Caudotestis ventichthysi, Bray, R. A., Waeschenbach, A., Dyal, P., Littlewood, D. T. J. & Morand, S., 2014

Bray, R. A., Waeschenbach, A., Dyal, P., Littlewood, D. T. J. & Morand, S., 2014, New digeneans (Opecoelidae) from hydrothermal vent fishes in the south eastern Pacific Ocean, including one new genus and five new species, Zootaxa 3768 (1), pp. 73-87 : 80-82

Caudotestis ventichthysi n. sp.

( Figs. 4–7 )

urn:lsid:zoobank.org:act:96F5B7AE-B2D0-4FBA-9A01-13465C5EF4D8 Type host. Ventichthys biospeedoi Neilsen, Møller & Segonzac, 2006 (Ophidioformes: Ophidiidae ), East-Pacific ventbrotula.

Site.? intestine (not given)

Type locality. South East Pacific Rise, hydrothermal vent site Oasis, 17°25.38’S, 113°12.29’W; Biospeedo cruise, submersible Nautile, R/V Atalante, dive PL 1582, baited trap B2, depth 2586 m, 22 April 2004. Biospeedo label: 1582–7.

Type specimens. MNHM holotype 1 slide MNHN HEL 402, paratype 1 wholemount slide MNHN HEL 403, 1 section slide MNHN HEL 404; BMNH paratype 2013.12.3.14.

Etymology. This species is named after the host-genus.

Description. Based on 4 specimens, one sectioned subsequent to study as wholemount. Measurements and ratios in Table 1. Body narrow fusiform, widest at level of ventral sucker ( Figs. 4 , 5 ). Tegument unarmed. Oral sucker cup-shaped, subterminal. Ventral sucker rounded, larger than oral sucker, equatorial. Prepharynx short. Pharynx oval, small. Oesophagus long, sinuous, thin-walled. Intestinal bifurcation distinctly anterior to ventral sucker. Caeca blind, divergent, narrow, reaching to posterior edge of ventral sucker.

Testes oval to rounded, oblique to symmetrical, adjacent or contiguous, in mid-hindbody. Cirrus sac overlaps to mid- to posterior part of ventral sucker, seen clearly only in sections ( Figure 6 ). Internal seminal vesicle saccular ( Fig. 7 ). Pars prostatica thick-walled, with scattered gland-cells. Ejaculatory duct not clearly delimited from pars prostatica, short. Genital atrium small. Genital pore dextrally submedian, close to anterior edge of ventral sucker.

Ovary oval to irregularly oval, anterior to dextral testis and separated by uterus. Seminal receptacle uterine. Laurer’s canal opens dorsally in anterior hindbody. Mehlis’ gland anterior to ovary. Uterus pre-testicular or overlaps to posterior margin of testes, runs dorsally along median line of ventral sucker. Eggs large, operculate, tanned, few. Distinct metraterm not detected. Vitellarium follicular, lateral fields reaching posterior pharynx or anterior oesophagus to anterior testis, interrupted at level of ventral sucker, approaching but not confluent in forebody.

Excretory pore terminal. Vesicle shape I-shaped, reaches to ovary.

Remarks. With its cirrus sac, uterine seminal receptacle, vitellarium not reaching posteriorly to the testes and non-lobate ovary, Caudotestis ventichthysi appears to be a fairly straightforward member of the genus Caudotestis and is distinguished as follows:

Caudotestis nicolli differs in its longer caeca reaching to the testes or nearly so, longer cirrus sac with more elongate internal seminal vesicle, more extensive vitellarium not interrupted at the level of the ventral sucker, shorter forebody, larger eggs (80–120 x 48 –60 µm) and many other features.

Caudotestis opisthorchis differs in its longer caeca overlapping the testes, longer cirrus sac with more elongate internal seminal vesicle, more extensive vitellarium not interrupted at the level of the ventral sucker, shorter forebody, larger eggs (74–108 x 37 –65 µm) and many other features.

Caudotestis kerguelensis differs in its longer caeca reaching almost to the testes or overlapping them, more extensive vitellarium not interrupted at the level of the ventral sucker, larger eggs (82–92 x 45 –50 µm) and many other features.

Caudotestis glacialis is similar to C. nicolli and differs from C. ventichthysi in its longer caeca reaching to the testes, longer cirrus sac, more extensive vitellarium not interrupted at the level of the ventral sucker, shorter forebody, larger eggs (93–115 x 51 –64 µm) and many other features.

Caudotestis patagonensis is much larger and more elongate than C. ventichthysi . The forebody is short (about 24–25% of body-length), the suckers are of similar size (width ratio 1:0.89–1.38), there are big gaps between the ventral sucker and the ovary and the ovary and the anterior testis and the testes are in an elongate tail-like extension.

Figures

FIGURES 1 – 4. 1. Biospeedotrema jolliveti n. sp. ventral view of holotype. 2. Biospeedotrema parajolliveti n. sp., ventral view of holotype. 3. Biospeedotrema biospeedoi n. sp. a. Ventral view of holotype. b, c. Illustration of variation in body-shape. 4. Caudotestis ventichthysi. n. sp. Ventral view of holotype, cirrus-sac obscured by eggs. Abbreviations: C, caecum; CS, cirrussac; E, egg; Ov, ovary; T, testis; V, vitelline follicle. Scale-bars: 1, 3 a, b, c, 4, 200 µm; 2, 100 µm.

FIGURES 5 – 7. Caudotestis ventichthysi n. sp. Horizontal sections. 5. Overall view. 6. Showing cirrus-sac (cs). 7. With internal seminal vesicle indicated (isv). Scale-bars: 5, 200 µm; 6, 7, 100 µm.