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 elegans Vervoort, 1993 Figs 1D , 5C , 15 , 16 ; Table 3 Gonaxia elegans Vervoort, 1993: 19 C, 21B–C, 22.— Galea, 2016: 13 , fig. 4B–D. Material examined. KANACONO, Stn. CP 4691, MNHN-IK-2015-2669: two colonies, of which one is 10 cm high and bears ♂ gonothecae, while the other is 5 cm high and sterile; GenBank: MZ 099696 (16S), MZ 099684 (18S), MZ 099669 (28S).—KANACONO, Stn. DW 4728, MNHN-IK-2015-2666: two sterile colonies, both 5.5 cm high; GenBank: MZ 099697 (16S).—KANADEEP, Stn. DW 5027, MNHN-IK-2019-2064: a 4 cm high colony bearing ♀ gonothecae . Remarks. For descriptions of this quite easily-recognizable species, refer to both Vervoort (1993) and Galea (2016) . Bathymetric distribution. Between 150–850 m ( Vervoort 1993 ; Galea 2016 ; present study).