Rhombic Night Adder

Causus rhombeatus is a venomous viper species found in subsaharan Africa. No subspecies are currently recognized.

With an average length of 60 cm, this is the largest member of the genus Causus. The longest individual ever recorded was a 93 cm male collected in eastern Zimbabwe.

The head has a snout that is relatively blunt (i.e. more rounded that other members of this genus), on the sides of which the nostrils are positioned. The circumorbital ring consists of 2-3 preoculars, 1-2 postoculars, and 1-2 suboculars that separate the eye from the supralabials. The temporal scales usually number 2+3, sometimes 2+4, but very rarely 2+2 or 3+3. There are 6 supralabial scales, very rarely 7. The sublabial scales usually number 7 or 10, rarely 8 and very rarely 11, 12 or 13. The first 3-4 sublabials are in contact with the chin shields. The posterior chin shields are small and often indistinguishable from the gulars.

At midbody there are 15-21 rows of dorsal scales that are moderately keeled and have a satiny texture. The ventral scales number 120-166, the subcaudals 15-36.

The color pattern consists of a ground color that is usually some shade of brown (possibly pinkish or grayish-brown), but occasionally olive green. This is overlaid with a pattern of 20-30 rhombic blotches that have pale edges, as well as a sprinkling of black scales and oblique black bars on the sides. Each oblique black bar is topped by one or two black spots, each with a pale centre, and strongly resembling an eye. Northern populations may be patternless, making them difficult to identify, while in others the pale edges may be missing, the rhombic blotches may be a darker color, or there may even be a dark brown vertebral stripe. The head has a characteristic V-shaped mark that may be solid black, or brown with a black outline.

Rhombic night adder, demon night adder, Cape night adder, African night adder, Cape viper.