Distribution of the Order Lampriformes in the Mediterranean Sea with Notes on Their Biology, Morphology, and Taxonomy

SIMPLE SUMMARY: The distribution of teleost fishes is of fundamental importance to comprehending how these species contribute to the ecological equilibria of marine areas. In these terms, fishes of the order Lampriformes are circumglobally distributed, and are characterized by a peculiar morphology. Information on this fish group is scarce to absent regarding both their biological and distribution features, especially for the Mediterranean Sea. Moreover, the systematics of the group underwent several rearrangements, and molecular support is still scarce. This review aimed to describe the biological and ecological characteristics of the order Lampriformes, and to compile the scattered Lampriformes records from the literature. Lampriformes represent a taxon of high biological and ecological importance whose knowledge is limited by their low commercial value and rarity. The bathymetrical range of distribution also makes these species very interesting from an adaptive point of view. Four families are present in the Mediterranean Sea—Lampridae, Lophotidae, Regalecidae, and Trachipteridae—with a total of six species. Despite the scarce information on this taxon, the present review, which collected all reports of the Mediterranean Sea, represents a baseline to increase the knowledge of these rare and important species, and to encourage new studies in this area. Moreover, a phylogenetic reconstruction of Lampriformes based on the cytochrome oxidase subunit 1 (mt-COI) gene sequences questions the current evolutionary relationships between some species. ABSTRACT: Lampriformes are circumglobally distributed and contain several families of strictly marine bony fishes that have a peculiar morphology. Lampriformes systematics is affected by limitations in biometric, meristic, and molecular data; for this reason, it underwent several rearrangements in the past. This review aimed to describe the biological and ecological characteristics of the order Lampriformes, summarizing the current taxonomy of the group. The main aim was to clarify what is known about the distribution of the order Lampriformes in the Mediterranean Sea, collecting all the scarce and fragmented reports and notes on their occurrence. Knowledge scarcity is due to their solitary nature, in addition to their low to absent economic value. Despite this, the order Lampriformes represents a taxon of high biological and ecological importance. The high depth range of distribution characterizes their lifestyle. In the Mediterranean Sea, four families are present—Lampridae, Lophotidae, Regalecidae, and Trachipteridae—with the following species respectively, Lampris guttatus (Brünnich, 1788), Lophotus lacepede (Giorna, 1809), Regalecus glesne (Ascanius, 1772), Trachipterus arcticus (Brünnich, 1788), T. trachypterus (Gmelin, 1789), and Zu cristatus (Bonelli, 1819). Data deficiencies affect information on this taxon; the present review, which collected all the reports of the Mediterranean Sea, creates a baseline for depicting the biogeography of these rare and important species.