As you mention, Latin hippopotamus, -i comes from Greek ἱπποπόταμος, which is a compound of ἵππος (hippos = horse) and ποταμός (potamos = river).
In Latin, Lewis and Short cites instances in Pomponius Mela (AD 45), Pliny (AD 79), and Ammianus Marcellinus (AD 400). In Greek, the LSJ includes references from Dioscorides (AD 90), Galen (AD c. 200), and ...
Well, I don't know if it counts, but I think you should search among recent species re-classing.
When Linnaeus wrote, Latin names were the logical option to choose a scientific name from. That is why it seems hard to even find one single example of what you're looking for. More recent descriptions of old species (especially when a single common name is ...
Yes, double diminutives are possible in Latin. I found a few other examples from a search on Perseus of Lewis and Short (I looked for words ending in "llula", "llulus" and "llulum"):
arcellula < arcella < arca
a very little box, Diom. p. 313 P.
lamellula < lamella < lamina
a small plate of metal: “glebulas emi, lamellulas paravi,” Petr. ...
The Online Etymological Dictionary states
His [Castor's] name was given to secretions of the animal (Latin castoreum), used medicinally in ancient times. (Through this association his name replaced the native Latin word for "beaver," which was fiber.)
Castoreum has been used medicinally since Classical times, prominently as an ingredient in material ...
Bambusa tulda Roxb.
synonym Dendrocalamus tulda (Roxb.) Voigt
In the Monaco Nature Encyclopedia, Giuseppe Mazza writes:
The name of the genus comes from the local Malay name “bambu”; the specific name is the local one, tulda bans, in Bengali language.
Roxb. refers to the botanist who listed the name:
Dr William Roxburgh FRSE FRCPE FLS (3 or 29 June ...
A straightforward translation is Homō docēns. (Macrons are optional; they represent a difference in sound which disappeared in later Latin.)
Homō is a straightforward word for "human". Docēns is the present participle of doceō, a straightforward word for "to teach". See L&S for more information on the latter.
There are a few other words for "teach": ...
The derivation from salire is probably a folk etymology, especially since it does not explain the second syllable of salmo.
Walde, Latein. Etym. Wb., says that salmo, and also salar “trout”, are borrowed from Celtic, comparing Old Irish selige “turtle”, the Celtic source being cognate with Latin saliva, though this too does not explain the final -mo(n). ...
To complement @brianpck answer:
First, let's state right away the obvious: since all known species of llamas are endemic to South America, it is highly unlikely that there is a classical latin word to name them.
Wheeler (2005) offered a short review of the taxonomical history of llamas:
In 1758, Linnaeus described the two domestic New World ...
As you mentioned in your question, Linné originally grouped the llama under the genus "Camelus", as you can see in Systema Naturae:
Camelus dorso laevi, pectore gibboso
Camelus peruvianus Glama dictus
It appears that this was later revised to be the genus Lama and the species Glama in 1758. (Source: ...
As Aristotle is generally considered as the father of biology — Darwin wrote: “Linnaeus and Cuvier have been my two gods… but they were mere school-boys to old Aristotle.” (in a letter to W. Ogle, 1882) —, it is logical to search for such a definition in his works.
According to Pierre Pellegrin (in particular in Une zoologie sans espèce, 1984), the ...
There certainly are double diminutives in Latin. Here are some examples explicitly indicated in Lewis and Short:
agellulus < agellus < ager
ancillula < ancilla < ancula (Yes, ancilla is a diminutive!)
arcellula < arcella < arca
asellulus < asellus < asinus
For the genus, you'd want it to end in -don, like the Iguanodon. Necro- though doesn't mean "deadly', but "dead." Were I a biologist having seen this, I'd think "dead-tooth bat" and presume it had a non-functional tooth or something.
For deadly, you have a few options. You could do thanatodon "death-tooth", or perhaps "olethriodon" "deadly-tooth."
That's perfectly understandable, as the word isn't Latin, but Greek. φελλός is the Greek for the 'cork oak', Quercus suber. Why this word was used in the binomial for a different species of oak, I can't say, except to note that since the willow oak is not native to Europe it would not have had a Greek or Latin name.
Here are two that I like:
Oscar E. Nybakken, Greek and Latin in scientific terminology (Ames, Iowa: The Iowa State University Press)
William T. Stearn, Botanical Latin: history, grammar, syntax, terminology and vocabulary (New York: Hafner Publishing Company)
I relied pretty heavily on both these books when I had to teach courses on bioscientific ...
Just to expand on Expedito Bipes's answer (and Alex B.'s and fdb's comments) and clarify a bit:
The word θλυπίς (thlypis) is a hapax legomenon ("thing said only once"), that is, a word found only once in the whole canon of Ancient Greek literature. In particular, it's found in a particular manuscript of Aristotle's Historia Animalium (VIII.3).
Sticking to the bird theme, meleagris used to mean a pheasant. Through a series of misadventures, the genus Meleagris no longer refers to pheasant, but to turkeys, a genus unknown to the ancients.
I hesitate to mention Acacia, since the renaming of that genus is highly controversial (a bit like saying Pluto is not a planet). But some botanists excluded ...