Homalocantha granpoderi, Merle & Garrigues, 2011

Merle, Didier & Garrigues, Bernard, 2011, Description of four new species of Muricidae (Mollusca, Gastropoda) from the Philippines and the Caribbean area, Zoosystema 33 (4), pp. 557-575 : 562

Homalocantha granpoderi n. sp. ( Figs 1 A-D; 2B)

TYPE MATERIAL. — Philippines. Mactan Island, 150 m deep, holotype ( MNHN. IM. 24626) (H: 47 mm). — Mindanao, Balut Island, 150-200 m deep, 1 paratype ( MNHN. IM. 24627) (H: 24 mm).

TYPE LOCALITY. — Philippines. Mactan Island, 150 m deep.

OTHER MATERIAL EXAMINED. — Philippines. Balut Island, 1 specimen (Coll. BG) (H: 28 mm). — Palawan, 1 specimen (Coll. GG) (H: 39.9 mm).

ETYMOLOGY. — Named in honour to Gilles Granpoder.

DESCRIPTION OF HOLOTYPE

Protoconch paucispiral, broken. Teleoconch of four whorls, club-shaped, 47 mm high, 27 mm wide.Spire low, shouldered, of three whorls. Suture impressed, but region surrounding suture deeply excavated.Last whorl narrow, fusiform.Last whorl adherent to spire, 78% of teleoconch height.Apical angle 90° (excluding spines), 110° (including spines).Spiral sculpture with marked primary cords of flat ribbon shape,with surface scabrous. First and second whorls: cords IP and P1 spiny; spines on IP and P1 almost welded, squared distally; third whorl: P2, P3 and P4 (none spiny) visible on each whorl; last (fourth) whorl: spines of cords IP and P1 almost welded proximally; P2, P3, P4 with spines developed,of the same length on each cord; P5 spine atrophied, situated on base of convex part of whorl; P6 spine atrophied, situated on top of siphonal canal;ADP and MP spines developed,of same length as P3 and P4; ABP spine shorter than MP and EAB1 spines shorter than ABP. Longest cord spines distally palmate. Secondary cords s2, s3, s4, s5, s6, ads, ms and abs present.Tertiary cords present. Axial sculpture of6 varices on first whorl,7 varices on second whorl, 8 varices on third and fourth whorls.Terminal variceal expansion on convex part of whorl produces webbed shape of last varix.Intervariceal spaces concave on two earliest teleoconch whorls, convex on other whorls. Aperture oval, 23% of diameter (including spines), 69% of shell height. Columellar lip smooth, adherent. No anal sulcus. Outer lip finely crenulate and lirate within. Siphonal canal inclined to right, 50% of shell height. First and second whorls white, other whorls with varices dark brown and intervarices whitish. Operculum and radula unknown.

GROWTH SERIES

The studied material includes four specimens from a juvenile, 24 mm in height (paratype), to the adult holotype, 47 mm in height. The juvenile has a club-shaped teleoconch and very rounded varices. Its spiral sculpture has very poorly developed spines on the convex part of the whorl and short spines on the siphonal canal. Two other specimens of intermediate height (height 28 and 39.9 mm) have rounded varices, weak development of cord spines (especially on the convex part of the whorl) and a club-shaped teleoconch. They bear EAB2, which is missing on the holotype. The holotype shows a sculptural change on the last half of the last whorl. Here the cord spines on the convex part of the whorl become more and more developed. The shape of the varices also changes and becomes concave instead of convex as on the preceding whorl. The overall shape of the teleoconch does not vary, but remains club-shaped.

INTERSPECIFIC COMPARISONS

Homalocantha granpoderi n. sp. needs to be compared to H. scorpio , which is the most closely similar species. Juvenile specimens of H. scorpio ( Figs 3A ; 4A ) differ by their angulate last whorl, by their concave intervariceal spaces, by having IP and P1 cord spines developed and quickly later by developing P3 and P4 cord spines, and by the brown colour of the distal part of the varices. Adult specimens of H. scorpio ( Figs 3B, C ; 4B ) are distinguished by a wider last whorl, and by a higher and more disjunct spire. Long cord spines (IP, P1, P2, P3, P4, MP and ABP) occur quickly on the last whorl in H. scorpio , while they remain shorter in H. granpoderi n. sp.

Figures

FIG. 1. — Homalocantha granpoderi n. sp. and H. ninae n. sp., primary cords in dorsal and apical views: A-D, H. granpoderi n. sp.; A, paratype MNHN.IM.24627 (H: 24 mm); B, Coll. GG, Palawan, Philippines (H: 39.9 mm); C, holotype MNHN.IM.24626 (H: 47 mm); D, paratype (apical view); E-H, H. ninae n. sp.; E, syntype 1 MNHN.IM.24628 (H: 25 mm); F, Coll. BG, Balicasag Island, Philippines (H: 26.6 mm); G, syntype 2 (H: 37.8 mm); H, syntype 1 MNHN.IM.24629 (apical view). Scale bars: 10 mm.

FIG. 3. — Homalocantha scorpio (Linnaeus, 1758) and H. pisori d’Attilio & Kosuge, 1989, primary cords in dorsal and apical views: A-D, H. scorpio; A, Coll. BG, 10 m, Bantayan Island, Cebu, Philippines (H: 24.7 mm); B, Coll. BG, 10 m, Calituban, Bohol, Philippines (H: 36.8 mm); C, Coll. BG, Calituban, Philippines (H: 51.6 mm); D, Coll. BG, Balut Island, Mindanao, Philippines (H: 28 mm) (apical view);E-H, H. pisori; E, Coll. BG,Philippines (H: 14 mm);F, H (apical view), Coll.BG, Davao at 80-120 m deep, Philippines (H: 29 mm); G, Coll. BG, Bohol at 20 m deep, Philippines (H: 40 mm). Scale bars: 10 mm.

FIG. 4. — Homalocantha scorpio (Linnaeus,1758) and H.pisori d’Attilio & Kosuge,1989, primary cords in ventral view:A, B, H.scorpio; A, Coll. BG, Balut Island, Mindanao, Philippines (H: 29 mm); B, Coll. BG, Calituban, Philippines (H: 51.6 mm); C, D, H. pisori; C, Coll. BG, Bantayan Island, Cebu, Philippines (H: 24.7 mm); D, Coll. BG, Mactan Island, Philippines (H: 44.2 mm). Scale bars: 10 mm.