What in god's green earth is Gigantometrus?

[khil]

Saw a facebook post with some big scorps, thought it was a joke. Googled it turns out it's true. I'm a pretty big scorpion nerd so I probably know all the genera of at least the common giant species, but I've been out of the hobby for a few years now...is this a new development? Did they change Heterometrus to Gigantometrus or something? I can't really find any information by doing some googling.

 

[Joey Spijkers]

Yeah, you missed that in your few years out of the hobby.
There was a revision of Heterometrinae in 2020, andthe genus has been split into multiple different genera and some new species were described as well.
Previous H. swammerdami and H. titanicus were assigned their own genus Gigantometrus.
Quite a few other common previous Heterometrus species have been assigned to new genera as well, including Javanimetrus (ex Heterometrus) cyaneus and Chersonesometrus tristis (ex H. mysorensis), along with many less common species.
Here's a link to download the article if you're interested in reading up on it:

https://www.researchgate.net/publication/346203386_Systematic_Revision_of_the_Asian_Forest_Scorpions_Heterometrinae_Simon_1879_Revised_Suprageneric_Classification_of_Scorpionidae_Latreille_1802_and_Revalidation_of_Rugodentidae_Bastawade_et_al_2005

 

[Collin Clary]

Saw a facebook post with some big scorps, thought it was a joke. Googled it turns out it's true. I'm a pretty big scorpion nerd so I probably know all the genera of at least the common giant species, but I've been out of the hobby for a few years now...is this a new development? Did they change Heterometrus to Gigantometrus or something? I can't really find any information by doing some googling.

Like Joey said, you missed Prendini's ~400 page revision in 2020.

As far as implications go for some of the species in the hobby:

• The Pandinus subgenera Pandinopsis and Pandipalpus are elevated to full genera (and thus the species are Pandinopsis dictator and Pandipalpus viatoris).

• Hobby "Heterometrus petersii" are actually H. silenus. Real H. petersii is apparently a cryptic species morphologically indistinguishable from H. spinifer (but are genetically distinct) and has only been confirmed from Singapore and the Malaysian island of Penang.

• Heterometrus cimrmani and H. minotaurus are conspecific and are synonymized with H. laevigatus. (This has been disputed to some extent however and warrants a separate discussion.)

• Heterometrus bengalensis is now Deccanometrus bengalensis.

• Heterometrus madraspatensis and H. fulvipes are now in the genus Chersonesometrus (and are indeed separate species). C. madraspatensis appears to be the more common species in the pet trade based on morphology.

• Heterometrus mysorensis is now Chersonesometrus tristis.

• Heterometrus swammerdami is now Gigantometrus swammerdami. The subspecies titanicus is reinstated and elevated to full species, and thus animals found on Sri Lanka are G. titanicus. Outside of a few select individuals keeping them, I have only ever seen G. swammerdami in the hobby

• Heterometrus cyaneus is now Javanimetrus cyaneus

 

[Diao]

Like Joey said, you missed Prendini's ~400 page revision in 2020.

As far as implications go for some of the species in the hobby:

• Heterometrus swammerdami is now Gigantometrus swammerdami. The subspecies titanicus is reinstated and elevated to full species, and thus animals found on Sri Lanka are G. titanicus. Outside of a few select individuals keeping them, I have only ever seen G. swammerdami in the hobby

From the very little I have seen of G. titanicus they appear to be extremely difficult to visually differentiate from G. swammerdami, are you familiar with any notable physical differences between the two species?

 

[Joey Spijkers]

From the very little I have seen of G. titanicus they appear to be extremely difficult to visually differentiate from G. swammerdami, are you familiar with any notable physical differences between the two species?

If I recall correctly, there are no notable physical differences, but they are genetically distinct. I'd have to look at the paper again to be sure.

 

[Collin Clary]

From the very little I have seen of G. titanicus they appear to be extremely difficult to visually differentiate from G. swammerdami, are you familiar with any notable physical differences between the two species?

Apologies for the late reply.

There are a few differences, but the most obvious is the shape of the chelae. In G. titanicus the chelae are generally more triangular, while in G. swammerdami the chelae are more rectangular. Additionally the upper margin of the chelae also slopes to a hump in G. swammerdami, while in G. titanicus the slope is more gradual and continuous.

 

[The Snark]

AFS revisions, 2020 https://digitallibrary.amnh.org/items/a8d7965c-c2ac-46a9-b178-0bc05b3935ec

 

[GreenTip]

Revisions happen. As a dino nerd I see it all the time in paleontology.

 

[Tbone192]

Revisions happen. As a dino nerd I see it all the time in paleontology.

Ayy, let's go Megaraptor!

 

[GreenTip]

Wow. I did not know there was another species in the Gigantometrus genera!

Ayy, let's go Megaraptor!

They are sweet and so mysterious! Pretty much the exact opposite of tyrannosaurs with their smaller heads and bigger arms! May even be related to the tyrannosaurs tho!

Hopefully we will discover more specimens and get a better picture of them in the future!