Ceratothoa carinata (Bianconi, 1869)

Lumayno, Sanny David P., Labrador, Hannah Kathleen S., Barnuevo, Kyle Dominic E., Cabebe-Barnuevo, Roxanne A., Cadiz, Rowena E. & Babaran, Ricardo P., 2023, Infection parameters of Norileca indica and a new record of Ceratothoa carinata (Crustacea: Isopoda: Cymothoidae) on Selar crumenophthalmus (Actinopterygii: Carangiformes: Carangidae) in the waters of the Sibuyan Sea, the Philippines, Acta Ichthyologica et Piscatoria 53, pp. 147-155 : 147

Ceratothoa carinata (Bianconi, 1869)

(Fig. 4)

Cymothoa carinata .- Bianconi 1869: 210-211, pl. II, figs 2 (a-b).- Schioedte and Meinert 1883: 327-329, pl. XIII (Cym. XX) figs 1-2.- Trilles 1986: 623, tab. 1. Trilles 1994:-116-117.- Kensley 2001: 232.- Bruce 2007: 278.- Trilles 2008: 23.- Martin et al. 2013: 397-401, figs 1-3.- Nagasawa et al. 2014: 59-61, fig. 1.-Martin et al. 2015a: 266-267.

Cymothoa (Ceratothoa) carinata .- Hilgendorf 1879: 846.

Meinertia carinata .- Lanchester 1902: 378.- Stebbing 1910: 103-104.- Trilles 1972a: 1244-1245, 1256, pl. I, photos 5-7.- Trilles 1972b: 3-7, photos 1-4.- Avdeev 1979: 48, 50.

Codonophilus carinatus .-Nierstasz 1931: 132.

Ceratothoa curvicauda .- Nunomura 2006: 36-38, figs 12-13.

Ceratothoa sp. Saito 2009: 7-9, photos 1-2.

Material examined.

SC005 (non-ovigerous female) extracted from the buccal cavity of the host fish: 20.30 mm TL, host S. crumenophthalmus , Sibuyan Sea.

Morphological description.

Body shape rectangular, maintaining straight posture; longitudinal medial ridge along dorsal pereon surface present; widest part undetermined because of slight damaged of perionite 4 and 5; narrowest part observed at perionite 1. Cephalon: subtriangular in shape with rounded and broad apex. Eyes: circular, moderately small. Perionites: seven in total, becoming narrower from perionites 5 to 7. Perionite 1: shortest; posterior margin straight; small conspicuous pointed structure extending to middle of eyes. Perionites 2-4: posterior margins straight. Perionites 5-6: posterior margins arched medially. Perionite 7: narrowest; posterior margin strongly curved medially. Pleonites: very narrow, positioned just behind perionite 7 extending to pleonite 1. Pleotelson: rather wide than long; dorsal surface with two sub-median depressions; posterior margins strongly concave. Uropods: weak; visible on both sides of pleotelson in dorsal view; similar in length to pleotelson. Pereopods: seven pairs of soft-fleshed pereopods. Pereopod 1: smallest. Pereopods 2-3: similar in size; slightly larger than previous. Pereopods 4-7: gradually increasing in size. Pereopods 5-7: largest. Color in preserved state: dorsal surface generally brown; anterior region white to brown, transitioning to darker color towards posterior region; ventral area light brown; pereopods white.

DNA barcoding.

The morphological identification of the recovered parasites was confirmed by molecular analysis. Sequence analysis based on the mitochondrial CO1 gene showed a high sequence similarity (more than 99%) of SC30 and SC064 to N. indica . The phylogenetic tree showing the relation of this study’s specimens with other relevant cymothoid species is shown in Fig. 5 . The resultant topology clearly indicates clustering of the presently reported specimens with N. indica KY849589.1 recovered from S. crumenophthalmus in the Andaman Islands, India ( Praveenraj et al. 2019) and N. indica MF628260.1, MF628258.1, MF628259.1 from S. crumenophthalmus in Maputo Bay, Mozambique ( van der Wal et al. 2017) supported by 99% bootstrap probability.

On the other hand, specimen SC005 showed greater than 98.00% sequence similarity with C. carinata confirming the morphological identification. To our knowledge, this is the first record of C. carinata in the Philippines. Phylogenetic analysis based on mitochondrial CO1 genes also showed the clustering of the detected Isopoda with C. carinata LC724050.1, LC724049.1 recovered from Decapterus maruadsi (Temminck et Schlegel, 1843) in Sagami Bay, Kanagawa Japan ( Fujita et al. 2023) and C. carinata MK652479.1 ( Baillie et al. 2019) supported by 100% bootstrap probability (Fig. 5 ).

Prevalence and mean intensity of Norileca indica .

In this study, 88 out of 89 bigeye scad specimens (as one fish contained C. carinata ; specimen was not included in the analyses) of the bigeye scad collected during the month of April 2021 were examined, 13 individuals were found to have been infected with N. indica , leading to a prevalence of 14.77%. Of the 13 infected fish, 20 individual isopods (13 females and seven males) were extracted, resulting in a mean intensity of 1.53. All the female N. indica were extracted in the branchial cavities with their orientations mirroring the side of the branchial gill they attached to. Each male N. indica was seen along with the female isopod occupying the same gill holobranch on seven individuals of bigeye scad.

Figures

Figure 4. Non-ovigerous female (SC 005) Ceratothoa carinata collected from the buccal cavity of Selar crumenophthalmus captured in the Sibuyan Sea, Philippines in April 2021 (A = dorsal view; B = ventral view).

Figure 5. Neighbor-joining method used to estimate the phylogenetic relations among Cymothoidae based on mitochondrial CO 1 sequence. Bootstrap probabilities are indicated near the nodes. Penaeus merguiensis AF 279838 was used as outgroup.