Amalda cacao, Kantor & Castelin & Fedosov & Bouchet, 2020

Kantor, Yuri I., Castelin, Magalie, Fedosov, Alexander & Bouchet, Philippe, 2020, The Indo-Pacific Amalda (Neogastropoda, Olivoidea, Ancillariidae) revisited with molecular data, with special emphasis on New Caledonia, European Journal of Taxonomy 706, pp. 1-59 : 31-33

Amalda cacao sp. nov.

urn:lsid:zoobank.org:act:CE4694EC-3B8F-40C8-819D-F62DAFEF2AD9

Figs 7 K–L, 11

Amalda hilgendorfi richeri , partim – Kilburn & Bouchet 1988: 288, figs 23–24 (labelled as paratype, but not listed in text under type material).

Amalda cf. hilgendorfi richeri – Gratecap 2014: 14, 19, figs 24–25.

Diagnosis

Shell large, up to 75 mm, fusiform, with turreted whorls and small broadly dome shaped protoconch (diameter of first whorl ca 0.7 mm). Primary and secondary calluses distinctly microshagreened. Border between primary callus and cloak of body whorl very distinct with thin lighter line. Olivoid groove very shallow, obsolete on most part of last whorl. Anterior band separated by distinct fasciolar ridge into upper and slightly narrower lower bands. Upper anterior band with distinct triangular in section ridge. Body whorl cloak chestnut on apertural side and lighter on dorsal side, with axial lines alternating in colour; olivoid band and adjoining narrow zone of cloak of body whorl white, anterior band chestnut brown, plication plate white with weak yellowish spiral band. Primary and secondary calluses dark chocolate brown, parietal pad light, with bluish tint. Protoconch white.

Etymology

The species name refers to the chocolate colour of the shell. Used as a noun in apposition.

Type material

Holotype

CORAL SEA • Lord Howe Ridge , Nova Bank ; 22°25′ S, 159°13′ E; 315 m deep; MUSORSTOM 5; stn CP320; not sequenced; MNHN IM-2000-35296.

Material examined

Sequenced material

CORAL SEA • 1 lv; Nova Bank ; 22°17′ S, 159°27′ E; 360–370 m deep; EBISCO; stn DW2533; MNHN IM-2007-33287 .

Not sequenced material

CORAL SEA • 1 dd; Kelso Bank ; 24°06′ S, 159°41′ E; 295–310 m deep; EBISCO; stn DW2514 • 1 dd; Nova Bank; 22°07′ S, 159°25′ E; 487–610 m deep; MUSORSTOM 5; stn DW301 • 1 dd; Nova Bank ; 22°10′ S, 159°26′ E; 385–420 m deep; MUSORSTOM 5; stn DW304 • 1 dd; Kelso Bank; 24°12′ S, 159°41′ E; 270–385 m deep; KANADEEP 1; stn DW4940 • 1 dd; Capel Bank ; 25°29′ S, 159°49′ E; 310–320 m deep; KANADEEP 1; stn DW4951 • 1 dd; Argo Bank ; 23°08′ S, 159°31′ E; 280 m deep; KANADEEP 1; stn DW4958.

SOUTHERN NEW CALEDONIA – Norfolk Ridge • 1 dd; Kaimon Maru Bank ; 24°44′ S, 168°09′ E; 227–232 m deep; NORFOLK 1; stn CP1676 • 1 dd worn; 24°45′ S, 168°08′ E; 233 m deep; SMIB 3; stn DW08.

Description (holotype)

MEASUREMENTS. SL 74.9 mm, AL 40.0 mm, SW 29.3 mm.

