taxonID	type	description	language	source
8E64A331FFE13419FF38FB0AFB9791B8.taxon	description	urn: lsid: zoobank. org: act: 2 C 282 A 6 B-FAEE- 4 CCB- 848 F- 29 FC 94 BBA 1 F 7 (Figure 1 A – I)	en	Chernyshev, Alexei V. (2026): A new species of Ammonicera (Gastropoda, Heterobranchia) from Sesoko Island (Okinawa Prefecture, Japan). Zootaxa 5763 (2): 298-300, DOI: 10.11646/zootaxa.5763.2.9, URL: https://doi.org/10.11646/zootaxa.5763.2.9
8E64A331FFE13419FF38FB0AFB9791B8.taxon	materials_examined	Type material. Holotype: MIMB 52133; Paratypes: MIMB 52134 (lot of 6 specimens). Type locality. East China Sea, Sesoko Island (Okinawa Prefecture), 26.65019 ° N, 127.8728 ° E, intertidal zone [among green algae, July 30, 2001, collected by E. I. Shornikov].	en	Chernyshev, Alexei V. (2026): A new species of Ammonicera (Gastropoda, Heterobranchia) from Sesoko Island (Okinawa Prefecture, Japan). Zootaxa 5763 (2): 298-300, DOI: 10.11646/zootaxa.5763.2.9, URL: https://doi.org/10.11646/zootaxa.5763.2.9
8E64A331FFE13419FF38FB0AFB9791B8.taxon	etymology	Etymology. The species is named to honor my friend Valery V. Postnikov.	en	Chernyshev, Alexei V. (2026): A new species of Ammonicera (Gastropoda, Heterobranchia) from Sesoko Island (Okinawa Prefecture, Japan). Zootaxa 5763 (2): 298-300, DOI: 10.11646/zootaxa.5763.2.9, URL: https://doi.org/10.11646/zootaxa.5763.2.9
8E64A331FFE13419FF38FB0AFB9791B8.taxon	diagnosis	Diagnosis. Ammonicera with protoconch sculptured by several (6 – 7 on each surface) flat and wide spiral cords separated by narrow spiral grooves; nucleus of protoconch lacking spiral sculpture and covered by irregular depressions; teleoconch with low, smooth axial ribs and fine spiral microsculpture.	en	Chernyshev, Alexei V. (2026): A new species of Ammonicera (Gastropoda, Heterobranchia) from Sesoko Island (Okinawa Prefecture, Japan). Zootaxa 5763 (2): 298-300, DOI: 10.11646/zootaxa.5763.2.9, URL: https://doi.org/10.11646/zootaxa.5763.2.9
8E64A331FFE13419FF38FB0AFB9791B8.taxon	description	Description. Shell brown, planispiral, tightly coiled, with maximum shell diameter 0.31 – 0.47 mm (0.47 mm in holotype and 0.31 – 0.45 mm in five paratypes). In holotype, protoconch with approximately 0.8 whorl, 0.10 mm in maximal diameter; scar between protoconch and transition zone wide and poorly visible; slit-like scar between transition zone and teleoconch conspicuous (Fig. A, B) (for terms, see Oliver & Rolán 2015); in one of paratypes, scar between protoconch and transition zone conspicuous, but scar between transition zone and teleoconch indistinct (Fig. D, E); in most paratypes, both scars conspicuous (Fig. F). Protoconch sculptured by (5) 6 – 7 (8) flat and wide spiral cords on each surface, narrow spiral grooves between these cords; outer spiral cords more distinct than inner ones (Fig. B – F); closer to nucleus, spiral grooves becoming discontinuous and irregular. Nucleus of protoconch lacking spiral cords, covered by wrinkled sculpture (Fig. C, F). Very small pits forming fine spiral sculpture of both protoconch and teleoconch. Teleoconch approximately 1.2 – 1.5 whorls, without spiral cords, but with very thin spiral grooves (Fig. I). Apical and basal surfaces sculptured by wide and smooth axial ribs, 10 – 16, with interspaces ca. 0.9 – 1.4 times their width; ribs becoming almost invisible toward the aperture. Aperture rounded (Figs. G, H).	en	Chernyshev, Alexei V. (2026): A new species of Ammonicera (Gastropoda, Heterobranchia) from Sesoko Island (Okinawa Prefecture, Japan). Zootaxa 5763 (2): 298-300, DOI: 10.11646/zootaxa.5763.2.9, URL: https://doi.org/10.11646/zootaxa.5763.2.9
8E64A331FFE13419FF38FB0AFB9791B8.taxon	discussion	Remarks. The genus Ammonicera comprises 50 recent species (Alves et al., 2025) that differ in the teleoconch and protoconch sculpture. The diagnostic characters have been summarized in recent keys to Ammonicera species (Alves et al., 2025). The teleoconch sculpture of the new species is very similar to that of A. japonica by the lack of spiral cords and nodules (vs. the angulated and nodulous shell of A. angulata). However, the protoconch of A. japonica has two spiral ridges and an outer reticulate sculpture (Sleurs, 1983; Okutani, 2000). In the protoconch sculpture, the new species is very similar only to A. san Rolán, Luque & Peñas, 2009 from Namibia. Both species have 6 – 8 spiral cords (vs. 1 – 3 cords in other species) on each surface of the protoconch, but in A. san, the protoconch cords are nodulous, the teleoconch lacks axial ribs, and the shell is much larger (to 0.67 mm in diameter) (Rolán et al., 2009).	en	Chernyshev, Alexei V. (2026): A new species of Ammonicera (Gastropoda, Heterobranchia) from Sesoko Island (Okinawa Prefecture, Japan). Zootaxa 5763 (2): 298-300, DOI: 10.11646/zootaxa.5763.2.9, URL: https://doi.org/10.11646/zootaxa.5763.2.9
