French ichthyological records for 2019 Author Iglésias, Samuel P. Author Bariche, Michel Author Beau, Florent Author Bérenger, Lucas Author Beucher, Renaud Author Chabrolle, Antoine Author Cottalorda, Jean-Michel Author Cousin, Bertrand Author Curd, Amelia Author Danet, Valentin Author Duhamel, Erwan Author Duval, Audrey Author Farque, Pierre-André Author Goascoz, Nicolas Author Jadaud, Angélique Author Larnaud, Pascal Author Bouter, Mathieu Le Author Bras, Yvan Le Author Bris, Sylvain Le Author Lombard, Laurent Author Louisy, Patrick Author Mandine, Alain Author Mas, Lise Author Menut, Thomas Author Metral, Luisa Author Poussard, Pierre Author Quéro, Jean-Claude Author Raybaud, Virginie Author Renoult, Julien P. Author Richard, Thomas Author Spitz, Jérôme Author Ternon, Quentin Author Thiriet, Pierre Author Tournier-Broer, Ruben text Cybium 2021 45 3 169 188 http://dx.doi.org/10.26028/cybium/2021-453-001 journal article 10.26028/cybium/2021-453-001 2101-0315 12712628 Lebetus guilleti ( Le Danois, 1913 ) Three Guillet’s gobies, Gobiidae ( Fig. 8G ), were observed and collected by S.P. Iglésias while scuba diving on 30 Aug 2019 during an excursion targeting fishes inhabiting maerl beds, about 2 km off the Kelenn beach at Caran- tec, Bay of Morlaix ( 48.688°N , 3.903°W , Finistère), at 4.6- 5.9 m depth at low tide. Seawater bottom temperature was 17° C. The specimens, two adult males of 21 mm TL and an adult female of 18 mm TL were preserved with the collection Nos. MNHN-IC 2021-0151 , 2021-0153 and 2021-0152 Figure 8. – Significant French ichthyological records for 2019 (continued). A : Gobius couchi , ~7 cm TL, 15 June 2019 (© S. Le Bris); B : G. couchi , ~8 cm TL, 19 Aug 2019 (© L. Bérenger); C : G. couchi , 26 mm TL, 15 Sep 2019, MNHN-IC 2021-0149 (© S.P. Iglésias); D : Gobius gasteveni , 27 mm TL, 30 Aug 2019 MNHN-IC 2021-0150, in aquarium, reversed image (© S.P. Iglésias); E , F : Lebetus guilleti , 19.5 and 19 mm TL, male and female, 15 Sep 2019, MNHN-IC 2021-0154, and 2021-0155, respectively (© S.P. Iglésias); G : L. guilleti , 21 and 18 mm TL, two males and a female, 30 Aug 2019, MNHN-IC 2021-0151, 2021-0153 and 2021-0152 from left to right respectively, in aquarium (© S.P. Iglésias). and tissue samples were preserved under Nos. BPS-4277 and 4278. The individuals were found on a flat maerl seabed, the same bottom type of the Bay of Morlaix, where the species was first observed ( Le Danois, 1910 ). The habitat, mostly composed by the variety minimum (according to Cabioch, 1966 , 1970 ) of the coralline seaweed Lithothamnion corallioides (P.L Crouan & H.M. Crouan) P.L. Crouan & H.M. Crouan, 1867 form in maerl, was largely dominat- ed by the species Pomatoschistus pictus (Malm, 1865) and immature Callionymus lyra (Linnaeus, 1758) . The species Diplecogaster bimaculata (Bonnaterre, 1788) and immature Gobius gasteveni (this article) were more rarely observed. Guillet’s goby was observed on maerl colonized by very small epiphyte red seaweeds. Two other specimens were observed and collected in the same conditions on 15 Sep 2019 off Porz Kerid, Bay of Brest ( 48.3170°N , 4.3989°W , Finistère), at 3.7 and 4.1 m depth at low tide. Seawater bottom temperature was 17°C. The adult specimens, a male and a female, measuring 19.5 and 19 mm TL, respectively ( Fig. 8 E-F) were preserved with the collection Nos. MNHN-IC 2021-0154 and 2021-0155, respectively and a tissue sample from the male was preserved under No. BPS-4279. The specimens were found on a maerl bed forming dunes composed of mixed live and dead L. corallioides coralline seaweeds of small diameter, sheltering a high variety of small invertebrates. After some minutes in an aquarium, the two specimens showed the typical motion of the first dorsal fin as described by Schliewen et al. (2019) . Guillet’s goby is very uncommonly recorded, due to its very small size which avoids its capture by most fishing gears and to its cryptic coloration which makes its detection by scuba divers very difficult. The species is known in very few localities from Norway to the Adriatic Sea ( Riolo and Betti, 2015 ; Schliewen et al. , 2019 ). In French waters it has been recorded only in the Bay of Morlaix ( Le Danois, 1910 , 1913 ) and Banyuls-sur-Mer, in the Mediterranean ( Zander, 1982 ). The species has been regularly recorded in unpublished observations in the Bay of Morlaix, Bay of Brest and at Trévignon (south Finistère) over the last 25 years during surveys on maerl seabeds dominated by L. corallioides (Jacques Grall, pers. comm.).