Genus Profundiconus Kuroda, 1956

Lizaconus da Motta, 1991 (type species: Asprella (Endemoconus?) teramachii Kuroda, 1956).

Type species

Chelyconus (?) (Profundiconus) profundorum Kuroda, 1956 (by original designation).

Description

SHELL CHARACTERS (Fig. 1). Conical to narrowly conical shell, usually thin, very small to very large in size; shoulders become rounded in outer whorls, although a ridge is present in some cases; a few cords present on early whorls and become numerous and smaller in outer whorls; nodules obsolete early; anal notch shallow; larval shell either paucispiral or multispiral; operculum large and serrate; periostracum smooth.

RADULAR TOOTH (Fig. 2). Blade and barb present (may be poorly differentiated); blade pointed, moderate in length, up to half length of anterior section of tooth; serrations absent; adapical opening large; a structure that we will refer to as external cusp (non-homologue of a posterior blade) starting at base of adapical opening and extending towards waist; external cusp often laterally expanded and serrated, with several small denticles (Fig. 2C, F); external cusp may appear partially covered by rolled sheet, which conforms to anterior portion of tooth; barb, blade and external cusp arranged in three different planes, which form angle of c. 120º between them; waist evident; characteristic fringe composed of closely spaced projections pointing towards apex present immediately below waist (Fig. 2C, F); anterior section of tooth shorter than posterior section; shaft fold present; slanted base with large basal spur.

INTERNAL ANATOMY (Figs 4–5). The internal anatomy of Profundiconus tuberculosus (Tomlin, 1937) (Fig. 1G) has been studied in detail by Taki (1937), and can be considered representative for other members of the genus. Taki’s work was reviewed by Röckel (1994). Some details of the external anatomy and radular apparatus of several other species of Profundiconus are presented in Rolán & Raybaudi-Massilia (1994). We hereby reproduce some of the figures from Taki (1937) (Figs 4–5) to illustrate the details of the internal anatomy in Profundiconus .

Taki (1937) remarked that the anatomical features of P. tuberculosus indicate in many aspects the ancestral nature of this species. The proboscis sheath (Fig. 3A: RS) has longitudinal folds on the inner side; the inner wall of the respiratory siphon (Fig. 3A–B: SI) is smooth, lacking the furrows or invaginations that have been reported in other species of cone snails; the osphradium (Fig. 3B: OS) is simple and not divided, with the small lobules arranged like feather banners on both sides of the longitudinal axis; there is only one salivary gland (Fig. 3B: SD), consisting of a multitude of small lobules.

The anterior lobe of the midgut gland (Fig. 4A: L1, L2) has a bifurcated excretory duct. The male genitalia (Fig. 4B) have been described in detail. The organs that Bergh (1896) described as testes are considered to be the prostate in the opinion of Taki (1937). The testis consists of two lobes (Fig. 4B: HA, HP), which are spirally coiled and reach the tip of the spire. The prostate (Fig. 4B: PG) is separated into three parts (PGA, PGD, PGS), with irregular shallow grooves on its surface. Both cerebral ganglia (Fig. 4C: C) largely merge with each other and can be distinguished only by a slight constriction in the middle; the right parietal and right visceral nerves (Fig. 4C: PA, V) go together as a single nerve from the subintestinal (IN) ganglion. They separate only after a prolonged course.

Geologic range

Cretaceous to Recent.

Geographic distribution

The Holocene species included in the genus (Table 2) occur in the Indo-Pacific region, except for Profundiconus emersoni (Fig. 1F), which occurs in the East Pacific region. Extinct species are known from the Indo-Pacific region and North America (Tucker & Tenorio 2009). For a listing of fossil species placed in the genus Profundiconus, see Tucker & Tenorio (2009).

Living species of Profundiconus Kuroda, 1956

Remarks

The shells of species in Profundiconus are morphologically related to species included in the fossil genus Conilithes Swainson, 1840 . Both taxa contain shells with square nodules that are interconnected by carinae on the body whorl, which constitutes a plesiomorphic trait. However, the anal notch is deep in Conilithes and shallow in Profundiconus . Furthermore, Rolán & Raybaudi-Massilia (1994) have suggested that Conilithes antidiluvianus (Bruguière, 1792) (Fig. 1E) and P. teramachii (Fig. 1B) are close relatives. Based upon similarities in shell morphology Tucker & Tenorio (2009) placed both genera, Conilithes and Profundiconus, within the family Conilithidae and separate from Conidae . However, shell traits can be ambiguous. The serrated operculum and the morphology of the radular tooth are more robust proxies for placing a given specimen in Profundiconus . The presence on the radular tooth of a laterally widened, often serrated external cusp, along with a characteristic fringe located immediately below the waist composed of closely spaced projections pointing towards the apex in addition to other morphological features (i.e., barb, pointed blade, shaft fold, etc.; see Fig. 2), allow the immediate identification of an individual as a member of Profundiconus . The function of the coronated fringe on the tooth in species of Profundiconus is unknown, but it resembles a similar structure (collar-shaped band of tubercles) observed on the radular teeth of several members of the genus Lienardia Jousseaume, 1884, family Clathurellidae, such as Lienardia tagaroae Fedosov, 2011, L. jousseaumei (Hervier, 1896) or L. cf. rosella Hedley, 1922 (Fedosov 2011; Bouchet et al. 2011).