SHELL. Shell fusiform with relatively narrow base, SW/SL 0.39; body whorl evenly convex on right side, evenly convex on periphery and shell base on left side, slightly concave subsuturally, greatest width of body whorl median. Protoconch ( Fig. 11 D–E) small, broadly domed, first 1.5 whorls with distinct impressed suture, suture further overlaid by callus. Limit of protoconch indistinct, rendering whorl count impossible. Diameter of first whorl 0.68 mm. Spire high, turreted; primary callus not thick and covering all whorls except protoconch and uppermost teleoconch whorls, distinctly impressed on suture; surface of callus glossy, distinctly microshagreened, more dense in suture areas. Secondary callus very thin, forming distinct thickened pad on parietal wall, extending to right ventral side of last whorl and continuing up to form a fairly thin, tongue-shaped pad, reaching suture of antepenultimate whorl. Surface of secondary callus very similar to that of primary one, its borders indistinct. Body whorl cloak glossy, covered by indistinct spiral riblets of variable width. Olivoid groove very shallow, obsolete on most part of last whorl and present on last ¼ whorl. Rear edge of anterior band very sharp and distinct near columella, becoming blurred and sinuous on dorsal side of last whorl towards aperture lip. Anterior band subdivided in upper and lower anterior bands by distinct, step-like, fasciolar ridge. Upper anterior band slightly broader, with distinct, nearly median, additional ridge, triangular in section. Lower anterior band nearly flat. Plication plate with shallow, rather broad, median groove. No ridges on plication plate and columella. Aperture narrow oval, acute posteriorly, widest in its lower third; outer lip thin, very slightly opisthocline in sideview, weakly concave, without visible labral denticle; siphonal notch shallow, symmetrically U-shaped. Body whorl cloak chestnut on apertural side and lighter on dorsal side, with axial lines alternating in colour, corresponding to growth lines; olivoid band and adjoining narrow zone of body whorl cloak white, anterior band chestnut brown, plication plate white with weak yellowish spiral band. Primary and secondary calluses dark chocolate brown, parietal pad light, with bluish tint. Protoconch white. Outer lip with broad spiral brownish band, corresponding to cloak, white deeper inside.

OPERCULUM. Large, spanning most of aperture, lanceolate, with subterminal nucleus near lower operculum edge.

RADULA (holotype) ( Fig. 7 K–L). Lateral teeth thick, hook-shaped. Central teeth strongly overlapping, tricuspid, with broad lateral flaps. Lateral cusps and lateral flaps with several distinct grooves on outer side, flattened and broad. Central cusp narrow, sharp, much shorter than lateral ones.

Remarks

This very distinct species differs from most other known species of Amalda in the combination of its dark brown colour and a rather broad shell with high turreted spire. In colour pattern, it resembles specimens of Amalda raoulensis Powell, 1967 illustrated by Hart (1995) from about 100 m depth on Colville Ridge off the North Island of New Zealand, but the latter differs in having a smaller (up to 56 mm) shell with a relatively lower spire. It should be mentioned that the holotype of Amalda raoulensis is a beach worn faded specimen with a very strong, callused, peripheral spiral keel which dominates the shell appearance ( Powell 1967), and the conspecificity of the specimens illustrated by Hart (1995) with the types of Amalda raoulensis needs confirmation.

The shell of the only sequenced specimen of A. cacao sp. nov. is broken into pieces, but the intact upper teleoconch whorls ( Fig. 11F ) are identical to the holotype, leaving no doubt on their conspecificity. Kilburn & Bouchet (1988) considered it to be a colour variant of Amalda hilgendorfi richeri , but Cox1 data clearly indicate that it is a separate species.

Distribution

Live collected in the Coral Sea; dead specimens also known from Kaimon Maru Bank on Norfolk Ridge. Depth range: alive at 315–360 m, empty shells at 227– 487 m.

Figures

Fig. 7. Radulae of species of Amalda H. Adams & A. Adams, 1853. A–G. A. hilgendorfi (von Martens, 1897). A–B. MNHN IM-2019-621 (shell on Fig. 4D). C. MNHN IM-2009-11961 (shell on Fig. 4J). D. MNHN IM-2013-58045, Papua New Guinea. E. MNHN IM-2013-19909, Papua New Guinea. F. MNHN IM-2013-63430, southern New Caledonia. G. MNHN IM-2007-33312 (shell on Fig. 5F). H. A. aureomarginata Kilburn & Bouchet, 1988, MNHN IM-2013-63421, specimen not sequenced, southern New Caledonia. I–J. A. miriky sp. nov. I. Miriky, stn CP3210, specimen not sequenced, Madagascar. J. Miriky, stn DW3215 (shell on Fig. 10J). K–L. A. cacao sp. nov., holotype, MNHN IM- 2000-35296 (shell on Fig. 11A–E).

Fig. 11. Amalda cacao sp. nov. A–E. Holotype, MNHN IM-2000-35296, SL 74.9 mm (D–E =enlarged apical and lateral views of the protoconch), specimen not sequenced. F. MNHN IM-2007-33287, SL 61 mm, sequenced specimen. G. KANADEEP 1, stn DW4951, 25°29′ S, 159°49′ E, 310–320 m, Capel Bank, SL 50 mm, specimen not sequenced. H. NORFOLK 1, stn CP1676, 24°44′ S, 168°09′ E, 227–232 m, Norfolk Ridge, SL 67.1 mm, specimen not sequenced. Shells at the same scale.