Taxonomic research on &lt;i&gt;Squalus megalops&lt;/i&gt; (Macleay, 1881) and &lt;i&gt;Squalus blainvillei&lt;/i&gt; (Risso, 1827) (Chondrichthyes: Squalidae) in Tunisian waters (central Mediterranean Sea)

Marouani, Sondes; Chaâba, Raja; Kadri, Hasna; Saïdi, Béchir; Bouaïn, Abderrahmen; Maltagliati, Ferruccio; Séret, Bernard; Bradaï, Mohamed Nejmeddine

doi:10.3989/scimar.03440.22b

Cited by 22 publications

(51 citation statements)

References 10 publications

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“…Chondrocranial measurements and nomenclature, with some minor modifications, follow Muñoz-Chápuli & Ramos (1989) and Marouani et al (2012) (Figure 2). Chondrocranial measurements were expressed as a percentage of the total length of the chondrocranium.…”

Section: Chondrocranial Measurementsmentioning

confidence: 99%

“…A subsample of 12 specimens was used for genetic analysis; six specimens were selected from those with a chondrocranium with a single lateral process of the basal plate and the other six from individuals with a double lateral process of the basal plate; according to Marouani et al (2012) the former is characteristic of S. blainville while the latter is characteristic of S. megalops.…”

Section: Genetic Analysismentioning

confidence: 99%

“…This sample was chosen by first categorizing the total available specimens as males and females, and, within each, as mature and immature, and then selecting individuals at random from each category. Parameters considered for differentiating between Squalus species were selected from the characters used by various authors (Bigelow & Schroeder, 1957;Compagno, 1984;Muñoz-Chápuli & Ramos, 1989;Last et al, 2007;Marouani et al, 2012).…”

Section: Morphological Studiesmentioning

confidence: 99%

“…However, it still proved difficult to distinguish between S. megalops and S. blainville due to the degree of variability of key features that supposedly differentiate between the two. The question was ultimately resolved through genetic analysis, DNA barcoding having been shown to be a powerful tool in distinguishing between different species of squalids, although very few studies have been made on S. blainville or S. megalops Marouani et al, 2012;Landi et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…According to the detailed study by Marouani et al (2012), more or less clear-cut characters that differentiate between these two problematic species are the flank denticles, teeth and the number of cartilaginous processes on each side of the basal plate of the chondrocranium (Table 1). Despite detailed morphological comparisons of S. blainville and S. megalops, there is still much uncertainty as to what exactly constitutes S. blainville.…”

Section: Introductionmentioning

confidence: 99%

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Not all that clear cut: intraspecific morphological variability inSqualus blainville(Risso, 1827) and implications for identification of the species

et al. 2015

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Of the three species of the genus Squalus that occur in the Mediterranean Sea, S. blainville and S. megalops are very difficult to distinguish. This study assesses the variability in morphological features that have been used to differentiate between these species. Squalus were collected from stations within the 25-nautical mile Fisheries Management Zone around the Maltese Islands; 349 specimens were dissected and categorized into male and female, mature and immature, and individuals were randomly selected from each category to make up a sample of 169 specimens. For each individual, total length and first dorsal fin parameters were measured, and morphology of denticles isolated from the laterodorsal area, of the upper and lower teeth and of the chondrocranium was analysed. The first dorsal spine was shorter that the fin base in 93% of the specimens, which is typical of S. megalops; this character was not related to either gender or maturity. Chondrocrania with one lateral process (typical of S. blainville) and two lateral processes (typical of S. megalops) were present. Teeth from the same individuals showed morphological features that overlap between S. blainville and S. megalops. Both unicuspid (typical of S. megalops) and tricuspid denticles (typical of S. blainville) were observed on the same individuals. Twelve specimens (six having one and six having two lateral chondrocranial processes) were analysed genetically by sequencing of the mtDNA marker Cytochrome Oxidase Subunit I (COI). All resulted to be S. blainville showing that intraspecific variability in supposedly diagnostic morphological features is large enough to render these unreliable to tell apart these two species, especially in the field.

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Section: Chondrocranial Measurementsmentioning

confidence: 99%

Section: Genetic Analysismentioning

confidence: 99%

Section: Morphological Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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