Pseudorhabdosynochus maternus, 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 : 16-20

Pseudorhabdosynochus maternus n. sp.

( Figs 9–11 )

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

Type locality: Lagoon off Nouméa, New Caledonia.

Site: Between secondary gill lamellae.

Type specimens: Holotype, JNC 1536A111, off Ouen Toro, Nouméa, New Caledonia (22°19'S, 166°27'E, 18.v.2005).

Material examined: 11 specimens: 10 ‘carmine’ (c), 1 ‘picrate’ (p), all from JNC 1536.

Material deposited: Holotype (c) and 8 paratypes (7 c, 1 p), MNHN; 1 paratype (c), BMNH 2007.6.1.5; 1 paratype (c), USNPC 99870.

Prevalence: 50% (1/2).

Intensity: See Table 1. A rare species (7% of the diplectanids).

Etymology: refers to the local name of the host, ‘mère loche’ ( Laboute & Grandperrin 2000) or ‘mother grouper’.

Description. Body wide; length h 570, c 564 (450–690, n = 8), width h 320, c 320 (290–380, n = 8). 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 49, c 45 (33–61, n = 10), of posterior eye-spot pair h 45, c 38 (28–60, n = 10).

Haptor differentiated from rest of body, as wide as body, width h 300, c 290 (260–300, n = 6), 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 h 56, c 61 (56–66, n = 5), width h 69, c 68 (64–70, n = 5), with 11–12 (n = 6) rows of rodlets and 0–1 closed oval, total number of rodlets h 153; dorsal squamodisc, length h 52, c 58 (52–65, n = 8), width h 64, c 65 (60–72, n = 8), with 10–12 (n = 8) rows of rodlets and 0–1 closed oval, total number of rodlets h 147. Ventral hamulus with thick handle and distinct guard, outer length h 58, c 58 (50–63, n = 17), p 63 (n = 2), inner length h 44, c 44 (41–45, n = 16), p 42 (n = 2). Dorsal hamulus with indistinct guard, outer length h 50, c 47 (44–51, n = 17), p 48 (n = 2), inner length h 30, c 29 (28–32, n = 17), p 28 (n = 2). Dorsal (lateral) bars straight, with flattened medial extremity and thick cylindrical lateral extremity, length h 107, c 106 (101–110, n = 16), p 125 (n = 2), maximum width h 26, c 26 (21–28, n = 15), p 27 (n = 2). Ventral bar flat, with slightly constricted median portion and pointed extremities, length h 135, c 135 (127–141, n = 8), p 156, maximum width h 21, c 20 (14–24, n = 8), p 22; groove visible on its ventral side.

Pharynx subspherical, length h 53, c 51 (40–60, n = 10), width h 48, c 43 (36–55, n = 10). 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 85, c 74 (60–85, n = 4), width 56, c 72 (56–84, n = 4). 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, enlarges into small pyriform organ, then connects with quadriloculate organ. Prostatic reservoir inconspicuous, 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 44, c 45 (42–49, n = 9), p 61; cone length h 9, c 10 (9–12, n = 9), p 11; tube length h 18, c 18 (17–18, n = 9); tube diameter h 3, c 3 (n = 9), p 3; filament length h 5, c 0–16 (n = 9), p 0.

Ovary subequatorial, intercaecal, pre-testicular, encircles right caecum. Ovary width h 85, c 92 (75–128, n = 5). Oviduct passes medially to form oötype, surrounded by conspicuous 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, 112–124 × 38–52 (n = 4), 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 10 ). Sclerotised vagina comprises anterior trumpet, followed by primary canal, big spherical primary chamber and small spherical secondary chamber; anterior edge of trumpet ornamented with longitudinal (or radial) ribs; primary canal tubular, with posterior region slightly thinner than anterior region; primary canal with one coil (or bend) at midlength; canal connects to primary chamber; primary chamber spherical with heavily sclerotised wall; transverse internal wall visible in most specimens ( Figure 9 C,D, 10); secondary chamber ventral and adjacent to primary chamber, resulting in very short secondary canal; secondary chamber roughly spherical, with wall less sclerotised than primary chamber; accessory structure weakly sclerotised, ventral, curved, connected to secondary chamber, 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 29, c 28 (19– 35, n = 10), p 31; primary chamber external width h 9, c 9 (8–10, n = 10), p 10; primary chamber internal width h 6, c 6 (6–7, n = 10), p 8; secondary chamber external width h 5, c 5 (4–6, n = 10), p 6; primary chamber internal width h 3, c 3 (2–4, n = 10), p 3. Orientation of sclerotised vagina: trumpet always anterior.

