Ilanga comes, 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 : 242-244

Ilanga comes n. sp.

( Figs 22 A–L, Table 13, Key 2: 5)

DNA ref: Ilanga 12 ( Williams et al. 2013; Sumner-Rooney et al. 2016)

COI sequence data: GenBank Accession number: HF586267 .

Type material. Holotype (5.9× 11.3 mm) MNHN IM-2009-13303 . Paratype MNHN IM-2007-18221 (as listed below) .

Type locality. Philippines, PANGLAO 2004, stn T27, 09°33’N, 123°51’E, 106–137 m (lv) .

Material examined. Philippines. PANGLAO 2004: stn T27, 09°33’N, 123°51’E, 106–137 m, 2 lv (holotype and paratype) .

Distribution. Only known from the type locality.

Diagnosis. A medium-sized Ilanga species with a depressed, conical spire, a rounded periphery, 4 spiral cords on first teleoconch whorl, cords vanishing on third whorl, subsutural pleats and folds on median whorls, weakly subangulate umbilicus bordered by a spiral cord and about 45 axial grooves, 6 smooth spiral cords and axial threads inside.

Description. Shell: Medium-sized for genus (H up to 6.8 mm, W to 11.3 mm), much wider than high, shape conical; spire depressed, height 0.52–0.62×width, about 1.69×to 1.94×aperture height; nearly rounded periphery; umbilicus very broad and deep. Protoconch ca. 250 μm wide, 1.25 whorls, rounded, translucent, with one thin spiral thread and a straight, slightly expanded terminal lip. Teleoconch up to 4.6 convex whorls; early teleoconch whorls with 4 spiral cords; intermediate whorls with subsutural axial pleats; last whorls smooth with faint spiral cords on periphery. Suture canaliculated on first whorls, impressed on last whorls. First teleoconch whorl convex, with 4 spiral cords appearing immediately and thin axial threads; P2 strongest; distance between cords about 1.5×to 2×width of cords. On second whorl, all cords widening and flattening after half whorl; low axial beads appearing, turning into elongated pleats covering adapical third of whorl. On third whorl, subsutural pleats stronger, especially in subsutural area; all spiral cords almost vanishing. On fourth whorl, axial pleats weakening and vanishing; a few faint spiral cords, poorly visible, around periphery. Aperture subelliptical quadrate; peristome incomplete; outer and inner lip thin; inner lip with a weak thickening against umbilical rim; umbilical rim crenulated at intersection with spiral cords within umbilicus. Base strongly convex; two outer thirds smooth, inner third with reticulate pattern made by 2–6 spiral cords and axial grooves on inner third; about 45 axial pleats reaching spiral cord bordering umbilical rim. Umbilicus in depression of base, very broad (diameter 26–28% of shell width), central, with perspective to apex, with subangulate rim, convex wall, axial threads and 5–8 spiral cords making reticulate pattern inside.

Colour: Teleoconch greyish white, with brownish flames, one or two bands of brown and white patches, regular brownish patches on periphery; base paler, with brownish maculations.

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

Remarks. Ilanga comes n. sp. is rather close to I. dongshaensis from South China Sea that has a similar size but differs in having a more elevated spire (height 0.64–0.76×width, instead of height 0.52–0.62×width here), 5 spiral cords on the first teleoconch whorl (instead of 4), a narrower umbilicus and fewer axial pleats around it (about 30–35 instead of about 45 here).

Ilanga comes n. sp. resembles I. cosmia from Tonga and Solomon Islands regarding its subangulate umbilicus and size, but I cosmia differs considerably by its conical (not coeloconoidal) shape and has no axial threads inside the umbilicus.

Ilanga comes n. sp. is also rather close to I. fulgens but I. fulgens , which also occurs in the Philippines, is slightly larger (H up to about 7.7 mm, W up to about 12.9 mm), not as depressed (height 0.53x to 0.66x width, instead of height 0.52–0.62×width in I. comes n. sp.) and lacks both subsutural pleats and axial threads inside the umbilicus.

Etymology. Earl (Latin: comes, -itis), used in apposition as a noun—with reference to the crown of an earl, that has the most numerous beads in heraldry.

Figures

FIGURE 22. Ilanga comes n. sp., Philippines, PANGLAO 2004, stn T27, 09°33’N, 123°51’E, 106–137 m. A–I. Holotype MNHN IM-2009-13003, 5.9×11.3 mm. A–B. Shell, apertural view (with and without animal). Scale 5 mm. C. Detail of internal lip of the aperture. D–F. Shell, apical and basal views. G. Details of protoconch and first whorl. Scale 100 µm. H. Sculpture on whorls. Scale 1 mm. I. Details of umbilical area. Scale 1 mm. J–L. Paratype MNHN IM-2007-18221, 6.8×11.0 mm.