Ophiotaenia oumanskyi, de Chambrier & Gil de Pertierra, 2012

De Chambrier, Alain, Gil de Pertierra, Alicia, P. O. & Ch-, 2012, Ophiotaenia oumanskyi sp. n. (Eucestoda: Proteocephalidea), a parasite of Lepidobatrachus laevis Budgett, 1899 (Anura: Leptodactylidae) from Paraguay, Revue suisse de Zoologie 119 (4), pp. 561-570 : 562-566

Ophiotaenia oumanskyi sp. n.

Figs. 1-8

TYPE MATERIAL: Holotype MHNG-PLAT-62560, 1 whole mounted slide . – Paratype 1, MHNG-PLAT-82004, 1 whole mounted slide. – Paratype 2, MHNG-PLAT-82005, 3 whole mounted slides, 10 cross sections . All material is from the type locality and was collected by Carlo Dlouhy 4.02.2002, field number Py 9044.

DESCRIPTION (BASED ON THREE ENTIRE SPECIMENS): Proteocephalidae , Proteocephalinae. Large-sized worms, 50-96 mm long, up to 1.23 mm wide, flattened dorsoventrally, with last proglottides elongated. Strobila acraspedote, anapolytic, with about 150 proglottides; 101-138 (x = 125) immature proglottides (up to appearance of spermatozoa in vas deferens), 5-9 (x = 7) mature proglottides (up to appearance of eggs in uterus), 2-6 (x = 4) pregravid proglottides (up to appearance of hooks in oncospheres); 10-17 (x = 13) gravid proglottides. Proliferation zone, 1000-1400 long. Immature proglottides wider than long; and mature, pregravid, gravid proglottides longer than wide. Last gravid proglottides elongated (length: wide ratio 2.3-5.7).

Scolex spherical, 350-410 wide, contains numerous cells with granular inclusions in the apical region. Apical organ present, 38-56 (x = 43) × 50-65 (x = 54, n = 3), ratio of the width of the apical organ to the width of the scolex 14-17%. Four small uniloculate suckers, 150-170 in diameter (Fig. 1).

Internal longitudinal musculature developed (Figs 3-5), forming small anastomosed bundles of muscular fibres. Osmoregulatory canals usually situated between vitellaria and testes. Ventral canal rarely overlapping vitellaria. Ventral canals 25-50 in diameter, with secondary canals ending beneath the tegument; dorsal canals 10-15 in diameter (Figs 1, 3-5).

Testes medullary, oval, 60-75 (x = 70) × 35-45 (x = 40, n = 21) in diameter, numbering 85-119 (x = 103, n = 21, CV = 8%), in one or two layers, in two lateral fields between anterior margin and preovarian space, reaching to ovary (Figs 4, 7), degenerated in last gravid proglottides. Occasionally, some testes overlap uterine stem. Vas deferens coiled, thin-walled, reaching to midline of proglottis (Figs 5, 7). Cirrussac elongate to pyriform, thick-walled, 180-260 long, representing 20-27% (x = 23%, n = 25, CV = 8%) of proglottis width. Cirrus occupying up to 70% of cirrus-sac length (Fig. 2).

Genital ducts passing between osmoregulatory canals. Genital atrium present. Genital pores irregularly alternating, situated at 35-61% (x = 41%, n = 21, CV = 14%) of proglottis length.

Vagina posterior (in 52% of the proglottides) or anterior (in 48% of the proglottides, n = 46) to cirrus-sac, in proximal part lined with intensely staining cells. Muscular terminal sphincter present, 35-40 in diameter (Figs 2, 7, 8). Mehlis’ glands 70-105 in diameter, 9-13% of proglottis width.

Ovary medullary, bilobed, small, with follicles on ventral side 445-620 wide, occupying 61-70% (x = 66%, n = 29, CV = 4%) of proglottis width (Figs 4, 7, 8). Ovary occupying 6.7% of proglottis surface in mature proglottis and 8.3% of proglottis surface in gravid proglottis (see Ammann & de Chambrier, 2008 and de Chambrier et al., 2012 for methodology of measuring the ovarian surface).

