Clupei

Arratia, Gloria, 2018, Otomorphs (= otocephalans or ostarioclupeomorphs) revisited, Neotropical Ichthyology 16 (3), pp. 1-24 : 5-6

Clupei.

Clupei (s ensu Betancur-R et al., 2017) or Clupeiformes are characterized by a series of characters, with the most conspicuous being an otophysic connection between the swim bladder and inner ear involving a pair of anterior extensions of the swim bladder that enters the skull through the exoccipital to connect with the utriculus of the inner ear, forming ossified bullae in the prootic, and usually also in the pterotic too; base of hypural 2 fused to ural centrum 2 (= of polyural terminology sensu Schultze, Arratia, 2013; Wiley et al., 2015) from early ontogenetic stages and an autogenous hypural 1 without connection with the vertebral column from early ontogeny; one or more abdominal scutes (including pelvic scutes), each of a single element that crosses the ventral midline; and development of dorsal scutes with a median keel. For other characters see Grande (1985), Di Dario (2004), and Di Dario, de Pinna (2006) and the compilation of synapomorphies by Wiley, Johnson (2010).

The clupeiforms are represented by about 400 extant species in ca. 90 genera and five families ( Nelson et al., 2016) and an extensive fossil record, extending back to the Early Cretaceous (e.g., Grande, 1985; Malabarba, Di Dario, 2017). Two extant suborders (Denticipitoidei and Clupeoidei) and a fossil one (†Ellimmichthyioidei) are currently recognized ( Nelson et al., 2016). Clupeiforms have a worldwide distribution. They typically inhabit marine water, but about 80 species are primarily freshwater. Many species are economically important (e.g., Whitehead, 1985; Whitehead et al., 1988; Lavoué et al., 2014).

Despite the biological and economic importance of the group, it is remarkable that the only comprehensive study including fossil and extant species supporting the monophyly of the group was published a few decades ago ( Grande, 1985). Only few studies, either morphological ( Di Dario, 2002, 2004, 2009; Di Dario, de Pinna, 2006; de Pinna, Di Dario, 2010) or molecular ( Li, Orti, 2007; Lavoué et al., 2013; Bloom, Lovejoy, 2014), were published on extant clupeomorphs during this period. In contrast, contributions on fossils have maintained the attention on the group, either on potentially oldest representatives, analyses of characters, and/or past biogeographical patterns of distribution ( Maisey, 1993; Chang, Maisey, 2003; Zaragueta-Basil, 2004; Forey, 2004; Alvarado-Ortega et al., 2008; Murray, Wilson, 2013; Alvarado-Ortega, 2014; Malabarba, Di Dario, 2017).