Viriola, Jousseaume, 1884

Viriola View in CoL thochuensis n. sp.

( Figs 2 O–U View FIG , 7 View FIG ; Table 1)

Zoobank registration: urn:lsid:zoobank.org:act:

Type material. Holotype VNMN M-000.002.349 (shell height 6.2 mm, shell width 2.2 mm, Figs. 2 S–T View FIG ) . Paratypes: VRTCM.Ga 27051019.04 (4 shells), Tai-Tu N. (10 shells), same data as holotype .

Type locality: Hon Xanh Island , Tho Chu Islands, Kien Giang province, Vietnam, 09°16’45.4’’N, 103°29’16.0’’E, depth 12 m. GoogleMaps

Etymology: This species is named after the type locality, where the type species was found Tho Chu Islands, Kien Giang province, Vietnam.

Material examined. South China Sea, Spratly Islands, Khanh Hoa Province, Vietnam: Barque Canada Reet , on dead corals and under stones, 08°16’35.3’’N, 113°21’10.7’’E, depth: 12 m, coll. Tai-Tu N., 29.5.2019, VRTCM.Ga 27051019.04 (2 shells); on dead corals and under stones, 08°16’54.4’’N, 113°21’51.8’’E, depth: 8–9 m, coll. Tai-Tu N., 30.10.2020, VRTCM.Ga 27051019.05 (3 shells); Namyit Island , on dead corals and under stones, 10°11’03.8’’N, 114°22’05.2’’E, depth: 16–18 m, coll. Tai-Tu N., 11.10.2020, VRTCM.Ga 27051920.04 (2 shells); Tho Chu Islands , Kien Giang Province, Vietnam: Hon Xanh Island , on dead corals and under stones, 09°16’45.4’’N, 103°29’16.0’’E, depth: 12 m, coll. Tai-Tu N., 13.6.2023, VRTCM.Ga 38080923.02 (7 shells) GoogleMaps .

Diagnosis. The shell is short, conoid, rather flat sides, base wide. Protoconch has 5–5½ whorls. Teleoconch has 8–9 whorls, with three spiral cords. The first and third spiral cords are smooth, appearing as granulated spiral cords on the first 2 teleoconch whorls. The second spiral cord is granular, developing later on the second teleoconch whorl. Spiral microsculpture of fine threads and axial ribs between the main spiral cords. The last whorl has 26–28 axial ribs. The shell has a white background with patches of brown to dark brown. The third spiral cord on the teleconch whorls is more brightly colored than the first and second spiral cords.

Description. The shell is short, conoid, rather flat sides, base wide. The shell has a white background with patches of brown to dark brown. The third spiral cord on the teleconch whorls is more brightly colored than the first and second spiral cords. Protoconch is reddish brown, with 5–5½ whorls. First protoconch whorl has hemispherical granules; protoconch whorls 2–3 have one median spiral thread, protoconch whorls 4–5½ have 2 median spiral threads; uninterrupted axial riblets on protoconch whorls. Teleoconch has 8–9 whorls, with three spiral cords. The first and third spiral cords are smooth, granulated on the first 2 teleoconch whorls. The second spiral cord is granular, developing later on the second teleoconch whorl. Spiral microsculpture of fine threads and axial ribs between the main spiral cords. The last whorl has 26–28 axial ribs. Base with an additional granulated spiral cord ( Fig. 7C, S View FIG 1 View FIG ) and a small, smooth spiral cord ( Fig. 7C, S View FIG 2 View FIG ). Peristome with an additional tuberculed spiral cord ( Fig. 7D View FIG , Sp1). Aperture sub- quadrate. Outer lip rather thick and flared. Anterior siphonal canal oblique, subtubular, rather short.

Measurements. Shell height 3.6–6.3, shell width 1.1–2.2 (n = 14).

Distribution. This species is known from Tho Chu islands and Spratly Islands islands.

Ecology. This species collected under stones and on dead corals.

Remarks. Viriola thochuensis n. sp. is superficially similar to V. intergranosa . However, V. thochuensis n. sp. differs from V. intergranosa in having the shell short, conoid, with rather flat sides, base rather wide ( vs. the shell short, cyrtoconoid); protoconch with 5–5½ whorls ( vs. 6 whorls); the first and third spiral cords appeared as granulated spiral cords on the first 2 teleoconch whorls ( vs. appeared as granulated spiral cords on the first 3 teleoconch whorls); the second spiral cord appears on the second teleoconch whorl ( vs. appears on the fifth teleoconch whorl); spiral microsculpture of fine threads and axial ribs ( vs. strings of granules and axial ribs); the last whorl has 26–28 axial ribs ( vs. 22–24 axial ribs); outer lip rather thick ( vs. rather thin).