Well, the largest scorp commonly available would be P. imperator, but H. swammerdami has measured as slightly heavier (they are not often found for sale though and are usually a pretty high price). Females will have the just classification of larger, because larger tends to conform to the word heavier in sizing scorps (females becoming gravid and extremely thick). If you prefer the larger pedipalps and thinner bodies, males will be the ones you'll prefer. As far as the largest scorps avail all together for you to obtain, it would be difficult to determine, because one may find an H. swammerdami and though they have been known to grow to a very large size, the one purchased may only exceed 7 inches, as the same goes with all other large species. Still, it's a great big scorp!