Post-1958 new families for new living species.

Most changes in the number of extant families recognized (for example, between 450 in Nelson, 1976 and 515 in Nelson, 2006) results from lumping and splitting of existing families—usually as a result of cladistic analysis, but sometimes for just subjective preferences. Occasionally, however, and most excitingly, a new species is discovered that is so distinct that a new family is recognized for it at the time of its description.
The following are examples of such cases since 1959.

DENTICIPITIDAE—established in 1959 by H.S. Clausen for Denticeps clupeoides, Denticle Herring, Clausen, 1959, a freshwater fish of Nigeria. This family is still recognized as valid with one species (Nelson,2006:128-129).

GRASSEICHTHYIDAE — established in 1964 by J. Géry for Grasseichthys gabonensis Géry 1964, a freshwater fish of Gabon, Africa. Recognized in Kneriidae in Nelson (1976-2006).

HEXATRYGONIDAE —established in 1980 by P.C. Heemstra and M. M. Smith for Hexatrygon bickelli Heemstra & Smith, 1980,Sixgill Stingray, a marine fish in the Indo-West Pacific. This family is still recognized as valid and probably with one species (Nelson,2006:77), although other nominal species have been described.

SUNDASALANGIDAE — established in 1981 by T.R. Roberts for Sundasalanx praecox Roberts, 1981. The freshwater sundaland noodlefishes of southeast Asia, with about 7 species, are now thought to be clupeoids. Although provisionally recognized as a subfamily of Clupeidae in Nelson (2006:13), they could continue to be recognized at the family level.

MEGACHASMIDAE — established in 1983 by L.R.Taylor, Jr., L.J.V. Compagno, and P.J. Struhsaker for Megachasma pelagios Taylor, Compagno & Struhsaker, 1983, Megamouth Shark, a marine fish in the Atlantic, Indian, and Pacific oceans. This family is still recognized as valid with one species (Nelson,2006:58-59).

LACANTUNIIDAE—established in 2005 by R. Rodiles-Hernández, D. Hendrickson, and J.G. Lundberg in a paper by R. Rodiles-Hernández, D. Hendrickson, J.G. Lundberg, and J.M. Humphries for Lacantunia enigmatica Rodiles-Hernández, Hendrickson & Lundberg, 2005. This freshwater catfish known from the Río Lacantún, southern Mexico, although given in Nelson (2006:163), was described too late to be incorporated in the classification. For now, it may be placed near Ictaluridae.

But more generally—
ANCHARIIDAE. There are many examples of families being erected for species described much earlier. Here is a recent and particularly interesting case for the freshwater catfish family Anchariidae.
     According to Ng, H. H., and J. S. Sparks, 2005 [Ichthyol. Explor. Freshwaters 16(4):303-323], Stiassny, M.L.J. and N. Raminosoa,1994 [The fishes of the inland waters of Madagascar. pp133-149. In: G.G. Teugels, J.-F. Guégan and J.-J. Albaret (eds.) Biological diversity of African fresh- and brackish water fishes. Ann. Mus. R. Afr. Centr., Sci. Zool. 275], placed Ancharius in its own family, but without justification. Ng and Sparks in above 2005 article diagnosed the family, endemic to Madagascar, but considered it of uncertain affinity, and with two genera, Ancharius and Gogo (which they described as a new genus), with 5 species. The type species of the type genus of the family is Ancharius fuscus Steindachner, 1880 of Madagascar .
     Ancharius was placed in Nelson (2006:176), based on T.-P. Mo (1991), in Mochokidae, but has generally been recognized in Ariidae. Further taxonomic changes may be expected once the sister group of the Anchariidae clade is known.

1 family or 3? – an example

As noted in Nelson (2006:200), some authors recognize the three subfamilies of Salmonidae at the family level, either as two families (Coregonidae and Salmonidae) or three (Coregonidae, Salmonidae , and Thymallidae. Since these three taxa form a monophyletic clade, it is purely subjective whether we lump or split. This is also an old issue and D.S. Jordan in his 1923 classification of fishes recognized three families (but with more genera than presently recognized).

Major changes in families—an example

D.S. Jordan in his 1923 classification of fishes recognized the family Galeidae for many genera of sharks that are now placed in Scyliorhinidae, Leptochariidae, Triakidae, Hemigaleidae, and Carcharhinidae, with Galeus placed in Scyliorhinidae .
Currently, there is no Galeidae recognized! Why (in terms of names used, not the taxonomic treatment) do we recognize Galeidae as a synonym of Scyliorhinidae, Carcharhinus (placed by Jordan in Galeidae) as type of Carcharinidae and all plced in the order Carchariniformes, superorder Galeomorphi?
The answer—please discover it yourself . To appreciate fully why changes occur, students must not only be familiar with the principles of systematics, but students of ichthyology should become familiar with the code of the International Commission of Zoological Nomenclature (ICZN) in the fourth edition of the “International Code of Zoological Nomenclature” published in 1999 and effective 1 January 2000. The rules of the Code regulate only the family group, genus group, and species group names (Article 1.2.2). Sometimes the Code is difficult to interpret or its hard to find the relevant Article, and sometimes people differ in their interpretation (who is “right”). There is a need for the younger generation of ichthyologists to understand the rules of nomenclature as they proceed with their high-powered research, or I fear that in a few years we will be left with a new generation unable to deal with nomenclatural issues. I encouage young ichthyologists to become familiar with both the Code (& see http://www.iczn.org/) and the Bulletin of Zoological Nomenclaure (& see http://www.iczn.org/new%20the%20Bulletin.htm).

Items relating to orthography of family names Nelson (2006) — see Preface xii (yes, please read the Preface!);  34; 182-183; 228.

Joseph S. Nelson. 22 Feb 2006