Author: Agassiz, 1843
Diagnostic Features:
Snout broadly rounded in dorsoventral view; gill slits very long, 3 to 3.5 times the eye length in adults; mouth trapezoidal-parabolic and long, length 50 to 70% of its width; lower jaw truncated at symphysis; ends of upper labial furrows behind rear corners of eyes; a toothless space at midlines of both jaws; upper anterolateral teeth with serrated (smooth in young) mesial edges and short cusps; lower anterolateral teeth with very long, stout, strongly hooked cusps, and serrations and cusplets variably developed on the crown feet; lower crown feet and roots deeply arched, giving teeth an inverted Y shape; lower teeth protrude prominently when mouth is closed; tooth row counts 26 to 30/30 to 36, with 4 to 9 more lower rows than uppers. Fins strongly falcate, posterior margins of anal, second drosal, pectoral and pelvic fins deeply concave; second dorsal height 2/5 to slightly less than 3/5 of first dorsal height.
Remarks:
The genera Dirrhizodon and Heterogaleus are considered junior synonyms of Hemipristis (see Bass, D'Aubrey and Kistnasamy, 1975, Compagno, 1979), which has as its type the fossil H. serra. Fossil Hemipristis species were distributed worldwide in the Tertiary, but the living species is confined to the Indian and western Pacific Oceans. Some of the fossils apparently attained a larger size than the living H. elonuatus, between 3 and 5 m.
Compagno (1973d) distinguished the living species as a separate genus, Dirrhizodon, by virtue of tooth histological differences from fossil Hemipristis he had examined, but later (Compagno, 1979) reunited these genera because these differences did not hold.
Apart from a number of fossils, there have been four nominal species of living sharks that fall in this genus, all of which are probably synonyms of H. elongatus (Klunzinger, 1871). In the case of Carcharias ellioti Day, 1878, the issue was confused by the juxtaposition of figure titles of this species with Carcharias acutidens (= Negaprion acutidens), but the description identifies the figure and both make the identity of this species clear. The same applies for Heterogaleus ghardaguensis Gohar and Mazhar, 1964 and Paragaleus acutiventralis Chu, 1960 (which is apparent from descriptions and figures of the former in Gohar and Mazhar, 1964, and the latter in Chu et al., 1964), while Hemipristis pingali Setna and Sarangdar (1946) was synonymized with H. elongatus by its describers (Setna and Sarangdhar, 1949b).