Afonsoconus crosnieri, Tenorio, Monnier & Puillandre, 2018

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 : 10-15

Afonsoconus crosnieri sp. nov.

urn:lsid:zoobank.org:act:BE37EA7A-7F2A-4F32-82BA-8E8D6205154D

Figs 4 A–H, 5A–L

Afonsoconus aff. kinoshitai – Monnier et al. 2018: 638, figs 1–5.

Etymology

This new species is named after Alain Crosnier, oceanographer at Office de la Recherche Scientifique et Technique d’Outre-Mer (ORSTOM – which later became IRD, Institut de Recherche pour le Développement). In the early 1970s, while he was based in Nosy Bé, Alain Crosnier used the RV Vauban to conduct surveys of the benthic fauna in the Mozambique Channel, which resulted in the discovery of many new species of marine invertebrates – including the first specimens of the present new cone. Later in the 1970s–1980s, Alain Crosnier was instrumental in launching the MUSORSTOM expeditions (‘Campagnes MUSORSTOM’), initially also on the RV Vauban, and the resulting volumes of scientific results – initially as Résultats des Campagnes MUSORSTOM, which later became Tropical Deep-Sea Benthos. Alain Crosnier was himself a specialist of penaeid shrimps.

Type material

Holotype

COMOROS: 59.6 × 24.8 mm, Mozambique Channel , S of Grande Comore, stn BIOMAGLO DW4838, 11°59´S, 43°31´E, 185–267 m ( MNHN IM-2013-62927 ; GenBank accession number (cox1 sequence): MH 777765 ) ( Fig. 4 A–B).

Paratypes

COMOROS: 1 juv., 11.9 × 6.0 mm, same data as for the holotype ( MNHN IM- 2013-62933; GenBank accession number (cox1 sequence): MH 777764 ) ( Fig. 4C ); 1 juv., 11.5 × 5.7 mm, same data as for the holotype ( MNHN IM- 2013-62932; GenBank accession number (cox1 sequence): MH 777763 ) ( Fig. 4 D–F).

MOZAMBIQUE: 1 ex., 81.5 × 34.6 mm, S Mozambique, 180–250 m (EM) (not figured); 1 ex., 65.5 × 26.4 mm, same data as for the preceeding (EM) (Fig. 5H); 1 ex., 83.8 × 34.8 mm, S Mozambique, off Quissico (CR) (Fig. 5I); 1 ex., 70.9 × 28.3 mm, S Mozambique, off Inhambane, 180–200 m ( FP) (Fig. 5J).

MADAGASCAR: 1 ex., 64.2 × 25.3 mm, Banc du Leven, off Nosy Bé, RV Miriky, expedition MIRIKY, stn DW3211, 12°32´S, 47°52´E, 244–300 m ( MNHN IM- 2000-33924) (Fig. 5C); 1 ex., 51.5 × 21.4 mm, Cap St. André, Majunga, RV Miriky, expedition MIRIKY, stn DW CP3260, 15°35´S, 45°45´E, 179– 193 m ( MNHN IM- 2000-33925) (Fig. 5D); 1 ex., 67.5 × 27.4 mm, NW Madagascar, East of Banc du Leven, 12°43´S, 48°16´E, 245–255 m, coll. Crosnier ( MNHN IM- 2000-33926) (Fig. 5E); 1 ex., 54.6 × 22.2 mm, NW Madagascar, East of Banc du Leven, 12°41´S, 48°16´E, 308–314 m, coll. Crosnier ( MNHN IM- 2000-33927) (Fig. 5F).

FRANCE: 1 ex., 71.0 × 27.4 mm, Mozambique Channel, Iles Glorieuses, RV Antéa, expedition BIOMAGLO, stn DW4809, 11°30´S, 47°29´E, 293–301 m ( MNHN IM- 2013-62925; GenBank accession number (cox1 sequence): MH 777766 ) (Fig. 5A); 1 ex., 73.1 × 31.3 mm, same data as for the preceeding ( MNHN IM- 2013-62924; GenBank accession number (cox1 sequence): MH 777767 ) (Fig. 5B); 1 ex., 65.2 × 27.1 mm, Réunion Island (GH) (Fig. 5G).

