Description
Duttaphrynus scaber is a moderate sized frog with snout vent length of 21.8 – 24.2mm in males and 26.5 – 27.0 mm in females. The head length, measured from the posterior margin of the tympanum to the end of the snout, is 7.8 mm. The distance from the anterior border of the eye to the end of the snout is 3.2 mm. The head length comprises 29 per cent of the distance from the snout to the vent. Viewed from above the snout terminates in a blunt point; in profile, the convexly rounded snout projects above the lower jaw. The interorbital distance is less than one-third of the diameter of the head. The tympanum is round and moderately distinct, and its diameter (1.4 mm.) is half of that of the eye, measured horizontally. The canthus rostralis is distinct, and the canthal ridges extend from the supraorbital crests almost to the end of the snout, where they terminate above and slightly beyond the nostrils, the inner edges of which are scarcely 1.6 mm. apart. The parietal and postorbital crests are approximately as well developed as the supraorbital crests. The parietal ridge is confluent with the anterior end of the parotoid gland, which is irregular in shape and nearly twice as long as the distance between the anterior margin of the eye and the end of the snout. The parotoid glands are 5.5 mm. in length, and each has a maximum width of 2.8 mm (Bogert and Senanayake 1966).

The fingers are moderately long, the first, second, and fourth being approximately equal in length, whereas the third is nearly twice as long. The subarticular tubercles are moderately well developed, but rounded rather than sharply convex. The tips of the toes are similar to those on the fingers; the third toe is slightly larger than the fifth, and the fourth is much the longest. The three distal phalanges of the fourth toe are free, but the webbing extends to the base of the distal phalanx on the other toes. The inner metatarsal tubercle is more nearly round and slightly shorter than the oval-shaped outer metatarsal tubercle. Spiny tubercles are more pronounced on the inner edge of the tarsals. The length of the tibia is 0.33 of the snout-vent length (Bogert and Senanayake 1966).

The skin is covered with wartlike tubercles that are less pronounced on the ventral surface than on the dorsum, where they vary in size, particularly at the middle of the body. Under magnification it may be seen that each tubercle is actually a clump of smaller tubercles, the largest of which projects above the others near the center of each group. On the dorsum the central tubercle is cornified and spinelike, whereas on the ventral side the clumps are less elevated, and the central tubercle is neither spinelike nor cornified. Anteriorly there are fewer tubercles in each clump, and on the dorsal surface they are more widely spaced, as they are on the interorbital surface and the eyelids. Tubercles are present on the sides of the head, except in the loreal concavities. Tubercles with the spinelike cornification are irregularly distributed on the snout, and along the upper lip to the angle of the mouth, with a few at the lower anterior margin of the tympanum. Enlarged tubercles behind and below the level of the tympanum are whitish in color, without the cornification. Similar whitish tubercles are present on the fold of skin that extends from the anterior surface of the femur. The spiny tubercles on the upper surfaces of the limbs are slightly smaller than those on the adjacent portions of the body (Bogert and Senanayake 1966).

The color of the preserved specimen is grayish brown, with faintly discernible markings. On the head a pale bar extends from the interorbital area onto the anterior portion of the eyelids. There are traces of irregular darker blotches bordering a faint vertebral stripe that widens to form a much lighter, broader streak between the parotoid glands. The light streak is the most conspicuous marking, though vestiges of bars or blotches are discernible on the limbs. The sides of the head are light gray, and a pale gray area extends from the tympanum backward and somewhat downward and onto the forearm. The under surfaces are dingy white, mottled with darker spots along the median line of the belly; the spots are larger and more pronounced anteriorly, with a darker area that extends along the posterior portion of the gular sac and onto the pectoral region (Bogert and Senanayake 1966).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: India, Sri Lanka

View distribution map in BerkeleyMapper.

Duttaphrynus scaber is found in India and in the low land wet zone and dry zone of Sri Lanka (Bogert and Senanayake, 1966; Dubois and Ohler, 1999; Batuwita et al., 2019; Jayawardena et al., 2017)

Life History, Abundance, Activity, and Special Behaviors
It is a terrestrial species that occurs in various habitats: wet evergreen tropical forest, tropical dry forest, dry scrubland, grassland, coastal marshes and rural farmland areas (Bogert and Senanayake, 1966).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Habitat fragmentation

Comments
Duttaphrynus scaber is named after Harold Stuart Ferguson who was a Scottish zoologist and Director of the State Museum of Trivandrum, India (Dubois and Ohler 1999).

Duttaphrynus atukoralei was thought to be an endemic species to Sri Lanka; however, molecular phylogenetic analysis showed that the uncorrected pairwise genetic distance between D. scaber and D. atukoralei was between 0.97 – 1.55% for the 16s rRNA fragment which means they are genetically too close to each other to be considered as a separate species (Jayawardena et al 2017).

References

Batuwita S, Udugampala S, DeSilva M, Diao J and Edirisinghe U. (2019). "A review of amphibian fauna of Sri Lanka: distribution, recent taxonomic changes and conservation." Journal of Animal Diversity, 1(2), 44-82. [link]

Bogert C.M. and Senanayake R. (1966). "A New Species of Toad (Bufo) Indigenous to Southern Ceylon." American Museum Novitates., 2269, 1-17.

Dubois A. and Ohler A. (1999). "Asian and Oriental toads of the Bufo melanostictus, Bufo scaber and Bufo stejnegeri groups (Amphibia, Anura): A list of available and valid names and description of some name bearing types." Journal of South Asian Natural History, 4(2), 133-180.

Jayawardena B., Senevirathne G., Wijayathilaka N., Ukuwela K., Manamendra-Arachchi K., and Megaskumbura M. (2017). "Species boundaries, biogeography and evolutionarily significant units in dwarf toads: Duttaphrynus scaber and D. atukoralei (Bufonidae: Adenominae)." Ceylon Journal of Science, 46(5), 79-87. [link]

Species Account Citation: AmphibiaWeb 2021 Duttaphrynus scaber <https://amphibiaweb.org/species/6048> University of California, Berkeley, CA, USA. Accessed Sep 24, 2021.

Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Sep 2021.

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