreys.

Sites: gills, gonads, intestinal lumen, kidney, liver, mesenteries

Host: Lethenteron appendix

Distribution: Ontario

Records: Pybus et al. 1978a; Pybus et al. 1978b; Anderson 1996

Figures

FIGURE 86. Truttaedacnitis spp.: heads showing cephalic plates. A. T. truttae; B. T. sphaerocephala; C. T. clitellarius; D. T. pybusae. (A., B. and C. redrawn from Choudhury & Dick 1996 b; D. redrawn and rotated from Pybus et al. 1978 a)

FIGURE 87. Truttaedacnitis clitellarius (Ward & Magath, 1917) Petter, 1974. A. male, anterior end showing excretory pore and duct, lateral view; B. male, posterior region showing pre-cloacal sucker, spicules and papillae, lateral view; C. female, posterior end showing posterior coiled ovary, rectal glands, phasmid and mucron, lateral view. (Redrawn from Choudhury & Dick 1996 a)

FIGURE 88. ** Truttaedacnitis pybusae Anderson, 1992. Female, posterior end showing phasmids, ventral view. (Redrawn from Pybus et al. 1978 a)