Rectidens lauris Zieritz et al.

Zieritz, Alexandra, Pfeiffer, John, Rahim, Khairul Adha A., Prayogo, Hari, Anwari, Muhammad Sofwan, Diba, Farah, Froufe, Elsa, Blackwell, Tabitha, Hartikainen, Hanna & Lopes-Lima, Manuel, 2024, High endemic freshwater mussel (Bivalvia: Unionida) diversity in western Borneo, with description of three new species, Zoological Journal of the Linnean Society 201, pp. 1-15 : 12-13

Rectidens lauris Zieritz et al. , sp. nov.

( Fig. 4 )

Type locality: Sungai Rempangi (Pawan Drainage), 17 km SSW of Randau, Ketapang Regency, West Kalimantan, Indonesia.

Type: Holotype, FKH_MFw_x533. Paratype, FKH_MFw_ x519, Sungai Melayu [Pawan Drainage], 18.7km SSW of Randau, Ketapang Regency, West Kalimantan, Indonesia.

Material examined: Two lots: FKH_MFw_x533, FKH_MFw_x519.

Diagnosis: Morphologically very similar to Rectidens sumatrensis .

Description: Shell thin, elongate shell outline; dorsal margin slightly rounded; ventral margin straight; posterior slope slightly biangulate; umbo even with hinge line; periostracum, yellowish/ greenish brown. Psedocardinal teeth, long, thick, one tooth in less valve* two teeth in right valve. Lateral teeth long* curved* two in less valve* one in right valve; Nacre white* with peach tint near the umbo. Soss anatomy unavailable for study.

Distribution: Known from only two localities in the Pawan drainage in West Kalimantan % Fig. 5 ).

Etymology: Ŋe species is named asser the river catchment of its type locality* i.e. the Laur River basin* and the ethnic group indigenous to this area* i.e. ‘Dayak Laur’.

Figures

Figure 4. Holotypes of Ctenodesma bersinara, Sungai Rempangi, Pawan River basin, West Kalimantan, Indonesian Borneo; Ctenodesma mawonae, Sungai Sebua Jebung, Sarawak River basin, Jambusan, Bau, Sarawak, Malaysian Borneo; and Rectidens lauris, Sungai Rempangi, Pawan River basin, West Kalimantan, Borneo. Abbreviations: FKH, Fahutan Kapuas Hulu Collection, Tanjungpura University, Indonesia; FRST, Faculty of Resource Science and Technology Collection, Universiti Malaysia Sarawak, Malaysia.

Figure 5. Images of type localities of (A) Ctenodesma mawonae, i.e. Sungai Sebua Jebung in the Sarawak River basin, Jambusan, Bau, Sarawak, Malaysian Borneo, and (B) Ctenodesma bersinara and Rectidens lauris, i.e. Sungai Rempangi, Pawan River basin, West Kalimantan, Indonesian Borneo.