Pseudorhabdosynochus malabaricus, 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 : 11-14

Pseudorhabdosynochus malabaricus n. sp.

( Figs 6–8 )

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

Type locality: Lagoon off Nouméa, New Caledonia.

Site: Between secondary gill lamellae.

Type specimens: Holotype, JNC 1536A107, off Ouen Toro, Nouméa, New Caledonia (22°19'S, 166°27'E, 18.v.2005).

Material examined: 9 specimens: 8 ‘carmine’ (c), 1 ‘picrate’ (p), all from JNC 1536.

Material deposited: Holotype (c) and 6 paratypes (5 c, 1 p), MNHN; 1 paratype (c), BMNH 2007.6.1.4; 1 paratype (c), USNPC 99869.

Prevalence: 50% (1/2).

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

Etymology: From the host name.

Description: Body very wide; length h 630, c 543 (450–650, n = 7), width h 390, c 317 (240–410, n = 7). Tegument scaly; posterior region with scales on ventral and dorsal faces from squamodiscs to level of ovary and testis. Anterior region with 3 pairs of head organs and 2 pairs of eye-spots; distance between outer margins of anterior eye-spot pair h 51, c 43 (37–51, n = 8), of posterior eye-spot pair h 44, c 40 (29–50, n = 8).

Haptor differentiated from rest of body, wider than body, width h 390, c 331 (270–420, n = 7), 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 row often dislocated; central rows forming almost closed ovals; rodlets adjacent and of similar width in all rows except last row with very thin, separated rodlets; ventral and dorsal squamodiscs similar, but ventral slightly larger; ventral squamodisc length c 63 (54–69, n = 6), width c 77 (74–79, n = 6), with 11–12 (n = 6) rows of rodlets and 1–2 closed ovals, total number of rodlets h 147; dorsal squamodisc, length h 65, c 64 (59–68, n = 6), width 79, c 71 (68–79, n = 6), with 10–12 (n = 6) rows of rodlets and 0–1 closed oval, total number of rodlets h 133. Ventral hamulus with thick handle and distinct guard, outer length h 62, c 58 (53–63, n = 13), p 61 (n = 2), inner length h 42, c 42 (39–45, n = 14), p 42 (n = 2). Dorsal hamulus with indistinct guard, outer length h 48, c 48 (45–50, n = 16), p 49 (n = 2), inner length h 31, c 30 (27–32, n = 16), p 29 (n = 2). Dorsal (lateral) bars straight, with flattened medial extremity and thick cylindrical lateral extremity, length h 118, c 113 (103–124, n = 15), p 128 (n = 2), maximum width h 23, c 24 (19–31, n = 15), p 26 (n = 2). Ventral bar flat, with slightly constricted median portion and pointed extremities, length h 140, c 132 (92–156, n = 7), p 150, maximum width h 17, c 17 (14–19, n = 7), p 20; groove visible on its ventral side.

Pharynx subspherical, length h 53, c 52 (43–75, n = 8), width h 54, c 49 (42–60, n = 8). 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 h 110, c 101 (83–110, n = 3), width h 110, c 90 (80–110, n = 3). Vas deferens emerges from antero-sinistral part of testis, enlarges into seminal vesicle; seminal vesicle in middle region of body, coiled, transforms into duct; duct forms bends then connects with quadriloculate organ; terminal portion of duct enlarged. Prostatic reservoir connects with quadriloculate organ. Quadriloculate organ with fourth (posterior) chamber slightly more sclerotised than 3 anterior chambers; first chamber with very thin anterior wall; 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 57, c 52 (45–57, n = 7), p 75; cone length h 11, c 11 (10–11, n = 8), p 11; tube length h 15, c 16 (15–18, n = 8), p 16; tube diameter h 3, c 3 (n = 8), p 3; filament length h 4, c 0–19 (n = 8), p 5.

Ovary subequatorial, intercaecal, pre-testicular, encircles right caecum. Ovary width h 100, c 92 (74–114, n = 4). Oviduct passes medially to form oötype, surrounded by Mehlis’ gland; oötype short, opens into uterus. Uterus dextral. Unsclerotised vagina inconspicuous. 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, 115–124 × 56–65 (n = 2), 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 7 ). Sclerotised vagina comprises anterior trumpet, followed by primary canal, big spherical primary chamber and small spherical secondary chamber; primary canal tubular, with posterior region slightly thinner than anterior region; primary canal with one coil (or bend) at midlength; primary canal connects to primary chamber on its ventral side; connection is oblique within wall ( Figure 7 E); primary chamber spherical with heavily sclerotised wall; internal wall, inserted laterally, visible in certain specimens ( Figure 7 C,F); secondary chamber ventral and adjacent to primary chamber, resulting in very short secondary canal; secondary chamber spherical, with wall less sclerotised than primary chamber; accessory structure, weakly sclerotised, ventral, connected to secondary chamber and directed anteriorly; total length of sclerotised vagina (measured from extremity of trumpet to posterior extremity, i.e. not taking in account curved length along bend and coil of canal) h 38, c 38 (34–44, n = 8), p 38; primary chamber external width h 13, c 13 (12–14, n = 8), p 16; primary chamber internal width h 9, c 9 (8–10, n = 8), p 12; secondary chamber external width h 8, c 8 (7–8, n = 8), p 9; primary chamber internal width h 5, c 5 (5–6, n = 8), p 6. Orientation of sclerotised vagina: trumpet always anterior. Differential diagnosis. See after P. m a t e r n u s n. sp.

Figures

FIGURE 6. Pseudorhabdosynochus malabaricus n. sp. A. Composite drawing; tegumental scales drawn only on edges. B. Sclerotised vagina, holotype, carmine.

FIGURE 7. Pseudorhabdosynochus malabaricus n. sp. A. Quadriloculate organ. B – G. Sclerotised vaginae. F – G. Superposed plans of vagina drawn separately for two vaginae. A, holotype; B – G, paratypes. B – D, F, dorsal view; A, E, G, ventral view; all carmine.

FIGURE 8. Pseudorhabdosynochus malabaricus n. sp. A. Ventral squamodisc. B. Dorsal squamodisc, same individual. C. Ventral tegumental scales. D. Dorsal tegumental scales, same individual. E. Ventral hamulus. F. Dorsal hamulus. G. Ventral bar. H. Dorsal bar. A – D, holotype, ventral view, carmine; E – H, paratype, picrate.

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.