Holocentricola sp. A

Cutmore, Scott C. & Cribb, Thomas H., 2021, A new order of fishes as hosts of blood flukes (Aporocotylidae); description of a new genus and three new species infecting squirrelfishes (Holocentriformes, Holocentridae) on the Great Barrier Reef, Parasite (Paris, France) 28 (76), pp. 1-17 : 11

Holocentricola sp. A

Host: Sargocentron rubrum (Forsskål) , Red squirrelfish ( Holocentriformes : Holocentridae ).

Locality: Off Heron Island (23 ° 270 S, 151 ° 550 E), southern Great Barrier Reef, Australia.

Site in host: Branchial arteries, vessels of liver, wash of head split.

Prevalence: 3 of 17 Heron Island (adult worms in three); 0 of 2 Lizard Island.

Intensity: 1 worm per fish, when adult worms were detected.

Voucher material: Two voucher specimens ( QM G239129– 30), both hologenophores.

Representative DNA sequences: Partial cox 1 mtDNA, three identical sequences (one submitted to GenBank, OK421329); ITS2 rDNA, one sequence (submitted to GenBank, OK422502); partial 28S rDNA, one sequence (submitted to GenBank, OK422505).

Remarks

This putative, undescribed species was found co-infecting, with H. rufus , three individuals of S. rubrum at Heron Island; only three specimens were collected, and just two hologenophores were available for morphological analysis. This species is genetically distinct from but sister to H. rufus in all phylogenetic analyses; despite the shared host and close phylogenetic affinity, the two species are clearly distinct morphologically. Specimens of Holocentricola sp. A are much smaller than those representing H. rufus , with the two hologenophores being narrower (107–130 vs. 142–222), having a shorter testis length (70 vs. 100–233), post-testicular space (203–210 vs. 250–351), post-ovarian space (153–181 vs. 216–301), post-oötype space (55–74 vs. 81–138), post-male genital pore space (55–56 vs. 66–96), and post-female genital pore space (55–74 vs. 81–138). Specimens of Holocentricola sp. A also have fewer spines per row than H. rufus (7 vs. 8–9), smaller spines (6 long vs. 7–8 long) and shorter spine rows (8–11 wide vs. 11–22). The two hologenophore slides have been lodged as voucher specimens in the QM in the hope that future collecting in the region will enable the description of this species.