Ethalia anomphala Herbert 2024, sp. nov.
Creators: name: Herbert, David G.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Trochida
Trochidae
Ethalia
Ethalia anomphala

description: Ethalia anomphala sp. nov.
urn:lsid:zoobank.org:act: 8F0C73C8-973B-4710-BD6A-8D4B5262E846
Figs 2–4
Diagnosis
Ethalia anomphala sp. nov. is characterised by its glossy, lenticular shell with completely occluded umbilicus, even in juvenile specimens. Last adult whorl less globose and not as deep as in the co-occurring E. montrouzieri, and not attaining such a large size (maximum diameter 13.5 vs 22.0 mm).
Etymology
From the Greek ‘ omphalos ’ (ΟΜφαλός) m. – a navel or umbilicus; ‘ anomphalos ’ – without a navel; in reference to the completely occluded umbilicus.
Material examined
Holotype (Fig. 2A–D) NEW CALEDONIA • empty shell; Plateau Chesterfield-Bellona, Stn D56; 21°24.4′ S, 159°08.8′ E; depth 60 m; Jul. 1984; CHALCAL 1 leg.; MNHN-IM-2000-38840.
Paratypes NEW CALEDONIA – Plateau Chesterfield-Bellona • 1 specimen, dead; Stn DW156; 19°49′ S, 158°21′ E; depth 42 m; 1 Aug. 1988; NO Coriolis -CORAIL 2 leg.; MNHN-IM-2000-38841 • 3 specimens, dead; Plateau Chesterfield-Bellona, Stn D45; 20°48.93′ S, 158°30.21′ E; depth 50 m; Jul. 1984; CHALCAL 1 leg.; MNHN-IM-2000-38842 • 1 specimen, dead; same data as for holotype; MNHN-IM-2000-38843. – Lansdowne-Fairway Banks • 3 specimens, dead; Stn DW26; 20°22′ S, 161°05′ E; depth 62 m; 22 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN-IM-2000-38844 • 1 specimen, dead; Bancs Lansdowne–Fairway, Stn DW02; 20°50′ S, 161°37′ E; depth 62 m; 20 Jul. 1988; NO Coriolis - CORAIL 2 leg.; MNHN-IM-2000-38845. – Belep • 1 specimen, living; Lagon Nord, Stn 487; 18°55′ S, 163°31′ E; depth 37 m; 2 Mar. 1985; B. Richer-ORSTOM leg.; MNHN-IM-2000-38846. – Grande Terre • 1 specimen, living; Nouméa, Grand Récif Sud, Stn 391; 22°46′ S, 167°01′ E; depth 65 m; 22 Jan. 1985; B. Richer-ORSTOM leg.; MNHN-IM-2000-38847.
Other material
NEW CALEDONIA – Plateau Chesterfield-Bellona • 1 specimen, dead; Plateau des Chesterfield, Stn DW144; 19°28′ S, 158°23′ E; depth 50 m; 28 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 1 specimen, dead; Plateau des Chesterfield, Stn DW 125; 19°28′ S, 158°24′ E; depth 54 m; 29 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 1 specimen, dead; Plateau des Chesterfield, Stn DW 14 ± 3; 19°37′ S, 158°25′ E; depth 45 m; 30 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 3 specimens, dead; Plateau des Chesterfield, Stn DW 133; 19°31′ S, 158°25′ E; depth 45 m; 30 Jul. 1988; NO Coriolis - CORAIL 2 leg.; MNHN • 1 specimen, dead; Plateau Chesterfield-Bellona, Stn D46; 20°52.26′ S, 158°33.74′ E; depth 65 m; Jul. 1984; CHALCAL 1 leg.; MNHN • 1 specimen, dead; Stn DW 50; 19°18′ S, 158°34′ E; depth 50 m; 23 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 1 specimen, dead; Plateau Chesterfield-Bellona, Stn D26; 19°10.72′ S, 158°34.95′ E; depth 48 m; Jul. 1984; CHALCAL 1 leg.; MNHN • 2 specimens, dead; Plateau Chesterfield-Bellona, Stn D49; 20°58.2′ S, 158°35.0′ E; depth 48 m; Jul. 1984; CHALCAL 1 leg.; MNHN • 1 specimen, dead; Plateau Chesterfield-Bellona, Stn D50; 21°04.4′ S, 158°40.7′ E; depth 70 m; Jul. 1984; CHALCAL 1 leg.; MNHN • 1 specimen, dead; Stn DW 65; 19°15′ S, 158°41′ E; depth 62 m; 24 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 1 specimen, dead; Plateau Chesterfield-Bellona, Stn DC39; 20°29.8′ S, 158°48.7′ E; depth 40 m; 23 Jul. 1984; CHALCAL 1 leg.; MNHN • 1 specimen, dead; Plateau des Chesterfield, Stn DW 82; 19°12′ S, 158°50′ E; depth 62 m; 25 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 2 specimens, dead; Plateau Chesterfield-Bellona, Stn D55; 21°23.9′ S, 158°59.6′ E; depth 60 m; Jul. 1984; CHALCAL 1 leg.; MNHN • 3 specimens, dead; Stn D62; 21°46.60′ S, 159°30.70′ E; depth 40 m; 26 Jul. 1984; CHALCAL 1 leg.; MNHN. – Lansdowne-Fairway Banks • 1 specimen, dead; Stn DW18; 20°44.1′ S, 161°00′ E; depth 69 m; 21 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 3 specimens, dead; Bancs LansdowneFairway, Stn DW 09; 20°53′ S, 161°35′ E; depth 62 m; 20 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 2 specimens, dead; Bancs Lansdowne – Fairway, Stn DW04; 20°52′ S, 161°37′ E; depth 64 m; 20 Jul. 1988; NO Coriolis -CORAIL 2 leg.; MNHN • 1 specimen, living; Stn D6; 20°57′ S, 161°43′ E; depth 45 m; Jul. 1984; CHALCAL 1 leg.; MNHN. – Belep • 1 specimen, living; Stn 1159; 19°13′ S, 163°07′ E; depth 50 m; 30 Oct. 1989; B. Richer-ORSTOM leg.; MNHN. – Grande Terre, Yaté • 1 specimen, dead; Stn 618; 22°05′ S, 166°56′ E; depth 53–58 m; 6 Aug. 1986; B. Richer-ORSTOM leg.; MNHN. – Grande Terre, Nouméa • 2 specimens, dead; Grand Récif Sud, Stn 545; 22°52′ S, 166°50′ E; depth 37 m; 15 Jul. 1985; B. Richer-ORSTOM leg.; MNHN.
