Spinitectus acipenseri Choudhury & Dick, 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 : 107

Spinitectus acipenseri Choudhury & Dick, 1992

Includes: Spinitectus gracilis acipenseri of Choudhury, Dick, Holloway & Ottinger (1990); Spinitectus acipenseri of Choudhury & Dick (1991); Spinitectus gracilis acipenseri of Swanson, Kansas, Matkowski & Graveline (1991). Description (after Choudhury & Dick 1992). With characteristics of the genus. “Head” region without spines but rest of body possessing transverse rows of spines. Spine rows discontinuous over lateral lines, appearing as two semicirclets of spines in same plane. First spine row with 20 to 22 spines, numbers increasing posteriorly to as many as 30 (row 6). Spines <0.015 long. Mouth slit-like, bordered by two sublabia with straight inner margins. Four barely visible cephalic papillae, two posterior to each lip base. Amphids not observed. Excretory gland short and narrow with basal nucleus lying beside muscular oesophagus; excretory pore opens between the 4th and 5th spine rows. Nerve ring immediately posterior to 2nd row of spines. Buccal cavity short ( Fig. 65 A).

Males (measurements of holotype, and range of paratypes in parentheses): Body 4.85 (3.65–6.1) long, 0.091 (0.805–0.124) wide. “Head” 0.104 (0.073–0.132), buccal capsule 0.032 (0.029–0.044), muscular oesophagus 0.243 (0.226–0.336) and glandular oesophagus 0.918 (0.700–1.066) long. Nerve ring 0.125 (0.102–0.161) from anterior end. Left spicule 0.315 (0.300–0.350) long; arcuate, scoop shaped distally, pointed tip. Right spicule 0.100 (0.096– 0.103) long; helically bent like ram’s horn, prominent terminal barb, resembling an heel ( Fig. 65 C). Tail 0.127 (0.102–0.139) long. Maximum spine size 0.012 (0.012–0.013). Tail end often twisted into one or two turns. Four pairs pre-cloacal and six pairs post-cloacal pedunculated papillae present ( Fig. 65 B). Area rugosa comprises about eight longitudinal rows of cuticular elevations.

Females (measurements of allotype, and range of paratypes in parentheses): Body 7.25 (4.2–8.8) long, 0.136 (0.085–0.175) wide. “Head” 0.125 (0.073–0.139), buccal capsule 0.043 (0.029–0.044), muscular oesophagus 0.300 (0.227–0.416), and glandular oesophagus 0.909 (0.643–1.336) long. Nerve ring 0.143 (0.139–0.0.197) from anterior end. Two folded ovaries, one posterior near end of gut ( Fig. 65 D), the other in region of glandular oesophagus. Amphidelphic, vagina fairly long, directed anteriorly, opening into prominent vulva with bulbous lip ( Fig. 65 E). Tail 0.068 (0.066–0.110) long, bears terminal spine. Maximum spine size 0.012 (0.011–0.015). Vaginal eggs 0.037 (0.034–0.040) x 0.023 (0.023–0.025).

Site: alimentary tract

Host: Acipenser fulvescens

Distribution: Central Canada, Hudson Bay Drainage, Manitoba, Ontario, Saskatchewan

Records: Choudhury et al. 1990 (MB, ON, SK); Choudhury & Dick 1991 (MB, SK); Swanson et al. 1991 (MB);

Choudhury & Dick 1992 (MB, SK); Choudhury & Dick 1993 (CC); Choudhury & Dick 2001 (HBD)

Figures

FIGURE 65. Spinitectus acipenseri Choudhury & Dick, 1992. A. female, anterior end, lateral view; B. male, posterior end; C. spicules; D. female, posterior end, ventral view; E. female, vaginal region. (Redrawn from Choudhury & Dick 1992)