Afonsoconus Tucker & Tenorio, 2013

Tenorio, Manuel J., Monnier, Eric & Puillandre, Nicolas, 2018, Notes on Afonsoconus Tucker & Tenorio, 2013 (Gastropoda, Conidae), with description of a new species from the Southwestern Indian Ocean, European Journal of Taxonomy 472, pp. 1-20 : 8-10

Genus Afonsoconus Tucker & Tenorio, 2013

Type species

Chelyconus kinoshitai Kuroda, 1956 , by original designation.

Diagnosis

SHELL ( Fig. 1 A–H). Elongated conical to cylindrical shell; spire low and conical in shape; posterior notch deep and cords present on whorl tops; columella twisted, but without anterior notch; shell and spire coloration variable; operculum small, ovate-shaped; periostracum thin and translucent, with multiple fine spiral rows of small tufts.

RADULAR TOOTH ( Fig. 1 I–J). Narrow and elongated, with a large to medium relative size; waist indistinct; anterior section equal or slightly longer than the posterior section; tooth serrated with a fairly long row of small serrations; terminating cusp small; barb and blade very short; blade barely twice as long as barb; base large; basal spur present; basal ligament present (not shown in Fig. 1 I–J).

Geographic distribution

The species included in the genus occur in the Indo-Pacific region.

Geologic range

Recent.

Remarks

Afonsoconus is here treated as a genus, following Tucker & Tenorio (2013) and Monnier et al. (2018), but Puillandre et al. (2014) ranked it as a subgenus within Conus .

There are currently two species included in genus Afonsoconus (WoRMS editorial board 2018).A number of taxon names associated with A. kinoshitai are considered synonyms (forms). These are tamikoanus Shikama, 1973, calliginosus Shikama, 1979 and brontodes Shikama, 1979 , and were already presented in the Introduction (vide supra). The name Conus (Chelyconus) wistaria Shikama, 1970 has occasionally been associated to A. kinoshitai especially among amateur shell collectors, but the name actually applies to a color form of Pionoconus fulmen ( Röckel et al. 1995; Filmer 2012; Tucker & Tenorio 2013).

The food habits of the species in Afonsoconus are not known, but the radular morphology ( Fig. 1 I–J) suggests that they prey on worms. Based upon conotoxin analysis, it has been inferred that A. kinoshitai is a piscivorous species ( Bulaj et al. 2005; Puillandre et al. 2010). However, this is not supported by direct observation of prey capture ( Olivera et al. 2015). In analogous fashion, other species of Conidae in the genera Embrikena Iredale, 1937 and Asprella have been considered piscivorous based upon the presence of certain conotoxins in their chemical repertoire ( Olivera et al. 2015). However, this assumption is not supported either by direct observation of prey capture nor by the morphology of the respective radular teeth of these species, which are more consistent with a vermivorous feeding mode ( Tucker & Tenorio 2013). Several conotoxins have been identified for A. kinoshitai , most notably the μ-conotoxin μ-KIIIA ( Bulaj et al. 2005; Zhang et al. 2007; Khoo et al. 2009). This conotoxin blocks mammalian neuronal tetrodotoxin (TTX) resistant voltage-gated sodium channels (VGSCs) and is a potent analgesic ( Bulaj et al. 2005; Zhang et al. 2007; McArthur et al. 2011).

Phylogenetic analyses

Afonsoconus is recovered as a monophyletic group with high support (Posterior Probability PP = 1) ( Fig. 3 ). The Afonsoconus clade is sister to the Textilia clade ( Puillandre et al. 2014), which contains fish-eating species characterised by their polished and shining subcylindrical to cylindrical shells ( Fig. 2 ), and by their harpoon-shaped radular teeth ( Fig. 2 ). Afonsoconus is clearly split in three subclades, each of them fully supported (PP = 1), and with high genetic distances between them (> 8%). Conversely, genetic distances within each subclade are all <1%, except between the two samples of kinoshitai , with a genetic distance of 5.4%. The three subclades correspond to different geographic regions, one with specimens from the Philippines, another with specimens from New Caledonia, and a third one containing the specimens from the Mozambique Channel (BIOMAGLO expedition). The specimens from the Philippines and New Caledonia correspond respectively to the species A. kinoshitai and A. bruuni . According to the phylogenetic relationships and the genetic distances, the specimens from the Mozambique Channel deserve specific status, and this new species is hereby introduced. It is interesting to note that the observed p-distance between the two specimens of A. kinoshitai from GenBank (sequences FJ937341.1 and KJ550543.1) is consistent with a separation at the species level, as found for other species of cone snails (e.g., Duda et al. 2008; Puillandre et al. 2011). Both specimens come from the Philippines, and one of them (sequence KJ550543.1) appears labelled in GenBank as Conus kinoshitai tamikoae (= tamikoanus). Given the fact that the tamikoanus from Japan / China is a synonym (form) of A. kinoshitai , as recognised by its author in Shikama (1979), the results of the phylogeny actually suggest that there may be at least two different species of Afonsoconus in the Philippines. If we accept that the specimen associated with the sequence FJ937341.1 is A. kinoshitai , the other one would be a putative new species, morphologically similar to the form tamikoanus according to its label. The specimens from the Philippines labelled as tamikoanus are treated as a subspecies of A. bruuni in Raybaudi-Massilia (2008) , or as a full species in Monnier et al. (2018). It is likely that the tamikoanus -like specimen in GenBank is a representative of the taxon featured in Raybaudi-Massilia (2008) and in Monnier et al. (2018). Unfortunately, no voucher specimen or photo thereof is associated with the GenBank sequence KJ550543.1, so any further taxonomical claim on this matter would be merely speculative at this stage.

Description of new species

Figures

Fig. 3. Bayesian phylogenetic tree. Posterior probabilities (above 0.95) are indicated for each node. Sequences are labelled with the MNHN registration number or the GenBank accession number, and the species name.

Fig. 2. A. Pionoconus fulmen (Reeve, 1843), specimen from Kii Peninsula, Wakayama prefecture, Japan, 51.9 mm (INHS 44603). B. Textilia bullatus (Linnaeus, 1758), specimen from Ua Huka, Baie Kuiapaku, Marquesas Archipelago, 58.1 mm (MNHN IM-2012-20656). C–D. Textilia dusaveli (H. Adams, 1872). C. Specimen from off Balut Island, Mindanao, Philippines, 260 m, 82.1 mm (INHS 44868). D. Radular tooth, specimen from New Caledonia, SL 67.0 mm (MJT). Scale bars = 10 mm, unless otherwise stated.