Allenii Scorpion, Nullibrotheas allenii

Allenii Scorpion, Nullibrotheas allenii. Scorpion collected made in the Las Cuevas area of Baja California Sur, December 2017. Length: 4.2 cm (1.7 inches). Collection courtesy of Kyle Rousseau, Maple Ridge, British Columbia, Canada. Photograph courtesy of Julie Mikes, Maple Ridge, British Columbia, Canada.

The Allenii Scorpion, Nullibrotheas allenii, is a member of the Chactidae family of Fatclaw Scorpions.  The Chactidae family consists of two hundred eleven species placed in fifteen genera. This family is characterized by large bulbous claws, a uniform body size and a uniform sized and fairly wide tail. Globally, there is only one species in the genus Nullibrotheas and this species is the only representative of the Chactidae family in the Nearctic region. The Allenii Scorpion is known in Mexico as Escorpión Allenii.

The Allenii Scorpion reaches 3.0 cm (1.3 inches) in length and their coloration and pattern varies depending on their location. Overall, they have a light base color of light yellow to orange brown with dusky to dark brown markings on their carapace and tergum. These markings are outlined with a dirty yellow to light brown color. Their cephalothorax is slightly narrower than their abdomen and is about the same color as the markings on their carapace and tergum. Their eye tubercles are black in color and unlike other members of the Chactidae family, the Allenii Scorpion has eyespots. Similar to other members of the Chactidae family, their claws are large and bulbous with the medial sides more rounded than the lateral sides. In addition, the claws usually have dark reddish or reddish brown fingers. Nullibrotheas can be easily distinguished from other genera due to the presence of six trichobothria on the brachium of the pedipalps along the ventral side. They have 4 pairs of legs that are a light brown/orange color. Their tail is a medium to dark orange/brown color with darker brown vertical markings on each metasomal segment. Males have large distinct genital papillae on the inner margins of the genital operculum. 

Due to its variability in color and size, this species may be commonly mistaken for other scorpion species found in the Baja California Sur.

From a conservation perspective the Allenii Scorpion’s conservation status has not been formally established. Further study is needed. 

Caution: Like other scorpion species, the Allenii Scorpion possesses venom that is dangerous to humans and other organisms. The toxicity of its venom is unknown so extreme caution should be used.