Description
Copiula obsti is a small terrestrial species with a snout-urostyle length between 19.1 and 21.7 mm for adult males and between 21.6 and 24.5 mm for adult females. The dorsal surface fades laterally from light to dark brown. The canthus rostralis and upper eyelid have white stripes. There is an irregularly shaped dark brown or black stripe that runs laterally from behind the eye to the middle of the flank. The belly in smooth and white, absent of any speckles.

C. obsti has a small, triangular head with a roundish snout tip that clearly projects in profile. The nostrils are laterally directed and closer to the tip of the snout than to the eyes. The canthus rostralis is gently rounded and well defined, and is only in the parts of the nares that are bent outwards. The distance between the eye and the naris is smaller than the distance between the nares. The margin of the tympanum is not clearly visible, and there is a weak supratympanic fold extending to the posterior margin of the eye. The pupils are horizantal and the eyes are small. The fore limbs, along with the fingers, are short. The hind limbs are muscular and long with medium sized toes. Toes II through V have broader terminal discs than the penultimate phalanxes. There is no outer metatarsal tubercle and the subarticular tubercles and inner metatarsal tubercle are weakly developed. The toes lack webbing and all of the fingertips and toe tips have circummarginal grooves. The head, extremities, and the dorsal and ventral surfaces of the body are all smooth. There is a thickened stratum corneum on the tip of the snout that is whitish. The dorsum is brown, but it has fine, dark irregular middorsal line. The sides of the body are lighter in color than the dorsum and thney are covered with dark spots. There is a distinct cantho-rostral stripe extending from the tip of the snout to the upper eyelid. The dorsal surface of the extremities and the ventral surfaces of the tibia and the tarsus have dark brown mottles and spots, and the loreal region is dark brown. The ventral surface of the thighs, as well as the belly, is unpigmented and whitish. The tympanum is lighter in color than the lateral stripe, and the throat is finely speckled.

There are a few major differences between male and female specimens. Females are significantly larger, and the tip of the snout is longer and more pointed in males than in females. Males have a white cap on the tip of the snout, while females have a short snout with no well-defined cap.

There is a denticulated and strongly developed prepharyngeal ridge, a bean shaped choanae, and a small and half-free tongue which broadens posteriorly. The vocal slits lie close to the mandibles and each palatine has a visible crest. The subarticular tubercles rae nt well pronounced and are sometimes missing.

The holotype is an adult male collected on the eastern slopes of the Wondiwoi Mountains, at the base of the Wandammen Peninsula in West Papua, Indonesia. The frog was found at an altitude of 600 meters. Paratypes were found in the vicinity at altitudes ranging from 500 to 750 meters.

Copiula obsti is the smallest species in the genus Copiula, with a snout-urostyle length of up to only 25 mm. C. obsti has longer tibiae and a less pointed snout than C. minor. C. obsti also has differences in its advertisement call from the other members of this genus.

Distribution and Habitat

View distribution map in BerkeleyMapper.

Advertisement calls are made up of many short and high pitched notes, resembling the sound of crickets. The shortest interval recorded between two consecutive calls was 0.5 seconds. The length of advertisement calls is between 1 and 5 seconds, with a mean length of 2.52 seconds and each note has a duration between 16 and 31 milliseconds, with a mean duration of 27 milliseconds. Internote intervals have a duration of about 27 to 46 milliseconds, with an average of 35 milliseconds, and the note repetition rate in C. obsti is about 17 per second. The notes are unpulsed and can usually be divided into three subnotes, and there a conspicuous frequency modulation can be observed. The fundamental frequency of the calls is about 2.8 kHz, while the dominant frequency of the calls centers around 5.6 kHz.

Specimens were mostly terrestrial, some active during the day. None of the specimens were seen on the bushes, and none were seen living subterraneanly. Calling males were found sitting on the soil between fallen leaves in areas not covered from above, and they usually start calling right after it turns dark, continuing on until about midnight. Rainy nights bring louder and more frequent calling. Usually, males are found calling singly, and not in groups.

Life History, Abundance, Activity, and Special Behaviors

Most of the C. obsti specimens were found in a primary rainforest on the lower parts of slopes that were not too steep and in the bottom of valleys. C. obsti specimens are usually found in areas where the trees formed a closed canopy. Leaf litter, fire wood, and various herbs and bushes were present under the canopies where C. obsti were found.

Relation to Humans
C. obsti is dedicated to Fritz Jurgen Obst.

Comments
Primary paper: Günther, R. 2002. Westernmost records of the Papuan frog genus Copiula with descriptions of two new species (Amphibia: Anura: Microhylidae). Faunistische Abhandlungen. Staatliches Museum für Tierkunde in Dresden 23: 35–58.

Species Account Citation: AmphibiaWeb 2016 Copiula obsti <https://amphibiaweb.org/species/6183> University of California, Berkeley, CA, USA. Accessed Dec 25, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 25 Dec 2024.

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