Flagellotrema reburrus, Hall, Kathryn A. & Cribb, Thomas H., 2008

Hall, Kathryn A. & Cribb, Thomas H., 2008, Revision of Flagellotrema Ozaki, 1936 (Digenea, Gyliauchenidae Fukui, 1929), including the description of two species from acanthuroid fishes from the Great Barrier Reef, Queensland, Australia, Zootaxa 1718, pp. 1-35 : 12-15

Flagellotrema reburrus n. sp.

( Figs 4–5 )

Type-host: Siganus punctatus (Schneider, 1801) , Siganidae ; goldspotted spinefoot.

Site: intestine.

Type-locality: Heron Island, Great Barrier Reef, Queensland, Australia (23°27'S 151°55'E).

Other hosts: Siganus corallinus (Valenciennes, 1835) , Siganidae , blue-spotted spinefoot; S. doliatus Cuvier, 1830 , barred spinefoot; and S. vulpinus (Schlegel & Mueller, 1845) , foxface.

Other locations: Wistari Reef, Great Barrier Reef, Queensland, Australia (23°28'S 151°52'E); Lizard Island, Great Barrier Reef, Queensland, Australia (14°40'S 145°27'E).

Prevalence: Local prevalence ( S. corallinus, Lizard Island): 1 of 5 (20.0%); local prevalence ( S. doliatus, Heron Island and Wistari Reef) 3 of 15 (20.0%); local prevalence ( S. punctatus, Heron Island and Wistari Reef) 2 of 24 (8.3%); local prevalence ( S. vulpinus, Heron Island): 2 of 13 (15.4%); local prevalence ( S. vulpinus, Lizard Island): 1 of 6 (16.7%); total prevalence (all known hosts, all known locations): 10 of 64 (15.6%); total prevalence (all known Siganus , all known locations): 9 of 63 (14.3%); total prevalence (all Siganus examined, all locations studied): 9 of 312 (2.9%).

Intensity: Data not recorded.

Deposition of specimens: Holotype QM G222223 (coll. T.H. Cribb, 8 Jan. 1993); 2 paratypes QM G222224–25 ex intestine S. vulpinus, Heron Island (coll. I. Ernst, 20 Jan. 1998).

Etymology: This species is named from the Latin reburrus , meaning “the one with bristling hair”, in reference to the brush-like lining of the genital atrium.

Description. Based on 12 (10 mature (8 lateral and 2 dorsoventral) and 1 immature) specimens. Measurements in Table 4. Body elongate, fusiform, distinctly curved dorsoventrally; pale orange in life. Tegument smooth. Ventral sucker round, posterior, not ventrosubterminal. Pharynx pyriform, ventrosubterminal, surrounds mouth, longer than ventral sucker; fleshy pre-oral lip, prominent, massive. Oesophagus long, with 2 loops in figure-8 formation ( Fig. 4 ); first loop anticlockwise, crosses midline; second loop clockwise, immediately anterior to first loop; posterior thick-walled chamber absent; invested with glands along entire length. Oesophageal bulb well-developed, spheroid, distinct, smaller than pharynx, approximately same size as ventral sucker. Intestinal bifurcation immediately posterior to oesophageal bulb; caeca 2, blind, occupy approximately 1/4 of body length; gastrodermis very thick.

Testes 2, entire, ovoid, diagonal, in posterior 1/3 of body, sometimes contiguous in mature specimens. Cirrus-sac encased in muscular capsule. Seminal vesicle partially external to cirrus-sac, bipartite; anterior portion globular, internal to cirrus-sac, connected to posterior portion via short, narrow duct, surrounded by muscular capsule contiguous with cirrus-sac; posterior portion elongate, external to cirrus-sac. Va s a e ff eren t ia arise ventromedially from testis, proceed anteriorly, unite to form vas deferens, which swells immediately into seminal vesicle. Pars prostatica large, cylindrical; prostate gland cells external to cirrus-sac, very dense. Cirrus-sac prominent, median, generally posterior to caeca, sometimes overlapping posterior margin, globular; ejaculatory duct long, convoluted within cirrus-sac, with distal expansion, eversible; everted cirrus thick, with cuticular ridge-like markings ( Fig. 5 A). Genital atrium large, regular, with cilia-like lining. Genital pore, round, at level of termination of caeca.

