Tetraclita kuroshioensis Chan, Tsang & Chu, 2007 Figure 16a-g, Table 1: species no. 62

Tetraclita squamosa viridis: Hiro 1936b: 635.

Tetraclita squamosa squamosa: Utinomi 1968a: 178.

Tetraclita pacifica Chan et al., 2007 a: 88, figs 4-6.

Tetraclita kuroshioensis Chan et al., 2007: 56; Chan et al. 2009a: 192, fig. 164; Pochai et al. 2017: 21, fig. 6.

Material examined.

Ambon Island: 1 specimen, MZB Cru Cir 097, Hatu, 3°43'52.7"S, 128°02'51.4"E, coll. Adin, 20 Sep 2017; 6 specimens, MZB Cru Cir 098, Ureng, 3°40'14.0"S, 127°56'47.6"E, coll. Adin, 20 Sep 2017. Saparua Island: 1 specimen, MZB Cru Cir 100, Dermaga Ihamahu, 3°31'13.0"S, 128°41'14.9"E, coll. P. Pitriana & D. Tala, 11 Apr 2016.

GenBank accession numbers.

COI gene (MK995363, MK995364, MK995367), 18S (MK981375, MK9876, MK981379).

Diagnosis.

Shell conical with four plates, tubiferous; radii solid; tergum broad, apex not beaked.

Description.

Shell with four inseparable, multi-tubiferous plates, greyish black to purplish-grey or deep green to green, surfaces with mosaic scales pattern radiating randomly from base to apex, internal surface of parietes smooth, white with dark grey striations around aperture; radii solid (Fig. 16a-c); basis membranous; scutum larger than tergum, triangular, external surface with horizontal striations, occluding margin with fine teeth; tergum broad, higher than wide, apex not produced as beak, spur sharp, basi-scutal angle smaller than that of Tetraclita squamosa (Fig. 16d, e); external surface of operculum grey and yellowish-light brown, internal surface greyish-dusky green; mandible with four large teeth; maxillule not notched with eleven setae; labrum with five small teeth on each side; cirrus I possessing serrulate setae. Basal length 12.1-21.6 mm, basal width 18.1-21.8 mm, height 7.3-10.4 mm. Orifice length 3.2-5.3 mm, orifice width 2.4-4.2 mm (measurements for five specimens are presented in Suppl. material 1: Table S15).

Distribution.

Tetraclita kuroshioensis was previously recorded from Japan, Taiwan, Palau, and Thailand (Chan et al. 2009a; Pochai et al. 2017). In this study, T. kuroshioensis was found on Ambon Island (at Hatu and Ureng) and Saparua Island (at Dermaga Ihamahu) on rocks and concrete wall of a port (a map with the occurrence of Tetraclita kuroshioensis in the Moluccas is shown in Suppl. material 1: Fig. S4).

Remarks.

Tetraclita kuroshioensis and T. squamosa share great morphological similarity. However, DNA sequences separate the two species (Chan et al. 2007), which was confirmed in this study (Fig. 29). Morphologically, the shape of the tergum is definitive; that of T. kuroshioensis is broader and the apex blunter compared to T. squamosa (Chan et al. 2007).