Haustorius, Muller, 1775

Hancock, Zachary B. & Wicksten, Mary K., 2018, Two new species of sand-burrowing amphipods of the genus Haustorius Müller, 1775 (Amphipoda: Haustoriidae) from the northwestern Gulf of Mexico, Zootaxa 4459 (1), pp. 101-127 : 103

Genus Haustorius

(Modified from LeCroy 2002; Barnard & Karaman 1991; Bousfield 1973; Bousfield 1965)

Diagnosis. Body broad, fusiform; rostrum medium to strong, acute or subacute; head broad with weak, unpigmented eyes below anterolateral apices; antenna 1, accessory flagellum 2–5 articulate, inserted terminally on peduncle article 3; antenna 2, peduncle article 5 without posterodistally produced lobe; mandible with incisor; left mandible with lacinia mobilis, cleft or uncleft; mandibular palp article 3 with median row of comb setae; maxilla 2 outer plate broad or slender, rounded or lanceolate distally, roughly twice the size of inner plate; maxilliped palp article 3 geniculate; gnathopod 1 simple, dactyl nail-like; gnathopod 2, minutely chelate; pereopod 3 and 4 similar; pereopod 7, article 4 much wider than long, subtrapezoidal or subtriangular; pleonite 3 overhanging urosome; epimeron 3 rounded posteroventrally without tooth; uropod 1 variously spinose; telson variously cleft.

Type Species. Haustorius arenarius Slabber.

Known Range. Northern Europe , Mediterranean Sea, North Africa, West Atlantic, Gulf of Mexico.

Remarks. Sweet (1996) proposed dividing Haustorius into two separate genera on either side of the Atlantic, and reclassified H. canadensis as ‘Genus one canadensis .’ In this scheme, the most common ancestor of H. arenarius and H. canadensis dated to the Cretaceous separation of the ‘Euramerican continent.’ Haustorius arenarius then presumably radiated into the Mediterranean Sea and across northern Europe, while ‘Genus one canadensis ’ spread down the western Atlantic coast. However, a case solely using character states does not support this, as traits such as the number of antenna 1 accessory flagellum articles, curvature of maxilla 2 outer lobe, shape of pereopod 7 article 4, and telson cleft in the Mediterranean species, H. orientalis and H. algeriensis , more closely match species in the Gulf of Mexico, particularly H. allardi sp. nov. A revision of the genus, if necessary, will likely not proceed until molecular data is available to support a deep historical division.