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Pufferfish of the family Tetraodontidae possess tetrodotoxin (TTX) and/or saxitoxins (STXs), but the toxin ratio differs, depending on the genus or species. In the present study, to clarify the distribution profile of TTX and STXs in Tetraodontidae, we investigated the composition and intra-body distribution of the toxins in Canthigaster valentini. C. valentini specimens (four male and six female) were collected from Amami-Oshima Island, Kagoshima Prefecture, Japan, and the toxins were extracted from the muscle, liver, intestine, gallbladder, gonads, and skin. Analysis of the extracts for TTX by liquid chromatography tandem mass spectrometry and of STXs by high-performance liquid chromatography with post-column fluorescence derivatization revealed TTX, as well as a large amount of STXs, with neoSTX as the main component and dicarbamoylSTX and STX itself as minor components, in the skin and ovary. The toxins were also detected in the other tissues, but in much lower amounts than in the skin and ovary. The TTX/STX ratio varied greatly, depending on the tissue, but TTX was the major toxin component in the whole body, and STXs accounted for 25% and 13% of the total toxin amount in males and females, respectively. Like the marine pufferfish of the genus Arothron, C. valentini should be considered a pufferfish with considerable amounts of both TTX and STXs present simultaneously., Toxins, 12(7), art.no.436; 2020

Canthigaster valentini (Bleeker 1853) —Black-saddled toby Status at New Ireland. First recorded from New Hanover by Günther (1910: 474). BMNH material. A specimen photographed at Lissenung Island, Kavieng District at 6 m depth by Dean Tully on 26 June 2013. Distribution and habitat. New Ireland: 1, 2.—General distribution: Red Sea, East and South Africa, Madagascar and Mascarenes east to Tuamotu Archipelago, north to South Korea, southern Japan and Ogasawara Islands, south to Lord Howe Island. Found in coastal reefs and lagoon habitats, 0–91 m depth. Marine., Published as part of Andréfouët, Serge, Chen, Wei-Jen, Kinch, Jeff, Mana, Ralph, Russell, Barry C., Tully, Dean & White, William T., 2019, Checklist of the marine and estuarine fishes of New Ireland Province, Papua New Guinea, western Pacific Ocean, with 810 new records, pp. 1-360 in Zootaxa 4588 (1) on page 335, DOI: 10.11646/zootaxa.4588.1.1, http://zenodo.org/record/2988163, {"references":["Gunther, A. C. L. G. (1910) Andrew Garrett's Fische der Sudsee. Band III, Heft IX. Journal des Museum Godeffroy, Hamburg, 6 (17), i-vi + 389 - 515, pls. 161 - 180."]}

A new species, Hurleytrematoides justinei n. sp., is described from Valentinni’s sharpnose puffer, Canthigaster valentini, from Heron Island, Queensland, Australia. It is characterized within the genus by a sinistral genital pore opening anterior to the posterior margin of the ventral sucker, a spiny ejaculatory duct ranging from 34 to 61 µm in length, and vitelline follicles extending from about the anterior margin of the testis to the posterior margin of the ventral sucker. Monorchiids are rare in the tetraodontids. This is the third species reported from the family and the first from the genus Canthigaster.

The inflation response of pufferfishes is one of the most iconic predator defence strategies in nature. Current dogma suggests that pufferfish inflation represents a breath-holding response, whereby gill oxygen uptake ceases for the duration of inflation and cutaneous respiration increases to compensate. Here, we show that the black-saddled pufferfish ( Canthigaster valentini ) has an excellent capacity for oxygen uptake while inflated, with uptake rates increasing to five-times that of resting levels. Moreover, we show that this species has negligible capacity for cutaneous respiration, concluding that the gills are the primary site of oxygen uptake while inflated. Despite this, post-deflation recovery of aerobic metabolism took an average of 5.6 h, suggesting a contribution of anaerobic metabolism during pre-inflation activity and during the act of ingesting water to achieve inflation.

