Hysterothylacium analarum Rye & Baker, 1984

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 135-137

** Hysterothylacium analarum Rye & Baker, 1984

Description (after Rye & Baker 1984, 1992). With characteristics of the genus. Body cuticle with narrow transverse striations and wide, irregularly spaced transverse folds. Lateral alae absent. Narrow caudal alae present. Cephalic lips equal in length and width. Dorsal lip with two double papillae, subventral lips each with one double papilla, one single papilla and one amphid. Interlabia prominent ( Fig. 78 A). Intestinal caecum and ventricular appendix present. Excretory pore at level of nerve ring ( Fig. 78 B). Tail tip of both sexes covered with numerous blunt spines ( Fig. 78 D).

Males: 18.1 (13.5–19.1) long. Intestinal caecum 1.19 (0.54–2.30) and ventricular appendix 0.300 (0.225– 0.325) long. Excretory pore 0.390 (0.325–0.475) and nerve ring 0.390 (0.325–0.440) from anterior end ( Fig. 78 B). Tail conical 0.240 (0.160–0.190) long. Posterior half of tail with four pairs of papillae: two pairs lateral and two pairs subventral (one or more may be missing). Anterior half of tail with three pairs of subventral papillae. Anterior lip of anus with one unpaired papilla. Pre-cloacal region with 18 (13 to 21) pairs of subventral caudal papillae extending anteriorly. Pre-cloacal subventral region with numerous caudal muscles. Spicules equal, 0.580 (0.450– 0.625) long, alate, rounded distally, with blunt capitulum ( Fig. 78 C). Gubernaculum absent.

Females: 22.05 (19.82–25.55) long. Preventriculus 2.1 (2.45–3.87) long. Intestinal caecum 1.11 (1.55–1.93) and ventricular appendix 0.375 (0.350–0.480) long. Excretory pore 0.390 (0.345–0.410), nerve ring 0.390 (0.345– 0.460) and vulva 7.10 (6.96–8.80) from anterior end. Eggs oval, 0.080 in diameter, thin walled, embryos at 1- or 2- cell stage. Tail conical, 0.370 (0.380–0.440) long. One pair post-cloacal lateral papillae present.

L4: 3.367–5.863 long (male); 3.582–5.755 (female). Mouth opening triangular. Lips well developed. Dorsal lip with two double papillae, subventral lips each with one double papilla, one single papilla, and an amphid. Each lip with two single inner papillae. Interlabia triangular, apically pointed, height about one-third at base, similar to those of adult. Narrow lateral alae extending length of body. Vulva at middle of body, nonpatent. Posterior end of tail with numerous blunt projections.

L3: 1.355–4.172 long. Lips absent. Mouth opening triangular, boring tooth absent. Two subdorsal and two subventral double papillae and two single sublateral papillae present. Lateral alae extend length of body. Genital primordium in early 3rd stage similar to that of 2nd -stage larvae. In late 3rd -stage larvae genital primordium Y-shaped with undifferentiated vagina in females and an elongate column of cells in males. Tail conical with six to eight blunt projections.

L2: 0.190–0.249 long (freshly hatched); 0.312–0.587 (recovered from various sites in fishes). Mouth opening triangular, lips absent. Head end with large ventral boring tooth. Two subdorsal and two subventral cephalic papillae present. Lateral alae extend length of body. Genital primordium oval, comprising four to eight cells. Tail conical with six to eight spiny protuberances.

Sites: intestinal lumen, mesenteries, serosal nodules Host: Lepomis gibbosus

Distribution: Ontario

Records: Rye & Baker 1984; Rye & Baker 1987; Rye & Baker 1992

Figures

FIGURE 78. ** Hysterothylacium analarum Rye & Baker, 1984. A. head, dorso-lateral view; B. anterior end, lateral view; C. male, posterior end, lateral view, D. male, tail tip, lateral view. (Redrawn from Rye & Baker 1984)