Dasyrhynchus Pintner, 1928

Jr, Joaber Pereira & Boeger, Walter A., 2005, Larval tapeworms (Platyhelminthes, Cestoda) from sciaenid fishes of the southern coast of Brazil, Zoosystema 27 (1), pp. 5-25 : 20

Genus Dasyrhynchus Pintner, 1928

Dasyrhynchus pacificus Robinson, 1965 ( Fig. 6 )

HOSTS. — Menticirrhus americanus (NH) (LH = 39.7;

P = 2.04; MI = 2.0; MA = 0.04); Cynoscion jamaicensis

(NH) (LH = 22.0-32.3; P = 5.0; MI = 1.0; MA = 0.05); Cynoscion guatucupa (NH) (LH = 16.5-44.0; P = 6.67; MI = 3.14; MA = 0.21); Macrodon ancylodon (NH) (LH = 22.0-35.2; P = 5.0; MI = 1.0; MA = 0.05).

SITES OF INFECTION. — Coelomic cavity, pericardial cavity, and kidneys.

SPECIMENS DEPOSITED. — CHIOC 33908 a-c; USNPC 87417, 87418, 87419, 87420; MNHN-C- IX-144 (JJ 1055-4-1; JJ 1390-2-1).

DESCRIPTION

Based on 30 larvae examined; 26 measured. Scolex 13.29 ± 1.38 (9.90-15.42) long; two cordiform bothridia with margins free and an indentation on posterior margin; pars bothridialis 0.71 ± 0.08 (0.50-0.87) long. Tentacle sheath regularly coiled; pars vaginalis 8.37 ± 0.81 (6.50-10.32) long. Prebulbar organ absent, bulbs elongate, 2.43 ± 0.30 (1.97-3.00) long, 0.17 ± 0.06 (0.12-0.22) wide, posterior extremity overlapping pars postbulbosa. Length/width ratio of bulbs 14.43 ± 5.79 (11.25-20.40). Length of scolex/length of bulb ratio 5.48 ± 0.49 (4.44-6.51). Pars postbulbosa 1.68 ± 0.47 (1.07-2.35) long. Basal armature distinct on discrete swelling of the tentacle. Single chainette, continuous from basal armature to tip of tentacle. Chainette hooks with cordiform base. Principal rows in ascending alternate half spiral, with 10 principal hooks, and five or six intercalary hooks. Principal hooks diminishing in size along half spiral. Hooks 1 (1’)-3 (3’) larger, uncinate. Hooks 4 (4’)-10 (10’) falciform; intercalary hooks falciform, between hooks 4 (4’)-7 (7’).

REMARKS

Adults of D. pacificus were reported from the coast of South Brazil by São Clemente & Gomes (1989a) and São Clemente et al. (1991) in Carcharhinus brachyurus (Günter, 1860) (Carcharhinidae) . This is the first record of the larva of this species in Brazil. The tentacular armature described here confirms the descriptions of São Clemente & Gomes (1989a) and Beveridge & Campbell (1993). However, the scolex of the larvae collected in the present study are larger.

In their key for species of Dasyrhynchus ,

Figures

FIG. 6. — Dasyrhynchus pacificus Robinson, 1965; A, larva in toto; B, portion of the chainette; C, posterior portion of bulbs and appendix; D, half spiral of principal hooks, intercalary hooks (in black) and chainette (c). Scale bars: A, 0.1 mm; B, D, 0.05 mm;