Bioacoustics of Gephyromantis decaryi

Diagnosis. A member of the subgenus Gephyromantis in the genus Gephyromantis on the basis of (1) presence of intercalary elements between ultimate and penultimate phalanges of fingers and toes (verified by external examination), (2) small size (SVL below 35 mm ), (3) slightly enlarged terminal discs of fingers, (4) presence of outer metatarsal tubercle, (5) absence of webbing on hands and presence of only rudimentary webbing on feet, (6) tight connection of tissue surrounding the two lateral metatarsalia, (7) presence of femoral glands in males ( Fig. 9 ), (8) presence of paired or bilobed blackish vocal sacs in males, (9) diurnal calling behavior not restricted to water bodies. Within the subgenus, distinguished from all other species by combination of (1) comparatively moderate size (male SVL 25–28 mm ), (2) dorsum with several larger tubercles; usually with presence of distinct inner and outer dorsolateral ridges which usually are continuous over a significant stretch and not merely rows of elongated tubercles, (3) upper lip with light gray (but not white or yellow) color interrupted by 2–4 dark brown markings, (4) lower lip ventrally without a distinct alternating series of brown and yellowish markings; (5) body slender, forelimbs and hindlimbs very long (tibiotarsal articulation reaching beyond snout tip when hindlimbs are adpressed along body), (6) calls consisting of a rather long series of>30 notes of indistinctly pulsed structure with a low note repetition rate of 3.6–4.6/s. Assigned to the group of species here informally defined as the Gephyromantis decaryi complex based on its molecular phylogenetic relationships (see above) and its advertisement call characters namely long series of notes with a low note repetition rate. For a morphological and bioacoustic comparison to the newly described species in the complex see the diagnoses of these species below, Table 2 and Fig. 5 . Natural history. Specimens were regularly observed calling from shrubs and fern vegetation at the edge of the rainforest. They were common in the vegetation along the main road near Valbio biological station and the entrance of Ranomafana National Park. Calling males were heard from low perches of ca. 10 cm in ferns, but also from higher perches of 100–150 cm above the ground. They typically called during the day, but calls were also heard at night. Reproduction and larval stages are unknown but the fact that calling males are not concentrated close to water bodies suggests a possible nidicolous reproduction as in other species of the subgenus Gephyromantis . Advertisement calls. Glaw & Vences (2000) described the call of Gephyromantis decaryi (under the name Mantidactylus decaryi ) based on recordings from 26 February 1996 at Ranomafana. Temporal data from this description are reproduced in Table 2 . One call consisted of 44 notes, each peaking in intensity at its beginning. Fundamental frequency was 1450–1650 Hz, dominant frequency was 2950–3600 Hz. Own recordings from the campsite next to Valbio biological station (from specimen ZCMV 5585) largely agree with this previous description (see Table 2 for temporal call data). Note repetition rate was 4.6/s. The notes had a very indistinctly pulsed structure, with 14–16 intensity peaks per note (n=3) that can be regarded as pulses. A fundamental frequency band was present at 1800–2000 Hz, dominant frequency ranges between 3000–4200 Hz, some low intensity components seemed to reach up to 8000 Hz.