Chaunocephalus ferox (Rudolphi, 1795)

Greben, О. B., Kudlai, O., Korol, E. N., Kornyushin, V. V., Vasilkovska, I. B. & Kobylinsky, V. V., 2016, A New Record Of Chaunocephalus Ferox (Digenea, Echinostomatidae) From Ciconia Nigra In Ukraine Including Morphological And Molecular Data, Vestnik Zoologii 50 (2), pp. 99-104 : 100-103

Chaunocephalus ferox (Rudolphi, 1795)

H o s t: Ciconia nigra (Linnaeus, 1758) ( Ciconiiformes , Ciconiidae ).

S i t e i n h o s t: Intestine, crypts in the intestinal wall.

L o c a l i t i e s: Kiev Zoo (originated from Borodianka, Kyiv Region).

R e p r e s e n t a t i v e D N A s e q u e n c e: KT447522 (partial 28S rRNA gene).

Description ( fig. 1 )

[Based on 8 contracted specimens from intestine]. Body elongate, divided into bulbous forebody (FO = 53–56 %) with maximum width 1,182 –1,709 (1,452) and shorter narrow hindbody, with maximum width 595–1,279 (968). Body length 3,115 –3,628 (3,417). Tegument armed with large spines.

Head collar reniform, strongly muscular, and well differentiated from body, 194–302 × 405–479 (245 × 448). Collar spines 27; four angle spines on each ventral lappet, larger than marginal spines, 120–148 × 20–25 (136 × 22); lateral spines in single row, 90–115 × 13–19 (102 × 15); dorsal spines in double row, 85–113 × 13–18 (99 ×15). Oral sucker terminal, transversely oval, 116–159 × 131–182 (133 × 155). Ventral sucker strongly muscular, with deep cavity, 502–690 × 497–614 (610 × 553). Sucker-ratio 1: 3.0–4.3 (1: 3.6). Prepharynx short, 69–75 (72). Pharynx muscular, elongate-oval, larger than oral sucker, 217–278 × 111–154 (244 × 136). Oesophagus 986–1,448 (1,168) long with saccular lateral diverticula. Intestinal bifurcation just anterior to ventral sucker. Caeca reach close to posterior extremity and open into excretory vesicle to form uroproct.

Testes tandem, post-ovarian, elongate-oval, entire; right testis 200–41 × 163–343 (299 × 232); left testis 258–355 × 165–364 (303 × 230). Post-testicular region 531–792 long, occupying 15–23 % of body length. Cirrus-sac small, elongate-oval, 181 × 146, anterodorsal to ventral sucker. Internal seminal vesicle not observed. Genital pore median, closely anterior to ventral sucker.

Ovary large, sinistral, pretesticular, transversely oval, 171–392 × 232–477 (281 × 338). Mehlis’ gland strongly developed, dextral, immediately pretesticular, 222–410 × 280–572 (305 × 382). Laurer’s canal and uterine seminal receptacle not observed. Uterus short with numerous eggs, 87–111 × 54–75 (99 × 60). Vitellarium extensive, follicles large, in whole forebody and two lateral fields in hindbody, confluent in forebody. Excretory vesicle not observed; pore terminal.

Remaks

The material described above agrees well with the diagnosis of Chaunocephalus given by Kostadinova (2005). The presence of 27 collar spines in our specimens is consistent with four species in the genus, namely Ch. ferox , Ch. gerardi , Ch. similiferox and Ch. sinensis (table 1).

The present species differs from:

(i) Ch. gerardi in having a distinctly smaller collar (194–302 × 405–479 vs 530 × 830– 1,000) and oral sucker (116–159 × 116–159 vs 380–400), shorter and narrower angle and marginal spines (120–148 × 20–25 vs 210–240 × 32; 90–115 × 13–19, 85–113 × 13–18 vs 130–135 × 21–30);

(ii) Ch. similiferox in having a narrower collar (405–479 vs 590–670), shorter and narrower angle spines (120–148 × 20–25 vs 190–210 × 35–45), smaller oral sucker (116–159 × 131–182 vs 210–230 × 300–330) and ovary (207–487 × 157–391 vs 400–500 × 500), and higher limits for the length and width of eggs (87–111 × 54–75 vs 67–109 × 42–65);

(iii) Ch. sinensis in having longer angle spines (120–148 vs 77–109), larger pharynx (217–278 × 111–154 vs 168–186 × 96–132), narrower Mehlis’ gland (252–495 vs 537–645) and higher lower limits for ventral sucker and eggs, and low or higher upper limits for testes and ovary (table 1).

The morphology of the present form generally agrees with the description of Ch. ferox by Dietz (1910) and description by Iskova (1985); the latter based on material from C. ciconia in Danube Delta. However, specimens from our collection exhibit substantially smaller length of the body that we consider is due to the fixation of the worms inside the host intestine. Notably, the size of angle spines and the width of the pharynx of our specimens lie outside the lower range of variation reported by Dietz (1910). Also the length of the prepharynx and the maximum width of the ventral sucker in our specimens are distinctly larger. Specimens reported by Iskova (1985) differ from ours in having distinctly shorter dorsal spines and smaller lower limits for the length of the angle spines and egg width (table 1).

,

The genus Chaunocephalus requires detail taxonomic revision to assess the validity of all species included with a special emphasis on these from India. Such a large variability of number of spines (table 1) makes the validity of the species somewhat doubtful.

Recently, the sequence of Ch. ferox generated in our study was used in the comprehensive molecular phylogeny of the Echinostomatoidea Looss, 1899 ( Tkach et al., 2016). The analyses show no support for the subfamily Chaunocephalinae Travassos, 1922 , which resulted in a synonymisation of the Chaunocephalinae with the Echinostomatidae (sensu stricto). We believe the sequence provided by our study will be also useful for the molecular identification of the life-cycle stages of the species in the future studies.

Figures

Fig.1. Chaunocephalus ferox: 1— ventral view; 2 — head collar;3 — head collar of hologenophore;4 — uroproct.