Stillabothrium amuletum ( Butler, 1987 ) Healy et Reyda, 2016

Reyda, Florian B., Healy, Claire J., Haslach, Andrew R., Ruhnke, Timothy R., Aprill, Tara L., Bergman, Michael P., Daigler, Andrew L., Dedrick, Elsie A., Delgado, Illari, Forti, Kathryn S., Herzog, Kaylee S., Russell, Rebecca S. & Willsey, Danielle D., 2016, A new genus of rhinebothriidean cestodes from batoid elasmobranchs, with the description of five new species and two new combinations, Folia Parasitologica (038) 63 (38), pp. 1-28 : 22-23

Stillabothrium amuletum ( Butler, 1987) Healy et Reyda comb. n.

Figs. 1 , 15

ZooBank number for species:

urn:lsid:zoobank.org:act:DFCD1070-9190-4890-ADEE-5474390DB2BF

S y n o n y m: Anthobothrium amuletum Butler, 1987 .

I n f o r m a l s y n o n y m s: Rhinebothriinae New genus 3 sp. n. 7 of Healy et al. (2009), Caira et al. (2014), Ruhnke et al. (2015), Marques and Caira (2016).

T y p e a n d o n l y k n o w n h o s t: Glaucostegus typus [Anonymous (Bennett)], Giant shovelnose ray (Rhinopristiformes: Rhinobatidae ) (= Rhinobatos armatus ).

Ty p e l o c a l i t y: Moreton Bay, Northern Territory, Australia.

A d d i t i o n a l l o c a l i t y: Fog Bay , Timor Sea (Indian Ocean) off Dundee Beach (12°45'33''S; 130°21'7''E), Queensland, Australia (AU-56) .

S i t e o f I n f e c t i o n: Spiral intestine.

S p e c i m e n s e x a m i n e d: AU-56, QM GL4621 (holotype), GL4622 (paratype).

Remarks. Butler (1987) provided a comprehensive description of this species, which included scanning electron micrographs and drawings, and represents the only treatment of this species, to date. Although examination of the holotype for the present study confirmed many of Butler’s (1987) observations, it refuted some of her observations, and revealed additional details missing from the original description. According to Butler (1987), the anterior region of the bothridia lack transverse septa. However, at least 4 transverse septa are visible in the anterior region of the scolex of this holotype ( Fig. 15 ). These septa, and other septa not described by Butler (1987), are best visible using differential interference contrast microscopy (DIC). Examination of additional material of this species and, ideally, histological sections of the scolex, would be very useful in determining the exact number and extent of the septa (and the loculi) in this species. Not stated in the description, but visible in the holotype, are the following features: the vas deferens joins the cirrus sac at the middle of its anterior margin; the genital atrium has internally convoluted margins; when at least partially expanded with spermatozoa, the vas deferens extends from between the anterior lobes of the ovary to the level of the recurvature of the vagina.

The morphology of the ovary, posterior vitelline follicles and posterior part of the uterus as drawn by Butler (1987) differ from that observed in the terminal proglottid of the holotype: the ovary is tetralobed and H-shaped; vitellarium is interrupted at the level of the ovary and some vitelline follicles are present in the lateral margins of the proglottid, posterior to the ovary; uterus extends posterior to the ovary.

This species possesses transverse septa and non-medial longitudinal septa, as well as other characteristics consistent with its placement in Stillabothrium , such as a posterior row of loculi that are longer than wide ( Fig. 15 ). Thus, this species is herein transferred into this genus as Stillabothrium amuletum comb. n.

Stillabothrium amuletum possesses diagonal septa on the sides of the posterior bothridia, which overlap several longitudinal septa ( Fig. 15 ). This feature distinguishes it from S. ashleyae ( Fig. 2B ) and S. davidcynthiaorum ( Fig. 4B ), and from S. campbelli ( Fig. 6B ), which possess marginal ( S. ashleyae and S. davidcynthiaorum ) or diagonal ( S. campbelli ) septa that abut but do not overlap longitudinal septa, and from S. hyphantoseptum ( Fig. 8B ), S. jeanfortiae ( Fig. 10B ) and S. cadenati ( Fig. 12B ) which each lack marginal or diagonal septa.

One sequence of Stillabothrium from G. typus , the type host of S. amuletum , was included in the phylogenetic analysis in this study ( Table 1 , Fig. 1 ). It was from Healy et al. (2009), who referred to it as ‘Rhinebothriinae New genus 3 sp. n. 7’.

Figures

Fig. 1. Phylogram based on Bayesian analysis of 1084 bp region of D1–D3 28S rDNA. Numbers above branches indicate Bayesian posterior probabilities, numbers below indicate Bootstrap percentage values, based on 1000 replicates. Scale indicates expected num- ber of substitutions per site. Diagrammatic line drawings of fully opened bothridia of the seven described species mapped onto the clades representing those respective species. Host species information in Table 1.

Fig. 15. Line drawing of bothridium of the holotype (QM GL4621) of Stillabothrium amuletum (Butler, 1987) comb. n. from Glaucostegus typus [Anonymous (Bennett)].

Fig. 2. Line drawings of Stillabothrium ashleyae sp. n. from Dasyatis biasa (Last, White et Naylor). A – whole worm (holotype; MZUM [P] 2016.6 [H]); B – scolex (LRP 9011); C – terminal proglottid (LRP 9010) with position of sections labeled (uterus not shown); D – section of mature proglottid at level of testes (LRP 9037); E – section of mature proglottid posterior to ovarian bridge (LRP 9030).

Fig. 4. Line drawings of Stillabothrium davidcynthiaorum sp. n. from Himantura heterura (Bleeker). A – whole worm (LRP 9046); B – scolex (holotype, MZUM [P] 2016.9 [H]); C – terminal proglottid (LRP 9046).

Fig. 6. Line drawings of Stillabothrium campbelli sp. n. from Himantura cf. pastinacoides. A – whole worm (holotype; MZUM [P] 2016.11 [H]); B – scolex (LRP 9066); C – terminal proglottid (LRP 9067).

Fig. 8. Line drawings of Stillabothrium hyphantoseptum sp. n. from Pastinachus solocirostris Last, Manjaji et Yearsley. A – whole worm (holotype; MZUM [P] 2016.13 [H]); B – scolex (LRP 9092); C – terminal proglottid (LRP 9088).

Fig. 10. Line drawings of Stillabothrium jeanfortiae sp. n. from Himantura australis Last, White et Naylor. A – whole worm (holotype; QM G235198); B – scolex (LRP 9123); C – terminal proglottid (holotype; QM 235198).

Fig. 12. Line drawings of Stillabothrium cadenati comb. n. from Zanobatus schoenleinii (Müller et Henle). A – whole worm (LRP 9135); B – bothridium (LRP 9134); C – terminal proglottid (LRP 9136).