Acta Herpetologica 12(2): 125-132, 2017 DOI: 10.13128/Acta_Herpetol-20740 Meristic and morphometric characters of Leptopelis natalensis tadpoles (Amphibia: Anura: Arthroleptidae) from Entumeni Forest reveal variation and inconsistencies with previous descriptions Susan Schweiger1, James Harvey2, Theresa S. Otremba1, Janina Weber1, Hendrik Müller1,* 1 Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich Schiller Universität Jena, Erbertstrasse 1, 07743 Jena, Germany. *Corresponding author. E-mail: [email protected] 2 41 Devonshire Avenue, Howick, 3290, South Africa Submitted on: 2017, 5th June; revised on: 2017, 31st August; accepted on: 2017, 3rd October Editor: Rocco Tiberti Abstract. The tadpole ofLeptopelis natalensis is described based on a series of 32 specimens from Entumeni Forest, KwaZulu-Natal, South Africa. Previous descriptions are brief, lack morphometric data, or are based on specimens of imprecise origin. The tadpole resembles other Leptopelis tadpoles and is generally in agreement with existing accounts, although some differences exist. Some of these differences seem to fall within the range of natural variation. Others, such as the presence of a fifth anterior row of keratodonts, might be indicative of variation at the population level and should be considered in future taxonomic revisions. Leptopelis natalensis tadpoles seem to be most readily dis- tinguished by their more narrowly keratinized beaks from the geographically overlapping or adjacent L. mossambicus and L. xenodactylus. Keywords. South Africa, KwaZulu-Natal, Eastern Cape, taxonomy, buccal morphology, ontogenetic variation. INTRODUCTION thermore differ in a number of diagnostic characters, such as labial keratodont formula. These differences in The genus Leptopelis currently comprises 53 the existing descriptions could be the result of variation described species (Frost, 2017) of medium to large tree or population-specific differences that might be signifi- frogs that are distributed throughout most of Sub-Saha- cant in future taxonomic revisions (Penske et al., 2015). ran Africa (Schiøtz, 1999). The most southerly distrib- To differentiate between these options, it is important to uted species of the genus is L. natalensis, which is found provide detailed locality information, which is lacking in in a variety of habitats along the eastern region of the some works providing information on tadpole morphol- South African provinces of KwaZulu-Natal and part of ogy of L. natalensis (e.g., du Preez and Carruthers, 2009). Eastern Cape (Schiøtz, 1999; Bishop, 2004; Venter and While detailed, or at least limited, locality data are pro- Conradie, 2015). Although some, mostly brief, descrip- vided by Wager (1930, 1965, 1986), Pickersgill (2007) and tions and illustrations of L. natalensis tadpoles have been Channing et al. (2012), these accounts provide mostly published (Wager, 1930, 1965; van Dijk, 1966; Lambiris, meristic data but few or no morphometric data that 1988; Channing, 2001; du Preez and Carruthers, 2009; would help in assessing subtle differences that might exist Channing et al., 2012), Channing (2001) considered between populations. We here provide a description and none of the South African Leptopelis tadpoles to have measurements of an ontogenetic series of tadpoles of L. been adequately described. The various descriptions fur- natalensis based on a series collected at Entumeni Forest, ISSN 1827-9635 (print) © Firenze University Press ISSN 1827-9643 (online) www.fupress.com/ah 126 Susan Schweiger et alii KwaZulu-Natal, assess variability and ontogenetic chang- The tail is about 2.5 times as long as the body (see Table es, and highlight differences between these and previous 1 for measurements) and very muscular. The myomeres descriptions. are visible in the posterior half of the tail, but are other- wise indistinct or obscured by the dense pigmentation. The tailfins are very low, with the dorsal fin marginally MATERIALS AND METHODS deeper than the ventral fin. The dorsal fin has a low ori- gin on the base of the tail, just behind the tail-body junc- A total of 32 tadpoles were collected at Entumeni For- tion, and gradually rises towards the middle of the tail, est, KwaZulu-Natal, South Africa on 3 December 2014. The where it reaches its maximum height. The ventral tailfin tadpoles were collected in a small forest stream (28.888334°S, is very even, with the margin of the fin running more or 31.365928°E). Some tadpoles were preserved on the day of col- less parallel to the ventral edge of the muscular tail. The lection, while others were raised on a diet of commercial aquar- ium fish food and sampled in regular intervals to obtain dif- overall deepest point of the tail is at about half its length. ferent