The taxonomy and phylogeny of Cones

Many questions are raised as to how cone specimens should be named or labelled. The problems have arisen above species level within the family tree ie generic and supra-generic names, where different approaches have been proposed which have produced conflicting results in the use of genus and family names.

Below, you can view a spreadsheet document which lists for each species the genus, subgenus and family names for each of the three methodologies which have been proposed ie the traditional Conidae as one family and one genus Conus; the 2009 proposal by Tucker & Tenorio based on shell morphology and radula features; the 2014 proposal by Puillandre et al which developed a phylogenetic tree based on a DNA study of 300 plus species.

Listing (As at September 2014)

The precise meaning of the term “species” is the subject of some debate but there is convergent understanding that two specimens which can interbreed are considered the same species. The challenge is how to prove the lack of interbreeding ability in different specimens or populations. Substitute criteria highlighting differences are widely used to infer this lack of interbreeding such as morphology of the shell, radula features, biological anatomy and feeding habits etc.

The meanings of genus, subgenus and family are even more loosely defined. The term “genus” has been considered as a group of species with a closely related lineage. Terms such as “family” represent amalgamations of the genera and species. The purpose of this naming hierarchy is to provide a means of simple communication which leads to common understanding.

Whilst several authors have introduced “above species” names for groups of cones, very few hypotheses ever reached the status of being widely accepted and used consistently in literature. Such acceptance is perhaps the hardest criteria for any newly proposed grouping to meet.

In 2009, John Tucker and Manuel Tenorio published a classification grouping which proposed splitting Conidae into 5 families with 89 genus names replacing the single genus name Conus. Their work used statistical techniques and was based on key identification factors of the shell morphology and the radula features. The number of genus names in this classification has been refined to approximately 115. Their proposals have been used in many recent publications and by Cone Collectors

DNA analysis has also been progressing. This technique used on selected genes can indicate the level of similarity of the gene structure of specimens and can be statistically interpreted to provide a family tree of the species showing their lineage going back to geological times. In 2014, a phylogenetic analysis was undertaken on 329 out of approx 800 accepted cone species by Nicolas Puillandre and several other noted authors. The DNA analysis indicated that there were 4 main groups; the resulting publication of the results reflected these groups as one family ie Conidae with 4 genera; Conus , Conasprella, the deep water cones Profundiconus and a single member group Californiconus.

The decision to consider Conidae as one family was based on DNA work which had sampled specimens from many families, estimated the evolutionary structure of the Conus species and tried to relate the positioning to accepted genus and family names in similar groups ie Terebridae, Turridae etc

A second paper by Puillandre et al proposed a new classification for Conidae analysing the key groups in the phylogenetic tree and proposed 71 groups within the 4 genera, which were incorporated as subgenera. Except for the difference in generic rank approx 50% of the subgenera names for species are the same name proposed as genera by Tucker and Tenorio. The selection and naming of groups within the phylogenetic tree as subgenera also considered other factors such as shell morphology, types of prey, bathymetric data

Three approaches therefore are available for use. Acceptance will be dictated by their use in future scientific publications

1)Conidae ;one Family-one genus used by those who await acceptance of the more recent approaches.

2)Cones are 5 Families(Conidae,Conilithidae,etc ) 115 genera based on shell morphology and radula features as proposed by Tucker & Tenorio

3)Conidae a single family with 4 genera and 71 subgenera proposed following DNA analysis and judgements applied to the resulting phylogenetic tree.

With the support and cooperation of Nicolas Puillandre, we are able to offer a spreadsheet list which includes the overall naming structure for each species name for the two classifications as at the time of publication in September 2014.

The spreadsheet has the following columns:

Name: The names which are valid species within WoRMS database were chosen.

Three columns with classification by Tucker & Tenorio and whether they proposed the name as valid species or synonym.

Status as valid species in WoRMS database

Status regarding whether this name was DNA sequenced or positioned in classification using other criteria.

Two columns with classification proposed by Puillandre et al.

At the end of spreadsheet is a table showing names used in T&T but not considered valid and reasons for their omission.

References:

Systematic Classification of Recent and Fossil Conoidean Gastropods by John K Tucker and Manuel Tenorio.

Molecular phylogeny and evolution of the cone snails (Gastropoda, Conoidea). May 2014 in Molecular Phylogenetics and Evolution

Puillandre N, Bouchet P, Duda TF Jr, Kauferstein S, Kohn AJ, Olivera BM, Watkins M, Meyer C.

One, four or 100 genera? A new classification of the cone snails. September 2014 in Journal of Molluscan studies

N. Puillandre, T. F. Duda, C. Meyer, B. M. Olivera and P. Bouchet.