The largest member of the eight species of the Echeneidae family is the whalesucker (Remora australis; Bennett, 1840), which can reach up to 76 cm in total length (TL; Eschmeyer et al., 1983). This echeneid occurs mainly in tropical and temperate water at a depth range of 0 to 50 m (Eschmeyer et al., 1983; Robertson & Allen, 2015). It is most often found attached to cetaceans, which allows it to feed on its feces or regurgitations, external parasites, and skin (Sazima et al., 2003; Fertl & Landry, 2018).
Whalesuckers are commonly observed in species such as the blue whale (Balaenoptera musculus), fin whale (Balaenoptera physalus), long-beaked common dolphin (Delphinus delphis bairdii), bottlenose dolphin (Tursiops truncatus), spinner dolphin (Stenella longirostris), and the killer whale (Orcinus orca) (Notarbartolo di Sciara & Watkins, 1980; Fertl & Landry, 1999; Guerrero-Ruiz & Urban, 2000).
Most of the records of echeneid--cetacean interactions have been made using photographs due to the difficulties of the obtention of echeneid specimens (Sazima et al., 2003; Silva-Jr & Sazima, 2003; Fertl & Landry, 2018). These observations usually lead to the assumption that any echeneid spotted on cetaceans is R. australis; however, this could be considered as problematic as the identification of echeneids to species level is difficult without the available specimen in hand (Fertl & Landry, 2018).
The present study constitutes the first documented and confirmed record of R. australis obtained from short-beaked common dolphins (Delphinus delphis), and the first record of Remora sp. from long-beaked common dolphins (D. delphis bairdii) from the Gulf of California, Mexico.
A total of ten photographs of unidentified echeneids on long-beaked common dolphins were taken during two scientific expeditions in La Paz Bay: in the southern Gulf of California on 7 March 2014 (24[degrees] 17' 18" N; 110[degrees] 21' 4" W) and on 5 June 2014 (24[degrees] 13' 21" N; 110[degrees] 21' 45" W), respectively, using a reflex camera Canon EOS Rebel T6 with a resolution frame of 2,034 x 1,321 and 3,130 x 1,921 pixels and a Canon 75-300 mm telephoto lens (Figures 1 & 2). In both expeditions, only one dolphin with its own respective echeneid was observed. The estimated size of the echeneid was 30 to 40 cm, and it was observed on the trunk of each dolphin near the dorsal fin. The dolphin pods were relatively small, with 30 to 40 long-beaked dolphins in each expedition. In both occasions, the photographs were obtained at an estimated distance of 25 to 30 m. These echeneids were not...