Diplectanum maa Justine & Sigura, 2007, n. sp.
Creators: name: Justine, Jean-Lou
name: Sigura, Aude
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Dactylogyridea
Diplectanidae
Diplectanum
Diplectanum maa

description: Diplectanum maa n. sp.
(Figs 21–22)
Type host: Epinephelus malabaricus Bloch & Schneider (Serranidae).
Type locality: Lagoon of New Caledonia.
Site: Between secondary gill lamellae.
Type specimens: Holotype, JNC 2130A59, Baie Maa, New Caledonia (22°12’780S, 166°19’933E, 9.iii.2007).
Material examined: 29 specimens: 22 ‘carmine’ (c), 7 ‘picrate’ (p).
Material deposited: Holotype (c) and 26 paratypes (19 c, 7 p), MNHN; 1 paratype (c), BMNH 2007.6.1.6; 1 paratype (c), USNPC 99871; 1 paratype (c), HCIP M-441.
Prevalence: 50% (1/2).
Intensity: See Table 1. A relatively abundant species (22% of the diplectanids) in one of the fish examined.
Etymology: refers to type locality; indeclinable.
Description. Body elongate; length h 520, c 475 (440–550, n = 10), width at level of ovary h 250, c 209 (160–250, n = 11). Tegument apparently smooth (no tegumental scales). 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 34 (24–42, n = 12), of posterior eye-spot pair h 36, c 31 (23–42, n = 12).
Haptor differentiated from rest of body, less wide than body, width h 180, c 171 (140–210, n = 10), provided with 2 similar squamodiscs, 2 pairs of lateral hamuli, 3 bars and 14 marginal hooklets. Squamodiscs small, made up of rows of small rodlets; central rows forming almost closed ovals; rodlets progressively thinner from centre to periphery; rodlets adjacent in central rows, separated in peripheral rows; ventral squamodisc round in shape, length h 34, c 33 (28–35, n = 3), width h 27, c 30 (27–34, n = 3), with 9–12 rows of rodlets (n = 3) with 0–1 closed oval, total number of rodlets h 65; dorsal squamodisc round in shape, length h 29, c 33 (28–36, n = 4), width h 33, c 34 (32–35, n = 4), with 10–12 rows of rodlets (n = 4) with 0–1 closed oval, total number of rodlets h 64. Ventral hamulus with distinct guard and handle, outer length h 45, c 46 (42– 50, n = 22), p 49 (48–51, n = 8), inner length h 40, c 40 (37–43, n = 22), p 40 (31–43, n = 8). Dorsal hamulus with indistinct guard and handle, outer length h 41, c 41 (38–42, n = 22), p 42 (39–43, n = 8), inner length h 24, c 24 (23–25, n = 22), p 26 (23–30, n = 8). Dorsal (lateral) bars with flattened medial extremity and cylindrical lateral extremity, length h 57, c 57 (54–62, n = 22), p 60 (55–62, n = 8), maximum width h 19, c 18 (14– 21, n = 22), p 19 (16–23, n = 7). Ventral bar flat, massive with blunt extremities, length h 66, c 72 (66–78, n = 11), p 77 (73–81, n = 3), maximum width h 18, c 18 (16–20, n = 9), p 19 (18–19, n = 3); groove visible on its ventral side.
Pharynx subspherical, length h 38, c 40 (35–46, n = 12), width h 41, c 39 (34–48, n = 12). 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 34, c 35 (25–55, n = 11), width h 62, c 57 (39–85, n = 11). Sclerotised male copulatory organ (MCO) a small tubular penis; no accessory part. Penis ‘spoon-shaped’, a funnel, made up of anterior cone and straight posterior tube of regular diameter; tube oriented in same axis as cone or slightly oblique. Within penis anterior cone, 4 very thin transverse walls limit 4 chambers. Posterior protruding cirrus visible in certain specimens (Figure 22 A,G). Penis length h 36, c 36 (34–38, n = 12), p 34 (31–36, n = 5); maximum diameter h 14, c 13 (12–15, n = 12), p 12 (11–14, n = 5); tube diameter h 4, c 4 (4– 5, n = 12), p 4 (4–5, n = 5).
Ovary subequatorial, intercaecal, pre-testicular, encircles right caecum. Ovary width h 102, c 78 (65–102, n = 11). Oviduct passes medially to form oötype, surrounded by Mehlis’ gland; oötype short, opens into uterus. Uterus dextral. 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.
Differential diagnosis and generic status. This species belongs to a group of diplectanids from groupers (Epinephelinae) which are provisorily attributed (Justine 2007a) to Diplectanum Diesing. The group already includes three species: D. grouperi Bu, Leong, Wong, Woo & Foo, 1999 from E. coioides off Malaysia and South China, D. uitoe Justine, 2007 from E. maculatus off New Caledonia, and a species from Cephalopholis sonnerati (Justine 2007b). In this group, the MCO is similar to the spoon-shaped or funnel-shaped penis of members of Laticola Yang, Kritsky, Sun, Zhang, Shi & Agrawal, 2006, but the described species of Laticola have much larger male copulatory organs (Yang et al. 2006; Journo & Justine 2006) and a characteristic vaginal structure, not seen in this group.
Table 4 compares the species of diplectanids from groupers provisorily attributed to Diplectanum.
D. grouperi is different from D. maa by its shorter MCO.
D. uitoe has a MCO of similar length but can be differentiated from D. maa by larger squamodiscs, more numerous rodlets, and presence of ‘spurs’ on the rodlets; in addition, its ventral and dorsal hamuli are smaller.
The species from C. sonnerati can be distinguished from D. maa by shorter MCO, smaller body size, and a dorsal squamodisc very different from the ventral; in addition, the dorsal and ventral bars are thinner and more elongate, and the ventral and dorsal hamuli are smaller.
D. maa can thus be differentiated from all species already described of this group of ‘ Diplectanum’ from groupers; characters of the squamodiscs and haptoral hard parts are necessary to identify these species, which have inconspicuous female organs and very similar male organs.
description: Published as part of 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), pp. 1-44 in Zootaxa 1543 on pages 34-36, DOI: 10.5281/zenodo.177917