stages of development. Identification of the tadpoles was Tip of tail is pointed, with the muscular tail terminating confirmed by raising some through metamorphosis. Specimens some distance before the tail tip (Fig. 1B). The vent tube were euthanized in an aqueous solution of tricaine methanesul- is attached to the right side of the ventral tailfin, with a fonate (MS222; Fluka), fixed in 4% neutral buffered formalin, very large opening forming a pointed arch. The coiled gut and transferred to 70% ethanol. Voucher specimens have been is well visible through the ventral body wall. deposited in the herpetological collection of the Museum für Oral Disc. The oral disc is positioned subterminally Naturkunde Berlin, Germany (ZMB85717). and is not visible in dorsal view. The oral disc is light- Staging followed Gosner (1960). Standard measurements ly emarginated and has a broad rostral gap. One row and labial tooth row formula followed Altig and McDiarmid (1999) and description of buccopharyngeal morphology Was- of globular marginal papillae is present anterolaterally sersug (1976). Drawings were prepared with the aid of a camera and laterally; posteriorly, two rows of papillae are pre- lucida attached to a Zeiss SV12 stereomicroscope. For inspec- sent. Papillae are largest anterolaterally and laterally, and tion of the buccopharyngeal morphology, one tadpole of stage smaller posteriorly. A few submarginal papillae are pre- 36 was dissected, postfixed with 1% osmium tetroxide, dehy- sent laterally. Keratodont formula is 4(2-4)/3(1) in the drated and critical point dried in an Emitech K850 critical point majority of the examined specimens (see below for vari- dryer, sputter coated with gold-palladium using an Emitech ation). Moving inwards, supralabial keratodont rows are K500 and investigated using a Phillips XL30 ESEM scanning progressively smaller (Fig. 1A), infralabial rows are of electron microscope with a digital image capture system. nearly equal length, with P3 being slightly shorter than P1 and P2. Interruption of P1, if present, is very nar- row in some specimens (Fig. 1A) but more pronounced DESCRIPTION in others. Keratodonts are about equally sized in most rows, except in P3 where they get progressively smaller Tadpole. The description is based on 32 tadpoles laterally. The individual keratodonts are spoon-shaped from Gosner (1960) stages 25 to 42 (see Table 1 for and have eight or nine cusps along their margins, with measurements and detailed information). The tadpole the apical cusps being larger than the more laterally is slender overall, with a moderately elongated, slightly positioned ones (see inset in Fig. 2A). The jaw sheaths dorsoventrally flattened body (wider than deep) and a are serrated but only narrowly keratinised (indicated relatively long tail with low dorsal and ventral fins. The by the dark pigmentation). By stage 42, the lower jaw widest point of the body is just behind the eyes (Fig. 1). sheath and all keratodonts are absent and the papillation No nares are visible until stage 34. From stage 35 to 37, is much reduced in extent. the nares are indicated as light coloured spots, but do Buccopharyngeal Morphology. The prenarial area of not seem to be open until stage 38. When fully formed, the buccal roof (Fig. 2A) is somewhat elongated and con- the nares are positioned dorsolaterally, about twice as far tains a few scattered pustules. In addition, a pair of short from the eye than the tip of the snout in lateral view. The ridges is present and somewhat slanted laterally. The ori- eyes are positioned dorsally. A small anlage of the devel- entation of the choana is oblique to the midline (about 45 oping eyelid is first visible at stage 40, anterior of the degrees) and both choanae form a forward-pointing angle eye. The spiracle is sinistral, about as far from the snout of approximately 90 degrees. The jagged narial valves pro- as from the body-tail junction. The spiracular opening is ject deep into the buccal cavity and obscure the choanal an upright oval, slightly slanted forward; its largest diam- openings. Anterolateral of each choana is a broad, flap- eter almost as large as the diameter of the eye lens. The like papilla with a pustulate edge. Three to four thick, spiracular tube is angled upwards at about 45°; the pos- broad-based papillae are present posterolaterally to each terior end, including its inner wall, is free from the body. Tadpole of Leptopelis natalensis 127 Table 1. Measurements of Leptopelis natalensis. All measurements in millimeters (arithmetic mean ± SD). * indicates a damaged tail in one of the specimens of the series, which was omitted from the calculations. 25 31 34 35 36 37 38 39 40 41 42 Gosner Stage (n=3) (n=1) (n=1) (n=2) (n=14) (n=2) (n=2)