The complete mitogenome of the Critically Endangered smalltooth sand tiger shark,Odontaspis ferox(Lamniformes: Odontaspididae)

Abstract

Here, we report the first complete mitochondrial genome for the smalltooth sand tiger shark, Odontaspis ferox (Risso, 1810). The circular mitochondrial genome was found to be 16,682 bp in length and contains 37 genes, a control region and the replication origin of the L-strand (O L ). The base composition of this mitogenome is 32.6% A, 23.3% C, 12.8% G, and 31.3% T. Phylogenetic analysis of Lamniformes indicates that O. ferox did not group with Carcharias taurus and so the taxonomic classification of Odontaspididae needs to be revised. This study promotes conservation genetics for this poorly studied shark species which is listed critically endangered in the Mediterranean Sea.

The importance of the appendicular skeleton for the phylogenetic reconstruction of lamniform sharks (Chondrichthyes: Elasmobranchii)

“…Furthermore, the differences in skeletal or terminological interpretations may also obscure the phylogenetic signal of the appendicular skeleton. For example, Stone and Shimada (2019) reported a sternum in Odontaspis noronhai, but we determined through this present study that this structure is absent in the species or any other lamniform (note: the only taxon with a sternum observed among the extant sharks we examined was the hexanchiform (Bowden et al, 2015;Doane et al, 2018;Kousteni et al, 2021;Martin & Naylor, 1997;Naylor et al, 2012;Vélez-Zuazo & Agnarsson, 2011;Vella & Vella, 2020). In contrast, previous morphology-based hypotheses suggest that Carcharias is either a member of the family Odontaspididae (Shirai, 1996) or a sister taxon to the remaining Lamniformes (Compagno, 1990), except for the basalmost genus Mitsukurina.…”

“…According to the molecular data, the “( Pseudocarcharias + Megachasma ) + Odontaspididae” clade would be a sister group to a basal Alopiidae. In other cases, the “Alopiidae + Odontaspididae” clade would form a sister group to a basal clade including “ Peseudocarcharias + Megachasma .” The phylogenetic position of the genus Carcharias is also distinct, and this taxon is consistently recovered as a sister group to “ Cetorhinus + Lamnidae.” Additionally, some molecular hypotheses even suggest the non‐monophyly of the family Alopiidae (Bowden et al, 2015; Doane et al, 2018; Kousteni et al, 2021; Martin & Naylor, 1997; Naylor et al, 2012; Vélez‐Zuazo & Agnarsson, 2011; Vella & Vella, 2020). In contrast, previous morphology‐based hypotheses suggest that Carcharias is either a member of the family Odontaspididae (Shirai, 1996) or a sister taxon to the remaining Lamniformes (Compagno, 1990), except for the basalmost genus Mitsukurina .…”

“…One of the main problems within the systematics of Lamniformes involves the monophyly of Odontaspididade and, consequently, the phylogenetic position of C. taurus . Additionally, the systematic position of Alopias superciliosus , Megachasma , and Pseudocarcharias remains controversial, with the family Alopiidae often recovered as nonmonophyletic (Naylor et al, 2012; Vélez‐Zuazo & Agnarsson, 2011; Vella & Vella, 2020). Two recent morphological studies (Shimada, 2005; Stone & Shimada, 2019) resulted in the phylogenetic position of several taxa unresolved.…”

Allometric Growth of the Enigmatic Deep-Sea Megamouth Shark Megachasma pelagios Taylor, Compagno, and Struhsaker, 1983 (Lamniformes, Megachasmidae)

“…Perhaps the difference in the shape of the caudal fin, or the growth trend, raises the possibility that the foraging mode of megamouth sharks is different from that of basking sharks. Another explanation, perhaps simpler, is that because megamouth sharks are phylogenetically less derived than basking sharks and other lamnid species within Lamniformes (e.g., [11,[41][42][43]), they retain their morphologically basal condition throughout their lifespan.…”

A new goniopholidid crocodylomorph from the Late Jurassic of Portugal

“…Greenfield (2022b) noted whether †Otodontidae lies outside of the 'Cetorhinidae+Lamnidae' clade has never been tested. However, it should be pointed out that there has been no test conducted on or supporting the ' †Otodontidae+Lamnidae' clade either, unlike the existing strong support of the sister relationship between Cetorhinidae and Lamnidae both morphologically and molecularly (Stone and Shimada, 2019;Vella and Vella, 2020;Kousteni et al, 2021;Silva et al, 2023). Even if Cetorhinidae and Lamnidae are not sisters hypothetically (vs.…”