Ilanga harrytaylori, Vilvens & Williams, 2020

Vilvens, Claude & Williams, Suzanne T., 2020, New species of Ilanga (Gastropoda: Trochoidea: Solariellidae) from the Indo-West Pacific, Zootaxa 4732 (2), pp. 201-257 : 232-234

Ilanga harrytaylori n. sp.

( Figs 17 A–O, Table 8, Key 2: 8)

DNA ref: Ilanga cf. norfolkensis ( Williams et al. 2013; Sumner-Rooney et al. 2016)

COI sequence data: GenBank Accession numbers: HF586272 , HF586273 , HF586270 , HF586271

Type material. Holotype (6.3× 10.8 mm) MNHN IM-2007-18324 . Paratypes: 3 MNHN (IM-2007-18325, IM-2007- 35580, IM-2007-35581) and 1 NHMUK 20190458 (as listed below) .

Type locality. New Caledonia, Chesterfield , EBISCO, stn DW2603, 19°36’ S, 158°43’ E, 568–570 m.

Material examined. New Caledonia, Chesterfield. MUSORSTOM 5: stn DW340, 19°49’S, 158°41’E, 675– 680 m, 1 dd, 1 dd sub, 7 dd juv . — Stn DW341, 19°46’S, 158°43’E, 620–630 m, 1 dd sub . — Stn DC357, 19°37’S, 158°46’E, 630 m, 1 dd, 2 dd sub . —EBISCO: stn DW2603, 19°36’ S, 158°43’ E, 568–570 m, 7 lv (with holotype MNHN IM-2007-18324, paratype MNHN IM-2007-18325), 4 dd sub, 6 dd juv . — New Caledonia, Bellona. EBI- SCO: stn DW2561, 20°29’S, 158°42’ E, 197–230 m, 1 dd . — New Caledonia, Entrecasteaux reefs. BATHUS 4: stn DW918, 18°49’S, 163°16’E, 613–647 m, 1 dd, 1 dd sub . — New Caledonia, Grand Passage. MUSORSTOM 4: stn DW159, 18°46’S, 163°16’E, 600 m, 1 dd sub . — Stn DW160, 18°42’S, 163°13’E, 675 m, 1 dd sub, 1 dd juv . —BA- THUS 4: stn CP921, 18°47’S, 163°17’E, 610–613 m, 3 lv . —CONCALIS: stn CP3010, 18°46’S, 163°19’E, 603 m, 2 lv (paratypes MNHN IM-2007-35580 and IM-2007-35581) . — Stn CP3012, 18°50’S, 163°14’E, 616–628 m, 21 lv, 3 lv sub, 1 dd juv (paratypes NHMUK 20190458 ) . — Fiji. BORDAU 1: stn DW1432, 17°20’S, 178°44’W, 477– 493 m, 6 dd, 1 dd sub, 3 dd juv . — Stn DW1486, 19°01’S, 178°26’W, 395–540 m, 1 dd . — Stn DW1488, 19°01’S, 178°25’W, 500–516 m, 2 dd, 1 dd juv . — Tonga Islands. BORDAU 2: stn CP1510, 21°05’S, 175°23’W, 461–497 m,

1 lv. — Stn CP1545, 21°17’S, 175°17’W, 444–447 m, 2 lv . — Stn DW1549, 20°38’S, 175°00’W, 500 m, 1 dd . — Stn DW1551, 20°38’S, 175°01’W, 511 m, 2 dd . — Stn DW 1552, 20°38’S, 174°58’W, 491–500 m, 1 juv sub . — Stn

CH 1596, 19°06’S, 174°18’W, 371–437 m, 2 lv.

Distribution. New Caledonia, 230–675, lv at 570–616 m; Fiji Is., 493–500 m (dd); Tonga Is., 437–511 m, lv at 437– 461 m.

Diagnosis. A medium sized Ilanga species with a moderately depressed, conical spire, a subangulate periphery with several faint spiral cords, 6–7 spiral cords on first whorl vanishing on third whorl, subsutural pleats and folds on median whorls, an angulate umbilicus bordered by a granular spiral cord, with 30–40 axial pleats around it, 4–6 smooth spiral cords and thin axial threads inside.

