Penetrocephalus ganapattii (Rao, 1954) Rao, 1960

Figs. 9–13, 19, 20, 22, 23

Syns. Bothriocephalus ganapattii Rao, 1954; Bothriocephalus penetratus Subhapradha, 1955.

Type host: Saurida tumbil.

Other hosts: S. micropectoralis, S. undosquamis.

Site of infection: The scolex and neck (scolex deformatus) is coiled within a cyst on the wall of pyloric caeca, whereas the strobila lies freely in the intestinal lumen.

Type locality: Coast of Waltair, Bay of Bengal, Andhra Pradesh, India, Indian Ocean.

Distribution: Indian Ocean (India, Indonesia).

Prevalence: In Indonesia, S. micropectoralis – 27%; S. tumbil – 5%.

References: Subhapradha (1955); Rao (1960); Devi (1975); Radhakrishnan et al. (1983).

Re-description: Bothriocephalidea, Bothriocephalidae. Large worms, up to 125 mm long. Strobila with markedly craspedote segments with prominent lateral wing-like projections (Figs. 10, 19, 23). External segmentation present, may be incomplete (missing medially). Two pairs of longitudinal osmoregulatory canals present. Longitudinal musculature well developed, forming numerous bundles of muscle fibres (Figs. 10, 11). Surface covered with small filiform microtriches similar in shape and size.

Scolex unarmed, 700–750 long by 150–200 wide, changed to scolex deformatus (Fig. 9, 12). Apical disc absent. Anterior part of body including neck often degenerated, becoming filiform (Fig. 9), up to 60 mm long, penetrating through intestinal wall, and encysted on pyloric caeca.

Segments short, much wider than long (up to 14 times in mature segments). Immature segments 50–620 long by 100–2,540 wide. Mature segments 40–220 long by 1,080–2,900 wide (Fig. 10). Gravid segments 70–620 long by 890–3,140 wide (Figs. 19, 23).

Testes medullary, oval, 40–60 in number per segment, 10–60 long by 10–40 wide, in two lateral fields separated medially, continuous between segments (Fig. 10). Cirrus-sac submedian (Fig. 11), irregularly alternating, round or slightly oval, 65–195 in diameter, just anterior to ovary (Fig. 10, 13). Cirrus unarmed, covered with long filiform microtriches (Fig. 20), opening to small genital atrium. Genital pore dorsal, slightly submedian (Figs. 11, 23).

Ovary transverse elongate, lobulate, median, 240–720 wide (Fig. 10). Vagina tubular, lateral or anterolateral to cirrus-sac. Vitelline follicles cortical, oval, 10–40 in diameter, numerous, in two lateral fields separated medially, reaching to posterolateral projections (Fig. 10, 11). Uterine duct sinuous, leading to thick-walled, median uterus (Figs. 10, 13), dilated ventrally in gravid segments. Uterine pore ventral, median, at distance from anterior margin of segment (Fig. 19). Eggs oval, operculate, unembryonated, 50–74 long by 33–42 wide; operculum 9–18 in diameter (Fig. 22).

Remarks: The original description of Bothriocephalus ganapattii was very brief (Rao, 1954), which led Protasova (1977) and Bray et al. (1994) to consider B. ganapattii a nomen nudum. However, the species is clearly recognizable on the basis of its original description because it possesses a scolex deformatus that penetrates the intestine and forms a cyst in the mesentery or in the liver (Rao 1954). Subhapradha (1955), probably not aware of Rao’s (1954) publication, described an apparently conspecific cestode, Bothriocephalus penetratus. Both taxa parasitize the same fish host in the same region and are morphologically indistinguishable. Therefore, they are considered synonymous (Rao 1960; Kuchta & Scholz 2007; Kuchta et al. 2008b).

Rao (1960) proposed a new genus, Penetrocephalus, to accommodate B. ganapattii (the type- and only species was misspelled as P. ganapatii). The genus was invalidated by Protasova (1977) and Bray et al. (1994), but resurrected by Kuchta et al. (2008b); the validity of the genus is also supported by molecular data (Kuchta 2007, fig. 10).