Shark and ray diversity in the Tropical America (Neotropics)—an examination of environmental and historical factors affecting diversity

Abstract

We present the first comprehensive review of the present and past shark and ray diversity in marine waters of Tropical America, examining the patterns of distribution in the Eastern Central Pacific (EP) and Western Central Atlantic (WA) realms. We identified the major regions of diversity and of endemism, and explored the relations to physical variables. We found a strong relationship between shark and ray diversity with area and coastal length of each province. The Tropical Northwestern Atlantic Province is characterized by high diversity and greater occurrence of endemic species, suggesting this province as the hotspot of sharks and rays in Tropical America. The historical background for the current biogeography is explored and analyzed. Referential data from 67 geological units in 17 countries, from both shallow and deep-water habitats, across five time-clusters from the Miocene to the Pleistocene were studied. New data include 20 new assemblages from six countries. The most diverse Neogene and extant groups of shark and ray are Carcharhiniformes and Myliobatiformes, respectively. The differentiation between Pacific and Atlantic faunas goes to at least the middle Miocene, probably related with the increasing closure of the Central American Seaway acting as a barrier. The highest faunal similarity between the assemblages from the EP and the WA at the early Miocene could be related to the lack of a barrier back then, but increased sampling is needed to substantiate this hypothesis.

A rhinopristiform sawfish (genus Pristis) from the middle Eocene (Lutetian) of southern Peru and its regional implications

“…That said, what happened to the southeastern Pacific pristids, leading to their eventual extirpation from the southern Peruvian latitudes? Recent research (CARRILLO-BRICEÑO et al, 2018;PARTAR-RIEU et al, 2018;VILLAFAÑA et al, 2019) has investigated the role of physiological, ecological, and life-history traits, as well as the influence of environmental and historical factors in controlling the diversity and distribution of Pacific South American chondrichthyans in Neogene and Quaternary times, but sawfishes have not been specifically addressed by these studies. Nonetheless, some answers could come from observing that another iconic tropical cartilaginous fish, the extinct snaggletooth shark Hemipristis serra AGASSIZ, 1843, is thought to have contracted its range northwards as cool conditions took hold along the coasts of southern Peru, during a middle or late Miocene phase of a stronger Humboldt Current (BOSIO et al, 2020).…”

Updated taxonomic list and conservation status of chondrichthyans from the exclusive economic zone of Venezuela, with first generic and specific records

“…Recently, Carrillo‐Briceño et al . () showed that the VEEZ shares two of the six marine provinces for tropical America, the tropical north‐western Atlantic Ocean and the north Brazil shelf. The tropical north‐western Atlantic Ocean was the most diverse province, with 92 shark and 68 skate and ray (batoid) species, the north Brazil shelf had a lower diversity of 51 shark and 35 batoid species.…”

“…In the present study the VEEZ was defined as covering 8.40–16.74° N and 58.95–72.12° W (Flanders Marine Institute, ; Figure ). This region is located along two marine regions of the American tropics: tropical north‐western Atlantic Ocean and north Brazil shelf (Carrillo‐Briceño et al, ). The area comprises four differentiated eco‐regions: (a) the Atlantic platform, including Paria Gulf, strongly influenced by a large river (Orinoco) and Guyana Current; (b) the north‐eastern region, influenced by upwelling and also by the Orinoco River during the rainy season; (c) the central region influenced by oceanic water without much river or rain effect and with several oceanic Caribbean islands and archipelagos; (d) the largest estuaries of Caribbean waters, such as the Maracaibo system, Venezuela, and the Venezuelan Gulf (Cervigón, ).…”

The southernmost record and an update of the geographical range of the Atlantic chupare, Styracura schmardae (Chondrichthyes: Myliobatiformes)

“…The difference in the relative abundance of S. schmardae at the limits of its distribution range ( i.e ., relatively “common” in parts of the Caribbean and “uncommon or rare” in north and northeastern Brazil) is compatible with a scenario in which the species has expanded its range from north to south in an evolutionary timescale. The Caribbean region has been suggested as a biodiversity hotspot for many different marine groups (Bowen et al ., 2013; Briggs & Bowen, 2013), including elasmobranchs (Carrillo‐Briceño et al ., 2018). Assuming that the Caribbean hotspot can produce and export biodiversity to peripheral regions (Bowen et al ., 2013; Briggs, 2003), and that S. schmardae is more common there (GIBF, 2020a,b; OBIS, 2020), it is reasonable to hypothesize that S. schmardae has historically expanded its range from the Caribbean to the south.…”