Rhipidocotyle jayai, Bray, Rodney A & Palm, Harry W, 2009

Bray, Rodney A & Palm, Harry W, 2009, Bucephalids (Digenea: Bucephalidae) from marine fishes off the south-western coast of Java, Indonesia, including the description of two new species of Rhipidocotyle and comments on the marine fish digenean fauna of Indonesia, Zootaxa 2223, pp. 1-24 : 9-15

Rhipidocotyle jayai n. sp.

( Figures 3–4 )

Type-host: Johnius macropterus (Bleeker) (Sciaenidae) largefin croaker.

Site: Intestine.

Type-locality: Pelabuhan Ratu, Java, Indonesia (06°59S, 106°32’E, (March 2008).

Deposition of specimens: Holotype ZMB Generalkatalog Entozoa, E.7455, paratypes ZMB Generalkatalog Entozoa, E.7456, BMNH 2009.5.22.1–2, NBC MZBTr 205.

Etymology: The species is named after Prof. Dr. Indra Jaya, Dean of the Faculty of Fisheries and Marine Sciences (2007–2011), Bogor Agricultural University, Indonesia, who supported the second author during his guest lectureship at IPB.

Description: Based on 20 whole-mount preparations. Measurements and ratios in Table 1. Body elongate, widest in mid-body, tapering anteriorly and posteriorly ( Figure 3 ); 7 specimens found with anterior extremity withdrawn ( Figure 4 ). Tegument spinous; spines squamous, tiny, reach to posterior extremity. Rhynchus broader anteriorly, aperture ventral; hood smooth. Mouth just anterior to ovary, at about mid-body. Pharynx globular. Caecum oval, mostly posteriorly to pharynx.

Testes 2, oval, tandem, in middle of posterior half of body, contiguous. Cirrus-sac elongate, more-or-less parallel sided, reaching anterior testis. Seminal vesicle subglobular, in proximal cirrus-sac. Pars prostatica long, lining of filaments in chevron arrangement pointing distally. Ejaculatory duct narrow, opening on large, curved genital lobe, inside genital atrium. Genital atrium large. Genital pore distinctly separated from posterior extremity.

Ovary oval, pretesticular, slightly separated from or contiguous with anterior testis. Mehlis’ gland subtriangular, nestled between ovary and anterior testis. Uterine seminal vesicle not seen in proximal uterus. Laurer’s canal opens dorsally at level of Mehlis’s glands, often not detectable. Uterus not anterior to vitelline fields, fills most of median region to level of genital pore. Eggs numerous, tanned, operculate; fully formed only in holotype. Metraterm rectilinear, not clearly delimited from uterus, about fifth of cirrus-sac length, only seen in non-ovigerous specimens. Vitellarium consists of 2 lateral fields of follicles, more or less symmetrical, but with one longer (16–20 follicles) than other (12–14 follicles), anterior extremity distinctly posterior to rhynchus and anterior to uterus, and always anterior to caecum and gonads; posterior extremity of long field at level of anterior testis or just anterior.

Excretory pore terminal; vesicle reaches about halfway between vitelline fields and rhynchus, seen only in some non-ovigerous specimens.

Taxonomic comparison: Using the visual keys discussed above to distinguish Rhipidocotyle jayai n. sp., it can be seen that in the comparison diagram ( Figure 5 ) only 5 species have no black squares against their names, R. danai n. sp., R. eggletoni Velasquez, 1959 , R. fluminensis , R. ghanensis and R. longleyi . Fourteen have one black square against their name, R. anguillae , R. coiliae , R. carangi Shen, 1960 , R. elongatum McFarlane, 1936 , R. indicus Gupta & Ahmad, 1976 , R. karthai , R. khalili , R. microovatum , R. minima ( Wagener, 1852) , R. nicolli Bartoli, Bray & Gibson, 2006 , R. pentagonum ( Ozaki, 1924) , R. scombropsis , R. tonimahnkei Reimer, 1985 and R. triglae (van Beneden, 1870).

Rhipidocotyle danai n. sp. differs from R. jayai n. sp. in its elongate seminal vesicle (22% of cirrus-sac length vs 11–15 (13) %), shorter vitelline fields (16–24 (20)% of body length vs 29–43 (36)%), and the uterus reaching anteriorly to the anterior vitelline extent (see pre-uterine distance, 16–20 (19)% of body-length vs 26–35 (29)%). It probably also differs in pre-mouth distance (41–43 (42) of body-length vs 46–51 (49)%), post-testicular distance (26–35 (30)% of body-length vs 17–23 (20)) and cirrus-sac reach (34–42 (39)% of body-length vs 29–32 (31)%).

