Taoniinae is a subfamily containing ten genera of glass squids.

Description

Right eye of T. pellucida.

Unlike Cranchiinae Pfeffer, 1912, the other subfamily within Cranchiidae Prosch, 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. 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.

In addition, males lack hectocotyli; these are arms that have evolved to specialize in the storage and transfer of spermatophores to females. Taoniinae are also often larger than Cranchiinae and have darker beaks. Another characteristic is that Taoniinae's caecum, is smaller than its stomach; in Cranchiinae, the caecum is larger than the stomach.

Taxonomic history and synonyms

When Georg Johann Pfeffer circumscribed this subfamily in 1912, he grouped its genera into three tribes:

  • Taonius-like Taoniinae Phasmatopsis Rochebrune, 1884 Toxeuma Chun, 1906 Taonius Steenstrup, 1861 Desmoteuthis Verrill, 1881 Megalocranchia Pfeffer, 1884 Taonidium Pfeffer, 1900 Crystalloteuthis Chun, 1906 Phasmatoteuthion Pfeffer, 1912 Galiteuthis Joubin, 1898 Corynomma Chun, 1906
  • Teuthowenia-like Taoniinae Teuthowenia Chun, 1910
  • Bathothauma-like Taoniinae Bathothauma Chun, 1906

Synonyms of Taoniinae include Galiteuthinae Berry, 1912 and Teuthoweniinae Grimpe, 1922. S. Stillman Berry's 1912 circumscription of the subfamily Galiteuthinae only consisted of its type genus Galiteuthis Joubin, 1898. Like Pfeffer's Taoniinae, this was a subfamily within the family Cranchiidae Prosch, 1847. This was in contrast to Louis Joubin's classification, which placed Galiteuthis in a new, distinct family: Cranchionychiae Joubin, 1898. Georg Grimpe's 1922 circumscription of Teuthoweniinae included its type genus Teuthowenia Chun, 1910 as well as Hensenioteuthis Pfeffer, 1900, Helicocranchia Massy, 1907, and Sandalops Chun, 1906. He placed the genus Bathothauma Chun, 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.

Phylogeny

Below is Nancy A. Voss and Robert S. Voss's 1983 proposal for a phylogeny of the Taoniinae subfamily.

Bathothauma Chun, 1906 Helicocranchia Massy, 1907 Sandalops Chun, 1906 Liguriella Issel, 1908
Bathothauma Chun, 1906 Helicocranchia Massy, 1907 Sandalops Chun, 1906
Bathothauma Chun, 1906 Helicocranchia Massy, 1907 Sandalops Chun, 1906
Bathothauma Chun, 1906 Helicocranchia Massy, 1907
Bathothauma Chun, 1906 Helicocranchia Massy, 1907
Bathothauma Chun, 1906
Bathothauma Chun, 1906
Helicocranchia Massy, 1907
Sandalops Chun, 1906
Liguriella Issel, 1908
Mesonychoteuthis Robson, 1925 Galiteuthis Joubin, 1898 Taonius Steenstrup, 1861 Teuthowenia Chun, 1910 Megalocranchia Robson, 1925 Egea Joubin, 1933
Mesonychoteuthis Robson, 1925 Galiteuthis Joubin, 1898 Taonius Steenstrup, 1861 Teuthowenia Chun, 1910 Megalocranchia Robson, 1925 Egea Joubin, 1933
Mesonychoteuthis Robson, 1925 Galiteuthis Joubin, 1898 Taonius Steenstrup, 1861
Mesonychoteuthis Robson, 1925 Galiteuthis Joubin, 1898
Mesonychoteuthis Robson, 1925
Galiteuthis Joubin, 1898
Taonius Steenstrup, 1861
Teuthowenia Chun, 1910 Megalocranchia Robson, 1925 Egea Joubin, 1933
Teuthowenia Chun, 1910 Megalocranchia Robson, 1925 Egea Joubin, 1933
Teuthowenia Chun, 1910
Megalocranchia Robson, 1925 Egea Joubin, 1933
Megalocranchia Robson, 1925 Egea Joubin, 1933
Megalocranchia Robson, 1925 Egea Joubin, 1933
Megalocranchia Robson, 1925
Megalocranchia Robson, 1925
Egea Joubin, 1933

Genera and species

Taonius borealis
Taonius pavo

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. 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. Nesis's classification had Taonius consisting of only the single species T. pavo, and had Belonella consisting of B. belone Chun, 1906, B. borealis Nesis, 1972 and an undescribed species from the Antarctic.

Notes

External links