SOUTH AFRICA: 1 ex., 71.2 × 30.0 mm, S KwaZulu-Natal, off Park Rynie, 110 m (SV) (Fig. 5K); 1 ex., 65.3 × 27.2 mm, same data as for the preceeding (SV) (Fig. 5L).

Description

MORPHOMETRIC PARAMETERS. S L = 52–84 mm; RD = 0.45–0.51; RSH = 0.13–0.18; PMD = 0.86–0.94.

SHELL. Moderately large. Maximum length: 83.8 mm. Shell profile narrowly conical, with convex sides adapically, and straight below. Spire of moderate height, of straight or very slightly convex outline. Multispiral protoconch with about three whorls, yellowish, glossy and translucent ( Fig. 4D ). First four teleoconch whorls weakly tuberculated ( Fig. 4E ), with tubercles becoming obsolete on fifth whorl, being absent in later whorls. Occasionally, the tubercles may fuse together forming a ridge over the

Fig. 5 (opposite page). Afonsoconus crosnieri sp. nov. Paratypes. A. 71.0 × 27.4 mm (MNHN IM-2013- 62925). B. 73.1 × 31.3 mm (MNHN IM-2013-62924). C. 64.2 × 25.3 mm (MNHN IM-2000-33924). D. 51.5 × 21.4 mm (MNHN IM-2000-33925). E. 67.5 × 27.4 mm (MNHN IM-2000-33926). F. 54.6 × 22.2 mm (MNHN IM-2000-33927). G. 65.2 × 27.1 mm (GH). H. 65.5 × 26.4 mm (EM). I. 83.8 × 34.8 mm (CR). J. 70.9 × 28.3 mm (FP). K. 71.2 × 30.0 mm (SV). L. 65.3 × 27.2 mm (SV). Scale bars = 10 mm.

suture, producing a spire with a slightly stepped aspect. Sutural ramp flat or slightly concave, with five increasing to eight spiral cords. Shoulder subangulate to rounded.

TELEOCONCH. Early teleoconch whorls white or yellowish. Late teleoconch whorls white with light brown irregular blotches and flecks. Ground colour white, pale yellow or pale violet. Last whorl overlaid with brown flammules or blotches, often fused forming spiral bands. There are two broad white, sparsely patterned spiral bands immediately above and below mid-body. Basal quarter and shoulder area also predominantly white and sparsely patterned. In addition, reddish-brown fine interrupted spiral lines and dots present in variable amounts, more evident in sparsely patterned areas. Columella white, callous and twisted. Aperture white or pale purplish, rather narrow adapically, widening abapically. Posterior notch rather deep. Periostracum yellow-brown, thin and translucent, with fine spiral rows of small tufts. Small and ovate operculum present.

RADULAR TEETH (examined in holotype ( Fig. 4H ) and in paratype MNHN IM-2013-62925 ( Fig. 4G )). 35 to 45 teeth in radular sac. Radular tooth medium-sized: its total length relative to shell length S L /T L = 42–48. Waist indistinct. Anterior portion equal to or slightly longer than posterior section of tooth (T L /AP L = 1.8–2.0). With one barb opposed to a pointed, very short blade, which covers 12–14% of anterior portion of tooth. Blade only slightly larger than barb, which covers 8–9% of anterior portion. Tooth serrated, with one long row composed of 40–60 small denticles, ending in a small, pointed terminating cusp. Base large, with small but prominent sharp spur pointing upwards. Basal ligament present (not shown in Fig. 4 G–H).