Rhipidocotyle eggletoni was described from immature specimens from the silver sillago Sillago sihama (Forsskål) (Sillaginidae) and the toothpony Gazza minuta (Bloch) (Leiognathidae) from Manila Bay, Luzon island, Philippines ( Velasquez 1959) and differs from R. jayai n. sp. in its slightly lobate rhyncheal hood. The cirrus-sac reach (about 23% of body-length vs 29–32 (31)%) may be another differentiating feature. A full comparison is not possible as ovigerous specimens of R. eggletoni are not known.

Rhipidocotyle fluminensis can be distinguished from R. jayai n. sp. by its distinctly lobate rhyncheal hood, its shorter vitelline fields, its oval seminal vesicle and the ovary overlapping the anterior testis and probably by its more squat appearance (width 23% of body-length vs 17–18 (17.5)%), its pre-vitelline distance (28% of body-length vs 17–24 (22)%) (Vicente & dos Santos 1973).

Rhipidocotyle ghanensis can be distinguished from R. jayai n. sp. by its 7-lobed rhyncheal hood and the inflated excretory vesicle in the anterior part of the body ( Fischthal & Thomas 1968). It may also differ in its pre-mouth distance (60–67% of body-length vs 46–51 (49)%) and in relative rhynchus length (about 13% of body-length vs 17–24 (22)%).

Rhipidocotyle longleyi and can be distinguished from R. jayai n. sp. by its rhynchus which has a distinctly seven-lobed hood and shorter vitelline fields ( Manter 1934). R. longleyi may possibly be slightly broader generally (width about 15–25% of body length vs 17–18 (17.5)%), and differ in its pre-uterine distance (about 22% of body-length vs 25–35 (29)%) and cirrus-sac reach (about 36% of body length vs 29–32 (31)%).

Rhipidocotyle anguillae was distinguished from R. jayai n. sp. in the visual key by its length range (1,520–1,600 vs 2,340–3,257 (2,740)). It also differs in the distinct five-lobed rhyncheal hood, and probably the width ratio (about 23–27% of body-length vs 17–18 (17.5)%) (Wang 1985).

Rhipidocotyle coiliae was distinguished from R. jayai n. sp. in the visual key by its post-testicular distance (about 34% vs 16–23 (20)%) and can also be distinguished by the lobed rhyncheal hood and the cirrus-sac restricted to the post-testicular region (Wang 1980). It also probably differs in width ratio (about 22–31% vs 17–18 (17.5)%) and shorter vitelline fields.

Rhipidocotyle carangi from the bigeye trevally Caranx sexfasciatus Quoy & Gaimard (Carangidae) off Hainan Island, China (Shen 1990) was distinguished from R. jayai n. sp. in the visual key by body-length (1,020–1,479 vs 2,340–3,297 (2,740)). It is also distinguished by its lobed rhyncheal hood. It also probably differs in pre-vitelline distance (about 30% of body-length vs 17–24 (22)%) and post-testicular region (about 30% vs 17–23 (20)%).

Rhipidocotyle elongatum from the lingcod, Ophiodon elongatus Girard (Hexagrammidae) from off British Columbia, Canada ( McFarlane 1936) was distinguished from R. jayai n. sp. in the visual key by body-length (860–1,500 vs 2,340–3,297 (2,740)). It also appears to differ in the testes being separated and the vitellarium being relatively short (about 27% of body-length vs. 29–43 (36)%).

Rhipidocotyle indicus from the roughscale tonguesole Cynoglossus lida (Bleeker) (Cynoglossidae) off Orissa, India ( Gupta & Ahmad 1976) was distinguished from R. jayai n. sp. in the visual key by its width (about 27–28% of body-length vs 17–18 (18)%). It has a seven-lobed rhyncheal hood. It may also differ in post-testicular region (about 31% of body-length vs 17–23 (20)%) and cirrus-sac reach (about 42% of bodylength vs 29–32 (31)%).

Rhipidocotyle karthai was distinguished from R. jayai n. sp. in the visual key by the pre-uterine distance (about 15% of the body-length vs 26–35 (29)%) and can also be distinguished by its 7-lobed rhyncheal hood. R. karthai probably has a relatively more posterior mouth (about 57% of body-length from anterior extremity vs 46–51 (49)%) ( Hafeezullah & Siddiqi 1970).

