Kapsulotaenia cannoni, Chambrier & Brabec & Scholz, 2020

Chambrier, Alain De, Brabec, Jan & Scholz, Tomáš, 2020, Molecular data reveal unexpected species diversity of tapeworms of Australasian reptiles: revision of Kapsulotaenia (Cestoda: Proteocephalidae), Zootaxa 4869 (4), pp. 529-561 : 549-550

9. Kapsulotaenia cannoni n. sp.

( Figs. 7 A–C, 8, 10G, H, 11I–P)

Type and only known host. Gould’s monitor, Varanus gouldii ( Squamata : Varanidae ).

Site of infection. Intestine.

Type locality. Port Pirie , South Australia, Australia .

Additional localities. Culgoa Floodplain National Park , Queensland, Australia ; Mount Glorious , Queensland, Australia ; Cadney Park, South Australia, Australia; Western Australia (locality not specified).

Type material. Holotype (three fragments of one specimen from V. gouldii ; field number Aus 140—marked by dots on the slide C-184 /51 with fragments of another specimen; collected on 8.xi.2003 by A. de Chambrier; MHNG-PLAT-130205); 3 paratypes (3 specimens from V. gouldii Aus 140 on the slides C 184/46, SAM 140.184 /46; C-184 /47, IPCAS C-832 /1 with fragments of other specimens; C-184 /48, MHNG-PLAT-130206.

DNA sequences. lsr DNA: MT 611162 , MT 611163 (Aus140, 146a); cox 1: MT 627452 , MT 627458 (Aus140, 146a).

Material studied. All specimens from V. gouldii : 4 slides with several specimens (5 with scoleces), Port Pirie, South Australia, 8.xi.2003 (Aus140; MHNG-PLAT-36703; hologenophore MHNG-PLAT-32839); 1 slide with immature specimen, Cadney Park , South Australia, 16.xi.2003 (Aus146b; MHNG-PLAT-86017; hologenophore MHNG-PLAT-36705); 3 slides with numerous gravid proglottids, Western Australia, 17.ix.1950 (Aus152; MHNG- PLAT-90430); see also list of material studied of K. nybelini below (1 specimen AHC 35832; 2 specimens AHC 35834) .

Etymology. The new species is named after Lester Cannon, Queensland Museum, Brisbane, Australia, for his outstanding contribution to the knowledge of parasitic flatworms and for helping the senior author to conduct his field trips in Australia in 2001 and 2003.

Morphological description (for measurements—see Table 2 ). Proteocephalidae , Acanthotaeniinae . Cestodes up to 73 mm in total length; maximum width up to 560. Strobila acraspedote, anapolytic. Immature proglottids wider than long to longer than wide (length: width ratio 0.60–3.26), mature, pregravid and gravid proglottids longer than wide (ratio 3.51–6.70) ( Fig. 8A , E–G). Strobilisation begins about 1 mm after posterior part of scolex, about 85 proglottids until the presence of spermatozoids within vas deferens (first mature), 91 proglottids in total (including only two mature proglottids). Inner longitudinal musculature present at level of neck region, composed of very few muscle fibres. Ventral osmoregulatory canals slightly sinuous, 10–15 in diameter. Dorsal osmoregulatory canals slightly sinuous, 2–4 in diameter ( Fig. 8A, C ). Canals situated between vitelline follicles and testes ( Fig. 8A, D, E ).

Scolex wider than neck ( Figs. 7 A–C, 11I–J). Suckers uniloculate, spherical, directed almost laterally ( Fig. 7 A–C). Rostellum dome-shaped, containing large apical organ ( Fig. 11K ), posteriorly surrounded by numerous circular muscular fibres ( Fig. 7A, B ). Retractor muscles connecting rostellum with neck present ( Fig. 7A, C ).

Testes medullary, in 1 layer, rounded to elongate, in 2 wide longitudinal bands in both sides of proglottids, with poral band separated by terminal genitalia into preporal and postporal groups ( Fig. 8A, E ); testes and ovary degenerate in gravid proglottids ( Fig. 8G ). Cirrus-sac oval to pyriform, thin-walled ( Fig. 8B ). Cirrus short, covered by spinitriches, its length representing up to 50% of cirrus-sac length ( Fig. 8B ). Internal sperm duct coiled. External sperm duct (vas deferens) strongly coiled, directed medially or anteriorly, situated between proximal part of cirrussac and midline of proglottids, sometimes reaching aporal side ( Fig. 8A ). Genital atrium narrow, deep ( Fig. 8B, D ); genital pores alternating irregularly, situated in posterior part of proglottid ( Fig. 8A , E–G).

Ovary bilobed, butterfly-shaped ( Fig. 8A, E, F ). Mehlis’ gland small ( Fig. 8A ). Vaginal canal straight in proximal part, enlarged to form small seminal receptacle anterodorsal to ovarian isthmus ( Fig. 8C ). Terminal (distal) part of vaginal canal (pars copulatrix vaginae) with a ring-like vaginal sphincter surrounded by few chromophilic cells ( Fig. 8B, D ). Vagina anterior (12%) or posterior (88%, n = 123) to cirrus-sac ( Fig. 8B, D ). Vitelline follicles arranged in 2 longitudinal bands composed of 1, rarely 2 rows of follicles, near lateral margins of proglottids; band interrupted at level of cirrus-sac and vagina ( Fig. 8 D–F).

