Cacosternum thorini sp. nov. Hogsback Dainty Frog (Figures 3, 4 & 6) Holotype. An adult male (PEM A10091, Fig. 3 A&B) deposited in the Port Elizabeth Museum (PEM), South Africa. Collected 7 October 2011, by W. Conradie & C. Morrison from a small wetland below the forestry fire lookout tower, Hogsback, Eastern Cape Province, South Africa (32°34’48” S; 26°56’34” E, 3225CA, 1530 m above sea level). Allotype. An adult female (PEM A10083, Fig. 3 C&D), identical collecting details as Holotype. Paratypes. 8 females (PEM A10084, - 10087, - 10088, - 10093, - 10100, - 10103; SAIAB 191643.1; NMB A8007) and 14 males (PEM A10082, - 10085, - 10086, - 10089, - 10090, - 10094, - 10096, - 10098, - 10099, - 10101, - 10102, - 10105; SAIAB 191643.2; NMB A8008), identical collecting details as Holotype. Diagnosis. A species referred to the genus Cacosternum on the following characters: pupil horizontal; vomerine teeth absent; no mid-tarsal tubercle; no webbing on fingers and toes; no terminal discs on fingers and toes; tympanum hidden; smooth immaculate ventral surface with fine mottling (Channing 2001); and molecular monophly for the 16S mitochondrial marker with other Cacosternum taxa (Fig. 2). This new species differs from other Cacosternum species with regard to the 16S fragment, by a net uncorrected p-distance value of 1.9–5.4%. The within-clade variation is zero (see Table 2). Although the net uncorrected pdistance between the new species and his closest relative is very low (1.9%), it is well in range with values provided by Channing et al. (2013) for other valid species. The new species forms part of the Cacosternum boettgeri complex (Fig. 2). The dorsum is smooth with no protruding skin glands or ridges, distinct from C. capense (with protruding lateral and dorsoventral skin glands), C. nanogularum and C. aggestum (hourglass pattern skin glands), and C. parvum (longitudinal dorsolateral skin ridges); no webbing between toes, distinct from C. leleupi (webbing reaches proximal subarticular tubercle of fourth toe); tympanum absent (present C. kinangopensis); viewed from above, the nostrils are closer to the snout than in C. karooicum (nostril situated at least three nostril diameters from anterior margin of snout); supratympanic fold is indistinct, distinct from C. boettgeri, C. namaquense and C. striatum (form a thickened saddle); inner metatarsal tubercle is small, low, and equal to the width of the tip of the first toe, which distinguishes them from those where the inner metatarsal tubercle is twice the width of the tip of the first toe (C. leleupi, C. aggestum, C. parvum and C. plimptoni); rictal gland is smooth and uninterrupted, distinct from C. nanum and C. platys (interrupted and bumpy); no supernumerary tubercles on the palm, distinguishing it from species with 2–5 tubercles (C. aggestum, C. boettgeri, C. capense, C. karooicum, C. leleupi, C. namaquense, C. nanogularum, C. nanum and C. platys). The vocal sac of breeding males is yellow-beige with a very light mottled appearance (Fig. 3 B), which distinguishes it from species with dark throats (C. boettgeri, C. capense, C. kinangopensis, C. leleupi, C. namaquense, C. nanogularum, C. nanum, C. parvum, and C. platys), species where the throat is beige with bolder fine mottling (C. aggestum, C. australis, C. karooicum), but indistinct from species with white to yellow throats (C. plimptoni, C. rhythmum and C. striatum); ventrum is immaculate with lateral margins with small speckles, which distinguishes it from all other Cacosternum species except C. parvum, C. rhythmum and C. striatum. The advertisement call consists of a string of ‘chirps’ followed by a number of longer ‘creaks’, produced with a distinctive beat. It differs from the simple series of single or multiple clicks of C. boettgeri, C. kinangopensis, C. leleupi, and C. plimptoni or the creaking calls of C. capense, C. karooicum, C. namaquense, C. nanogularum, C. parvum, and C. striatum or the brief chirps of C. nanum. It differs from those species producing a 'bouncing marble' call of pulses that speed up such as C. aggestum, C. australis and C. platys. Call structure mostly resembles that of C. rhythmum. Description of the holotype (all measures in mm). Small adult male, SUL 14.0. Body slender, widest at midbelly, with a narrow head (HW/SUL 0.3). The head is acutely rounded from above and in profile. Head length measured from the angle of the jaw is moderate (HL/SUL 0.4). Canthus rostralis rounded, straight from eye to nostril, loreal region convex; nostrils small, rounded, directed laterally. The nostrils are placed closer to the snout than to the eye (EN/SL 0.5). Internostril distance is less than distance between eye and nostril (NN/EN 1.2). Eyes directed anterolaterally, the eyes protrude, and barely visible from below, relatively small (ED/HW 0.4; ED/SUL 0.1), nearly equal to snout (ED/SL 0.8). Distance between anterior corners of eyes nearly double the internostril distance (NN/EE 0.5). The angle of the jaw is posterior to a line drawn vertically from the back of the eye. Tympanum not visible. Jaws without dentition; choanae small, round, located at anterior margins of roof of mouth; vomer processes and teeth absent; tongue long (2.9), narrow proximally, broad distally (maximum 2.0), slightly bifurcated distally, proximal third attached to lower jaw. No median lingual papilla present. The dorsal surfaces of the head, trunk and limbs are smooth, with no glands and skin folds present; the rictal gland is smooth, continuing posteriorly unbroken to just before arm insertion. Supratympanic fold inconspicuous to absent. Ventrally smooth, with very light mottled appearance, vocal sac yellow-beige with a slight mottled appearance (Fig. 3 B). The forelimb is slender, hand small (HAN/SUL 0.3), finger tips bluntly rounded without discs. Relative finger lengths I

Published as part of Conradie, Werner, 2014, The King of the Dwarves: a new cryptic species of Dainty Frog (Anura: Pyxicephalidae: Cacosternum) from the eastern Great Escarpment of South Africa, pp. 438-452 in Zootaxa 3785 (3) on pages 438-452, DOI: 10.11646/zootaxa.3785.3.6, http://zenodo.org/record/226166