Rhipidocotyle khalili was distinguished from R. jayai n. sp. in the visual key by its pre-vitelline region (about 54% vs 17–24 (22)%), and also differs in the five-lobed rhyncheal hood. R. khalili is probably narrower than R. jayai n. sp. (width about 11–12% of body-length vs 17–18 (17.5)%) ( Nagaty 1937).

Rhipidocotyle microovatum was distinguished from R. jayai n. sp. in the visual key by its egg-length (16– 19 vs 25–30 (27)). It can also be distinguished by its 7-lobed rhyncheal hood ( Zhukov 1977), and probably by pre-vitelline distance (about 32% of body-length vs 17–24(22)%) and pre-mouth distance (about 40% of body-length vs 46–51 (49)%).

Rhipidocotyle minima from triglids in the Mediterranean Sea and northeastern Atlantic was redescribed and reviewed by Bartoli et al. (2006). It was distinguished from R. jayai n. sp. in the visual key by its egglength (38–46 (42) vs 25–30 (27)). It can also be distinguished by its 7-lobed rhyncheal hood, and probably by pre-uterine distance (about 18–19% of body-length vs 26–35 (29)%).

Rhipidocotyle nicolli from the East Atlantic red gurnard Aspitrigla cuculus (Linnaeus) and the grey gurnard Eutrigla gurnardus (Linnaeus) (both Triglidae ), from off Great Britain (Bartoli el al. 2006) was distinguished from R. jayai n. sp. in the visual key by its pre-uterine distance (11–12% of body-length vs 26– 35 (29)%). It can also be distinguished by its fan-shaped, lobed rhyncheal hood, and probably by posttesticular distance (29–34% of body-length vs 17–23 (2)%) and egg-length (35–38 (36) vs 25–30 (27)).

Rhipidocotyle pentagonum differs from R. jayai n. sp. in the visual key by pre-uterine distance (about 49% of body-length vs 26–35 (24)%). It also species differs from R. jayai by its seven-lobed rhyncheal hood and possibly in post-testicular region (about 27% of body-length vs 16.5–23 (20)%) and cirrus-sac reach (about 24% of body-length vs 29–32 (31)%).

Rhipidocotyle scombropsis differs from R. jayai n. sp. in the visual key by pre-uterine distance (about 14% of body-length vs 26–35 (24)%) ( Yamaguti 1938). It can also be distinguished from R. jayai n. sp. by its gonads always being distinctly separated by uterine slings and, apparently, by a weakly incised rhyncheal hood. The post-testicular distance (about 30% of body-length vs 17–23 (20)%) may also be a distinguishing feature.

Rhipidocotyle tonimahnkei from the blackbanded trevally Seriolina nigrofasciata (Rüppell) (Carangidae) off Mozambique ( Reimer 1985) differs from R. jayai n. sp. in the visual key by pre-uterine distance (about 15% of body-length vs 26–35 (24)%). The rhynchus appears to bear papillae, the caecum lies anteriorly to the pharynx and the vitellarium is short (about 15% of body-length vs 29–43 (36)%). It also may differ from R. jayai n. sp. in pre-vitelline distance (about 34% of body-length vs 17–24 (22)%), pre-mouth distance (about 58% of body-length vs 46–51 (49)%) and egg-length (31–38 vs 25–30 (27)).

Rhipidocotyle triglae from the tub gurnard Chelidonichthys lucerna (Linnaeus) and the grey gurnard Eutrigla gurnardus (both Triglidae ) in the English Channel and the western Mediterranean Sea (van Beneden, 1870; Bartoli et al. 2006) was distinguished from R. jayai n. sp. in the visual key by the body-width (26–55 (37)% of body-length vs 17–18 (18)%). The rhyncheal hood is slightly lobed and the eggs are longer (33–44 (38) vs 25–30 (27)).

Other species of Rhipidocotyle reported in Sciaenidae are R. paruchini Gavrilyuk-Tkachuk, 1979 , R. croceae Ku & Shen, 1975 and R. transversale Chandler, 1935 . They can be distinguished from R. jayai n. sp. in the characters illustrated in the comparison diagram ( Figure 5 ).

Figures

FIGURE 3. Rhipidocotyle jayai n. sp. Ventral view of holotype, uterus in outline. Scale-bar = 500 μm.

FIGURE 4. Rhipidocotyle jayai n. sp. Ventral view of specimen with withdrawn anterior portion. Scale-bar = 500 μm.

FIGURE 5. Comparison diagram for Rhipidocotyle jayai n. sp. (see text)