Vitelline follicles medullary, oval to elongate, in two lateral fields, interrupted porally by vagina and cirrus-sac, reaching almost anterior and posterior margins of proglottides, occupying porally 91-97% and aporally 91-96 % of proglottis length, respectively (Figs 3-5, 7, 8).

Anlage of uterus medullary, already present in immature proglottides. Uterus with 18-25 (n = 13) dorsolateral diverticula on each side in gravid proglottides (Figs 5, 6). Formation of uterus of type 1 according to de Chambrier et al. (2004): uterine stem with tubular concentration of numerous intensely stained cells and with lumen in last immature and first mature proglottides (Fig. 7). In mature proglottides, thin-walled lateral diverticula appear, with distal part lined with some intensely staining cells. At this stage, uterus occupying up to 22% of proglottis width. In pregravid proglottides, eggs completely filling uterine stem and diverticula that occupy up to 34% of proglottis width. In gravid proglottides, thin-walled digitate diverticula growing laterally, occupying up to 72% of proglottis width, opening ventrally by several longitudinal apertures.

Eggs spherical, with thin, hyaline outer envelope, up to 55 in diameter; inner envelope consisting in two-layered embryophore, with external thick layer, 23-26 in diameter and nucleate irregular envelope, 18-21 in diameter; oncospheres 11-13 in diameter, with 3 pairs of embryonic hooks, 6-8 long (Fig. 6).

TYPE LOCALITY: Loma Plata , Filadelfia, Alto Paraguay Province, Paraguay (22°18'S, 68°18'W).

TYPE-HOST: Lepidobatrachus laevis Budgett, 1899 (Leptodactylidae) .

SITE OF INFECTION: Intestine.

PREVALENCE: 1/1.

INTENSITY: 3 specimens.

ETYMOLOGY: The new species is named in honour of Igor Oumansky, Geneva, who facilitated our field work in South America.

DIFFERENTIAL DIAGNOSIS: The new species belongs to the genus Ophiotaenia because of the medullary position of gonads, the presence of four simple unilocular suckers and two lateral field testes ( Freze, 1965; Schmidt, 1986; Rego, 1994).

Off the approximately 96 currently recognized species of Ophiotaenia parasitizing reptiles and amphibians ( Schmidt, 1986; de Chambrier et al., 2006; Marsella & de Chambrier, 2008; de Chambrier et al., 2010, 2012), 25 species of Ophiotaenia parasitize amphibians and 10 of them occur in anurans in the Neotropical Region (Caribbean, southeastern Mexico, Central America and South America; Table 1 ) ( Parodi & Widakowich, 1916; Vigueras, 1942; Wolffhügel, 1948; Szidat & Soria, 1954; Flores-Barroeta, 1955; Dyer & Altig, 1977; Dyer, 1986; Puga & Formas, 2005; de Chambrier et al., 2006; Marsella & de Chambrier, 2008).

Among the 10 species of Ophiotaenia found in anurans of the Neotropical Region, only O. bonariensis Szidat & Soria, 1954 and O. ecuadoriensis Dyer, 1986 possess an apical organ, whereas it is absent in O. alessandrae Marsella & de Chambrier, 2008 ; O. bonneti de Chambrier, Coquille & Brooks, 2006 ; O. bufonis ( Vigueras, 1942) ; O. calamensis Puga & Formas, 2005 ; O. ceratophryos ( Parodi & Widakowich, 1916) ; O. hernandezi (Flores-Barroeta, 1955) ; O. noei Wolffhügel, 1948 ; and O. olseni Dyer & Altig, 1977 . The new species resembles O. ecuadorensis in the size of the scolex (350-410 µm and 370-450 µm, respectively), but differs in the total length (50-96 mm vs. 29 mm), the position of the vagina to the cirrus-sac (anterior and posterior vs. only posterior) and the diameter of oncospheres (23-26 µm vs. 30 µm). Ophiotaenia oumanskyi is easily differentiated from O. bonariensis because the latter is very large (400-500 mm versus 50-96 mm), has a higher number of testes (120-140 versus 85-119) and the vagina is always anterior to the cirrus-sac versus anterior and posterior (see Table 1 ).

On the basis of the above differences, specimens found in Lepidobatrachus laevis are considered to represent a new species and the name Ophiotaenia oumanskyi sp. n. is proposed to accommodate it.