Ilanga philia, 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 : 245-247

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

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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.

Figures

FIGURE 24. Ilanga philia n. sp., Tonga Islands, BORDAU 2. A–D. Holotype MNHN (IM-2000-34406), stn DW1524, 351– 354 m, 6.4×11.2 mm. E–H. Paratype MNHN (IM-2000-34408), stn CP1525, 349–351 m, 5.8 x×11.2 mm. Scale 5 mm.