Ilanga philia Vilvens & Williams 2020, n. sp.
Creators: name: Vilvens, Claude
name: Williams, Suzanne T.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Trochida
Solariellidae
Ilanga
Ilanga philia

description: Ilanga philia n. sp.
(Figs 24 A–H, Table 15, Key 2: 14)
Type material. Holotype (6.5× 10.7 mm) MNHN IM-2000-34406. Paratypes: 3 MNHN MNHN IM-2000-34407, MNHN IM-2000-34408, MNHN IM-2000-34409 and 1 NHMUK 20190463 as listed below.
Type locality. Tonga Islands, Eua, BORDAU 2, stn DW1524, 21°17’S, 175°00’W, 351–354 m.
Material examined. Tonga Islands. BORDAU 2: stn DW1518, 21°21’S, 175°07’W, 336–347 m, 2 dd sub. — Stn DW 1524, 21°17’S, 175°00’W, 351–354 m, 2 lv (with holotype and paratype 1 MNHN IM-2000-34407). — Stn CP 1525, 21°17’S, 174°59’W, 349–351 m, 1 lv (paratype 2 MNHN IM-2000-34408). — Stn DW 1540, 21°15’S, 175°14’W, 317–329 m, 3 lv, 3 sub lv. — Stn CP 1541, 21°15’S, 175°14’W, 319–333 m, 3 lv (with paratype 3 MNHN IM-2000-34409 and paratype NHMUK 20190463). — Stn DW 1577, 19°42’S, 174°19’W, 257–265 m, 4 dd, 2 dd sub. — Stn DW 1604, 22°16’S, 175°17’W, 227–350 m, 1 dd.— Stn DW 1606, 22°16’S, 175°20’W, 313–316 m, 1 dd. — Stn DW 1611, 23°00’S, 175°47’W, 278–323 m, 1 dd, 1 dd juv.— Stn DW 1612, 23°02’S, 175°47’W, 327–342 m, 1 dd, 1 dd juv
.
Distribution. Tonga Islands, 265–351 m, lv at 329– 351 m.
Diagnosis. Medium-sized Ilanga species with a rather depressed, conical spire, a subangulate periphery, 4 spiral cords on first whorl, no subsutural pleats, angulate umbilicus with a slightly rounded rim and without spiral cord around it, no axial pleats around umbilicus except near aperture and with about 8 spiral cords inside.
Description. Shell: Medium in size for genus (H up to 6.4 mm, W up to 11.2 mm), wider than high, conical in shape with large apical angle, glossy; spire depressed, height 0.49–0.57×width, about 1.64×to 2.18×aperture height; slightly subangulate periphery; umbilicus broad and deep. Protoconch about 300 μm wide, 1.25 whorls, rounded, with a straight terminal lip. Teleoconch up to 4.8 slightly convex whorls; early teleoconch whorls with 4 smooth spiral cords; intermediate whorls without subsutural axial pleats; last whorls smooth. Suture canaliculated. On first teleoconch convex whorl, 4 smooth spiral cords Pi appearing immediately; axial threads lacking; subsutural ramp forming at end of whorl, with P1 on rim; distance between cords about 1.5×width of cords. On second whorl, all cords weakening and finally vanishing. Last whorls completely smooth, with a narrow translucent subsutural spiral band. Aperture subelliptical, horizontally elongated; peristome incomplete; outer and inner lip thin; inner lip with thickening against umbilical rim. Base convex, smooth; no axial pleats around umbilicus except near aperture, similar axial pleats visible on abapical part of penultimate whorl inside umbilicus. Umbilicus broad (diameter 20–25% of shell width), central, with perspective to apex, with slightly rounded rim, bordered by an internal smooth spiral cord; 7–8 spiral cords on umbilical shell walls, mainly visible on abapical part of wall.
Colour: Teleoconch nacreous white with three horizontal bands of chevron-shaped brownish flames; base paler, with one outer row of brownish patches.
Operculum: Corneous, multispiral with central nucleus, brown.
Remarks. Ilanga philia n. sp. resembles I. lauensis as described below regarding shell shape. However, I. lauensis develops Si cords on the second whorl, has a spiral cord around the umbilicus and more spiral cords inside the umbilicus.
Etymology. Friendly (for a thing) (Ancient Greek: φίλιος, α, ον)—After “ Friendly Islands ”, another name of Tonga Islands.
description: Published as part of Vilvens, Claude & Williams, Suzanne T., 2020, New species of Ilanga (Gastropoda: Trochoidea: Solariellidae) from the Indo-West Pacific, pp. 201-257 in Zootaxa 4732 (2) on pages 245-247, DOI: 10.11646/zootaxa.4732.2.1, http://zenodo.org/record/3663329