Unlike CranchiinaePfeffer, 1912, the other subfamily within CranchiidaeProsch, 1847, Taoniinae all lack cartilaginous strips that extend back from the funnel-mantle point of fusion. Their funnels are free laterally, and they have one to three photophores on the eyes.[3] The largest photophore is crescent-shaped for most genera, but it's triangular in Helicocranchia, a semicircle in Bathothauma, and circular in Sandalops. This is in contrast to glass squids in the subfamily Cranchiinae, which have at least four small photophores which are round or oval.[2]
In addition, males lack hectocotyli; these are arms that have evolved to specialize in the storage and transfer of spermatophores to females.[4] Taoniinae are also often larger than Cranchiinae and have darker beaks.[5] Another characteristic is that Taoniinae's caecum, is smaller than its stomach; in Cranchiinae, the caecum is larger than the stomach.[6]
Synonyms of Taoniinae include Galiteuthinae Berry, 1912 and Teuthoweniinae Grimpe, 1922.[2]S. Stillman Berry's 1912 circumscription of the subfamily Galiteuthinae only consisted of its type genus GaliteuthisJoubin, 1898. Like Pfeffer's Taoniinae, this was a subfamily within the family CranchiidaeProsch, 1847. This was in contrast to Louis Joubin's classification, which placed Galiteuthis in a new, distinct family: CranchionychiaeJoubin, 1898.[14][2]Georg Grimpe's 1922 circumscription of Teuthoweniinae included its type genus TeuthoweniaChun, 1910 as well as HensenioteuthisPfeffer, 1900,[h]HelicocranchiaMassy, 1907, and SandalopsChun, 1906. He placed the genus BathothaumaChun, 1906 into a new family, Bathothaumatidae Grimpe, 1922, now just treated as a junior synonym of Cranchiidae. Subsequent research did not pay much heed to Grimpe's taxonomy.[2]
As of 2017[update], the World Register of Marine Species classifies the Taoniinae as containing ten genera; they classify Belonella as a synonym of Taonius following Nancy A. Voss.[18] However, Patrizia Jereb and Clyde F. E. Roper recognize Belonella as a distinct genus from Taonius, although they also note they are frequently synonymized. Jereb and Roper also note Kir Nazimovich Nesis and Takashi Okutani as teuthologists who rejected Voss's synonymization of Belonella.[6] Nesis's classification had Taonius consisting of only the single species T. pavo, and had Belonella consisting of B. beloneChun, 1906, B. borealisNesis, 1972 and an undescribed species from the Antarctic.[19]
^ abPfeffer, Georg (1912). "Unterfamilie Taoniinae". Die Cephalopoden der Plankton-Expedition: Zugleich eine monographische Übersicht der Oegopsiden Cephalopoden. Erbebnisse der Plankton-Expedition der Humboldt-Stiftung. Vol. 2(a). Kiel & Leipzig: Lipsius & Tischer. pp. 695–755.
^Imber, M. J. (1978). "The squid families Cranchiidae and Gonatidae (Cephalopoda: Teuthoidea) in the New Zealand region". New Zealand Journal of Zoology. 5 (3): 453. doi:10.1080/03014223.1978.10428331.
^ abRoper, Clyde F. E.; Jereb, Patrizia (2010). "Family Cranchiidae Prosche, 1847". In Jereb, P.; Roper, C. F. E. (eds.). Cephalopods of the World: An Annotated and Illustrated Catalogue of Cephalopod Species Known to Date. Volume 2: Myopsid and Oegopsid Squids. FAO Species Catalogue for Fishery Purposes. Vol. 4. Rome: Food and Agriculture Organization of the United Nations. p. 158.
^Voss, Nancy A. (1988). "Evolution of the Cephalopod Family Cranchiidae (Oegopsida)". In Clarke, M. R.; Trueman, E. R. (eds.). Paleontology and Neontology of Cephalopods. The Mollusca. Vol. 12. San Diego: Academic Press. p. 296. doi:10.1016/B978-0-12-751412-3.50024-3. ISBN978-0-12-751412-3.
