Pseudorhabdosynochus manipulus, Justine, Jean-Lou & Sigura, Aude, 2007

Justine, Jean-Lou & Sigura, Aude, 2007, Monogeneans of the malabar grouper Epinephelus malabaricus (Perciformes, Serranidae) off New Caledonia, with a description of six new species of Pseudorhabdosynochus (Monogenea: Diplectanidae), Zootaxa 1543, pp. 1-44 : 20-25

Pseudorhabdosynochus manipulus n. sp.

( Figs 12–14 )

Type host: Epinephelus malabaricus Bloch & Schneider (Serranidae) .

Type locality: Lagoon off Nouméa, New Caledonia. Site: Between secondary gill lamellae.

Type specimens: Holotype, JNC 1536A101, off Ouen Toro, Nouméa, New Caledonia (22°19'S, 166°27'E, 18.v.2005).

Material examined: 9 specimens: 2 ‘carmine’ (c), 7 ‘picrate’ (p).

Material deposited: Holotype (c) and 8 paratypes (1 c, 7 p), MNHN.

Prevalence: 50% (1/2).

Intensity: See Table 1. A rare species (5% of the diplectanids).

Etymology: From ‘ manipulus ’ (Latin), handful, refers to the small number of specimens found.

Description. [Given as holotype, other carmine specimen, picrate specimens]. Body wide; length h 600, c 610, width h 400, c 400. Tegument scaly; posterior region with scales on ventral and dorsal faces from squamodiscs to level of ovary and testis; scales relatively large. Anterior region with 3 pairs of head organs and 2 pairs of eye-spots; distance between outer margins of anterior eye-spot pair h 40, c 39, of posterior eye-spot pair h 41, c 39.

Haptor differentiated from rest of body, less wide than body, width h 290, c 270, provided with 2 similar squamodiscs, 2 pairs of lateral hamuli, 3 bars and 14 marginal hooklets. Squamodiscs round in shape, made up of rows of rodlets; central rows forming almost closed ovals; rodlets of central rows with external face crenate; rodlets progressively thinner from centre to periphery; rodlets adjacent in all rows except last; last row with very thin, separated rodlets; ventral and dorsal squamodiscs similar, but ventral slightly larger; ventral squamodisc length h 69, c 61, width h 68, c 70, with 10–11 (n = 2) rows of rodlets and 0–1 closed oval, total number of rodlets h 105; dorsal squamodisc, length h 67, c 62, width h 64, c 63, with 12 (n = 2) rows of rodlets and 0 closed oval, total number of rodlets h 109. Ventral hamulus with thick handle and distinct guard, outer length h 59, c 62, p 63 (60–66, n = 14), inner length h 49, c 51, p 50 (48–54, n = 14). Dorsal hamulus with indistinct guard, outer length h 50, c 51, p 50 (48–52, n = 14), inner length h 29, c 30, p 32 (30–33, n = 14). Dorsal (lateral) bars straight, with flattened medial extremity and thick cylindrical lateral extremity, length h 93, c 94, p 99 (93–108, n = 14), maximum width h 25, c 26, p 26 (24–30, n = 12). Ventral bar flat, with slightly constricted median portion and pointed extremities, length h 132, c 131, p 133 (124–138, n = 7), maximum width h 21, c 25, p 24 (23–26, n = 7); groove visible on its ventral side.

Pharynx subspherical, length h 63, c 62, width h 47, c 46. Oesophagus apparently absent, such that intestinal bifurcation immediately follows pharynx. Caeca simple, terminate blindly at level of posterior margin of vitelline field.

Testis subspherical, intercaecal, length c 53, width c 75. Vas deferens emerges from antero-sinistral part of testis, enlarges into seminal vesicle; seminal vesicle in middle dextral region of body, transforms into duct; duct forms bends then connects with quadriloculate organ. Prostatic reservoir small, connects with quadriloculate organ. Quadriloculate organ with fourth (posterior) chamber slightly more sclerotised than 3 anterior chambers; fourth chamber ends in short sclerotised cone, prolonged by sclerotised tube; end of tube prolonged by thin unsclerotised filament of variable length. Inner length of quadriloculate organ h 60, c 60, p 70 (64–77, n = 6); cone length h 17, c 17, p 20 (18–21, n = 7); tube length h 18, c 19, p 18 (15–19, n = 6); tube diameter h 4, c 4, p 4 (3–4, n = 6); filament length h 0, c 30, p 3–38 (n = 6).

Ovary subequatorial, intercaecal, pre-testicular, encircles right caecum. Ovary width c 122. Oviduct passes medially to form oötype, surrounded by Mehlis’ gland; oötype short, opens into uterus. Uterus dextral. Unsclerotised vagina often inconspicuous, elongate ( Figure 13 F). Duct from sclerotised vagina to oötype inconspicuous. Vitelline fields extend posteriorly from posterior to pharyngeal level in 2 lateral bands, confluent in post-testicular region and terminate anterior to peduncle. Bilateral connections from vitelline fields to oötype inconspicuous. Egg in utero oval, 127 × 53 (n = 1), with wall thicker at one extremity suggesting presence of filament in mature egg.