Primordium of uterine stem ventral, present in immature proglottids. Development of uterus of type 1 according to de Chambrier et al. (2004, 2015). In pregravid proglottids, uterus occupies up to 69% of proglottid length, with lateral diverticula on each side, not overlapping ovary. In gravid proglottids, uterus occupies up to 82% of proglottid length, with 22–37 lateral diverticula ( Fig. 8F, G ). Intrauterine eggs spherical to subspherical, grouped in clusters of 3– 7 eggs (x = 4.3, n = 304) ( Fig. 10G, H ). Outer envelope thin, embryophore trilayered, oncosphere spherical, six embryonic hooks 7–9 long.

Differential diagnosis. The new species differs from the remaining species of Kapsulotaenia by a smaller scolex, the average width of which does not exceed 335 μm (see Table 2 ). In addition, K. cannoni can be distinguished from all species except K. chisholmae by a bigger cirrus-sac ratio (26% in average versus 16–21% in other species) and by a higher ratio of Mehlis’ gland width to the width of proglottids (16% in average versus less than 12% in other species including K. chisholmae with ratio of 7–10%). From K. chisholmae , K. cannoni differs by the presence of an armed cirrus and a lower number of eggs in cluster (3–7 versus 8–13).

Remarks. Kapsulotaenia cannoni n. sp. is a widely distributed parasite of Gould’s monitor and has been found in the Western and South Australia and in Queensland. Two of four hosts examined in the present study were infected, i.e., prevalence of 50%. Tapeworms found in Gould’s monitor No. Aus020 also had a small scolex (width of the scolex 330–400 μm), thus roughly resembling those of K. cannoni , but differed conspicuously in their lsr DNA and cox 1 sequences from all the remaining species of Kapsulotaenia characterized molecularly ( Figs. 1 , 2 ). Phylogenetic analyses found the specimen from Aus020 (= Kapsulotaenia sp. 2 of de Chambrier et al. 2015; AJ583455 ; MT627454 ) to form a clearly distinct lineage of Kapsulotaenia with an unresolved position ( Fig. 1 ) and thus, this specimen most likely represents a third species from V. gouldii (they certainly do not belong to K. nybelini , which is typified by a large, wide scolex—see below and Table 2 ).

Figures

FIGURE 1. Phylogenetic relationships of tapeworms of the subfamily Acanthotaeniinae (Cestoda: Proteocephalidae) based on a maximum likelihood analysis of concatenated (lsrDNA +cox1) data. Nodal values depict standard bootstrap supports (1,000 resamples) over 50, dashed lines are used for nodes with bootstrap values below 50. Branch length scale bar indicates number of substitutions per site. GenBank accession numbers can be found in Table 1.

FIGURE 2. Maximum likelihood single-gene phylogenies of Kapsulotaenia based on cox1 (above) and lsrDNA (below) data. Nodal values depict standard bootstrap supports (1,000 resamples) over 50, dashed lines are used for nodes with bootstrap values below 50. Branch length scale bar indicates number of substitutions per site. GenBank accession numbers can be found in Table 1.

FIGURE 7. Scoleces of Kapsulotaenia cannoni n. sp. (A, B—MHNG-PLAT-36703; C—AHC 35832) and Kapsulotaenia nybelini n. sp. (D–F—AHC 35834), both from Varanus gouldii, Australia.

FIGURE 8. Kapsulotaenia cannoni n. sp. from Varanus varius, Australia (Aus140; MHNG-PLAT-36703). A, E—mature proglottids, dorsally and ventrally, respectively; B, D—terminal genitalia, ventrally; C—posterior and anterior extent of vitelline follicles, dorsally; F, G—gravid proglottids, ventrally.

FIGURE 10. Egg capsules of species of Kapsulotaenia (eggs from unmounted proglottids drawn in distilled water). A—K. pythonis from Morelia viridis (syntype); B—Kapsulotaenia sp. 6 from Varanus varius (host AUS005); C—K. tidswelli from Varanus varius (host Aus135); D, F—K. varia from V. varius (hosts Aus016 and Aus137); E—K. beveridgei n. sp. from V. rosenbergi (host Aus028); G, H—K. cannoni n. sp. from V. gouldii (host Aus140).

FIGURE 11. Scanning electron micrographs of Kapsulotaenia spp. A–D. Kapsulotaenia varia from Varanus varius (Aus137; MHNG-PLAT-72084). A. Subapical view of the scolex. B. Coniform spinitriches and capilliform filitriches on the rostellum (apex of the scolex). C. Capilliform filitriches with sparse gladiate spinitriches on the outer rim of suckers. D. Gladiate spinitriches on the strobila. E–H. K. beveridgei n. sp. from V. rosenbergi (Aus029—MHNG-PLAT-36552). E. Frontal view of the scolex. F. Coniform spinitriches interspersed with capilliform filitriches on the rostellum (apex of the scolex). G. Gladiate spinitriches in-between the suckers. H. Gladiate spinitriches on the strobila. I–P. K. cannoni n. sp. from V. gouldii (Aus140; MHNG- PLAT-36703). I. Frontal view of the scolex. J.Apical view of the scolex. K. Subapical view of the partly withdrawn rostellum. L. Detail of the sucker rim with capilliform filitriches and coniform spinitriches. M. Coniform spinitriches of the rostellum (apex of the scolex). N. Capilliform filitriches of the outer rim of the suckers, with coniform spinitriches in the lower part (sucker cavity). O. Coniform spinitriches interspersed with papilliform filitriches in the sucker cavity. P. Gladiate spinitriches on the neck. Small letters within figures mark position of detailed pictures of microtriches.