Pseudorhabdosynochus maaensis, 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 : 28-30

Pseudorhabdosynochus maaensis n. sp.

( Figs 17–18 )

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

Type locality: Lagoon of New Caledonia.

Site: Between secondary gill lamellae.

Type specimens: Holotype, JNC 2130A85, Baie Maa , New Caledonia (22°12’780S, 166°19’933E, 9.iii.2007).

Material examined: 10 specimens: 9 ‘carmine’ (c), 1 ‘picrate’ (p).

Material deposited: Holotype (c) and 9 paratypes (8 c, 1 p), MNHN.

Prevalence: 50% (1/2).

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

Etymology: refers to the locality.

Description. [Given as holotype, mean of carmine specimens, picrate specimen]. Body elongate, length h 450, c 498 (435–570, n = 8), width h 125, c 154 (115–200, n = 9). 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 24, c 26 (20–34, n = 9), of posterior eye-spot pair h 21, c 24 (18–28, n = 9).

Haptor differentiated from rest of body, wider than body, width h 160, c 181 (160–210, 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 rows forming almost closed ovals; 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 44, c 44 (38– 51, n = 7), width h 48, c 45 (40–50, n = 7), with 10 (n = 7) rows of rodlets and 0–2 closed ovals, total number of rodlets h 72; dorsal squamodisc, length c 40 (39–40, n = 2), width c 37 (35–39, n = 2), with 10–13 (n = 6) rows of rodlets and 0–2 closed ovals, total number of rodlets h 76. Ventral hamulus with distinct handle and guard, outer length h 42, c 42 (40–44, n = 18), p 45 (n = 2), inner length h 34, c 35 (33–37, n = 18), p 35 (n = 2). Dorsal hamulus with indistinct guard, outer length h 38, c 39 (36–40, n = 17), p 40 (n = 2), inner length h 24, c 24 (22–26, n = 17), p 24 (n = 2). Dorsal (lateral) bars straight, with flattened medial extremity and cylindrical lateral extremity, length h 51, c 51 (46–54, n = 18), p 55 (n = 2), maximum width h 15, c 15 (13–17, n = 8), p 16 (n = 2). Ventral bar flat, with slightly constricted median portion and pointed extremities, length h 78, c 79 (74–86, n = 9), p 90, maximum width h 14, c 14 (14–15, n = 3), p 13; groove visible on its ventral side.

Pharynx subspherical, length h 32, c 32 (28–36, n = 9), width h 30, c 31 (28–36, n = 9). 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 39, c 54 (39–68, n = 6), width h 43, c 54 (34–75, n = 6). Vas deferens inconspicuous; seminal vesicle in middle region of body, transforms into duct; duct forms bends then enlarges into small pyriform organ, 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 long sclerotised cone, prolonged by sclerotised tube; end of tube prolonged by thin unsclerotised filament of variable length. Inner length of quadriloculate organ h 33, c 34 (32–36, n = 9), p 44; cone length h 17, c 17 (16–20, n = 9), p 16; tube length h 15, c 14 (12–15, n = 9), p 15; tube diameter h 2, c 2 (2–3, n = 9), p 2; filament length h 2, c 0–14 (n = 9), p 0.

Ovary subequatorial, intercaecal, pre-testicular, encircles right caecum. Ovary width h 42, 47 (37–60, n = 6). Oviduct passes medially to form oötype, surrounded by inconspicuous 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 unknown.

Sclerotised vagina (nomenclature of parts according to Justine 2007a, see Figure 20 ). Sinistral, a complex sclerotised structure; aspect slightly changes according to specimen and orientation ( Figure 18 ). Sclerotised vagina comprises anterior trumpet, followed by primary canal, and distal heavily sclerotised part including primary chamber and secondary chamber; primary canal cylindrical, coiled or bend 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 with primary chamber; primary chamber globular; thin internal wall in primary chamber, inserted posteriorly or obliquely, visible in certain specimens ( Figure 17 C, 18A,E,F); secondary canal very short; secondary chamber small, sometimes with two parts; accessory structure weakly sclerotised, curved, inserted on secondary chamber. Duct from sclerotised vagina to oötype inconspicuous. Total length of sclerotised vagina (measured from anterior extremity to posterior extremity of distal sclerotised part, i.e. not taking in account curved length along bend and coil of canal) h 45, c 43 (40–46, n = 9), p 44. Orientation of sclerotised vagina: bend of primary canal always anterior.

Differential diagnosis. P. m a n i f e s t u s, P. h u i t o e, P. serrani , and P. shenzhenensis share with P. maaensis the general structure of the vagina, with a long primary canal with anterior bend and primary and secondary chamber small in a common sclerotised part. However, proportions are very different: P. m a a e n s i s is characterised by a cylindrical (vs conical in the four other species) primary canal, with constant diameter along its length. Its vagina is longer than all four other species ( Table 2 ). In addition, P. maaensis has small squamodiscs with a small number of rodlets.

Figures

FIGURE 17. Pseudorhabdosynochus maaensis n. sp. A. Composite drawing; tegumental scales drawn only on edges. B. Quadriloculate organ. C. Sclerotised vagina. D. Ventral squamodisc. E. Dorsal squamodisc, same individual. F. Ve n tr a l hamulus. G. Dorsal hamulus. H. Dorsal bar. I. Ventral bar. B – E, holotype, carmine, dorsal view; F – I, paratype, picrate.

FIGURE 18. Pseudorhabdosynochus maaensis n. sp. Sclerotised vagina, variation according to specimen, orientation and fixation method. A – E, carmine, ventral view; F – H, carmine, dorsal view; I, picrate, ventral view; all paratypes.

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.