Australophiotaenia amphiboluri ( Nybelin, 1917 ) Chambrier & Beveridge & Scholz, 2018

Chambrier, Alain De, Beveridge, Ian & Scholz, Tomáš, 2018, Tapeworms (Cestoda: Proteocephalidae) of Australian reptiles: hidden diversity of strictly host-specific parasites, Zootaxa 4461 (4), pp. 477-498 : 480-482

Australophiotaenia amphiboluri ( Nybelin, 1917) n. comb.

( Figs. 1–4 )

Syns Crepidobothrium amphiboluri Nybelin, 1917 ; Proteocephalus amphiboluri ( Nybelin, 1917) Hughes, Baker & Dawson, 1941 ; Ophiotaenia amphiboluri ( Nybelin, 1917) Wardle & McLeod, 1952

Type and only host. Eastern bearded dragon, Pogona barbata (Cuvier, 1829) ( Squamata : Agamidae ).

Site of infection. Intestine.

Type locality. Tamborine Mountain , Queensland, Australia (27°58'21"S, 153°11'51"E)?, type host collected in October 1912 .

Distribution. Australia (Queensland).

Reference. Nybelin (1917).

Material studied. Syntypes—some pieces of strobila without scolex, 3 whole mounted slides ( SMNH 102310 – 102312), 1 slide with cross sections ( SMNH 102313), 2 cross sections of syntype material in ethanol ( SMNH 3279) mounted in MHNG, Geneva.

Redescription. Based on type material. No complete specimen nor scolex available. Strobila acraspedote, anapolytic. Mature proglottids wider than long (0.44–0.46 long and 1.47–1.55 mm wide; length: width ratio 0.28– 0.31), pregravid proglottids wider than long (0.98–1.180 long and 1.47–1.66 mm wide; length: width ratio 0.59– 0.81) and gravid proglottids (1.64–1.98 long and 1.22–1.47 mm wide; length: width ratio 1.11–1.62) longer than wide.

Inner longitudinal musculature not well-developed, composed from numerous isolated bundles of muscle fibres. Ventral osmoregulatory canals situated at about 12–18% from lateral margins of proglottids between vitelline follicles and testes, 10–15 wide. Dorsal osmoregulatory canals difficult to observe. Testes medullary, in one or two incomplete layers ( Fig. 2 ), forming two wide lateral bands median to dorsal osmoregulatory canals, not reaching anterior margin of proglottids ( Fig. 1 ); poral field separated by vaginal canal and vas deferens into preporal and postporal groups of vitelline follicles ( Fig. 1 ). Testes 127–152 (x = 135, n = 3; 110–115 according to original description) in number, with 63–79 (x = 70) aporal testes, 45–58 (x = 51) preporal testes and 13–15 (x = 14) postporal testes. Testes ovoid to elongate, 90–125 long and 45–55 wide, disappear in gravid proglottids.

Cirrus-sac ovoid to pyriform, thick-walled, 150–180 long and 105–125 wide; length: width ratio 1.28–1.80; length of cirrus-sac represents 10–14 % (x = 12%, n = 7) of width of proglottids. Cirrus robust, its length representing up to 80% of cirrus-sac length. Vas deferens coiled, occupying narrow and elongated field reaching medially to midline of proglottids. Genital atrium deep; genital pores alternating irregularly, postequatorial, at 62– 73% (x = 66%, n = 8) of proglottid length from its anterior margin.

Ovary medullary, bilobed, 1.17–1.50 mm wide, its width representing 68–74 % of proglottid width; relative size of ovary, i.e. ratio of surface of ovary to surface of proglottid (see de Chambrier et al. 2012), 6.8%. Mehlis’ gland 45–80 in diameter, representing 4–5% of proglottid width. Vaginal canal almost straight, enlarged in proximal part to form small seminal receptacle ventral to ovarian isthmus. Terminal (distal) part of vaginal canal (pars copulatrix vaginae) surrounded by discrete vaginal sphincter and numerous chromophilic cells ( Fig. 1 ). Vagina anterior (57%) or posterior (43%, n = 14) to cirrus-sac.

Vitelline follicles medullary, arranged in two lateral bands near margins of proglottids, occupying porally 88– 96% (x = 94%, n = 6) and aporally 90–98% (x = 95%, n = 6) of proglottid length; poral band interrupted at level of terminal genitalia (cirrus-sac and vagina) ( Fig. 1 ).

Primordium of uterine stem medullary; present in immature proglottids. Development of uterus of type 1 according to de Chambrier et al. (2004): in immature proglottids, uterine stem straight, not reaching anterior margin, occupying most of length of proglottid but never crossing ovarian isthmus, formed by wide longitudinal band of chromophilic cells situated along midline of proglottids. In pregravid proglottids, uterus occupying up to 20% of proglottid width, with 29–32 thin-walled lateral diverticula on each side, with chromophilic cells at tips ( Fig. 1 ). In gravid proglottids, diverticula occupying up to 84% of proglottid width.

Eggs in clusters of 9– 14 eggs (x = 12, n = 6; 13– 15 eggs according to the original description; Figs. 3, 4 ); Clusters 80–95 in diameter; eggs (measured in whole mount and cross sections) with bi-layered embryophore, external layer 30–35 in diameter, internal layer 20–25 in diameter, oncosphere spherical, 12–13 in diameter, with 6 embryonic hooks about 5–7 long.

Remarks. This species was described as Crepidobothrium amphiboluri by Nybelin (1917) based on incomplete specimens, none of which possessed the scolex. For this reason, considered A. amphiboluri (as Ophiotaenia amphiboluri ) as a species inquirenda. Even though the original description of A. amphiboluri was incomplete and no data on scolex morphology are available, a study of the type material of A. amphiboluri has shown that this species is valid. It has never been found since its original description and can be distinguished from congeners in Australia by the following morphological characteristics: 9– 14 eggs in a cluster, 127–152 testes, posterior position of the genital pore (62–73% of the length of proglottid), a high ratio of the surface of the ovarian surface to the surface of the proglottid (6.8%), short cirrus-sac, a small, ring-like vaginal sphincter, and a relatively small Mehlis’ gland (ratio of its width to the proglottid width only 4–5%). Only eggs in whole mounts could be studied and thus the structure of their embryophore could not be observed in sufficient detail to detect the presence of two or three layers.

In 2001 and 2003, five Pogona barbata from the type locality (Tamborine Mountain) were examined by one of the present authors (A. C.), but no proteocephalidean cestodes were found. Therefore, new material for redescription and DNA sequencing was not available.

Figures

FIGURES 1–4. Australophiotaenia amphiboluri (Nybelin, 1917) n. comb., syntype from Mount Tamborine, Queensland, Australia [Coll. No. SMNH 3279]. 1. Mature proglottid, ventral. 2. Cross sections at level of testes. 3. Cross sections at level of uterus with forming eggs. 4. Cross sections at level of eggs in capsules. Abbreviations (Figs. 1–20): cc—chromophilic cells; ci—cirrus; cs—cirrus-sac; doc—dorsal osmoregulatory canal; ec—egg capsule; em—bi-layered embryophore; ga—genital atrium; gc—gland cells; lm—internal longitudinal musculature; gm—Mehlis’ glands; mf—muscle fibres; mi—microtriches; oe—outer envelope; od—oviduct; on—oncosphere; ov—ovary; st—subtegumental muscle fibres; su—subtegumental cells; te—testes; tg—tegument; ud—uterine diverticula; us—uterine stem; va—vas deferens; vc—vaginal canal; vd—vitelloduct; vf—vitelline follicles; voc—ventral osmoregulatory canal; vs—vaginal sphincter.