Hysterothylacium tasmaniense ( Johnston & Mawson, 1945 )

Li, Liang, Xu, Zhen & Zhang, Luping, 2008, Redescription of three species of Hysterothylacium (Nematoda: Anisakidae) from marine fishes from the Yellow Sea, China, with the synonymy of Hysterothylacium muraenesoxin (Luo, 1999), Zootaxa 1878, pp. 55-67 : 62-63

Hysterothylacium tasmaniense ( Johnston & Mawson, 1945) ( Fig. 5 , 6 )

Synonyms: Contracaecum tasmaniense Johnston & Mawson, 1945

Thynnascaris tasmaniense ( Johnston & Mawson, 1945) Beumer et al., 1982

Host: Lophius litulon ( Jordan)

Site of infection: Intestine

Locality: Shidao Island (₁₂₂° ₂₆ʹ ₄₂ʹʹ Ε﹔ ³₆° ₅₂ʹ ₅₇ʹʹ Ν), Yellow Sea, Shandong Province, China

Prevalence and intensity of infection: 8.3% (1 out of 12 fishes) were infected with intensity of 7 specimens.

Voucher specimens: 4 males (HBNU-0713), 3 females (HBNU-0714)

General: Medium to large sized. Cuticle with prominent cervical rings. Lateral alae inconspicuous anteriorly. Anterior end with 3 lips, dorsal lip slightly smaller than subventrals, with prominent lateral flanges. Proximal part of each lip with four lobes. Dorsal lip with 2 lateral double papillae; subventral lips each with one amphid, one single papillae and one double papillae. Interlabia well developed, about 1/2 length of lips.

Oesophagus long, slightly broader posteriorly. Nerve ring encircling oesophagus between 1/6–1/3 of its length. Ventriculus almost spherical, approximately as wide as oesophagus. Ventricular appendix broad, usually somewhat shorter than intestinal caecum. Excretory pore slightly posterior to nerve ring. Rectum hyaline, tubular, surrounded by 3 large, unicellular rectal glands. Tail conical, tip of tail both male and female covered with numerous nodular protuberances.

Male (based on 4 mature specimens): Body 21.5–49.3 (39.6) mm long, maximum width 390–830 (650). Dorsal lip 120–270 (210) long, 100–230 (180) wide. Interlabia 49–140 (63) long, 97–200 (150) wide. Oesophagus 2.48–4.90 (4.08) mm long, 9.5–11.5 (10.5) % of body length; 160–290 (220) wide. Nerve ring 440–920 (790) and excretory pore 490–1020 (860) from anterior extremity. Ventriculus 97–240 (180) long by 150–290 (230) wide. Ventricular appendix 0.63–1.26 (1.06) mm long, 78–150 (130) wide. Intestinal caecum 0.92–2.43 (1.49) mm long, 27.1–49.5 (36.4) % of oesophagus length; 97–210 (160) wide. Ratio of intestinal caecum to ventricular appendix 1: 0.4–1.0 (1: 0.8). Ejaculatory duct 1.65–2.54 (1.84) mm long, 5.2–7.7 (6.6) % of body length. Spicules slender and equal in length, 1.21–2.15 (1.73) mm long, 69.3–93.5 (78.3) % of ejaculatory duct length or 3.8–5.6 (5.4) % of body length. Gubernaculum absent. Tail 150–190 (170) long; tail tip 39–48 (46) long, with numerous nodular protuberances. Caudal papillae arranged as follows: 22–27 (24) precloacal subventral pairs, 1 very small adcloacal pair, and 4–5 postcloacal pairs, with the second pair double.

Female (based on 3 gravid specimens): Body 26.1–63.5 (46.6) mm long, maximum width 580–870 (740). Dorsal lip 190–290 (250) long, 180–250 (220) wide. Interlabia 97–130 (120) long, 130–190 (170) wide. Oesophagus 3.01–5.83 (4.31) mm long, 8.1–11.5 (9.6) % of body length; 190–340 (280) wide. Nerve ring 920–1020 (950) and excretory pore 970–1120 (1020) from anterior extremity. Ventriculus 190–340 (290) long by 190–390 (290) wide. Ventricular appendix 0.92–1.80 (1.36) mm long, 110–170 (140) wide. Intestinal caecum 1.49–2.43 (1.88) mm long, 41.7–48.4 (44.3) % of oesophagus length; 130–180 (160) wide. Ratio of intestinal caecum to ventricular appendix 1: 0.6–0.8 (1: 0.7). Tail length 350–470 (420); tail tip 49–78 (62) long, with numerous nodular protuberances. Vulva slit-like, without salient lips, located pre-equatorially, 31.2–39.2 (34.3) % from anterior end. Vagina muscular directed posteriorly. Uteri opposed. Eggs embryonated, oval, 39–44 (41) long by 36–45 (41) wide.

Remarks: Johnston and Mawson (1945) described H. tasmaniense from Coelorhynchus australis based on immature females; their illustrations were incomplete. Bruce (1990) redescribed this species completely. There are several points of correspondence between the present material and Bruce’s descriptions: cuticle with prominent cervical rings, inconspicuous lateral alae, lip shape, lack of distinct postlabial grooves, the relative proportions of the intestinal caecum and ventricular appendage, and number and arrangement of the caudal papillae. However, the present specimens differ from those re-described by Bruce (1990) in having relative larger body size, and greater number of precloacal papillae (22–27 pairs vs. 18–25 pairs). These differences were regarded as individual variations. This species is reported for the first time in China.

Figures

FIGURE 5. Hysterothylacium tasmaniense (Johnston & Mawson, 1945). A, anterior part of body of male, lateral view; B, cephalic end of male, dorsal view; C, cephalic end of female, ventral view; D, posterior end of male, lateral view; E, caudal region of male, lateral view; F, posterior end of female, lateral view; Scale bars in mm.

FIGURE 6. Scanning electron micrographs of Hysterothylacium tasmaniense (Johnston & Mawson, 1945). A, cephalic extremity of female, apical view; B, cephalic extremity of female, ventral view C, dorsal lip; D, subventral lip; E, posterior end of male, lateral view; F, tip of male tail; G. cuticular stransverse striations of anterior part of body; H. I, posterior region of male tail, showing the caudal papillae; i, interlabium; d, double papillae.