Hortia macrocephala, Kantor, Yuri, Lozouet, Pierre, Puillandre, Nicolas & Bouchet, Philippe, 2014

Kantor, Yuri, Lozouet, Pierre, Puillandre, Nicolas & Bouchet, Philippe, 2014, Lost and found: The Eocene family Pyramimitridae (Neogastropoda) discovered in the Recent fauna of the Indo-Pacific, Zootaxa 3754 (3), pp. 239-276 : 253-256

Hortia macrocephala new species

Figures 2 I, 7A–D, 9

Type material. Holotype MNHN 24571, 5 paratypes MNHN 24572.

Type locality. South of New Caledonia, 22º15’S, 167º15’E, 440 m [BIOCAL st. DW77].

Material examined. South of New Caledonia. BIOCAL, st. DW 77, 22º15’S, 167º15’E, 440 m, 35 dd, 11 lv (holotype and paratypes). EXBODI, st. CP 3786, 22º15’S, 167º13’E, 408–442 m, 4 dd, 2 lv; st. CP 3787, 22º13’S, 167º06’E, 223–249 m, 1 dd; st. CP 3811, 21º44’S, 166º38’E, 387–668 m, 1 dd. TERRASSE, st. DW3086, Terrasse sud-est, passe de la Sarcelle, 21°55'S, 167°13'E, 400 m, 4 dd.

Description (holotype) ( Fig. 9 A–D). Shell small, narrowly fusiform, with high, elevated spire (LWL/SL 0.46) and attenuated, medium long canal. Shell of ca 1.5 protoconch whorls and 6.5 slightly convex teleoconch whorls. Protoconch ( Fig. 9 D) paucispiral, semitransparent, globose, smooth, diameter 670 Μm, height 610 Μm, transition to teleoconch marked by two weak opisthocline ribs. Suture impressed. Besides inconspicuous growth lines, axial sculpture of narrow, closely spaced, sinuous and slightly prosocline ribs, 18 on penultimate whorl, 19 on last whorl. Ribs run from suture to suture on spire whorls and become obsolete on shell base at transition to canal. Spiral sculpture of one weak spiral thread abapically of suture and distinct, broadly spaced, narrow cords, rounded in section, two on first whorl, three starting from second whorl and 19 on last whorl, of which 13 on shell base and canal, more closely spaced. Cords on spire whorls and four cords on last whorl form small but distinct rounded beads at intersection with axial ribs. Aperture low, narrow elongate, 0.37 (together with canal) of SL. Outer lip partially broken, concave at transition to long, narrow, and nearly straight canal. Shallow notch at shoulder. Columella short, straight, smooth. Callus narrow, of thin transparent glaze overlying parietal region. Siphonal notch absent. Canal well differentiated from aperture, recurved abaxially to left. Shell color off-white. Periostracum transparent, yellowish, peeling.

Measurements (holotype): SL 10.4 mm, LWL 4.8 mm, AL (with canal) 3.8 mm, SW 2.6 mm. Maximum SL 11.2 mm.

Radula of holotype ( Fig. 7 A–D) short, about 320 Μm long (8.4% of AL), consisting of about 35 rows of teeth, 4–5 nascent, with strong alary processes embracing anterior part of odontophore. Membrane folded along both sides of rachidian. Rachidian teeth with broad base, strongly arched anteriorly, and large cusp, sometimes with indistinct additional serration. Lateral teeth high, triangular, shallowly scoop-shaped. Inner side adjoining rachidian with one to three small additional denticles.

Distribution. South of New Caledonia, alive in 440–442 m, shells from 249 m.

Etymology. The name reflects the large, non-planktotrophic protoconch of the species.

Remarks. The paratypes and other specimens are very similar to the holotype in shell outline. Specimens may have a columella with slight swellings that look like weak columellar plaits, but are caused by threads of the spiral sculpture that are only partially overlaid by a very weak callus. In some specimens, the subsutural spiral thread is more pronounced and also forms beads at intersections with axial ribs.

Hortia macrocephala is most similar in shell outline to Hortia pseudotaranis n. sp., but differs in having more numerous and more closely spaced axial ribs (19 on last whorl in Hortia macrocephala vs. 13 in Hortia pseudotaranis ).

Figures

FIGURE 2. Overview of fossil and Recent Pyramimitridae. A. Endiatoma quadricincta (Cossmann, 1883), MNHN. F. A 47757, Lower Eocene, France. B – C. Pyramimitra terebraeformis (Conrad, 1848), MNHN. F. J 08748, Middle Eocene, USA. D – E. Pyramimitra quadralirata Dockery, 1977, MNHN. F. A 47750, Middle Eocene, USA. F. Hortia priabonica n. sp., MNHN. F. A 47752, Upper Eocene, France. G. Hortia arriuensis Lozouet, 1999, MNHN. F. A 47751, Upper Oligocene, France. H. Hortia pseudotaranis n. sp., New Caledonia, SL 8.4 mm. I. Hortia macrocephala n. sp., New Caledonia, SL 10.4 mm. J. Hortia paradrillia n. sp., New Caledonia, SL 8.1 mm. K. Hortia marshalli n. sp., New Zealand, SL 10.6 mm. L. Hortia spenceri n. sp., New Zealand, SL 9.0 mm. M. Hortia aotearoa n. sp., New Zealand, SL 9.0 mm. N. Hortia solitaria n. sp., South of Madagascar, SL 6.5 mm. O. Teremitra fallax n. sp., Solomon Islands, SL 11.8 mm. P. Teremitra efatensis (Aubry, 1999), Vanuatu, SL 10.8 mm. Q. Teremitra? hortensis (Vinassa de Regny, 1898), Upper Eocene, France. R. Teremitra sp., Taiwan, SL 16 mm. S. Vaughanites? superstes n. sp., Philippines, SL 19.1 mm.

FIGURE 7. Radulae of Recent Hortia species. A – D. Hortia macrocephala n. sp., holotype. A. Entire radular membrane. B. Enlarged lateral teeth. C. Enlarged anteriormost part of radular membrane. D. Enlarged rachidian teeth. E – F. Hortia paradrillia n. sp., holotype. E. Dorsal view of central part of radular membrane. F. Enlarged rachidian and lateral teeth.

FIGURE 9. Shells of Hortia macrocephala n. sp. A – D. Holotype, SL 10.4 mm. D. Enlarged protoconch. E. Paratype, SL 11.2 mm. F. Paratype, SL 8.8 mm. G. Paratype, SL 9.5 mm. H – I. SEM photographs of shell (H) and protoconch (I) of the specimen from the station DW 77, SL 8.7 mm. All shells at the same scale.