This species is named for the type locality in the Uluguru Mountains of Tanzania.
A robust, flat frog with a small head. The dorsum is uniform dark brown to black and smooth. A fold of skin angles from the eye to the base of the arm. The first finger is reduced and in males has three spines. Toe tips are expanded. Toes lack webbing. The ventral surface is yellow-brown without markings. Males have short, fat arms and legs with light-colored spines on the legs (Harper et al., 2010).
The is the description of a tadpole, MCZ A-13795, from Barbour and Loveridge (1928): Length of body twice is the width and one fifth the length of the tail. A pigmented spot marks the site of the external nares. Eyes are on the upper surface of the head; the distance between them is two times that between the pigmented spots and greater than the width of the mouth. The mouth opening is forward. The upper lip is arcuate; lower lip is folded. A median groove and two lateral flaps are most conspicuous. Over each branchial (gill) region is a peculiar flap, the function of which is unknown. The spiraculum on the lower surface is somewhat closer to the snout than the anus; it is not visible from above. Anus is median, opening on the lower surface of the subcaudal crest. Tail is three and a half times as long as deep, bluntly pointed. The total length of the fully developed tadpole is 15 mm, and from tip of nose to vent it measures approximately 5 mm.
This species is similar to Hoplophryne rogersi, but their distributions do not overlap (Harper et al., 2010).
Habit is moderately stout and small. Snout is subacuminate, and the mouth extends backwards beyond a vertical line from the posterior border of thfe eye. Interorbital space is three times the width of the upper eyelid, anteriorly a little more than twice. Arms (after preserved) are permanently bent inwards close to breast. The position of first finger is indicated only by a swelling, the second a sllightly shorter than fourth and a little more than half as long as the third. All three fingers are unwebbed and broadened at the tips without actual disks. Toes (five) are well developed and free of webbing. First toe is about half the length of second, which is half the length of the third; third is slightly longer than fifth, fourth is much longer than the rest. A very small, flat, ill-defined, inconspicuous, inner metatarsal tubercle is present. Hind limb is well developed. The tibio-tarsal articulation of the adpressed hind limb just reaches the posterior border of the eye. Skin is perfectly smooth above and below but covered with minute papillary tubercles dorsally. Numerous small tubercles border both the upper and lower lips, the region between mouth and forearm and the anterior part of the chest. A rosette of spines with nine points is present on either side of the chest, which is normally hidden by the forearms. A group of three spines is present on the site of the first finger (prepollex region), and adjacent to it on the back of the second finger (first functional finger) is another group of five spines. On the outer aspect of the tibia and foot are additional spines, about thirty-two on tibia and sixteen on the foot. These characters are sexual, and absent in the female (Barbour and Loveridge, 1928).
In life, dorsum is black, finely speckled with silvery white. One paratype had a bright, pale green dorsum with hind limbs of orange-brown; two others were dark olive-green, and yet another a reddish, almost orange, brown (Barbour and Loveridge, 1928). A series os speckles along the vertebral line almost confluent giving the appearance of a fine dorsal line; a similar line on each side from snout over eye along the side to hind limb. A black band, light-edged on both sides, obliquely crosses the thigh, and continues across tibia and foot (these black bands are not always visible on the limbs as they show only if darker than the body colour). Some white dots on the sides of the face are very conspicuous. Venter is brownish-black with silvery specklings, mostly on chin and throat (Barbour and Loveridge, 1928).
In alcohol, dorsum is brownish-black with a purplish bloom and indistinct light specks; a concentration of these forms a fine vertebral line, an uninterrupted irregular light lateral line from eye to knee of hind limb. A dark band is bordered on both sides by lighter, crosses the thigh obliquely and is continued on tibia. Venter is grey-brown, spotted with lighter on throat and with whitish vermiculations elsewhere (Barbour and Loveridge, 1928).
Males are up to 25 mm and females are up to 21 mm in snout-vent length (Harper et al., 2010). The male holotype measured 25 mm, the two largest paratype males measured the same and the other 35 males ranging from 17 to 25 mm. The largest female measured 21 mm, and the 7 female paratypes ranged from 19 to 21 mm (Barbour and Loveridge, 1928).
The diet of this species includes ants, beetles and weevils (Barbour and Loveridge, 1928). The only recorded predator is Buhoma procterae, the Uluguru forest snake (Channing and Howell, 2006).
This species is known from a number of areas within the Eastern Arc Mountains of Tanzania, including Nguru South, Nguu, Uluguru and Udzungwa Mountains. For more specific information regarding range within the Eastern Arc Mountains, see:
This is normally a leaf-litter species but can be found inside fallen bamboo stems or on wild bananas. It is not found in disturbed forest. The elevational range is unclear, but this frog can be found above 1200 m (Harper et al., 2010); it ranges higher than Hoplophryne rogersi.
Eggs are laid in water-filled tree holes, leaf axils, banana leaves or bamboo (Harper et al., 2010). Breeding takes place in late September through October. Clutches are approximately 28 eggs; eggs are 2.5-3.0 mm in diameter within 4.0-4.5 mm capsules. The female may guard the eggs. After hatching from the eggs, the tadpoles fall into the water trapped within the plant (Channing and Howell, 2006).