Today I met yet another new arrival in the animal room at the Harvard Museum of Natural History: Heterometrus petersii (Scorpiones: Scorpionidae), one of the many big Heterometrus species, sometimes called giant forest scorpions, that are distributed in southern Asia from Pakistan to Vietnam and Malaysia.
Our new specimen is an adult female with an outstretched length of about 12 cm. She is fast and aggressively defensive, wheeling about and jabbing her strong claws with boxer-like swiftness at the slightest provocation.
Heterometrus petersii is very similar to another species that inhabits its range, Heterometrus laoticus, but there are some slight diagnostic differences that can separate the two. (For details, see Kovařík, F. (2004), A review of the genus Heterometrus Ehrenberg, 1828, with descriptions of seven new species (Scorpiones, Scorpionidae), Euscorpius, 15: 1–60.) In one key difference, while the carapace of H. laoticus is uniformly smooth, the carapace of H. petersii is smooth in its central area but granulate at the margins, as you can see in the following photograph of the museum's specimen.
The genus Heterometrus includes what is probably the largest scorpion species in the world, Heterometrus swammerdami of India and Sri Lanka. The largest specimens of that species can attain an outstretched length of about 20 cm and weigh more than 30 grams.