Turtlemen (good name pending)
Physiology:
This species of Lizardmen averages in size at well over two meters, somewhat larger on the average than the regular Saurus. Their midsection is covered by a hard natural shell, while their limbs are scaled and even at young ages as tough as a veteran Kroxigor's.
They start out in vivid green coloring, that slowly darkens into an increasingly deeper grey as they age. The backside of their shells has unique patterns and colorations, that usually stand out in starker contrast to the dark-grey basic coloring in Veterans.
The bodies of this species are not only incredibly hardy, but also very resistant to extreme temperatures and changes in pressure, allowing them to survive several minutes in open space unaided (a time that only increases as they age). Their shells are highly conductive, allowing them to spread the heat of laser weaponry or any other heat-based attack evenly across it, thus protecting them from any heat-based attack, though anti-tank weapons will quickly heat up the entire shell beyond even their tolerances and cook the Lizardman inside it, killing it quickly. Still, the blast of a lasercannon being blocked reliably by a single body can be an advantage, even if that body dies.
The toughness of the regular body aside from the shell is caused mostly by a high density of the skin, muscle and bone, making the Turtleman heavier and slower than any other Lizardmen. This does not mean they have worse reflexes than other Lizardmen, only that their bodies are slower to carry out the signal, the larger the required motion is, the greater the difference.
Psychology:
The Turtlemans mind is designed from the basis of the Saurus mental makeup. While leader-qualities are much rarer among them than in Saurus, the general aptitude for combat, particularly small-team tactics is inborn. Additionaly the Turtlemen have an excellent spatial imagination, allowing them to easily see the layout of a maze (or city, or spaceship) they are in before their mind's eye.
In times of peace the Turtlemen are of limited use, being slower and weaker workers than Kroxigor, though they can work with a lesser amount of Skink-supervision.
Niche:
The relative slowness of the Turtlemen makes them of limited use in melee warfare, but with the advent of guns the concept of heavy but slow infantry becomes more interesting. In an open battle their use is still limted, though their greater size and strenght allows them to wield weapons that Saurus would struggle with and their natural armor (particularly when enhanced by enchanted actual armor) makes them hard to bring down.
They really show their advantages over Saurus though in limited battlefields, in narrow corridors and closed environments, say in cities or spaceships. Here the minimal motions needed to aim and shoot their guns are hardly hindered by their slowness, while they are unfazed by most return-fire.
Speaking OOC they are effectivly Terminator-equivalents, who can excell on any battlefield where limited mobility is not a big issue, while they are also resistant to hazardous environments and with some equipment able to work in ships that have lost lifesupport and may be airless, decompressed, hot, cold and irradiated.