The taxonomy of Myopterygius and Pervushovisaurus

fig-2-2x

The lectotype rostrum of ‘Ichthyosaurus‘ (= Myopterygiuscampylodon, from Fischer (2016) (CC BY 4.0).

Fischer (2016) attempted a taxonomic revision of the platypterygiine ichthyosaurs ‘Ichthyosaurus campylodon Carter, 1846 and Pervushovisaurus bannovkensis Arkhangelsky, 1998. He concluded that both species are valid and belong to the same genus, proposing the new combination Pervushovisaurus campylodon. This taxonomy has been followed by recent papers (e.g., Moon, 2019; Barrientos-Lara & Alvarado-Ortega, 2020; Cortés et al., 2021). However, Pervushovisaurus is not the oldest available genus for ‘I.’ campylodon; instead that is Myopterygius Huene, 1922. Fischer did discuss Myopterygius, but he discounted it for reasons that are not correct.

“However, the genus-group name Myopterygius Huene, 1922 is available. It was erected for a series of species: Ichthyosaurus campylodon, Ichthyosaurus strombecki (=nomen dubium Fischer et al., 2016), Ichthyosaurus hildesiensis (=nomen dubium Fischer et al., 2016), Ichthyosaurus kokeni (here regarded as Ophthalmosaurinae indet. see above), Ichthyosaurus indicus (=nomen dubium Fischer et al., 2016) and Ichthyosaurus marathonensis (=Ichthyosaurus australis (see Zammit, 2010)). There are thus two remaining candidates for the type species of Myopterygius: I. campylodon and I. marathonensis (= ‘Platypterygiusaustralis). […]

This leaves two distinct solutions: (i) transfer I. campylodon and Pervushovisaurus bannovkensis to Myopterygius, with I. campylodon as the type species, and declare Pervushovisaurus as a junior synonym of Myopterygius. The status and generic attribution of ‘Platypterygiusaustralis would be left undecided until a comprehensive study on the relationships of that taxon is undertaken, possibly needing a new genus-rank name for that taxon. (ii) Move Ichthyosaurus campylodon to Pervushovisaurus and leave the status of both Myopterygius and ‘Platypterygiusaustralis undecided until further study on this later taxon. In order to move forward and stabilise the complex taxonomy of Cretaceous ichthyosaurs, I opt here of the second solution, which leaves the possibility to resurrect Myopterygius with ‘Platypterygiusaustralis as its type species, but such a decision is beyond the scope of this paper.”

Fischer implied that Huene did not designate a type species for Myopterygius when he named it, with either ‘I.’ campylodon or ‘I.’ australis M’Coy, 1867 being available for that status. On the contrary, he explicitly designated ‘I.’ campylodon as the type species (Huene, 1922: 105).

“Die als Myopterygius in der Kreide zusammengefaßten Formen, deren Typus M. campylodon ist, haben große Ähnlichkeit und genetischen Zusammenhang mit Macropterygius.”

“The forms grouped as Myopterygius in the Cretaceous, whose type is M. campylodon, have great similarity and genetic connection with Macropterygius.”

Thus, ‘I.’ australis cannot be the type species of Myopterygius as Fischer suggested. If ‘I.’ campylodon and P. bannovkensis are considered to be congeneric, then Myopterygius has priority over Pervushovisaurus for the genus containing them. It is also possible that they are not congeneric, with both Myopterygius and Pervushovisaurus being valid. In either case, the combination ‘Pervushovisaurus campylodon‘ is invalid. ‘I.’ australis should be referred to Longirostria Arkhangelsky, 1998, whose type species ‘Platypterygius‘ longmani Wade, 1990 is a junior synonym (Zammit, 2010). The table below contains a summary of Fischer’s taxonomy versus my solutions.

Fischer (2016)This post (solution #1)This post (solution #2)
Genus: Pervushovisaurus
Arkhangelsky, 1998

Type: P. bannovkensis
Arkhangelsky, 1998

Referred: P. campylodon
(Carter, 1846)
Genus: Myopterygius
Huene, 1922

Type: M. campylodon 
(Carter, 1846)

Referred: M. bannovkensis
(Arkhangelsky, 1998)
Genus: Myopterygius
Huene, 1922

Type: M. campylodon 
(Carter, 1846)
Genus: Myopterygius
Huene, 1922

Type: M. australis 
(M’Coy, 1867)
Genus: Longirostria
Arkhangelsky, 1998

Type: L. longmani
(Wade, 1990) 
= L. australis (M’Coy, 1867)
Genus: Pervushovisaurus
Arkhangelsky, 1998

Type: P. bannovkensis
Arkhangelsky, 1998
Genus: Longirostria
Arkhangelsky, 1998

Type: L. longmani
(Wade, 1990) 
= L. australis (M’Coy, 1867)

References

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