Mammilla Schuhmacher, 1817

Hollmann, Thomas Huelsken Daniel Tapken Tim Dahlmann Heike Wägele Cynthia Riginos Michael, 2012, Systematics and phylogenetic species delimitation within Polinices s. l. (Caenogastropoda: Naticidae) based on molecular data and shell morphology, Organisms Diversity & Evolution (New York, N. Y.) 12 (4), pp. 349-375 : 371-372

Genus Mammilla Schuhmacher, 1817

Considering the paraphyletic arrangement of Polinices , with Mammilla grouping within the former clade in some of the phylogenetic analyses ( Figs. 2 , 3 and 4 ), the question may be posed whether Mammilla should be classified as a subgenus of Polinices . Despite a close genetic relationship between Mammilla and Polinices , both taxa are well separated by their distinct conchological characters (see Fig. 1). The phylogenetic trees show increasing resolution of Mammilla and Polinices from slow to fast evolving genes ( Figs. 2 , 3 ; Supplementary Figs. S1, S2), suggesting that Mammilla and Polinices represent two independent genera which were separated from each other more recently.

As mentioned above, the genus Mammilla in earlier classifications has been described occasionally as closely related to the Sininae . In his compilation of the Naticidae from Fiji, Cernohorsky (1971) stated that Eunaticina (subfamily Sininae ) “… may represent an intermediate group between Mammilla and Sinum …”. Mammilla and Sinum thus have been considered closely related taxa by Cernohorsky (1971), an idea that, amongst others, was later also taken up by Kabat (1996). Our morphological analyses indicate a high conchological concordance between members of these two taxa, such as the depressed shell shape, the thin shell, the shell texture, the widened aperture and the reduced operculum in some Mammilla species. As the molecular data presented here support a very close relationship between Mammilla and Polinices species, we conclude that the apparently similar shell characters in Sinum and Mammilla must have evolved independently at least twice within the Naticidae .

Figures

Fig. 2 Phylogram obtained through Bayesian inference based on the concatenated data set (COI, 16S, 18S, 28S, H3) for a reduced number of taxa. Posterior probabilities are indicated at the nodes. Branches supported by values>0.95 are indicated in bold. Polytomies are due to the cut-off value specified for the consensus tree (50 % used as the default value in MrBayes)

Fig. 3 Phylogram obtained through Bayesian inference based on the COI gene fragment. Posterior probabilities are indicated at the nodes. Branches supported by values>0.95 are indicated in bold. Polytomies are due to the cut-off value specified for the consensus tree (50 % used as the default value in MrBayes)

Fig. 4 NeighborNet network based on the concatenated data set (COI, 16S, 18S, 28S, H3). Bootstrap values are indicated