More than 65 species of the genus Microcotyle Van Beneden & Hesse, 1863, have been described to date, most of them infecting Perciformes. Among the scorpaenoids (Perciformes, formerly Scorpaeniformes) the species of the genus Microcotyle parasitize sebastids and scorpaenids worldwide. In this study, we provide new morphological and molecular data for Microcotyle spp. in sebastids and scorpaenids from the Western Mediterranean and north-east Atlantic. Specimens of Helicolenus dactylopterus (Delaroche, 1809) (n = 107) and Scorpaena spp. (n = 107) were examined and their microcotylid specimens morphologically and molecularly characterized. Microcotyle merche n. sp. ex H. dactylopterus and specimens of Microcotyle algeriensis Ayadi, Gey, Justine & Tazerouti, 2016 from a new host and locality (Scorpaena scrofa from the north-east Atlantic) are herein described. Both species are phylogenetically close, but their morphology is markedly different mostly because the anterior lobe of the haptor present in other Microcotyle species is almost absent in M. algeriensis. Findings of M. merche n. sp. in the Mediterranean also excludes the presence of Microcotyle sebastis in this sea, encouraging the review of the exceptionally large host range and geographical distribution of this species.

Black scorpion fish (Scorpaena porcus) is an important species for both artisanal and industrial fisheries in the Turkish Black Sea, with 306 tonnes landed in 2017. The diet composition of this species was investigated through the examination of their stomach contents. A total of 621 S. porcus (ranging from 12.79–765.5 g) were caught by trammel net in the south-eastern Black Sea (Turkish waters) from December 2015 to November 2016. The importance of prey items in the diet of S. porcus was assessed using the Index of Relative Importance (%IRI). Overall, the dominant species was the isopod Idotea balthica (52.8%IRI) followed by decapods (38.5%IRI) and teleosts (8.7%IRI). Seasonal variations in the diets were observed, with isopods predominant in autumn (>85%IRI), teleosts in winter (>77%IRI) and decapod crustaceans (>78%IRI) in spring and summer. The modified Costello's graphical analysis evinced a specialist feeding strategy for S. porcus during winter, spring and autumn while a shift to generalistic feeding strategy was exhibited in summer by a limited number of S. porcus individuals.

The Red Sea record of the Ambon scorpionfish Pteroidichthys amboinensis is confirmed based on two specimens collected at Eilat, Israel in 1966 and in 1997. The species is widespread but very rare, known from scattered localities in the Indo-West Pacific, otherwise occurring from India and Indonesia east to Marquesas Islands.

The presence of the offshore rockfish, Pontinus kuhlii (Scorpaeniformes, Scorpaenidae), is reported for the first time in Maltese waters (Strait of Sicily). One specimen was caught offshore Gozo (Maltese archipelago) in October 2013 by bottom longline. The eastward range expansion within the Mediterranean of this Atlantic species is discussed.

In this study, the presence and description of Scorpaena loppei in the Turkish seas is reported. Two specimens were caught in Mersin-Taşucu Bay on 24 August 2006 by trawl net. The first specimen was 42.8 mm standard length, and the second specimen was 52.3 mm.