Thorogobius ephippiatus (Lowe, 1839)

Borg, Joseph A., Evans, Julian, Knittweis, Leyla & Schembri, Patrick J., 2022, New and interesting records of marine fishes (Actinopterygii) from the Maltese Islands (central Mediterranean), Acta Ichthyologica et Piscatoria 52 (3), pp. 215-221 : 215

Thorogobius ephippiatus (Lowe, 1839)

Figs 1 , 2

Diagnosis.

Base coloration greyish with blue-green sheen on back; covered with large, round dark spots. Head, including predorsal area, covered with brown to dark orange, smaller round spots, usually lighter in colour and more reddish than blotches on body. Five to six large, dark brown or brown-purple to black midlateral blotches. Dark blotches above midline smaller than midlateral blotches.

Remarks.

In the SCUBA surveys there were six occurrences of this species from depths of between 8 and 32 m within caves, with four occurrences on soft sediment bottoms and two on rock (see Table 1 ). An additional single record from the ROV surveys was from a depth of 117 m on a rocky bottom having a thin layer of silt (Table 1 and Fig. 2 ). No cave or rock fissure or any other similar feature was present in the vicinity of this individual. Given that the literature indicates that T. ephippiatus is typical of cave habitats, crevices, overhangs or deep gullies ( Bussotti and Guidetti 2009; Bussotti et al. 2015; Ragkousis et al. 2021; Kovačić et al. 2022), the occurrence of this species outside this type of habitat is unusual. Thorogobius ephippiatus is a new record for Maltese coastal waters; it is a NE Atlantic and Mediterranean species. In the Mediterranean its distribution appears to be mostly along the northern shores of both west and east basins including the Aegean Sea, Cyprus, and Israel ( Kovačić et al. 2022). According to Froese and Pauly (2022), the depth range for T. ephippiatus is 6-40 m, with the fish being commonest in the 6-12 m range. The record from a depth of 117 m is therefore noteworthy, especially as the present authors are aware of only one previous deep-water record of this species, by Stern et al. (2018), who recorded it from a depth of 156 m off the north Israeli coast. Stern et al. (2018) attribute the deep-water occurrence of T. ephippiatus to its requirement for dark and cold conditions, which in the eastern Levantine Sea only occur in deep water. However, the species is present in shallow water in Cyprus ( Gerovasileiou et al. 2017), which raises doubts about this hypothesis. On the other hand, the present deep-water record from Malta confirms that T. ephippiatus has a much wider bathymetric range than previously thought. It may be significant that both the Maltese and Israeli deep-water records were from open rocky bottoms and not from caves, suggesting that the association with caves in shallow water is due to the fish’s requirement for a dark habitat, while in deep water the species can occur in the open. In fact, Kovačić (1997) had already noted that this species occurs deep within caves in very shallow waters, but closer to the mouth at the deeper end of the depth range studied by this author (32 m). It therefore also occurs outside of caves in deeper water.

Figures

Figure 1. Photograph of Thorogobius ephippiatus, taken on 27 June 2016 at a depth of 24 m within a cave (36 ° 04.879 ′ N, 014 ° 14.110 ′ E). Photograph: OCEANA / Carlos Minguell © LIFE BaĦAR for N 2 K.

Figure 2. Image grab from ROV footage collected on 7 July 2016 at a depth of 117 m (36 ° 00.776 ′ N, 014 ° 50.517 ′ E) showing an individual of Thorogobius ephippiatus. Image: OCEANA © LIFE BaĦAR for N 2 K.