Enenterum petrae, Huston & Cutmore & Cribb, 2022

Huston, Daniel C., Cutmore, Scott C. & Cribb, Thomas H., 2022, Enenterum kyphosi Yamaguti, 1970 and Enenterum petrae n. sp. (Digenea Enenteridae) from kyphosid fishes (Centrarchiformes: Kyphosidae) collected in marine waters off eastern Australia, Zootaxa 5154 (3), pp. 271-288 : 281-282

Enenterum petrae n. sp.

( Figs. 4 , 5 )

ZooBank LSID: http://zoobank.org/ urn:lsid:zoobank.org:act:A3CA58E4-F473-4D39-B30A-1B74794FC0FE

Type host: Kyphosus vaigiensis (Quoy & Gaimard) , brassy chub (Centrarchiformes: Kyphosidae ).

Site in host: Intestine.

Type locality: Off Lizard Island , Great Barrier Reef, Queensland, Australia (14°41'10''S, 145°28'15''E) .

Type material: Holotype ( QM G240095 ) and 19 paratypes, including three hologenophores ( QM G240096 – G240114 ).

Representative DNA sequences: ITS2 rDNA, four identical replicates (two from type-series hologenophores, two from whole worms), one submitted to GenBank ( ON228453 ). 28S rDNA, two identical replicates (one from a type-series hologenophore, one from a whole worm), one submitted to GenBank ( ON228456 ). COI mtDNA, two replicates (one from type-series hologenophore, one from a whole worm) submitted to GenBank ( ON228463 – ON228464 ).

Etymology: This species name serves as an eternal record of a mother and father’s joy and celebrates the birth of the first author’s daughter. May she live always, for in the taxonomic record there is promise of immortality in that even names relegated to synonymy are never fully forgotten.

Description: [Measurements in Table 2 . Description based on type-series and SEM images of four adult specimens]. Body elongate, cylindrical, broadest immediately anterior to ventral sucker, attenuates slightly towards posterior end; bright yellow to orange in life with colour fading after preservation in ethanol. Tegument armed with concentric rows of minute, palmate spines. Oral sucker terminal, infundibuliform, retractable, elaborate, divided into two sections; ventral section a single, posteriorly concave, truncate lobe; dorsal section comprised of two lateral, reniform lobes separated by distinct, sagittal cleft; when retracted, sucker folds along lines at points of connection between ventral and dorsal lobes and midway along each reniform lobe. Oral sucker appears three-lobed when protracted and six-lobed when retracted. Single line of papillae apparent along anterior margin of oral sucker lobes. Ventral sucker robust, round, in anterior quarter of body, with aperture rhomboid. Pre-pharynx distinct, muscular. Pharynx minute, ellipsoidal, in mid-forebody, contiguous with caecal bifurcation. Oesophagus essentially absent, with intestine appearing to open directly from pharynx. Intestine robust, domed in region of bifurcation, with gastrodermis well-developed, bifurcates in mid-forebody anterior to cirrus-sac; caeca reunite in posterior half of posttesticular region to form distinct common stem, attenuates posteriorly to small duct and opens at slightly dorsally subterminal anus.

Testes two, tandem, ellipsoidal, separated, in mid-hindbody, approximately equal in size, medial, ventral to caeca. Post-testicular region long. Vasa deferentia separate, swollen, convoluted in anterior hindbody, enter posterior end of cirrus-sac. Cirrus-sac thick-walled, heavily invested with darkly stained gland-cells, intercaecal, ellipsoidal and reniform in dorsoventral and lateral view, respectively; posterior half dorsal to ventral sucker, anterior portion posterior to caecal bifurcation. Internal seminal vesicle tubular, convoluted. Pars prostatica elongate, vesicular, lined with clear, cell-like bodies. Ejaculatory duct long, canalicular, muscular. Genital atrium small, distinct. Genital pore closed via muscular ‘cap’ arising from tegument. Small, subglobular genital sucker situated just posterior to genital pore.

Ovary subglobular, pre-testicular, ventral to caeca. Seminal receptacle adjacent to ovary, subglobular to pyriform. Mehlis’ gland anterior-dorsal to ovary, profuse. Laurer’s canal not observed. Uterus highly convoluted, preovarian, ventral to and between caeca, broadens significantly in region just posterior to ventral sucker, passes along ventral margin of cirrus-sac to genital atrium. Eggs numerous, elongate, operculate. Vitellarium follicular, restricted to hindbody; follicles profuse, distributed in dorsal, lateral, and ventral regions of body, extend from just posterior to ventral sucker to near posterior extremity, wrap around body from dorsal midline to ventrosinistral and ventrodextral regions anterior to testes, wrap around entire body posterior to testes; ventral gap in testicular region common. Vitelline reservoir contiguous with anterior margin of ovary, subglobular; collecting ducts indistinct.

Excretory pore terminal; excretory vesicle originates as small duct, enlarging to form relatively straight tube, but path obscured by vitellarium; collecting ducts extend as far as oral sucker.

Remarks: The structure of the oral sucker of E. petrae is unique among the known species of Enenterum , as is the relatively minute pharynx and the combination of a genital cap and accessory sucker. Together these unique features readily distinguish E. petrae from all congeners. Based on individual specimen and interpretation, the oral sucker of E. petrae might be considered to have three, five, or six lobes, highlighting potential issues of using lobe count as a means of species delineation in Enenterum . Regardless, counts of three and five lobes are not yet reported for any member of the genus and only E. mannarense possesses six lobes. The oral sucker lobes of E. mannarense are pointed, however, quite unlike the rounded lobes present in the oral sucker of E. petrae , and the orientation is different. Enenterum petrae has some superficial similarities to E. elongatum , which has been reported from Heron Island, on the Great Barrier Reef ( Bray & Cribb 2002). However, while E. elongatum has a genital sucker, it has never been described with a genital cap and has always been reported as having ten distinct oral sucker lobes and a robust pharynx.

Figures

FIGURE 4. Enenterum petrae n. sp. a. holotype, ventral view. b. cirrus-sac of paratype, lateral view. c. paratype, lateral view. Scale bars: a, c. 1,000 µm; b. 500 µm.Abbreviations:An, anus; As, accessory sucker; Cs, cirrus sac; E, egg; Ep, excretory pore; Ev, excretory vesicle; Ga, genital atrium; Gc, genital cap; Gp, genital pore; Int, intestine; Mg, Mehlis’ gland; O, ovary; Oes, oesophagus; Os, oral sucker; Ph, pharynx; PPh, prepharynx; Pp, pars prostatica; Sr, seminal receptacle; T, testis; U, uterus; Vd, vasa deferentia; Vf, vitelline follicle; Vs, ventral sucker.

FIGURE 5. Enenterum petrae n. sp., scanning electron micrographs of adult whole specimens ex Kyphosus vaigiensis from Lizard Island, Great Barrier Reef, Queensland, Australia. a, b, c. oral suckers. d. tegument of additional whole worm, showing spines. Scale bars: a, c. 200 µm; b. 100 µm; d. 20 µm. Abbreviations: Ds, dorsal section; Sc, sagittal cleft; Vs, ventral section.