Description. Shell: Rather tall for genus (H up to 7.9 mm, W up to 13.9 mm in type material, some large specimens up to 9x 15 mm [BATHUS 4]), much wider than high, shape conical with large apical angle, glossy; spire depressed, height 0.55×to 0.63×width, 1.54×to 1.81×aperture height; periphery subangulate; umbilicus very broad and deep. Protoconch ca. 300–400 μm wide, 1.25 whorls, rounded, translucent, with 3 weak spiral cords and with a slightly expanded terminal lip. Teleoconch up to 4.8 convex whorls with a weak subsutural ramp on first whorls but vanishing on last whorls; early whorls with 6–7 smooth spiral cords; penultimate whorl with a granular adapical cord and 3–4 low, thin spiral cords; last whorl nearly smooth with a subsutural smooth spiral cord and thin, poorly visible spiral threads, especially detectable on abapical half. Suture impressed, not canaliculated. First whorl convex, sculptured with 7 (possibly 6 only) smooth spiral cords, Pi (i=1–4) and Si (i=2–4) appearing immediately; P2 strongest, P1 almost as strong as P2, other cords thinner; distance between P1–P2 and P2–S2 similar to each other, other distances smaller except distance between suture and P1 being greater; thin axial threads between cords. On second whorl, all cords thickening; at half whorl, P1 made subgranular and finally granular by subsutural axial folds; axial threads thinner, weakening and finally vanishing at end of whorl. On third whorl, P1 flattened with beads transforming into low, separate nodules; other cords almost vanishing, forming weak, low smooth cords hard to detect; low axial folds covering whole surface. On fourth whorl, granular P1 vanishing, leaving only a smooth, rather thin subsutural spiral cord. On last whorls, about half a dozen weak spiral cords on abapical part and especially weak on periphery. Aperture subcircular; peristome incomplete; outer and inner lip thin; inner lip without obvious thickening against umbilical rim. Base moderately convex; two outer thirds smooth, inner third with 30–45 axial pleats reaching spiral cord bordering umbilical rim, cord granular at intersections with axial pleats; in some specimens up to 4 additional spiral grooves around umbilicus. Umbilicus broad (diameter 25–28% of shell width), central, with perspective to apex, with angulate rim, with vertical wall, 4–6 smooth spiral cords and thin axial threads inside.

Colour: Teleoconch silver-white or nacreous white, sometimes with strong pink-green iridescence or with rather thin axial brown flames.

Operculum: Corneous, multispiral with central nucleus, light brown.

Remarks. Regarding the distribution of I. harrytaylori , one may wonder about the gap between the New Caledonia, Fiji Islands and the more distant Tonga Islands. But all the specimens share the same peculiar conchological features, for example, the simultaneous Pi and Si or the spiral and axial sculpture combination inside the umbilicus. They were also all collected living in deep water (> 400 m). Note that sequenced specimens (all from New Caledonia) include both animals with coloured and uncoloured shells.

Although described by Williams et al. (2013) as being similar to I. norfolkensis ( Marshall, 1999) from off Norfolk Island (between New Caledonia and New Zealand), I. harrytaylori is larger, has stronger subsutural pleats, a moderately convex umbilicus wall (instead of vertical), much weaker axial pleats around the umbilicus and a protoconch without axial threads (instead of 3).

The new species weakly resembles I. navakaensis ( Figs 8 A–I) from Vanuatu, but I. navakaensis is smaller (H up to 5.7 mm, W up to 9.2 mm), has a more elevated spire (height 0.54×to 0.66×width, instead of height 0.55×to 0.63×width), a smaller protoconch (300–320 μm wide, instead of 300–400 μm), fewer spiral cords on the early whorls, a subsutural cord completely vanishing on the last whorls and never has spiral grooves around the inside of the umbilicus.

Etymology. After Harry Taylor, the NHMUK photographer who has taken all the photos of specimens used in the phylogenetic analysis in this paper and many other shell photos in papers by the second author.

Figures

FIGURE 8. Ilanga navakaensis (Ladd, 1982), Vanuatu, SANTO 2006. A–F. MNHN IM-2007-18446, Stn AT112, 150–168 m, 5.0×9.2 mm. A–C. Shell, apertural, apical and basal views. D. Details of protoconch and first whorl. Scale 100 µm. E. Sculpture on whorls. Scale 1 mm. F. Details of umbilical area. Scale 300 µm. G–I. Stn AT54, 68–79 m, 5.7×8.6 mm. Scale (except for SEM images) 5 mm.

FIGURE 17. Ilanga harrytaylori n. sp. A–I. New Caledonia, Chesterfield Is., EBISCO, stn DW2603, 568–570 m. A–F. Holotype MNHN IM-2007-18324, 6.3×10.8 mm. A–C. Shell, apertural, apical and basal views. D. Details of protoconch and first whorl. Scale 100 µm). E. Sculpture on whorls. Scale 1 mm). F. Details of umbilical area. Scale 1 mm). G–I. Paratype MNHN IM-2007-18325, 5.9×9.3 mm. J–L. New Caledonia, Grand Passage, CONCALIS, stn CP3012, 616–628 m, 8.5×14.2 mm. M–O. Tonga Islands. BORDAU 2, stn CP1545, 21°17’S, 175°17’W, 444–447 m, 7.1×11.5 mm. Scale (except SEM images) 5 mm.