Lateral Dorsoventral All specimens Mature specimens All specimens Variable n α Mean Min Max n Mean Min Max n Mean Min Max body length 9 1481 768 2608 8 1570 912 2608 2 1576 1248 1904 Footnotes: α number of specimens measured, β all ratios are calculated to 2 decimal places.

Ovary entire, generally intertesticular, rarely post-testicular ( Fig. 5 A), dextral, not contiguous with testes; oviduct associated with swollen insemination chamber ( Fig. 5 B). Canalicular seminal receptacle prominent, saccular, posterodorsal to ovary. Mehlis’ gland anterodorsal to ovary, overlies ootype. Laurer’s canal proceeds anterodorsal from intersection of oviduct and seminal receptacle, exits immediately anterodorsal to ovary. Ootype anterior to ovary. Uterus entirely pre-ovarian, coiled in median field. Opening of uterus unspecialised, enters genital atrium sinistral to cirrus-sac. Vitellarium follicular; follicles restricted from level of oesophagus to immediately anterior to testes, form distinctive X-shaped distribution in ventral field, dorsal field resticted to intercaecal field; vitelline ducts proceed posterolateral from termination of fields, unite in midline to form subtriangular vitelline reservoir immediately sinistrodorsal to ovary. Eggs large, tanned, operculate, apparently unembryonated in utero.

Excretory vesicle elongate, saccular. Excretory pore subterminal, opens on prominent, large papilla. Primary collecting ducts arise anterolaterally. Lymph system not observed.

Molecular data. Sequence data was obtained from 4 specimens for 3 genes: Specimen 1 ( S. vulpinus, Heron Island): 28S rDNA (D1–D3); ND1 mtDNA; Specimen 2 ( S. vulpinus, Lizard Island): ITS2 rDNA; 28S rDNA (D1–D3); ND1 mtDNA; Specimen 3 ( S. corallinus, Lizard Island): ND1 mtDNA; Specimen 4 ( S. corallinus, Lizard Island): 28S rDNA (D1–D3). GenBank accession numbers are in Table 1 .

Comments. In common with the specimens of F. amphitrite , the specimens of F. reburrus can be readily distinguished from F. convolutum by the morphology of the oesophagus; the figure-8 pattern is seen in both F. amphitrite and F. re b u r r u s and contrasts with the single loop of the oesophagus of F. convolutum . A single specimen of F. re b u r r u s was examined in which the cirrus was everted ( Fig. 5 A); the cirrus of the specimen had unusual ridge-like markings, like stripes, which ran horizontally across the cirrus. Similar ridge-like markings have been observed in some species of Hadrobolbus , but have not been seen in F. convolutum or F. amphitrite . In 2 of the 11 specimens of F. reburrus examined, the ovary was post-testicular, however, these specimens were mounted dorsoventrally, and the post-testicular position may be an artefact of preparation. (The excretory papilla of F. amphitrite is very large, and pressure must be applied to the specimens to effect a dorsoventral wholemount.) Morphologically, F. reburrus is very similar to F. amphitrite , however the pair of species can be distinguished by the comparative proportions of the oesophageal bulb and ventral sucker, and the pharynx and cirrus-sac. In specimens of F. reburrus the oesophageal bulb is approximately the same size as the ventral sucker. Specimens of F. amphitrite can be distinguished by the distinctly smaller size of the oesophageal bulb, which is approximately half the size of the ventral sucker. Further supporting the separation of this pair of species is the size of the cirrus-sac. In specimens of F. reburrus , the cirrus-sac is very large, and is often as large as the pharynx, whereas in specimens of F. amphitrite the cirrus-sac in never as large as the pharynx. Distinction between these two species is subtle and relies on a combination of morphometric variation and DNA sequence divergence.

Figures

FIGURE 4. Flagellotrema reburrus n. sp. from Siganus punctatus, Heron Island, Great Barrier Reef, Australia. Holotype. Scale bar = 500 µm.

FIGURE 5. Flagellotrema reburrus n. sp. from Siganus corallinus, Lizard Island, Great Barrier Reef, Australia. A, paratype. B, paratype, detail of egg forming complex. Scale bars: A = 500 µm, B = 250 µm.