Sclerotised vagina (nomenclature of parts according to Justine 2007a; see Figure 20 ). Sinistral, a complex sclerotised structure; aspect changes according to specimen and orientation ( Figure 13 ). Sclerotised vagina comprises anterior trumpet, followed by primary canal, primary chamber and secondary chamber; trumpet in continuity with unsclerotised vagina; primary canal cylindrical, coiled or bent once in its anterior part and straight in its posterior part; wall of anterior part thin, wall of posterior part slightly thicker; canal in continuity and aligned with primary chamber; primary chamber elongate, with wall no more sclerotised than primary canal; thin longitudinal median wall in primary chamber, inserted at mid-length, visible in certain specimens ( Figure 13 B,G); secondary canal curved, inserted laterally on anterior extremity of primary chamber; secondary chamber elongate, S-shaped, more sclerotised than primary chamber and primary canal, inserted grossly perpendicularly to axis of primary canal and primary chamber; accessory structure inserted on extremity of secondary chamber. Duct from sclerotised vagina to oötype connects to secondary chamber ( Figure 13 D,E). Total length of sclerotised vagina (measured from extremity of trumpet to extremity of primary chamber, i.e. not taking in account curved length along bend and coil of canal) h 39, c 35, p 38 (33–43, n = 7). Orientation of sclerotised vagina: trumpet always anterior.

Differential diagnosis. Several species of Pseudorhabdosynochus have a sclerotised vagina similar to that of P. manipulus n. sp. in general structure, with an anterior trumpet, a primary canal with a bend in its anterior part, a primary chamber aligned and in continuity with the primary canal, and a secondary chamber inserted laterally.

P. melanesiensis (Laird, 1958) from E. merra Bloch , P. cupatus ( Young, 1969) from Epinephelus fasciatus (Forsskål) , P. calathus Hinsinger & Justine 2006 from E. rivulatus (Valenciennes) and P. c y a t h u s Hinsinger & Justine, 2006 from E. howlandi (Valenciennes) , all from off New Caledonia and other localities, have a grossly similar vagina but their secondary chamber is more complex than P. m a n i p u l u s; in addition, these species have a special ‘telescopic” arrangement of their squamodisc (‘lamellosquamodisc’) in the three later species, and their haptoral parts are smaller ( Justine 2005a; Hinsinger & Justine 2006b).

P. hirundineus Justine, 2005 from Variola louti (Forsskål) off New Caledonia ( Justine, 2005b) and P. e p i - nepheli ( Yamaguti, 1938) from E. akaara (Temminck & Schlegel) off Japan and in South China Sea have a vagina similar to P. manipulus , with a lateral insertion of the secondary chamber, but the primary chamber is oriented anteriorly by a second bend of the primary canal ( Kritsky & Beverley-Burton 1986).

P. e u i t o e Justine, 2007 from E. maculatus has a vagina similar to P. m a n i p u l u s by the general arrangement of primary canal, distal primary chamber and laterally inserted secondary chamber; however, the primary chamber is more sclerotised, the secondary chamber is round vs elongate, and there is a heavy sclerotised ring on the trumpet.

P. manifestus , P. h u i t o e, P. serrani and P. shenzhenensis have a general structure of the vagina similar to that of P. manipulus . However, the shape of the primary chamber is round vs elongate, and the insertion of the secondary chamber is more distal.

P. manipulus can be differentiated from all these species by the structure of its sclerotised vagina.

Figures

FIGURE 12. Pseudorhabdosynochus manipulus n. sp. A. Composite drawing; tegumental scales drawn only on edges. B. Sclerotised vagina, holotype, carmine. A, B, ventral view.

FIGURE 13. Pseudorhabdosynochus manipulus n. sp. A. Quadriloculate organ. C – H. Sclerotised vagina, variation according to specimen, orientation and fixation method. B, ventral view, carmine; C – F, ventral view, picrate; G – H, dorsal view, picrate; all paratypes.

FIGURE 14. Pseudorhabdosynochus manipulus n. sp. A. Ventral bar. B. Dorsal bar. C. Dorsal hamulus. D. Ventral hamulus. E. Ventral squamodisc. F. Dorsal squamodisc, same individual. G. Ventral tegumental scales. H. Dorsal tegumental scales. A – D, picrate, paratype; E – H, ventral view, holotype.

FIGURE 20. Pseudorhabdosynochus spp: nomenclature and measurements (italics) of sclerotised vaginae. Abbreviations as in general diagram. P. s e r r a n i (voucher from E. coioides, MNHN JNA 6 A 1) drawn for comparison with P. m a n i - festus; P. shenzhenensis (voucher from E. coioides, MNHN JNA 5 A 1) drawn for comparison with specimens from E. malabaricus. pcid, primary chamber internal diameter; pced, primary chamber external diameter; scid, secondary chamber internal diameter; sced, secondary chamber external diameter.