This species is named for Mr. F. Rogers, who worked at the Amani Institute in the East Usambara Mountains at the time when this species was first collected.
A small frog with a smooth dorsum that is dark gray with darker blotches. The short snout comes to a sharp point. A dark band extends from the tip of the snout, under the eye to the base of the arm. The ventral surface is dark with small white blotches. The tips of the fingers and toes are slightly expanded and truncated. Females have only three fingers, while in males the first finger (or ‘thumb’) is modified into a spiny projection that presumably aids in clasping the female during mating. Males in breeding condition have enlarged glands in the pectoral region and on the arms (Harper et al., 2010).
According to Channing and Howell (2006), tadpoles originally identified as Parhoplophryne usambarica by Barbour and Loveridge (1928) were subsequently identified as this species. These tadpoles were not described, other that to state that they were found in wild bananas on November 30th and included four tadpoles with minute hind limbs, five tadpoles with hind limbs, and four frogs with long tails but well-developed limbs.
Harper et al. (2010) described the tadpoles as pale, slender and possessing long tails. They also possess a unique structure on the abdomen, a ‘belly-finger,’ which allows them to maneuver in small spaces.
Tadpoles reach 28 mm in length. They have a series of distinct papillae on the snout and upper lips, distinguishing them from H. uluguruensis. No labial teeth, jaw sheaths or external nares are present. The spiracle is median, ventral and located 1/3 along the body from the vent. (Channing and Howell, 2006).
There are no known similar species within the geographic range of H. rogersi (Harper et al., 2010).
Habit is moderately stout. Head is moderately small, snout is subacuminate, and mouth extends backwards beyond a vertical line from the posterior border of the eye. Interorbital space is slightly more than twice the width of the upper eyelid, anteriorly twice. Arms are somewhat bent inwards but not so markedly as in H. uluguruensis, and not so as to conceal the chest. This first finger is reduced, somewhat stump-like with a needlelike bone (prepollex) projecting from its truncated end. Second finger is much reduced, measuring half the length of the third (or less than half the length of third in paratype). All four fingers are unwebbed. The second, third and fourth fingers are broadened at the tips without actual disks. Well-developed tubercles are present beneath the fingers and toes. Toes (numbering five) are well developed and entirely free of webbing; second, third and fourth are broadened into squarish expansions at their tips. The first is very small, much less than half the length of second, the second is half the length of third, which is slightly longer than the fifth, the fourth is by far the longest. A very small, flat, ill-defined, inconspicuous, inner metatarsal tubercle is present. The hind limbs are well developed. The tibio-tarsal articulation of the adpressed hind limb just reaches the eye (also in all the paratypes, which are males). Skin is perfectly smooth above and below except for minute spines on the back and larger ones on the lips, throat, and limbs; those on the tibia near the knee are exceptionally large. A large group of spines surrounds the first finger and extends backwards almost to the elbow; a small group of eleven spines on the inner aspect of the fore arm close to its base, a larger group of about forty spines on the chest close to, but separated from, its fellow on the other side (Barbour and Loveridge, 1928).
In life, the dorsum of this species is slate blue, shading to blue-grey peripherally. A black band commences at the tip of snout, bounds the upper lip, envelops eye, passes over forelimb and broadens out on the side, narrows again at hind limb and terminates on thigh at knee. The following transverse black bans are present: two on the thighs, two on the tibia, one on tibio-tarsal articulation and two on foot. The rest of the upper surface of the limbs are blue-grey. Venter is black, vermiculated with white that is slightly tinged with blue. The ground colour of the forelimbs and thighs are brown rather than black. The glands on forearm and breast of males are blue (Barbour and Loveridge, 1928).
In alcohol, the dorsum of the holotype is greyish to black in color, with lighter patches on the flanks and limbs. Several well-defined dark bands are present on the thighs, tibiae and feet. Venter is white, vermiculated with dark brown (Barbour and Loveridge, 1928).
The holotype, a male, measured 24 mm, and the three male paratypes measured 24, 25 and 25 mm (Barbour and Loveridge, 1928). Males and females are 23-28 mm in length (Harper et al., 2010).
The stomach of the holotype held a small polydesmid, a wood-louse, two spiders and some ants. A worm (Mermithidae), over 50 mm. long was also found in the stomach of the type (Barbour and Loveridge, 1928).
This species is known with certainty only from the East Usambara Mountains and the Nguru South Mountains in north-eastern Tanzania. For additional information regarding the range within the Eastern Arc Moutains, see: http://www.tanzaniaherps.org/references.asp?id=267&f=
This is normally a leaf-litter species, but it can be found inside the axils of wild bananas. It is found at elevations from 600 – 1200 m (Harper et al., 2010).
Breeding takes place in water-filled tree holes or bamboo cups. A small number of unpigmented eggs are laid on the vertical surface above the water (Harper et al., 2010).