Bioacoustics of Breviceps carruthersi

The advertisement call of B. carruthersi is pulsatile, distinguishing it from all other Breviceps species (except B. branchi ), which have either pulsed or tonal calls. The advertisement call of B. branchi is unknown: the holotype specimen was collected north of Port Nolloth , 1800km from Hluhluwe , and resembles B. namaquensis and B. macrops in morphology, having large eyes and fleshy webbing). The calls of B. carruthersi are grouped within the call bout, with up to 28 calls/group. In B. poweri , which has grouped, tonal calls ( Minter 1997 ), the mean call duration is 0.14 s ( 0.07 s in B. carruthersi ) and occupies a lower frequency range of 1557–1903 Hz ( 2182–2481 Hz in B. carruthersi ). Breviceps adspersus , B. bagginsi , B. mossambicus ( Mozambique Island) and B. passmorei differ from B. carruthersi in having pulsed calls with a mean duration of 0.193, 0.198, 0.05 and 0.305 s , respectively ( Minter 1997 , 2003 , this publication), while B. sopranus has a very long tonal whistle with a mean duration of 1.5 s and a mean dominant frequency of 3332 Hz ( Minter 2003 ). This new species differs from other species within the Breviceps mossambicus complex with regard to the 16S marker, by a net uncorrected p-distance value of 6.8–11.3% (see Table 3). In the case of B. bagginsi reliable identified tissue was not available but this species differs from B. carruthersi in advertisement call structure (see above). Description of holotype ( Table 5 ; Figs. 3 A–C, E). Morphometrics are given in Table 5 . A male, SVL 34 mm . Snout extremely abbreviated; pupils horizontally elliptic; tympanum not distinguishable. Vent terminal. Skin of dorsum glandular: its surface consists of irregular folds and numerous small and large tubercles, giving it a densely granular appearance; the openings of the dermal glands are closely spaced and evenly distributed. Ventrum smooth. Limbs short. Fourth (outer) finger reaches the distal subarticular tubercle of the third finger; subarticular tubercles of third finger undivided. Webbing absent. No divided subarticular tubercles on hands or feet were observed. Welldeveloped inner metatarsal tubercle separated from outer metatarsal tubercle by a deep cleft. Outer toe very short, barely reaching basal subarticular tubercle of fourth toe. Colour in life: dorsum of body light orange-brown to dark brown, with very dark tubercles forming an incomplete border to the anterior pair of light brown paravertebral patches. Interocular bar present but indistinct; light paravertebral patches distinct; three light dorsolateral spots present, not sharply demarcated. Light vertebral line absent; indistinct heel-to-heel line and small, poorly demarcated cream patch over urostyle present. A broad black stripe runs obliquely downwards, from margin of lower eyelid towards base of arm, not reaching it; anterior to this, a broad white stripe runs down to angle of mouth and onto upper and lower lips and separates dark stripe from gular patch. Gular patch uniformly dark anteriorly, becoming mottled posteriorly. Sides of body between limbs light brown with scattered white speckles. Pectoral region and ventrum immaculate, white. In the preserved specimen orange-brown has faded to cream and shades of grey ( Figs. 3 B, C). Variable n Mean SD Range CV% No. of calls in call group 9 9.85 9.12 2–28 92.6 Call period within call group (s) 9 0.21 0.03 0.18–0.28 14.0 Call period between single calls/call groups (s) 9 4.77 3.26 0.47–15.47 68.3 Call rate within call group (min -1) 9 285 46.8 203–344 16.4 Call duration (s) 9 0.07 0.01 0.05–0.10 14.3 Dominant frequency (Hz) 9 2378 122 2182–2481 5.1 Measurement Holotype Paratypes Females Males n Mean Range SD n Mean Range SD Mass (g) 5.3 2 15.2; 32.9 9 15.2 3.4–7.6 1.2 EAD 5.6 2 7.5; 8.0 12 5.9 4.7–6.6 0.5 EPD 10.0 2 12.8;14.2 12 10.4 9.0–11.3 0.6 ES 1.4 2 2.8; 2.5 12 1.8 1.4–2.2 0.3 FL 12.5; 11.7 4 17.8 16.7–18.5 0.8 24 11.7 9.2–13.5 0.9 HW 11.2 2 13.0; 14.6 12 11.4 9.6–12.9 0.9 IMTL 3.3; 2.8 4 4.2 3.8–5.1 0.6 23 2.9 2.0–3.5 0.4 IND 1.8 2 2.5; 3.1 12 2.0 1.6–2.5 0.3 NL 2.1; 1.9 4 2.7 2.2–3.2 0.5 24 1.8 1.3–2.1 0.2 NOD 1.8; 1.4 4 2.5 2.2–2.8 0.3 24 2.0 1.7–2.5 0.3 PFL 3.7; 3.8 4 4.8 3.5–5.7 1.0 24 3.7 3.0–4.2 0.4 SVL 34 2 59; 47 9 33.9 28–39 3.3 T1L 0.6; 0.6 4 1.0 1.0–1.1 0.1 24 0.6 0.4–0.8 0.1 T1W 0.7; 0.5 4 1.35 1.0–2.4 0.7 24 0.7 0.5–0.9 0.1 T4L 6.2; 6.3 4 9.2 8.4–10.1 0.7 22 6.0 4.9–7.5 0.6 T5L 0.7; 0.7 4 1.4 1.2–1.6 0.2 23 0.7 0.4–0.8 0.1 T5W 0.7; 0.7 4 0.9 0.7–1.0 0.1 24 0.6 0.4–0.8 0.1 Holotype advertisement call ( Fig. 4 ). Several call bouts consisting of 16 call groups were recorded at the Sports Club in Hluhluwe, on 24th January 2017 at 