Diplectanum diacanthi, Porter & Barton & Francis & Shamsi, 2023

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, International Journal for Parasitology: Parasites and Wildlife 21, pp. 99-109 : 102-104

publication ID	https://doi.org/ 10.1016/j.ijppaw.2023.04.004
DOI	https://doi.org/10.5281/zenodo.10933397
persistent identifier	https://treatment.plazi.org/id/03B6294A-EE2C-FFCE-FCEB-469010DFF923
treatment provided by	Felipe
scientific name	Diplectanum diacanthi
status	sp. nov.

Treatment

Diplectanum diacanthi View in CoL n. sp. ( Fig. 3B, D, F View Fig , Fig. 4 View Fig , Fig. 5 View Fig )

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 About MAGNT ; Paratypes: MAGNT D001923 About MAGNT , 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)

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wide, peduncular spines absent. Haptor laterally expanded ( Figs. 3B View Fig ), 67 (51-101) long, 235 (151-301) wide. Squamodiscs subtriangular in shape, ventral and dorsal ( Fig. 3D View Fig ); each formed with approximately 12 rows of sclerotized dumbbell-shaped rods, anterior rows concentric, progressively tending to form straight line posteriorly ( Fig. 5B View Fig ); squamodisc 48 (23-74) long, 65 (35-101) wide. Anchors 2 pairs, ventral and dorsal ( Fig. 5E View Fig ). 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 View Fig ). 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 View Fig ). Hooks not observed. Ventral bar with tapering, rounded ends, constricted midregion, ventral longitudinal groove ( Figs. 5C View Fig ), 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 View Fig , 4 View Fig and 5D View Fig ).

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Male copulatory organ (MCO) sclerotized, elongate ( Figs. 5A View Fig ), 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 View Fig ). Accessory piece absent. Vitellarium well developed, most dense anteriorly from level of pharynx and extending posteriorly to anterior limit of peduncle ( Figs. 3B View Fig and 4 View Fig ). 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.