Conus tessulatus (Born, 1778)

Conus tessulatus uniformis (Bozzetti, 2021)

Conus edaphus (Dall, 1910)

Conus (Tesselliconus) georgesrichardi (Merle, 2026)

Descrizione e caratteristiche:

E’ una conchiglia di dimensioni da medie a moderatamente grandi, di costituzione da moderatamente solida a moderatamente pesante. L’ultimo giro varia da conico a conico allargato, a volte ventricosamente o allargato e ventricosamente conico; il profilo è convesso fino alla zona sottostante la spalla e diritto di seguito. La spalla è subangolata o angolata. La spira è bassa o di altezza moderata, con il profilo concavo. Le rampe suturali presentano 1 scanalatura spirale che si incrementa aumentando fino a 2-4 scanalature; spesso 2 sono più evidenti e due meno. L’ultimo giro presenta scanalature variamente distanziate, deboli o incise, spesso puntiformi. Il colore di base è il bianco. L’ultimo giro presenta file spirali di macchie arancioni o bruno-rossastro rettangolari, spesso alternate a macchie bianche. La colorazione presenta marcature più scure che di solito si fondono in bande a spirale su ciascun lato del centro. La base è di colore viola chiaro. I giri larvali sono di colore grigio o arancione chiaro. Le rampe suturali hanno marcature radiali corrispondenti alle barre sull’ultimo giro in termini di dimensioni e colore. L’aperturs è bianca, spesso soffusa di viola o rosa. Il Conus tessulatus assomiglia al Conus suturatus ed al Conus eburneus. Il Conus suturatus si differenzia per avere i primi 5-8 giri postnucleari tubercolati, e 3 bande di sfondo. Il Conus eburneus si differenzia per essere più piccolo, per avere macchie di colore marrone scuro e bande di sfondo di colore giallo-arancione ⁽¹⁾.

It is found across the entire Indo-Pacific into the western Pacific (Panamic) marine province, from Mozambique to the Sea of Cortez in Mexico. Its presence in the latter site, where it has become the most common Conus species, has only been noted in recent decades. C. tessulatus feeds on polychaete worms ⁽²⁾.

Age range: base of the Middle Miocene to the top of the Late/Upper Pleistocene or 15.97000 to 0.01170 Ma

Conus (Tesselliconus) georgesrichardi (Merle, 2026)

Description ⁽⁴⁾

Shell large (MNHN.F.A98439 (Fig. 13K) part of the last whorl = 89.6 mm), with low coeloconoid to conical spire. Apical angle 135°. Teleoconch of 7-8whorls, whorl tops smooth except for close-set, comma-shaped growth lines, concave, delimited by shoulder raised very slightly below suture. Suture weakly impressed. Subsutural sinus shallow, slightly curved, moder­ately asymmetrical. Last whorl with horizontal, flat subsutural platform, smoothy angled at shoulder placed almost at suture, regularly conical below, position of maximum diameter close below shoulder ^(*), not constricted at base. Siphonal fasciole weakly developed; a few weak, widely spaced cords over base and fasciole, strengthening slightly abapically. Aperture rela­tively narrow with parallel sides, widening abapically; siphonal canal short. Under UV light, residual colour pattern consisting of two components: (1) pale, yellow-white fluorescent spots, spirally aligned and (2) dark, non-fluorescent background. Small rectangular spots of unequal size, distributed on the last whorl in four zones from shoulder to base. Zone a (first posterior quarter of whorl): 3-4 rows of sparse dots; zone b (second posterior quarter of whorl): 3-6 rows of close-set dots; zone c (first anterior quarter of whorl: 2-3 spaced rows of sparse dots; zone c (second anterior quater of whorl): 4-8 rows of more or less spaced dots (Fig. 15A-D).

Comparisons ⁽⁴⁾

Among French Polynesian Conidae bearing spiral rows of dots, C. (Tesselliconus) georgesrichardi n. sp. may be compared with Conus (Elisaconus) litteratus (Linnaeus, 1758), C. (Tesselliconus) tessulatus Born, 1778 and C. (T.) eburneus (Hwass in Bruguière, 1792). C. (E.) litteratus differs in having a planispiral spire, a narrow, concave subsutural platform and a shoulder placed above the suture. Conus (E.) litteratus displays around 20-25 row of dots, instead 15-18 in C. (T.) georgesrichardi n. sp. In addition, the rows are regularly aligned from the shoulder to the base on last whorl, whereas those of C. (T.) georgesrichardi n. sp. are organised in four zones (a to d). The shell shape of Conus (T.) tessulatus is reminiscent to that C. (T.) georgesrichardi n. sp. and as in the Plio-Pleistocene species, the rows of dots are organised in four zones (Fig. 15E, F). However, Conus (T.) tessulatus species differs clearly by having in elongated larger dark dots. The colour pattern of C. (T.) erburneus consists in four similar zones of spiral rows of dots as in C. (T.) georgesrichardi n. sp. (Fig. 15G, H) However, the dots of C. (T.) georgesrichardi n. sp. are smaller and more close set in the zone b. Moreover, the spire of C. (T.) georgesrichardi n. sp. can be more conical, the shell shape is wider and some gerontic individuals can reach a larger size (H more than 89 mm).

^*) Last whorl more ventricosus than in Conus tessulatus and is wider towards the base.

Bibliografia Consultata

• (1) - Röckel, Korn & Kohn (1995) “Manual of the living Conidae” Volume I: Indo-Pacific Region

• (2) - Insights into the origins of fish hunting in venomous cone snails from studies of Conus tessulatus

• (3) - Cenozoic ·Fossil Mollusks From Western Pacific Islands; Gastropods (Eulimidae and Volutidae Through Terebridae)

• (4) - Evolutionary history of reef-dwelling and associated lagoonal mollusc assemblages of the uplifted Niau Atoll (Tuamotu, French Polynesia) since the Pliocene

• (5) - Abrard (R.), 1942 - Mollusques pleistocènes de la Côte française des Somalis, recueillis par E. Aubert de la Rüe. Archives du Muséum National d'Histoire Naturelle, sér. 6, t. 18