An integrative study of some species of Gonaxia Vervoort, 1993 from off New Caledonia, with the establishment of Gonaxiidae as a new family of thecate hydroids (Cnidaria: Hydrozoa) Author Galea, Horia R. Hydrozoan Research Laboratory, 405 Chemin Les Gatiers, 83170 Tourves, France. Author Maggioni, Davide 0000-0003-0508-3987 Università degli Studi di Milano-Bicocca, Dipartimento di Scienze dell’Ambiente e della Terra, Piazza della Scienza 1, 20126 Milano, Italy. davide. maggioni @ unimib. it; https: // orcid. org / 0000 - 0003 - 0508 - 3987 & Università degli Studi di Milano-Bicocca, Marine and High Education (MaRHE) Center, 12030 Faafu Magoodhoo, Republic of the Maldives davide.maggioni@unimib.it text Zootaxa 2021 2021-07-21 5004 3 401 429 journal article 10.11646/zootaxa.5004.3.1 1175-5326 5120645 0C4DFAA3-5822-456B-916B-84A7BABEB98F Gonaxia cf. intermedia Vervoort, 1993 Figs 1G , 10 , 15 , 16 ; Table 3 Gonaxia intermedia Vervoort, 1993: 157 , figs 23E, 24D, 25A–C, 26A.— Galea, 2016: 9 , figs 2D, 3G–K. Material examined. KANADEEP, Stn. DW4945, MNHN-IK-2015-2671: a 4.7 cm high, sterile colony; GenBank: MZ 099702 (16S). Remarks . This sterile material is only provisionally assigned to G. intermedia Vervoort, 1993 based on morphological similarities of its hydrothecae, despite their being more distant from one another compared to the original account (a similar variation was also observed in G. sinuosa Vervoort, 1993 , see under that species). However, their size approaches that of the holotype material (free adaxial wall 335–360 µm vs . 340–375 µm ; adnate adaxial wall 300–335 µm vs . 230–250 µm ; abaxial wall 400–470 µm vs . 320–370 µm ; maximum width 220–240 µm vs . 220–235 µm ; diameter at rim 150–165 µm vs . 135–150 µm ). Bathymetric distribution . Between 108–630 m ( Vervoort 1993 ; Galea 2016 ; present study).