Heteroxyidae Dendy, 1905

Santos, George Garcia, Pinheiro, Ulisses, Hajdu, Eduardo & Soest, Rob Van, 2016, New Genus and species of Heteroxyidae from Brazil (Axinellida: Demospongiae: Porifera), with a revised identification key for the family, Zootaxa 4158 (1), pp. 105-116 : 106-107

Family Heteroxyidae Dendy, 1905

Synonymy: Desmoxyidae Hallmann, 1917: 649 .

Definition (emended from Hooper (2002; as Desmoxyidae ); additions highlighted in boldface). Axinellida with smooth or spined, usually centrangulate microxea microscleres, or modified forms usually forming an ectosomal skeleton.

Diagnosis (emended from Hooper (2002; as Desmoxyidae ); additions highlighted in boldface). Encrusting, saccular, alveolar, massive or ramose sponges often with hispid or conulose surfaces bearing smooth or spined microxea/ acanthomicrostrongyles microscleres, often centrangulate or strongly bent centrally, sometimes acanthose and rhabdose, usually found on the ectosome, sometimes also with raphides occurring singly or in bundles (trichodragmata), or acanthose cladotoxa and birotules in one genus; megascleres monactinal (styles or tylostyles), diactinal (oxeas, strongyles) or both, may present modifications at the ends; choanosomal skeleton a confused arrangement of single spicules or widely spaced reticulate bundles of multispicular fibres, with little spongin, with poorly developed or no axial compression, and a relatively poorly differentiated extra-axial skeleton (disorganized-plumose); cortex absent in one genus.

Remarks. According to van Soest et al. (2016) Heteroxyidae comprises Acanthoclada Bergquist, 1970 ; Alloscleria Topsent, 1927 ; Desmoxya Hallmann, 1917 ; Didiscus Dendy, 1922 ; Heteroxya Topsent, 1898 ; Julavis de Laubenfels, 1936 ; Microxistyla Topsent, 1928 ; Myrmekioderma Ehlers, 1870 ; Negombo Dendy, 1905 ; Parahigginsia Dendy, 1924 .

Recent results derived from molecular phylogenies ( Morrow et al. 2012; Redmond et al. 2013) confirmed that Halichondrida (current Axinellida or Suberitida sensu Morrow & Cardenas 2015) is a non-monophyletic taxon (Erpenbeck et al. 2005; Erpenbeck & van Soest 2005; Erpenbeck et al. 2012; Morrow et al. 2012; Morrow & Cardenas 2015). Family-level taxa within this order are also polyphyletic, or likely so (e.g. Boury-Esnault 2006). Chombard (1998) and Chombard & Boury-Esnault (1999), using the 28S rDNA marker, first revealed a close relationship between Halichondriidae and Suberitidae and not with other families assigned to Halichondrida . Chombard & Boury-Esnault (1999) proposed the name Suberitina (= Suberitida) for this new clade. This clade was consistently confirmed in subsequent molecular phylogenetic studies, using more taxa and additional markers (e.g. Morrow et al. 2012; Morrow & Cardenas 2015). The other Halichondrida families were distributed amongst other clades: Axinellidae and Heteroxyidae in a well-supported clade for which the resurrected order name was Axinellida (see Morrow & Cardenas 2015). The finding by Morrow et al. (2012; PHASE analysis of 28S rRNA) that some heteroxyid genera cluster in a clade that includes Stelligera Gray, 1867 (strong posterior probability and bootstrap support), and is sister to the Raspailiidae Nardo, 1833 (Poecilosclerida) , prompted resurrection of Stelligeridae Lendenfeld, 1898 by these authors, who tentatively assigned all heteroxyid genera to this family, in view of the different conceptual framework proposed. This suggested amendment to the Porifera classification is already in use in the World Porifera Database (WPD), to which we prefer to adhere for stability reasons. Furthermore, the phylogenetic assignment of Heteroxya has not yet been verified by molecular techniques, so that it is premature to discard the possibility that Heteroxyidae may still have a place in the classification.