Nothing is known about the diet of Profundiconus cone snails, nor about the families of conotoxins which might be present in the species of the genus. Whereas most of the toxinological studies on cone snails carried out during the last three decades have focused on species that belong to only a few lineages (Puillandre et al. 2012), several lineages remain largely understudied or even not studied at all, as is the case for Profundiconus (Puillandre et al. 2014) . Radular morphology suggests a most likely vermivorous diet. However, Marshall (1981) reported finding the beaks of a small cephalopod in the stomach of an adult specimen of P. smirnoides (identified as smirna) from Wanganella Bank, New Zealand. This suggests that this species might produce a conotoxin of sufficient potency to rapidly immobilize a fastmoving prey.

Phylogenetic analyses

Ingroup sequences included 657 bp containing 192 variable sites, of which 127 were phylogenetically informative. Excluding redundant sequences, 27 sequences were unique in the ingroup. The ML and BA tree topologies were congruent (Fig. 5) and supported Profundiconus as a monophyletic group (PP = 1; BP = 87%). Within Profundiconus, several clades corresponding to different species were recovered, although their phylogenetic relationships were poorly resolved (Fig. 5). The individuals belonging to P. teramachii were split into two separate monophyletic groups corresponding to different geographic regions, one with specimens from the Indian Ocean (Madagascar) and another with specimens from the Pacific Ocean (China, Papua New Guinea and Solomon Islands). This splitting has previously been reported and discussed by Puillandre et al. (2014). The specimens of P. teramachii from the Indian Ocean belong to the forma neotorquatus da Motta, 1985 (Tucker & Tenorio 2013). In the Indian Ocean this species is widely distributed, from Somalia to South Africa (Natal), including Madagascar. According to the phylogeny and the genetic distances, the specimens from Madagascar deserve specific status, i.e., Profundiconus neotorquatus (da Motta, 1984), rather than consideration as a mere form of P. teramachii . In spite of the molecular divergence that exists between P. neotorquatus and P. teramachii, the morphological differences in their shells (Fig. 1B–C) and radulae (Fig. 6) are slight.

The genetic differentiation of P. smirnoides and P. teramachii was not supported. Moreover, the monophyly of the group was not supported by the ML and BA analyses. Reciprocal monophyly between this group and P. neotorquatus was therefore not demonstrated. This is usually the case for recently diverged species, due to the lack of time needed to coalesce (Knowles & Carstens 2007). It is interesting to note that one of the cox1 sequences of P. smirnoides in GenBank (KJ550448) is essentially identical to that of P. teramachii, which represents the haplotype for 18 specimens (Table 1). As the voucher specimen (MNHN IM-2009-18244) seems to be properly identified, this could be due to contamination. However, there also exists the possibility that the cox1 can simply not separate these two species, which on the other hand can be easily separated based on shell and radular morphologies. There are many examples in the literature of morphologically distinct species having identical or almost identical cox1 sequences (e.g., Mengual et al. 2006; McGuire et al. 2007; April et al. 2011; Chee 2014). In most cases this has been attributed to hybridization-mediated mitochondrial introgression, as well as incomplete lineage sorting.

Specimens attributed a priori to the species Profundiconus loyaltiensis (Röckel & Moolenbeek, 1995) based on shell morphology were segregated into two distinct lineages. One of these lineages formed a monophyletic group (PP = 1; BP = 83%) along with specimens assigned to P. vaubani (Röckel & Moolenbeek, 1995) and P. kanakinus (Richard, 1983) . Furthermore, some specimens of P. vaubani and P. loyaltiensis share the same haplotype. It is not clear at this stage whether this indicates one single polymorphic species, contamination, or simply the failure to separate the three closely related species based upon the cox1 gene fragment only. All of these specimens come from the same area (Isle of Pines, South New Caledonia). The group of specimens from the Solomon Islands labelled as “ Profundiconus n. sp. cf. loyaltiensis ” was monophyletic and highly supported by BA and ML analyses (PP = 0.97; BP = 99). If we assume that the specimens from New Caledonia are the genuine representatives of a population of the taxon P. loyaltiensis, we have to postulate that the specimens from the Solomon Islands belong to a separate group deserving recognition at the species level. The new species is introduced here under the name P. maribelae sp. nov. This taxon had previously been labelled as “ Profundiconus n. sp. c cf. loyaltiensis ” (Puillandre et al. 2014).

There are two groups containing specimens from Plateau des Chesterfield, and one with specimens from Norfolk Ridge and Loyalty Ridge, which do not match any known species of Profundiconus described to date. They are respectively introduced here as P. virginiae sp. nov., P. barazeri sp. nov. and P. puillandrei sp. nov. (previously considered in Puillandre et al. 2014 as “ Profundiconus n. sp. h”, “n. sp. b” and “n. sp. g”, respectively). Additionally, we found that in spite of the lack of support at the corresponding nodes in the tree, the specimens (3 individuals sharing identical haplotype) corresponding to P. cf. profundorum from Norfolk Ridge exhibit significant conchological differences with the nominal taxon P. profundorum known from Japan and China. Based upon these constant differences and the independent branch in the tree, we describe it here as P. neocaledonicus sp. nov.