Necterosoma W. J. Macleay, 1871

Balke, Michael, Toussaint, Emmanuel F. A., Hendrich, Lars & Hájek, Jiří, 2013, A new species of the Australian genus Necterosoma from Timor (Coleoptera: Dytiscidae: Hydroporini), Acta Entomologica Musei Nationalis Pragae 53 (1), pp. 65-74 : 67

Necterosoma W. J. Macleay, 1871

Necterosoma W. J. Macleay, 1871: 124 . Type species: Necterosoma vittipenne W. J. Macleay, 1871 (= Hydroporus penicillatus Clark, 1862 ) by subsequent designation of GUIGNOT (1946).

Necterosoma: SHARP (1882) : 412 (redescription); BRANDEN (1885): 44 (catalogue); ZIMMERMANN (1919): 145 (key); (1920): 63 (catalogue); WATTS (1978): 90 (redescription); ZWICK (1979): 179 (redescription); PEDERZANI (1995): 34 (key); NILSSON (2001): 174 (catalogue); HENDRICH et al. (2010a): 154 (redescription, catalogue); NILSSON (2013): 160 (catalogue).

Diagnosis. Small to medium-sized beetles (4.0– 5.4 mm), characterised by distinctly pentamerous protarsi, sides of elytra with small subapical spine, males with protibiae notched on inner side, often strongly so. Most species with distinct colour pattern on elytra, and raised elytral striae in three species. From Sternopriscus Sharp, 1880 , another Australian genus the members of which have pentamerous protarsi, Necterosoma differs with ‘normal’ mesepimeron being in more or less vertical position, at pronounced angle with metanepisternum, and with medially contiguous metacoxal cavities with the interlaminary bridge totally concealed (cf. ZIMMERMAN 1982).

Distribution. Eleven species were recently recognised in the genus: two species are endemic to New Caledonia; nine species occur in Australia (three species also reach Tasmania) ( WATTS 1978, 2002; ZWICK 1979; HENDRICH 2003; HENDRICH et al. 2010a). Presence of the genus in New Guinea is possible.