Distribution and habitat

Known from the Mozambique Channel including the Comoros, Iles Glorieuses, southern Mozambique, South Africa (Kwazulu-Natal coast) and NW Madagascar, between 180 and 314 m depth. Also present in Réunion Island ( Fig. 6 ).

Remarks

The specimens of A. crosnieri sp. nov. form a monophyletic group, with large genetic distances with respect to the two other species, A. kinoshitai and A. bruuni ( Fig. 3 ). Despite the overall similarities in shell characters, A. crosnieri sp. nov. can be separated from its sister species by shell morphometry. Thus, A. crosnieri sp. nov. and A. kinoshitai do not exhibit significant differences in shell length, but they do differ in RD, PMD and RSH. Analysis of the covariance (ANCOVA) for the shell parameters MD, HMD and SH, using species hypotheses as factor and shell length (S L) as covariate, yielded statistically significant results ( Table 2). In the case of A. bruuni , there are statistically significant differences in mean shell length with A. crosnieri sp. nov. There are no differences in PMD or RSH, but these two species do differ in RD: ANCOVA for MD, using species hypotheses as factor and S L as covariate indicates statistically significant differences ( Table 3). Thus, A. crosnieri sp. nov. is narrower-bodied and has a higher spire than the conoid-cylindrical A. kinoshitai , whereas A. bruuni has a shell which is usually smaller in length and broader at the shoulder, with a more conical appearance. A discriminant function analysis (DFA), performed with shell length (S L) and the shell morphometric parameters MD, HMD and SH as variables and species hypotheses as factor, correctly classified 100% of the specimens in the sample ( Fig. 7 ). According to the standardized coefficients, discriminant function 1 (DF1) represents mainly decrease in S L and increase in MD, whereas discriminant function 2 (DF2) represents mainly decrease in S L and increase in HMD, with a smaller contribution of increasing SH. These results indicate that A. crosnieri sp. nov. can be separated with a high degree of certainty from A. kinoshitai and A. bruuni based on significant differences in size and shell shape. The radular teeth of the three species show similar morphological characters. In spite of these similarities in the general aspect of the radular teeth, there are differences in their relative sizes. Thus, the radular teeth of A. kinoshitai and A. bruuni exhibit rather large relative sizes, with S L /T L in the range of 25 to 30. The radular teeth examined for A. crosnieri sp. nov. are clearly smaller, with S L /T L in the range of 42 to 48. This difference might indicate radular tooth adaptation to a specific type of prey, most likely a particular group of worms, and constitutes another useful trait for the separation of A. crosnieri sp. nov. from its sister species.

Figures

Fig. 4. Afonsoconus crosnieri sp. nov. A–B. Holotype, ventral and dorsal views, 59.6 × 24.8 mm (MNHN IM-2013-62927). C–G. Paratypes. C. Juvenile, 11.9 × 6.0 mm (MNHN IM-2013-62933). D–F. Juvenile, 11.5 × 5.7 mm (MNHN IM-2013-62932). D. Enlargement of the spire. E. Apical view of the spire. F. Shell. G–H. Radular teeth. G. Specimen of 71.0 × 27.4 mm (MNHN IM-2013-62925). H. Holotype. Scale bars = 10 mm, unless otherwise indicated.

Fig. 6. Distribution map for Afonsoconus crosnieri sp. nov. Red circles indicate the points where the species has been collected.

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. 7. 2D Scatter plot of the discriminant function analysis (DFA) for the species A. kinoshitai (Kuroda, 1956), A. bruuni (Powell, 1958) and A. crosnieri sp. nov. The analysis was performed using shell length (SL) and the shell morphometric parameters MD, HMD and SH as variables, and species hypotheses as factor. Both DF1 and DF2 are statistically significant at the 95% probability level (DF1: 69.9 % relative percent, Wilks lambda = 0.0449, χ2 = 138.085, df = 8, p = 0.0000; DF2: 30.1 % relative percent, Wilks lambda = 0.2946, χ2 = 54.38, df = 3, p = 0.0000).