Callorhynchocotyle hydrolagi Beverley-Burton & Chisholm, 1990

Vaughan, David & Christison, Kevin, 2012, Towards addressing the current state of confusion within the Hexabothriidae Price, 1942 (1908): Callorhynchocotyle Suriano & Incorvaia, 1982 (Monogenea: Hexabothriidae) re-visited, with the preliminary evaluation of novel parameters for measuring haptoral armature of hexabothriids, Zootaxa 3229, pp. 1-34 : 25-26

Callorhynchocotyle hydrolagi Beverley-Burton & Chisholm, 1990

Type host. Hydrolagus ogilbyi (Waite) ( Chimaeridae , Holocephali). Type locality. Offshore waters, Coffs Harbour, New South Whales, Australia. Site on host. Gills.

Material examined. USNPC 0 80982.00 paratypes MT25-15A and B.

Supplemental information. Total body length 4450 ± 212.1(4300–4600, n = 2), maximum body width 897 ± 78.5(841–952, n = 2). Oral sucker internally papillate, diameter 922 ± 397.7(340–903, n = 2). Pharynx 85 ± 1.3(84–85, n = 2) long, 63 ± 10.3(55–70, n = 2) wide. Branched intestinal caeca unite posterior to testes and extend into the haptor. Asymmetrical haptor 1990 ± 70.7(1940–2040, n = 2) long, 1076 ± 175.0(952–1200, n = 2) wide with 3 paired sucker sclerite complexes. Haptoral suckers papillate.

Sucker sclerites of complex 1 similarly sized to those of complex 2 and 3. Complex 3 sucker-sclerite circumference length 1048, n = 1; total length 450 ± 6.5(445–454, n = 2); total diameter 303 ± 7.4(298–308, n = 2); width 73 ± 0.2(72–73, n = 2); shaft length 452 ± 7.6(446–457, n = 2); inner diameter 234 ± 7.7(228–239, n = 2); aperture angle 56° ± 6.7(51°–61°, n = 2); aperture 245 ± 28.8(224–265, n = 2); hook-side curve length 90 ± 8.4(84–96, n = 2) and shaft-side curve length 95 ± 3.4(92–97, n = 2). Complex 3 sucker-sclerite hook length 114 ± 10.4(106–121, n = 2); hook curve length 19 ± 0.8(18–19, n = 2); aperture 81 ± 10.8(74–89, n = 2) and base-width 34 ± 1.9(32–35, n = 2).

Dorsal haptoral appendix 739, n = 1 long, 320, n = 1 wide. Single pair of hamuli present before terminal suckers. Hamulus total length 67, n = 1; hook point length 13, n = 1; shaft length 30, n = 1; total width 37, n = 1; hook distal point width 3, n = 1; outer aperture angle 30°, n = 1; aperture 73, n = 1; hook shank base width 7, n = 1; inner root-shaft length 42, n = 1; outer root-shaft length 40, n = 1; root base angle 100°, n = 1, and root base width 33, n = 1).

Testes irregular in shape, 65, n = 1 in number; 57 ± 5.60(48–66, n = 10) wide. Vas deferens sinuous, surrounded by small gland cells along the majority of its length. Vas deferens loop proximal to entrance into cirrus, absent. Unarmed muscular cirrus total length 319, n = 1; maximum width 86, n = 1; distal bulb length 175, n = 1, and distal bulb width 148, n = 1.

Ovary (sinistral = 1) 754, n = 1, anteriorly lobed, coiled posteriorly, ascending to oviduct, branching to saclike, reduced seminal receptacle.

Ootype smooth, leading to uterus, dorsal to ovary, ventral to vas deferens. Parallel vaginal ducts with glandulomuscular distal portion and thin-walled proximal portion. Ventral vaginal pores muscular, lateral to median portion of cirrus. Follicular vitellarium originates posterior to vaginal pores. Excretory pores not observed.

Remarks. Callorhynchocotyle hydrolagi was the first of the genus to be recorded from a holocephalan, Hydrolagus ogilbyi of the Chimaeridae . It was the first Callorhynchocotyle species to be described with sucker sclerites all of similar size. Beverley-Burton & Chisholm (1990) indicated that the sucker sclerite width of all the sucker sclerites of C. hydrolagi were thicker than those of C. marplatensis , C. callorhynchi and C. amatoi . Although the limitations of the 2 paratypes examined in the present study prevented the collection of a complete set of data for all 3 sucker sclerite complexes, complex 3 sucker sclerite measurements from paratype USNPC 0 80982.00 MT25- 15A overlap in width with those of C. marplatensis and C. callorhynchi . The appearance of being thicker is likely the result of the reduced sucker sclerite total and inner diameters in C. hydrolagi which are narrower than those of C. marplatensis , C. callorhynchi and C. amatoi . Additionally, the sucker-sclerite total and shaft lengths and suckersclerite hook-side curve length are shorter than those of C. callorhynchi and C. marplatensis .

Callorhynchocotyle hydrolagi can be distinguished from C. marplatensis by the presence of papillae in the oral and the haptoral suckers, but from C. marplatensis , C. callorhynchi and C. amatoi by the comparatively thick cirrus, similarity in sucker sclerite sizes of all 3 complexes and the unique shape of the hamulus.

The hamulus of C. hydrolagi is greater in total length, total width, hook shank length and base width, yet the hamulus-hook point length is less than those of C. marplatensis , C. callorhynchi and C. amatoi . Hamulus-hook shank base width is wider than that of C. amatoi . The hamulus-hook distal point width is wider than those of C. callorhynchi and C. amatoi . The outer root-shaft length is shorter than those of C. callorhynchi and C. amato i, but the inner root-shaft is longer than that of C. callorhynchi yet shorter than that of C. marplatensis . The root base angle is more acute than that of C. callorhynchi .