Astylosternus fallax Amiet, 1978

Griesbaum, Frederic, Hirschfeld, Mareike, F. Barej, Michael, Schmitz, Andreas, Rohrmoser, Mariam, Dahmen, Matthias, Muehlberger, Fabian, Christoph Liedtke, H., L. Gonwouo, Nono, Doumbia, Joseph & Roedel, Mark-Oliver, 2019, Tadpoles of three western African frog genera: Astylosternus Werner, 1898, Nyctibates Boulenger, 1904, and Scotobleps Boulenger, 1900 (Amphibia, Anura, Arthroleptidae), Zoosystematics and Evolution 95 (1), pp. 133-160 : 137

Astylosternus fallax Amiet, 1978

Material examined.

ZMB 82868 (GenBank MK318849), 3 tadpoles, Gosner stage 25, Cameroon, Ebo Forest, Njuma, 373 m, 4°20'54.66"N, 10°14'24.3"E, 16 July 2011, leg. M. Dahmen & M. Hirschfeld; ZMB 82869 (GenBank MK318850), 1 tadpole, Gosner stage 25, Cameroon, Ebo Forest, Njuma, 306 m, 4°20'35.64"N, 10°14'0.54"E, 29 September 2010, leg. M. Hirschfeld & M.-O. Rödel.

All tadpoles were caught in forest streams. The description is mainly based on ZMB 82868. Genotyped tadpoles have been compared with an adult from Bekop, Ebo forest, Cameroon (ZMB 82787; GenBank MK318851). The two tadpoles and the adult were genetically identical.

Description.

Long slender tadpole with long, muscular tail (Fig. 4); body oval in dorsal and lateral view; snout rounded in dorsal and lateral view; body length 36.3 ± 2.6% of total length; body height 40.3 ± 3.3% of body length; body width 56.2 ± 4.4% of body length; eyes positioned dorsolaterally, eye diameter 11.4 ± 0.5% of body length; nostrils positioned dorsolaterally, closer to snout tip than to eyes; inter-nostril distance 74.1 ± 7.0% of interorbital distance; tail fins narrow, dorsal and ventral fin originating from tail base; ventral fin height narrower, 68.9 ± 11.5%, than dorsal fin height; highest part of tail approximately in the middle of the tail; body height 96.6 ± 14.8% of maximum tail height; tail axis width 45.6% ± 10.0% of body width; tail axis height 69.3 ± 4.7% of maximum tail height; tail tip pointed; vent tube dextral; body with large lateral sacs, extending from spiracle to end of body; short spiracle, sinistral; mouth positioned rostroventral, narrower than interorbital distance; keratodont formula 1:2+2/2+2:1; anterior lip with lateral papillae and big rostral gap; posterior lip with 2 or 3 rows of app. 20 triangular papillae (Fig. 4c), papillae of inner row (or rows) shorter than in the marginal row; black jaw sheaths massive and serrated; upper jaw sheath with a small medial fang, lower jaw U-shaped with a broad medial notch.

The tadpoles (all Gosner stage 25) ranged from 45 mm to 74 mm total length.

Coloration in preservation.

Basic color light brown, the dorsal surfaces darker; back and tail with irregular, big, dark brown spots or blotches; venter light with few or no dark speckling; tail fins beige, semitransparent with dark brown spots.

Taxonomic remarks.

Morphologically and genetically tadpoles of this species were very similar to A. laurenti and a taxon (here termed A. cf. fallax ) which genetically was intermediate between A. fallax and A. laurenti (for respective tadpole descriptions see below). The uncorrected pairwise p-difference between A. fallax and A. laurenti was 2.55%, between A. fallax and A. cf. fallax it was 1.85%, and between A. laurenti and A. cf. fallax the distance was 1.99%. Further morphological and genetically research is necessary to conform if these three lineages represent distinct species or merely are representatives of one, genetically variable species.