Varioconus mercator ( Linnaeus, 1758 ) Tenorio & Abalde & Pardos-Blas & Cmim, 2020

Tenorio, Manuel J., Abalde, Samuel, Pardos-Blas, José R. & Zardoya, Rafael, 2020, Taxonomic revision of West African cone snails (Gastropoda: Conidae) based upon mitogenomic studies: implications for conservation, European Journal of Taxonomy 663 (663), pp. 1-89 : 70-72

Varioconus mercator ( Linnaeus, 1758) comb. nov.

Fig. 11 A–G

Conus mercator Linnaeus, 1758: 750 .

Cucullus aurelius Röding, 1798: 47 .

Conus lamarckii Kiener, 1847: 240 , pl. 83, fig. 4.

Conus orri Ninomiya & da Motta in da Motta, 1982: 15, fig. 14. syn. nov.

Conus cacao Ferrario, 1983: 146 .

Lautoconus senegalensis Gulden et al., 2017: 49 , figs 1–5.

Lautoconus fernandi Petuch & Berschauer, 2018: 166 , figs 2a–b. syn. nov.

Lautoconus gambiensis Petuch & Berschauer, 2018: 167 , figs 2c–e. syn. nov.

Lautoconus rikae Petuch & Berschauer, 2018: 169 , figs 3a–c. syn. nov.

Lautoconus stimpsonorum Cossignani & Allary, 2019: 23 . syn. nov.

Conus mercator – Monteiro et al. 2004: 58, pls 27–28.

Conus cacao – Monteiro et al. 2004: 32, pl. 34.

Material examined

Lectotype

Lectotype at LSL 254 ( Fig. 11A , 24.0 mm). Type locality not known.

Other material

SENEGAL • 1 spec., 34.7 mm; Gorée Island , Dakar; 14º40ʹ16ʺ N, 17º23ʹ57ʺ W; 3 Jul. 2015; MNCN exped.; GenBank mitochondrion, partial genome: KY801854 ; MNCN 15.05/78482 ( Fig.11B ) • 1 spec.; Ndayane, Petite Côte ; 14º33ʹ59ʺ N, 17º8ʹ3ʺ W; 2 Jul. 2015; MNCN exped.; GenBank mitochondrion, partial genome: KY801857 ; MNCN 15.05/78463 • 1 spec.; same locality as for preceding; 2 Jul. 2015; MNCN exped.; GenBank mitochondrion, partial genome: KY801856 ; MNCN 15.05/78473 • 1 spec., 39.1 mm; Les Almadies , Dakar; 14º44ʹ43ʺ N, 17º31ʹ44ʺ W; 6 Apr. 2014; MNCN exped.; GenBank mitochondrion, partial genome: KY801864 ; MNCN 15.05/78419 ( Fig. 11C ) • 1 spec., 35.5 mm, holotype of Lautoconus stimpsonorum ; Pointe des Almadies , Dakar; 3–8 m depth; MNHN .

GAMBIA • 1 spec., 35.4 mm, holotype of Lautoconus fernandi ; off Tanji beach ; MNHN IM-2000- 34012 ( Fig. 11D ) • 1 spec.; same collection data as for preceding; 19 Feb. 2019; L. Tamagnini leg.; GenBank mitochondrion, partial genome: MT240813 ; MNCN 15.05/90440 • 1 spec., 21.6 mm, holotype of Lautoconus gambiensis ; off Tanji beach ; MNHN IM-2000-34013 ( Fig. 11E ) • 1 spec.; same collection data as for preceding; 19 Feb. 2019; L. Tamagnini leg.; GenBank mitochondrion, partial genome: MT240812 ; MNCN 15.05/90437 • 1 spec., 17.9 mm, holotype of Lautoconus rikae ; off Tanji beach ; MNHN IM-2000-34014 ( Fig. 11F ) • 1 spec.; same collection data as for preceding; 19 Feb. 2019; L. Tamagnini leg.; GenBank mitochondrion, partial genome: MT240814 ; MNCN 15.05/90442 • 1 spec., 30.1 mm, paratype of Conus orri ; Bojol Island , Soliflor Point ; SNMS ZI0091234 ( Fig. 11G ) .

Geographical distribution

Senegal (Dakar area, Petite Côte) and Gambia.

