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Table 1 Comparison of morphological descriptions and measurements, between various Contracaecum larval types found in Lake Nasser fishes

From: The occurrence of Contracaecum sp. larvae (Nematoda: Anisakidae) in four teleostean species from Lake Nasser, Egypt: morphological and molecular studies

  Contracaecum A Contracaecum B Contracaecum C (SF) Contracaecum C (LF) Contracaecum D (SF) Contracaecum D (LF)
Number of larvae examined 10 4 10 10 10 10
Host Oreochromis niloticus Tilapia galilaea Lates niloticus Lates niloticus Hydrocynus forskalii Hydrocynus forskalii
Localization in host Free in pericardial cavity and gills Free in pericardial cavity and gills Body cavity adhering to the alimentary canal Body cavity adhering to the alimentary canal Body cavity adhering to the alimentary canal Body cavity adhering to the alimentary canal
Larva description • Mouth opening slit-like shape, surrounded by three small lips, one dorsal, two ventrolateral with ill boring tooth between them.
• Four cephalic papillae were present
• Cuticle striated, forming circular ridges. Cuticular ridges very closely anteriorly, covered with heavy host mucus.
Same previous Same previous except:
• A smooth transparent membrane covering it, head end rounded without host mucus and posterior end pointed.
• A triangular mouth opening
• Four cephalic papillae were present
• cuticle striated with fine transversely lines.
• Triangular mouth opening
• Four cephalic papillae were present, two on dorsal lip and the two others were one on each ventral lip.
• Tail provided with terminal process which appear as a projection and covered by thin membrane.
• cuticle was transversely striated with fine longitudinal lines
• Body covered by transparent sheath.
• anterior rounded, while posterior pointed.
• Four cephalic papillae were present
• The cuticle was transversely striated.
• Mouth opening triangular
• excretory pore was anteriorly
• Four cephalic papillae were present
• tail conical provided with rounded tapered process.
• The cuticle was striated longitudinally and transversely forming net – like shape
L 40–52 (47) 39–50 (45) 29–39 (34) 39–50 (46) 23–35 (30) 32–50 (42)
W 1.3–1.64 (1.45) 1.32–1.76 (1.48) 0.78–1.22 (1.05) 1–1.26 (1.16) 0.7–1.13 (0.96) 0.94–1.4 (1.15)
B.T. 0.007–0.009 (0.008) 0.007–0.0084 (0.008) 0.02–0.025 (0.023) 0.02–0.024 (0.022) 0.018–0.02 (0.019) 0.01–0.015 (0.013)
Oes. 4.4–6.2 (5.18) 4.2–5.9 (4.9) 2.46–3.72 (3.07) 3.6–4.6 (4.13) 3.2–5 (4.28) 2.9–4.4 (3.62)
Int.c. 3.4–5 (4.1) 3.2–4.8 (3.9) 1.91—3.12 (2.42) 2.8–3.8 (3.22) 2–4 (3.35) 2–3.6 (2.75)
VA 1.66–3.2 (2.43) 1.5–2.8 (2.15) 0.78–0.84 (0.81) 0.84–1.3 (1.11) 0.56–0.66 (0.6) 0.84–1.2 (0.98)
t. 0.16–0.38 (0.23) 0.16–0.35 (0.2) 0.1–0.24 (0.16) 0.1–0.2 (0.16) 0.06–0.24 (0.22) 0.2–0.22 (0.2)
t.p. 0.01–0.015 (0.012) 0.01–0.013 (0.012) 0.05–0.06 (0.055) 0.07–0.075 (0.072) 0.073–0.075 (0.07) 0.032–0.038 (0.035)
Oes./L 10–12% (11%) 10–12% (11%) 8.4–9.5% (9%) 9.2–9.6% (9.43%) 13.9–14.3% (14%) 9.1–10% (9.6%)
Int.c./Oes. 77–81% (79%) 76–81% (80%) 77–84% (78.8%) 78–83% (80%) 63–78% (76.2%) 69–80% (77%)
VA/Oes. 37.7–51.6% (46.9%) 35.7–47.4% (43.8%) 22–32% (26.4%) 23–30.6% (26.8%) 13–17.5% (14%) 23–29% (27%)
VA/Int.c. 48.8–64% (59%) 46.8–58% (55%) 27–41% (33.8%) 30–39% (34.5%) 16.5–28% (18%) 33.3–42% (35.6%)
t./L 0.4–0.7% (0.55%) 0.4–0.66% (0.53%) 0.34–0.6% (0.47%) 0.3–0.5% (0.35%) 0.3–0.6% (0.58%) 0.47–0.6% (0.5%)
  1. Measurements are in millimeters
  2. Abbreviations: LF long form, SF short form, L body length, W body width, B.T. boring tooth, Oes. length of esophagus, Int.c. length of intestinal caecum, VA length of ventricular appendix, t. tail length, t.p. tapered process