Description (Fig. 2)
SHELL. Of moderate size (diameter up to 13.5 mm), lenticular (H/D 0.59–0.66); teleoconch of up to 5.5 whorls; glossy throughout, except for umbilical callus and columella pillar; periphery rounded, close to mid-whorl; suture level with or slightly above periphery; base anomphalous. First teleoconch whorl with ±3 narrow spiral cords; cords broadening during second whorl and with additional intermediaries arising; sculpture appearing more like incised striae between low, broad cords at start of third whorl; subsequent whorls with only wide-set, incised striae; microscopic axial threads evident throughout, with more distinct, regularly spaced, collabral growth-lines on last adult whorl; base with fewer, more widely-spaced incised striae; striae more close-set and growth-lines more evident toward umbilicus; umbilicus entirely occluded by large callus lobe extending from parietal lip. Aperture roundly quadrate, peristome interrupted in parietal region; columella lip thickened and with indistinct transverse ridges; umbilical callus and columella lustreless with microshagreened surface; outer lip simple, strongly prosocline above periphery, orthocline below; interior smooth, nacreous in live-collected specimens.
COLOUR. Shell mottled or washed in shades of pale yellowish-white, pale orange-yellow, rose-pink, deep pink or crimson, with narrow capillary lines of alternating white and brownish dashes or chevronshaped marks; sometimes with greenish or brownish subsutural lines, spots or blotches; region bordering umbilical callus behind basal lip usually with bold reddish radiating markings; protoconch white.
DIMENSIONS. Holotype, height 8.0 mm, diameter 12.2 mm; largest specimen, diameter 13.5 mm.
PROTOCONCH (Fig. 3A–B). As in Ethalia montrouzieri; diameter ± 190 µm.
OPERCULUM AND RADULA (Fig. 3C–F). As in Ethalia montrouzieri.
EXTERNAL ANATOMY (from rehydrated specimens). Limited detail evident; inter-tentacular region (forehead) of moderate width; snout prominent, subterminally papillate; cephalic tentacles slender; eyestalks well developed, each distally expanded and containing a large black eye; left neck-lobe digitate; right neck-lobe with entire margin and rolled to form exhalant siphon; four micropapillate epipodial tentacles on each side with a white epipodial sense organ at base of each, one also beneath each neck-lobe. Sides of foot and epipodium with dense white to cream pigmentation, particularly the metapodium. Details of ctenidial structure not clear, but anterior portion not attached.
Habitat
No substratum data recorded; dead shells at depths of 37–70 m (living specimens 37–65 m).
Distribution (Fig. 4)
Known only from the eastern Coral Sea (Chesterfield-Bellona Plateau and Lansdowne-Fairway Banks), the Lagon Nord and the south of Grande Terre, New Caledonia.
Remarks
Ethalia anomphala sp. nov. is a distinctive species on account of its completely occluded umbilicus, even in juvenile specimens. The co-occurring Ethalia montrouzieri also has an extensive callus largely occluding the umbilicus in adult specimens, but the umbilicus is clearly patent in juvenile and subadult specimens and even adult specimens retain a small chink medial to the base of the columella. Ethalia montrouzieri also attains a larger size (diameter up to 22.0 mm), and has a more globose profile with a deeper last adult whorl. Ethalia lampra is a smaller species (diameter up to 8.0 mm) that lacks an expanded umbilical callus and has only a small reflection at the end of the umbilical funicle. The completely occluded umbilicus of E. anomphala is reminiscent of that of species of Umbonium, but it lacks the highly specialised anatomical modifications found in species belonging to that genus.
The distribution of Ethalia anomphala sp. nov. is unusual in that it seems to be restricted to isolated reefs away from the main land mass of Grande Terre, occurring only in the extreme north and south of the latter. Lamprell & Healy (2001) observed similar distributions in some species of Spondylus Linnaeus, 1758. This pattern may reflect a preference for ecosystems where the sediment is primarily bioclastic, with little or no terrigenous material.
description: Published as part of Herbert, David G., 2024, The Umboniinae (Mollusca: Gastropoda: Trochidae) of New Caledonia, with descriptions of two new genera and eight new species, plus an additional new species from the Bismarck Sea, pp. 1-143 in European Journal of Taxonomy 973 on pages 8-12, DOI: 10.5852/ejt.2024.973.2765, http://zenodo.org/record/14440264