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

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%)