Hemipecten A. Adams & Reeve, 1849

Dijkstra, Henk H. & Beu, Alan G., 2018, Living Scallops of Australia and Adjacent Waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae), Records of the Australian Museum (Rec. Aust. Mus.) 70 (2), pp. 113-330 : 235-236

Hemipecten A. Adams & Reeve, 1849

Venilia A.Adams & Reeve , in Anonymous, 1848: 776. Type species (by monotypy): Venilia concentrica A. Adams & Reeve , in Anonymous, 1848. Junior homonym of Venilia Duponchel, 1829 , Lepidoptera ( Petit, 2007: 100) .

Hemipecten A. Adams & Reeve, 1849: 133 ; Adams & Reeve, 1850: 72 [diagnosis]. Type species (by monotypy): Hemipecten forbesianus A.Adams & Reeve, 1849 ; living, Sulu Archipelago, Philippine Islands .

Hemipecten Reeve in Forbes & Hanley, 1849: 323 [nomen nudum].

Semipecten Fischer, 1886: 945 (incorrect subsequent spelling of Hemipecten A. Adams & Reeve ).

Diagnosis. Hemipectinae [sic] Habe (1977: 88) [in Japanese]: “Shell medium in size, attached to substrate with right valve, looks like Anomia chinensis . Shape of the shell irregular and thin, right valve with anterior auricle only, deep byssal notch, pectinated in anterior edge, left valve with welldeveloped anterior auricle (only anterior auricle is developed well)” [translation of original diagnosis]. An unevenly shaped ( Anomia -like), inaequivalve pectinid; antimarginal microsculpture fine; slightly auriculated posteriorly; hinge edentulous; resilium high, narrow (resembling that of Spondylus ); resilial teeth of right valve towards resilium; hinge plate broad with weak transverse grooves; byssal notch deep, ctenolium prominent.

Distribution. Pliocene–Recent. Indo-West Pacific (Hayami, 1989: 15), intertidal to sublittoral.

Remarks. Hertlein (1969: N354) placed Hemipecten in the Eburneopecten group, together with the extant genera Cyclopecten Verrill, 1897 (with subgenera Chlamydella Iredale, 1929 and Pectinella Verrill, 1897 ), Palliolum Monterosato, 1884 (with subgenera Delectopecten Stewart, 1930 , Hyalopecten Verrill, 1897 and Lissochlamis Sacco, 1897 ) and Pseudamussium Mörch, 1853 . Cyclopecten and Chlamydella are now considered to be genera of Cyclochlamydidae . Palliolum and Pseudamussium were placed by Waller (1991: 35; 1993: 198) in Palliolini, a tribe of Pectininae, although he later ( Waller, 2006a: 10) raised this to a separate subfamily Palliolinae of Pectinidae . Delectopecten is now the only extant genus of Camptonectinae Habe, 1977 (see Waller & Marincovich, 1992: 219). Ciclopecten has no Camptonectes –like (antimarginal) microsculpture and is closely related to the radially sculptured ancestor Praechlamys Allasinaz, 1972 (see Waller & Marincovich, 1992: 219). The remaining genus Lissochlamis has simple antimarginal microsculpture without radial macrosculpture and perhaps therefore could be placed in Camptonectinae . Yonge (1981) stated that H. forbesianus has a homorhabdic gill, unlike all other Pectinidae . However, Beninger & Decottignies (2008) demonstrated that it actually has the same heterorhabdic gill as all other pectinids, removing concerns about its taxonomic position. Habe (1977: 88) placed Hemipecten in a new subfamily Hemipectininae , but T. R. Waller (USNM, pers. comm. 2008) stated to us that it is most closely related to Laevichlamys and should be included in Pedini .