Conservation status in IUCN Red List

Endangered. Status revision required.

Remarks

This is one of the most classical species from Senegal. Specimens from Gorée Island ( Fig. 11B ) match perfectly the lectotype of this species ( Fig. 11A ), which is widely distributed from Dakar area to the south. This is a polymorphic species. Several taxon names introduced in the literature as distinct species (e.g., cacao and senegalensis ) correspond to the taxon V. mercator . Abalde et al. (2017b) showed that two different morphs identified as V. mercator , one from Goreé Island ( Fig. 11B ) and another from Pointe des Almadies ( Fig. 11C ), were actually separated by a genetic uncorrected p distance at exactly the threshold that delimits species. Based upon these grounds, the name V. stimpsonorum has been recently introduced for the population of mercator -like shells from Pointe des Almadies ( Cossignani & Allary 2019). However, the subtle differences in the reticulated shell pattern (coarse in V. stimpsonorum but fine in V. mercator ) do not justify the introduction of a new name. Furthermore, a transcriptomic study of the venom gland of two specimens of V. mercator , one from Almadies (i.e., form stimpsonorum ) and another from Ndayane (form cacao ), has shown that both individuals share a significant percentage of conotoxin precursors in their venom repertoires within the expected intraspecific variation ( Abalde et al. 2020). Therefore, we consider that the taxon V. stimpsonorum falls within the genetic and morphological variability of V. mercator and propose to consider it a mere form of the latter. Specimens of the species recently described from Gambia, including fernandi ( Fig. 11D ), gambiensis ( Fig. 11E ) and rikae ( Fig. 11F ), have been sequenced. The sequences of the mitogenomes of these taxa were almost identical, and showed a minimal divergence to that of V. mercator ( Fig. 2 ). The type material of the taxon Conus orri Ninomiya & da Motta, 1982 ( Fig. 11G ) described from Gambia is consistent with the observed variability of V. mercator . We therefore also consider orri as a synonym of the latter.

Conversely, a mitogenome examination has shown that certain names traditionally synonymized with V. mercator (e.g., reticulatus ) actually correspond to separate, valid species (see below). As it happens to most species living around the Dakar peninsula, V. mercator seems to be very resilient and has adapted very well to environments under heavy human influence as long as they are not affected by chemical or industrial contamination.

Figures

Fig. 11. A. Conus mercator Linnaeus, 1758, lectotype, 24.0 mm (LSL 254). B. Varioconus mercator (Linnaeus, 1758) comb. nov., 34.7 mm (MNCN 15.05/78482). C. Varioconus mercator f. stimpsonorum (Cossignani & Allary, 2019), 39.1 mm (MNCN 15.05/78419). D. Lautoconus fernandi Petuch & Berschauer, 2018, holotype, 35.4 mm (MNHN IM-2000-34012). E. Lautoconus gambiensis Petuch & Berschauer, 2018, holotype, 21.6 mm (MNHN IM-2000-34013). F. Lautoconus rikae Petuch & Berschauer, 2018, holotype, 17.9 mm (MNHN IM-2000-34014). G. Conus orri (Ninomiya & da Motta, 1982), paratype, 30.1 mm (SNMS ZI0091234). H. Conus reticulatus Born, 1778, lectotype, 25 mm (NHMW Mollusca 14159). I. Varioconus reticulatus (Born, 1778) comb. nov., 29.5 mm (MNCN 15.05/78439). J. Conus tacomae Boyer & Pelorce, 2009, holotype, 17 mm (MNHN IM-2000- 21046). K. Conus trencarti Nolf & Verstraeten, 2008, holotype, 26.3 mm (MNHN IM-2000-21455). L. Varioconus unifasciatus (Kiener, 1850) comb. nov., 39.8 mm (MNCN 15.05/78451). Scale bars = 10 mm.

Fig. 2. Phylogenetic relationships of West African cones and species delimitation. A time tree (relaxed molecular clock) was reconstructed following methods and calibrations in Abalde et al. (2017a). Dates are in million years. Bold names indicate new mitogenomes. A red line indicates the threshold (uncorrected p distance of 0.2%, based on the divergences between Africonus verdensis (Trovão, 1979) and its sister group and Varioconus guanche (Lauer, 1993) and its sister group) for species delimitation.