Batesian mimicry evolves when the 'umbrella' of protection provided by resemblance to a conspicuous unpalatable model species is sufficient to overcome increased predation risk associated with greater conspicuousness. However, the shape and extent of this umbrella, that is, how the level of protection provided by mimicry changes with degree of resemblance between model and mimic, is poorly known. We investigated the response of wild predatory fishes to plastic replicas of a model-mimic species pair of tropical reef fishes, Canthigaster valentini (a toxic pufferfish, the model) and Paraluteres prionurus (the putative mimic), and additional replicas with progressively lower degrees of resemblance to the mimic species. Our results reveal a relatively broad region of protection, indicated by a reduced approach rate by piscivorous fishes, surrounding the colour pattern of the model species. Protection increased with increasing resemblance. By contrast, the response of non-piscivorous fishes was unrelated to degree of resemblance of replicas to the model. Our results suggest that piscivorous fishes on the reef are educated regarding the toxicity of C. valentini, and that avoidance of fish having the pufferfish colour pattern has generated selection favouring mimetic resemblance by the palatable P. prionurus. The relatively broad protective umbrella has probably facilitated the initial evolution of resemblance in the palatable prey species despite the potential hazards of greater conspicuousness.

Sharpnose puffers (Tetraodontidae: Canthigasterinae) are small demersal fishes found on tropical and subtropical reefs. They are slow moving, often cryptically colored, and typically occur in low population densities (cf. Vail and Sinclair-Taylor 2011 for report of unusual mass schooling). Thus, they have been poorly studied compared with most groups of reef fishes. Indeed, of the 35 described species, spawning in the field has been reported for only 2, with the most recent report being over 2 decades ago. These include Canthigaster valentini in the Indo-Pacific (Gladstone 1987; Gladstone and Westoby 1988), and Canthigaster rostrata of the Caribbean and tropical Atlantic (Sikkel 1990). Spawning has also been reported in captivity but not in the field for Canthigaster rivulata (see Arai and Fujita 1988), and social organization but not spawning has been reported in the field for Canthigaster punctatissima (see Kobayashi 1988).

The sharpnose puffer,Canthigaster valentini, occurs in male-dominated harems of territorial females at Lizard Island (Australia). Spawning occurs daily and year-round. Males only spawn with the females of their social group, inside the female's territory. Females signal their readiness to begin courtship with a display that exposes their egg swollen abdomen. Courtship is long and males do not develop specific courtship colors or perform unique displays. Eggs are fertilized in a demersal nest and there is no parental care.

Sharpnose puffers, Canthigaster valentini (Pisces: Tetraodontidae) at Lizard Island, Australia, live in made-dominated haremic social and mating systems. The hypothesis was that mature females are restricted in their movements and can be monopolized by some males. Field experiments at Lizard Island, Great Barrier Reef, between January and March 1983 showed that mature females were still territorial in the absence of males and movements of females were not controlled by males. Males abandoned their territories when their females were removed. The territorial behavior of those males with access to females (territorial males) restricted the access of other males (bachelor males) to them. Bachelor males took over harems and became territorial males when established territorial males were removed. The results of the experiments thus supported the hypothesis. © 1987 Springer-Verlag.

The growth and reproduction of Cantigaster valentini were studied in two sites at Lizard Island, Australia. C. valentini was found to be a gonochore, with a sex ratio very close to 1:1; sexes could be distinguished externally. The growth (in length) of known individuals from both sites was measured at least every two months over two years. Growth rates of males and females decrease as their sizes increase. Growth rates differ between sexes and between sites: males generally grow faster than females and individuals at Mermaid Cove generally grow faster than individuals at Palfrey Island. Spawning is demersal, it occurs daily between 0800 and 1600h, and continues year-round. For females the interval between successive spawnings varies from about 4 days in the warm-water season to about 10 days in the cool-water season. From a comparison of local reproductive output and local recruitment survivorship of larvae in the plankton was estimated to be much higher than in another species (Pomacentrus wardi) for which a similar estimate was available. We suggest that some aspects of the reproductive strategy of C. valentini differ from other, non-toxic reef fishes in ways consistent with a reduced threat of predation upon adults, eggs, and larvae: courtship and spawning are unhurried and occur throughout most of the day; spawning is unrelated to lunar cycles; there is no parental care or defense of fertilized eggs; and embryos often hatch on rising tides.