Differential diagnosis (in common with P. malabaricus ). P. malabaricus and P. m a t e r n u s share the following characteristics of the sclerotised vagina: an anterior trumpet, a primary canal with a bend, a conspicuous heavily sclerotised primary chamber, and a smaller secondary chamber. Comparisons are here restricted to species with a distinct primary canal and large, heavily sclerotised chambers.

P. auitoe Justine, 2007 and P. duitoe Justine, 2007 , both from E. maculatus off New Caledonia, have a straight primary canal, vs coiled.

P. fuitoe Justine, 2007 , from E. maculatus off New Caledonia, has a long, heavily sclerotised, secondary canal, vs very short.

P. venus Hinsinger & Justine, 2006 from E. howlandi off New Caledonia, has a pear-shaped primary chamber (vs round) and the vagina is very large (total length 55) ( Hinsinger & Justine 2006a).

P. vagampullum ( Young, 1969) Kritsky & Beverley-Burton, 1986 from E. quoyanus off South China, in its redescription by Zeng & Yang (2007), has a wide straight primary canal (vs thin and coiled) and a very small secondary chamber (secondary chamber not seen in the original description nor in the redescriptions by Beverley-Burton & Suriano (1981) and Justine (2005a).

A species of Pseudorhabdosynochus from Cephalopholis sonnerati off New Caledonia has a vagina with coiled primary canal and round primary and secondary chambers connected by a very short secondary canal; however, the chambers are smaller, and the species is characterised by very small body size ( Justine 2007b).

Differentiation of P. malabaricus and P. maternus from all these species is thus easy, based on the characters mentioned above; in addition, none of these species has the proportions and shapes of the chambers of these two species.

The two new species P. malabaricus and P. m a t e r n u s are similar for many measurements, ventral and dorsal hamulus length, ventral bar length, and only slightly different for lateral bar length (113 vs 106); for the quadriloculate organ, proportions and measurements of cone and tube are similar, but inner length is slightly greater in P. malabaricus (52 vs 45). The general structure of the vagina is very similar in both species. Distinction can be done on the following characters: trumpet ornamented with ribs in P. maternus (vs unornamented in P. malabaricus ); size of chambers, greater in P. malabaricus (primary chamber 13 vs 9, secondary chamber 8 vs 5); vagina length, greater in P. malabaricus (38 vs 28), with minimal overlap. These two species are probably closely related.

Figures

FIGURE 9. Pseudorhabdosynochus maternus n. sp. A. Composite drawing; tegumental scales drawn only on edges. B. Quadriloculate organ. C – E. Sclerotised vagina, superposed planes drawn separately. A – E, holotype, carmine.

FIGURE 10. Pseudorhabdosynochus maternus n. sp. Sclerotised vagina, variation according to specimen, orientation and fixation method. Superposed planes drawn separately in certain specimens. A – C, G, carmine, ventral view; D – F, H – Q, carmine, dorsal view; R, picrate, dorsal view; all paratypes.

FIGURE 11. Pseudorhabdosynochus maternus n. sp. A. Dorsal squamodisc. B. Ventral squamodisc, same individual. C. Ventral tegumental scales. D. Dorsal tegumental scales. E. Dorsal hamulus. F. Ventral hamulus. G. Ventral bar. H. Dorsal bar. A – D, holotype, carmine, dorsal view. 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.