Diplectanum diacanthi Porter & Barton & Francis & Shamsi 2023, n. sp.
Creators: name: Porter, Megan
name: Barton, Diane P.
name: Francis, Nidhish
name: Shamsi, Shokoofeh
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Dactylogyridea
Diplectanidae
Diplectanum
Diplectanum diacanthi

description: Diplectanum diacanthi n. sp. (Fig. 3B, D, F, Fig. 4, Fig. 5)
Type host: Protonibea diacanthus (Lacep`ede, 1802) (Sciaenidae) ‘Black Jewfish’ or ‘Black-spotted croaker’.
Type locality: Caution Point, Beagle Gulf, Northern Territory, Australia. Other localities include Van Diemen Gulf, Timor Sea, Northern Territory, Australia.
Site in host: Gill filaments.
Type-material: Holotype: MAGNT D001922; Paratypes: MAGNT D001923, QM G240633, WAM V11010
GenBank accession: 28S (OQ846932-OQ846934), ITS1 (OQ846938- OQ846939)
Etymology: The specific name is derived from the host species from which the type specimen of Diplectanum diacanthi n. sp. was collected.
3.1.3. Description
Based on 22 specimens. Body medially rounded, fusiform, with smooth tegument; total length 1,087 (645–1,870); greatest width 253 (127-460), near level of testis. Four cephalic lobes moderately defined. Two pairs of head organs, 15 (10-24) long, 13 (9-21) wide, moderately developed as cephalic lobes, adjacent cephalic areas. Cephalic glands poorly defined, extending towards pharynx. Eye spots 2 when visible, poorly developed or represented by scattered granules, dorsal, anterior to pharynx. Mouth subterminal; pharynx bulbous, length 64 (38-101), width 62 (27-95). Oesophagus short to absent. Intestinal caeca bifurcates short distance posterior to pharynx, crura blind posteriorly. Peduncle slightly tapered posteriorly, 168 (89-366) long, 96 (54-163)
102
wide, peduncular spines absent. Haptor laterally expanded (Figs. 3B), 67 (51-101) long, 235 (151-301) wide. Squamodiscs subtriangular in shape, ventral and dorsal (Fig. 3D); each formed with approximately 12 rows of sclerotized dumbbell-shaped rods, anterior rows concentric, progressively tending to form straight line posteriorly (Fig. 5B); squamodisc 48 (23-74) long, 65 (35-101) wide. Anchors 2 pairs, ventral and dorsal (Fig. 5E). Ventral anchor length 60 (46-75), anchor base width 10 (4-20); anchor with elongate, slightly tapered deep root, longer than superficial root, knob-like superficial root with rounded point, curved shaft, short point (Fig. 5E). Dorsal anchor length 66 (46-78), anchor base width 10 (4-14); anchor with wide tapered deep root, incipient superficial root, straight shaft, short point (Fig. 5E). Hooks not observed. Ventral bar with tapering, rounded ends, constricted midregion, ventral longitudinal groove (Figs. 5C), 109 (93-124) long, greatest width 16 (8- 19). Paired dorsal bar, 61 (48-66) long, greatest width 20 (12-40); not overlapping each other, medial end expanding spatulate wider than lateral end, medial end often just overlapping lateral points of ventral bar, some cases overlapping with ventral bar absent (Figs. 3F, 4 and 5D).
103
Male copulatory organ (MCO) sclerotized, elongate (Figs. 5A), 96 (81- 110) long, greatest width 10 (9-12); composed of two nested tubes which appear to be joined at the distal end. MCO relatively straight, inner tube tapers slightly. Distal end bifurcates into two-pointed fork like expansion. Distal end of sclerotized piece curves concave between the two points (Fig. 5A). Accessory piece absent. Vitellarium well developed, most dense anteriorly from level of pharynx and extending posteriorly to anterior limit of peduncle (Figs. 3B and 4). Most reproductive and other internal structures throughout middle body not defined through vitellarium.
3.1.4. Remarks
The body shape of Diplectanum diacanthi n. sp. slightly resembles those described from D. timorcanthus n. sp. and D. oliveri, however the morphological resemblance ceases from this point. Of the haptoral structures, the ventral bar of D. diacanthi n. sp. is much narrower than
others described. The morphology of the dorsal bars and the squamodisc are in fact more similar to those from the type species Diplectanum aequans (Wagener, 1857) Diesing, 1858. The dorsal bars of these species are much shorter and wider and possess subtriangular ventral and dorsal squamodiscs with progressively straightening rows of rodlets at the posterior end. D. aequans does however exhibit distal tapering of the dorsal bars and a larger number of rows of the squamodisc, differentiating the type species to D. diacanthi n. sp.
description: Published as part of Porter, Megan, Barton, Diane P., Francis, Nidhish & Shamsi, Shokoofeh, 2023, Description of two new species of Diplectanum Diesing, 1858 (Monogenea: Diplectanidae) collected from Protonibea diacanthus (Lacep`ede, 1802) (Teleostei: Sciaenidae) from waters off northern Australia, pp. 99-109 in International Journal for Parasitology: Parasites and Wildlife 21 on pages 102-104, DOI: 10.1016/j.ijppaw.2023.04.004, http://zenodo.org/record/10668282