Sciadicleithrum frequens, Bellay, Sybelle, Takemoto, Ricardo Massato, Yamada, Fábio Hideki & Pavanelli, Gilberto Cezar, 2008

Bellay, Sybelle, Takemoto, Ricardo Massato, Yamada, Fábio Hideki & Pavanelli, Gilberto Cezar, 2008, A new species of Sciadicleithrum (Monogenea: Ancyrocephalinae), gill parasite of Geophagus brasiliensis (Quoy & Gaimard) (Teleostei: Cichlidae) from reservoirs in the State of Paraná, Brazil, Zootaxa 1700, pp. 63-68 : 64-66

Sciadicleithrum frequens n. sp.

( Figs. 1–10 )

Type-host: Geophagus brasiliensis (Quoy & Gaimard) ( Perciformes , Cichlidae ).

Site: Gill filaments

Type-locality: Mourão Reservoir (Ivaí River basin); State of Paraná, Brazil.

Other localities (reservoirs): Iraí, Júlio Mesquita Filho, Salto Osório and Salto Vau (Iguaçu River basin); Capivari and Guaricana (Litorânea basin); Melissa (Piquiri River basin); Harmonia (Tibagi River basin); State of Paraná, Brazil.

Specimens deposited: Holotype, CHIOC 36924; 6 paratypes, CHIOC 36921a-c, 36922, 36923; BMNH 2007.12.14.1.

Prevalence: 100% (examined 64, infected 64)

Mean Intensity: 69 parasites per parasited host

Specimens studied: 20 specimens in Hoyer’s medium and 4 stained with Gomori’s trichrome.

Etymology: The specific name is from Latin ( frequens = frequent) and refers to occurrence of the parasite in all of the specimens of Geophagus brasiliensis analyzed.

Description: (based on 24 adult specimens). Body fusiform, 243 (67–363; n= 14) long; greatest width 72 (15–130; n= 15) in posterior half. Cephalic lobes moderately developed. Eyes 4, subequal; members of anterior pair usually farther apart than those of posterior pair, eye granules elongate ovate; accessory granules sparse in cephalic area. Pharynx spherical, 14 (11–16; n= 11) in diameter; oesophagus short. Peduncle broad; haptor subhexagonal, 79 (58–101; n= 12) wide, 72 (56–96; n= 12) long. Ventral anchor 19 (18–21; n= 6) long, with well-developed roots, evenly curved shaft and point, with longitudinal lateral grooves; base 15 (15–16; n= 5) wide. Dorsal anchor 44 (42–48; n= 10) long, with elongate superficial root, short deep root, curved shaft, point with longitudinal lateral grooves; base 29 (26–31; n= 7) wide. Ventral bar 28 (20–33; n= 9) long, yoke-shaped, with delicate umbelliform membranes; dorsal bar 33 (32–35; n= 4) long, with expanded ends. Hooks similar, each with delicate point, upright thumb, shank varying in diameter along length; hook pair 5, reduced in size; hook pairs 1, 2, 3, 4, 6 and 7: 14 (12–16; n= 11) long; hook pair 5: 12 (12–13; n= 3) long. Filament hook loop ¾ shank length. Male copulatory organ (MCO) a clockwise coil of about 1 ½ rings, 33 (33– 34; n= 2) long, ring diameter 10 (10–11; n= 2). Accessory piece 19 (17–22; n= 5) long, articulating to MCO base, comprising variable sheath, enclosing distal portion of MCO. Gonads overlapping. Testis elongate, fusiform, 29 (21–35, n= 3) long, 14 (8–18; n= 3) wide; vas deferens conspicuous, looping left intestinal caecum; seminal vesicle small; prostatic reservoir large, spherical. Ovary with irregular margin; vagina nonsclerotized, sinistral, opening into large irregular seminal receptacle. Oviduct, ootype, uterus not observed. Vitelline follicles throughout trunk but absent in regions of gonads and copulatory complex. Egg oval, 58 (n= 1) long, 53 (n= 1) wide, with an appendage.

Remarks: This is the first dactylogyrid described from G. brasiliensis , and it is the first species of Sciadicleithrum described from Southern Brazil.

Figures

FIGURE 1. Sciadicleithrum frequens n. sp. from Geophagus brasiliensis. Composite drawing of whole-mount (ventral view). A = hook 5. Scale-bar: 75 µ m.

FIGURES 2 – 10. Sciadicleithrum frequens n. sp. from Geophagus brasiliensis. 2. ventral anchor; 3. dorsal anchor; 4. hook 5; 5. hook 1, 2, 3, 4, 6, 7; 6. Copulatory complex – ventral view; 7. Copulatory complex – lateral view; 8. ventral bar; 9. Dorsal bar; 10. Egg. Scale-bar: 25 µm.