Family Callianassidae Dana, 1852

Remarks. The family Callianassidae has a robust fossil record. In view of the delicate nature of the callianassid exoskeleton, however, only chelipeds (which usually are heavily calcified) are likely to be preserved in the fossil record (Bishop & Williams 2005). Nevertheless, in some cases, a complete or near-complete animal is preserved. Features of the carapace, maxillipeds, eyes, pleopods, uropods, and telson are used to assign extant species to the genus; these are very rarely if at all preserved in the fossil record. Systematics based on hard-part morphology is still debated. Discussion on this topic applied to the fossil material can be found in Schweitzer & Feldmann (2002), Schweitzer et al. (2006 b), and Hyžný & Müller (2010), for example.

Thirty-four extant callianassid genera are currently recognized (De Grave et al. 2009; see Sakai 2005, 2011 for a different view). However, as noted by Hyžný & Müller (2010: 37), less than a quarter of these has a fossil record which dates back beyond the Pliocene. This can be ascribed both to preservational and collecting biases. It should also be noted that many extant genera can be differentiated on the basis of soft-part morphology only, so if not rediagnosed they are bound to remain unrecognized in the fossil record.

Hyžný (2011a: table 2), in his listing of Middle Miocene callianassids of the Central Paratethys, showed that so far, virtually all of them were treated under " Callianassa " as a nomen collectivum in the widest sense. None of them, however, can be matched with Callianassa Leach, 1814 as defined by Manning & Felder (1991) or Ngoc-Ho (2003).