23h38; air temperature 24 °C. It was raining heavily and a strong chorus had developed. The calls are pulsatile, with amplitude modulation barely distinguishable in most calls, while a few are more strongly modulated; amplitude increases gradually from the start, falling rapidly at the end of the call. Frequency modulation absent. Two to three harmonics are present. All calls in the call bout are condensed into groups consisting of 8–21 calls (mean 12, sd 4). Means and ranges for three calls/call groups are: call period within call group 0.211 s (0.204–0.227); call rate 294 min -1 (290–301); call duration 0.078 s (0.074–0.086); dominant frequency 2378 Hz ( 2350–2392 ). Paratype variation ( Fig. 3 D; Tables 4–5 ). Morphometrics are given in Table 5 . All specimens resemble the holotype in the absence of a visible tympanum; skin densely granular dorsally and laterally, smooth ventrally; one specimen granular laterally, not dorsally. Outer finger reaches distal subarticular tubercle of third finger in 13 specimens , falling just short in one; subarticular tubercles on third finger not divided. Cleft separating inner and outer metatarsal tubercles deep in seven specimens, shallow in seven. Outer toe very short, wider than long, falling short of basal subarticular tubercle of fourth toe in 10 specimens ; reaching it in four. Colour in life: dorsum orange-brown in eight specimens, dark brown in five and pale cream in one unpigmented individual; dark tubercles on dorsum scattered in four, forming a dark border to the lighter paravertebral patches in 10; white lateral speckles present in 13, absent in one. Interocular bar present in seven specimens, indistinct in six, not visible in the unpigmented specimen; light paravertebral patches present in eight, indistinct in six; three light, dorsolateral spots present in 11, indistinct in three. Light mid-vertebral line absent in 12 specimens , present posteriorly in two. A distinct, light-yellowish patch present over the urostyle in four specimens, indistinct in eight, absent in two; light heel-to-heel line indistinct in three, absent in eleven. A broad, black stripe runs obliquely downwards from margin of lower eyelid towards base of arm, reaching it in seven specimens, falling short in seven; anterior to this, a broad white stripe runs down to angle of mouth and onto upper and lower lips in all individuals, separating the dark stripe from the gular patch. Gular patch with scattered, darkgrey mottles on a white background in the two female specimens. In males the gular region is unpigmented in one, uniformly grey or darkened along the lower jaw, becoming lighter medially, in six; in five specimens the gular patch is mottled posteriorly, on a grey to yellowish-brown background. Pectoral region white, with scattered spots in three males. Ventrum immaculate white in 13 specimens ; a few scattered spots in one. Colour in preservative: dorsum of body medium to dark grey. Paravertebral patches beige to dark brown or dark grey in some. Interocular bar indistinct and beige to dark brown. Dorsolateral patches distinct and pale. Heelto-heel line indistinct to absent. Cream patch over urostyle distinct, present in all but two specimens. Facial stripe prominent, dark grey to black. Gular patch uniformly dark anteriorly, becoming mottled posteriorly in most males, mottled in females. Ventrum immaculate, creamy-white. Advertisement call data for the paratype males is presented in Table 3. No significant differences between the calls of the holotype male and the paratypes were found.

Distribution and habitat. Currently known only from the area around Hluhluwe and Phinda Game Reserve ( Fig. 1 ; Table 1 ). (Vegetation types as defined by Mucina & Rutherford, 2006 ). Hluhluwe is situated in vegetation type SVI 23 (Zululand Lowveld), which grades into SVI 20 (Western Maputaland Clay Bushveld) on the eastern perimeter of the town. At Phinda Private Game Reserve B. carruthersi occurs mainly in the south, on SVI 20 and SVI 23, as well as SVI 6 (Southern Lebombo Bushveld), less commonly in the sandy soils of CB 1 (Maputaland Coastal Belt) to the north (Daryl Dell 2017, pers. comm.). The first 18 km of the R22 between Hluhluwe and Sodwana consists of SVI 21 (Makatini Clay Thicket), continuing northwards as CB 1. Field observations . Calls were recorded between 18h45 and 01h15, during and after moderate to heavy rain. Two males were calling from shallow depressions at the base of grasstufts, while the remainder called from exposed positions on the surface. When the vocal sac is inflated, the white stripe separating the gular patch from the dark eyestripe is conspicuous and may function as a visual signal.