Tetraclitella divisa (Nilsson-Cantell, 1921) Figure 13a, b, Table 1: species no. 59

Tetraclita divisa Nilsson-Cantell, 1921: 362, fig. 83, pl. 3 fig. 11.

Tetraclitella (Tetraclitella) divisa: Ross and Perreault 1999: 6.

Tetraclitella divisa: Ross 1968: 13; Dong et al. 1982: 111; Foster 1974: 45, figs 6E-F, 7E- F; Bacon et al. 1984: 86; Paulay and Ross 2003: 308; Chan et al. 2009a: 208, fig. 178.

Material examined.

Ambon Island: 1 specimen, MZB Cru Cir 120, Laha, 3°43'22.5"S, 128°05'02.5"E, coll. P. Pitriana & D. Tala, 7 Sep 2016.

Diagnosis.

Shell with four plates, flattened, not strongly articulated; radii tubiferous; summit of radii horizontal; tergal spur well separated from scutal margin.

Description.

Shell depressed, covered by furry chitinous integument; shell plates with prominent radiating ribs; radii wide, porose, tubes running parallel to base of shell; colour of shell pale purplish; orifice diamond shaped (Fig. 13a, b); scutum triangular, tergal margin straight; tergum higher than wide, scutal margin straight, spur short; mandible with four teeth, second and third teeth bidentate; labrum with smooth cutting edge (measurements for one specimen are presented in Suppl. material 1: Table S12).

Distribution.

Tetraclitella divisa was previously recorded from Western Africa, Java, Malaysia, Sumatra, Northern Australia, Singapore, South China Sea, China, Taiwan, Japan, the Pacific Ocean to Hawaii and Pitcairn (Jones and Hosie 2016). In this study, T. divisa was found on Ambon Island at Laha on a concrete wall at the port (a map with the occurrence of Tetraclitella divisa in the Moluccas is shown in Suppl. material 1: Fig. S2).

Remarks.

Tetraclita divisa exhibits a brooded phase to the cypris larval stage in the mantle cavity, whereas most other species release the first stage nauplius (Nilsson-Cantell 1921; Hiro 1939).