Saccocoelioides bacilliformis Szidat, 1973

Gallas, Moisés & Utz, Laura R. P., 2019, Revalidation of Saccocoelioides bacilliformis (Digenea, Haploporidae) parasitizing species of Astyanax (Characiformes, Characidae) from southern Brazil, Iheringia, Série Zoologia (e 2019039) 109, pp. 1-5 : 2-3

Saccocoelioides bacilliformis Szidat, 1973

( Figs 1, 2 )

Redescription. Haploporidae , Chalcinotrematinae . Based on 14 mature specimens. Body 1.03–1.85 mm (1.5 ± 0.3 mm; n = 13) long, 0.24–0.45 mm (0.37 ± 0.07 mm; n = 13) wide. Tegument spinose and delicate. Pigmented eyespots scattered in the region of pharynx and hermaphroditic sac. Oral suckEr 100–120 (106 ± 6) long, 110–150 (121 ± 10) widE. VEntral suckEr 90–110 (94 ± 6) long, 90–110 (96 ± 6) wide, distant 300–500 (344 ± 56) from anterior extremity. Ratio of total body lEngth/oral suckEr 1:14.1; ratio of oral suckEr/vEntral suckEr 1:1.13. PrEpharynx 20–120 (44 ± 29) long, 10–20 (12 ± 4; n = 13) wide. Pharynx 50–70 (58 ± 7) long, 40–70 (53 ± 9) wide. Esophagus 130–290 (204 ± 56; n = 11) long, caecal bifurcation at the level of posterior limit or bEhind thE vEntral suckEr, distant 320–560 (411 ± 65; n = 12) from anterior extremity; intestinal caeca sacculate, short, ending about next to the ovary or between ovary and testis.

One single testis, oval to rounded, 107–250 (159 ± 43; n = 13) long, 80–170 (120 ± 26; n = 13) wide, next to the middle of the hindbody. External seminal vesicle longer than internal seminal vesicle. Hermaphroditic sac 105–220 (155 ± 38; n = 13) long, 45–80 (58 ± 10; n = 13) wide, containing intErnal sEminal vEsiclE, pars prostatic and thE final portion of the metraterm, forming the hermaphroditic duct. Genital porE antErior to thE vEntral suckEr, distant 240–430 (308 ± 49) from anterior end. Ovary rounded, usually intercaecal, but always pretesticular, 70–125 (91 ± 17) long, 47–120 (73 ± 18) widE. LaurEr’s canal not obsErvEd, MEhlis’gland not observed. Uterus long, inter and extracaecal, occupying all of thE hindbody and rEaching thE vEntral suckEr. NumErous eggs, 90–110 (100 ± 6) long, 40–60 (50 ± 5) wide, some of them with developed miracidium, containing pigmented eyespot. Vitellarium constituted by generally spherical folliclEs, ranging from thE vEntral suckEr to thE postErior limit of the testis, where in some specimens they are divided in two groups: most of them are pretesticular and a few follicles are pos-testicular. Excretory vesicle not observed, excretory pore terminal, in the posterior extremity.

Taxonomic summary

Hosts: Astyanax aff. fasciatus (Cuvier, 1819) and Astyanax henseli MElo & Buckup, 2006 – nEw hosts rEcords.

Locality: LakE GuaÍba, city of Porto AlEgrE, statE of Rio Grande do Sul, Brazil – new locality record.

Site of infection: stomach.

PrEvalEncEs: 8.7% ( A. aff. fasciatus ) and 40% ( A. henseli ). MEan intEnsity of infEctions: 15.75 hElminths/host ( A. aff. fasciatus ) and 2 helminths/host ( A. henseli ).

MEan abundancE of infEctions: 1.37 hElminths/host ( A. aff. fasciatus ) and 0.8 helminth/host ( A. henseli ).

Amplitude of the intensity of infections: 1 to 54 helminths in A. aff. fasciatus and 1 to 3 helminths in A. henseli .

Voucher specimens of helminths deposited: CHIOC 40094; CHMU 291-1-1.

Figures

Figs 1, 2. Incomplete diagrams of Saccocoelioides bacilliformis Szidat, 1973: 1, composite, ventral view of a specimen in toto. Scale bar = 100 µm; 2, dEtail of thE final portion of thE rEproductivE systEm (gp, gEnital pore; hd, hermaphroditic duct; hs, hermaphroditic sac; m, metraterm; p, pars prostatic; isv, internal seminal vesicle; esv, external seminal vesicle). Scale bar = 40 µm.