Amnirana galamensis, (Dumeril & Bibron, 1841) (Dumeril & Bibron, 1841)

RESULTS View in CoL

In MNP, Amnirana galamensis hid in high grass, holes, beneath dead wood, or in leaf-litter during daytime. We heard male choruses throughout the entire study period. Males called from herbaceous vegetation at temporary ponds (fig. 1), or between short grasses that edged road puddles. They started calling after sunset, mostly with a peak around 19:00 h GMT. In a few cases, some males were heard calling during the day after heavy rainfall.

On 16 July 2020, we recorded seven advertisement calls from one male after heavy rainfall at 20:14 h GMT (site 1: 7°01’43.61” N, 5°57’3.32” W; 235 m asl; temperature 21°C). Six days later, a solitary female was seen at 21:20 h GMT, close to a road puddle that edged short grasses (site 2: 6°58’46.76” N, 5°57’43.70” W; 188 m asl; 22°C). When three of us (GUZ, NGK & ON) decided to capture this female, it puffed up its body for a few seconds, and uttered loud, frightening screams when we moved our hands towards it. Four of these calls were recorded. On 31 July 2020, a male was recorded at 20:25 h GMT, sitting between dense herbaceous vegetation at a pond edge (site 3: 6°59’44.89” N, 5°57’7.93” W; 179 m asl; temperature 21°C). The frog emitted distress calls when we captured it by hand. Three of these calls were recorded.

In Daloa, on 18 April 2019 at 20:55 h GMT, a solitary female was found sitting exposed in a long ditch (water depth ~ 90 cm) bordered by short grasses ( 6°54’22.20” N, 6°26’18.70” W; 285 m asl; temperature 26°C). The frog puffed up its body and uttered some warning calls, while leaping away, when NGK tried to capture it by hand. Four sequential calls from this female were recorded.

In Table 1 View Table 1 we summarised the acoustic properties of the different calls of A. galamensis from MNP and Daloa, as well as advertisement calls from Comoé National Park (CNP) in northern Ivory Coast (CD by T. U. Grafe in Rödel 2000), Bénoué and Mokolo in northern Cameroon (CD in Amiet & Goutte 2017), and an unknown locality in Tanzania (CD in Du Preez & Carruthers 2009). Advertisement calls are visualised in fig. 2.

Two types of (presumed) male advertisement calls are known, a more common hooting or barking “huhoot” call and a longer grunting “brrss” call ( sensu Rödel 2000). The first is an upward raising, frequency modulated call, whereas the second is a pulsed call with more or less stable frequency (fig. 2). Both call types comprise only one note. The “huhoot” and “brrss” calls were both audible together on each recording from CNP and Mokolo, while we only heard and recorded the “huhoot” calls from MNP.

Likewise, the recordings from Bénoué and Tanzania only contained the “huhoot” calls.

The duration of the “huhoot” calls from MNP, CNP and Mokolo were shorter than those emitted by males from Bénoué Reserve and the Tanzania locality (tab. 1). The shortest calls were recorded from MNP, while the longest call were registered from Bénoué Reserve. The highest dominant frequency was reported from CNP, while the lowest dominant frequency was recorded in the Bénoué Reserve. Likewise, the highest fundamental and maximum frequency was from CNP, the lowest values for both measures from Bénoué Reserve.

The “brrss” calls were shorter in CNP than in Mokolo. The values of the dominant frequency, the fundamental frequency, the maximum frequency, and the minimum frequency of CNP “brrss” calls were all higher than those from Mokolo (tab. 1).

The distress calls emitted by male 2 in MNP (tab. 1, fig. 3 a‒b), differed and was longer in duration than each of the two advertisement calls recorded in Ivory Coast, Cameroon, and Tanzania. Its duration was also longer those of females’ warning calls (see below and tab. 1). The frequency also differed from other call types (tab. 1). The frequency of the distress calls slightly changed through call duration. This call type comprised two repetitive, pulsed notes (fig. 3 b).

The warning calls from both females were identical, but differed from both advertisement call types. The frequency modulated calls were continuous, repetitive, comprising three high pitched notes, each with three pulses (fig. 3 d, f).