Astylosternus rheophilus 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 : 146

Astylosternus rheophilus Amiet, 1978

Material examined.

ZMB 82885 (GenBank MK318875), Gosner stage 25, ZMB 82886 (GenBank MK318876), Gosner stage 39 and ZMB 82886A, Gosner stage 25, Cameroon, Mt Manengouba, near summit, 2114 m, 5°0'51.78"N, 9°49'24.24"E, 8 November 2010, leg. M. Hirschfeld; ZMB 82887 (GenBank MK318877) and ZMB 82887A, Gosner stage 36, Cameroon, Mt Manengouba, Pola, 1719 m, 5°3'27.96"N, 9°49'39"E, 2 December 2010, leg. M. Hirschfeld; ZMB 82888 (GenBank MK318878), Gosner stage 25, Cameroon, Mt Manengouba, near Abdou, 2088 m, 5°2'7.6"N, 9°50'46.8"E, 3 August 2011, leg. M. Hirschfeld; ZMB 82889 (GenBank MK318879) and ZMB 82889A, Gosner stage 26, Cameroon, Mt Manengouba, near Abdou, 5°2'13"N, 9°51'24.5"E, 4 August 2011, leg. M. Hirschfeld; ZMB 82890 (GenBank MK318880), Gosner stage 25, Cameroon, Mt Manengouba, near summit, 2100 m, 5°1'4.6"N, 9°51'54.9"E, 5 August 2011, leg. M. Hirschfeld; ZMB 82891 (GenBank MK318881), Gosner stage 25, Cameroon, Mt Manengouba, near Caldera, 1889 m, 5°2'26.2"N, 9°48'30"E, 6 August 2011, leg. M. Hirschfeld; ZMB 82892 (GenBank MK318882), Gosner stage 25, Cameroon, Mt Manengouba, Pola, 1788 m, 5°3'26.6"N, 9°50'10.2"E, 2 September 2011, leg. M. Hirschfeld; ZMB 82893 (GenBank MK318883), Gosner stage 25, Cameroon, Mt Manengouba, Pola, 1719 m, 5°3'27.9"N, 9°49'39"E, 6 September 2011, leg. M. Hirschfeld; ZMB 82894 (GenBank MK318884), Gosner stage 25, Cameroon, Mt Manengouba, Nkikok, 1328 m, 5°5'34.5"N, 9°49'3.8"E, 8 September 2011, leg. M. Hirschfeld; ZMB 82895 (GenBank MK318885) and ZMB 82895A, Gosner stage 25, Cameroon, Mt Manengouba, M’Bouroukou, 1518 m, 5°3'48.2"N, 9°52'0.1"E, 22 September 2011, leg. M. Hirschfeld; ZMB 82896 (GenBank MK318886), Gosner stage 25, Cameroon, Mt Manengouba, near Abdou, 2042 m, 5°2'26.3"N, 9°51'18.9"E, 23 September 2011, leg. M. Hirschfeld; ZMB 82897 (GenBank MK318887) and ZMB 82897A, Gosner stage 25, Cameroon, Mt Manengouba, near Abdou, 1992 m, 5°2'13"N, 9°51'24.5"E, 24 September 2011, leg. M. Hirschfeld; ZMB 82898 (GenBank MK318888), Gosner stage 25, Cameroon, Mt Manengouba, near Abdou, 2088 m, 5°2'7.6"N, 9°50'46.8"E, 25 September 20011, leg. M. Hirschfeld; ZMB 82899 (GenBank MK318889), Gosner stage 25, Cameroon, Mt Manengouba, near summit, 2135 m, 5°0'35.4"N, 9°51'24.8"E, 28 September 2011, leg. M. Hirschfeld; ZMB 82900 (GenBank MK318890), Gosner stage 25, Cameroon, Mt Manengouba, Nkack, 1466 m, 5°2'17.4"N, 9°46'27.3"E, 13 October 2011, leg. M. Hirschfeld; ZMB 82901 (GenBank MK318891), Gosner stage 27, ZMB 82901A, Gosner stage 26, ZMB 82901B, Gosner stage 25, Cameroon, Mt Manengouba, near Caldera, 1889 m, 5°2'26.2"N, 9°48'30"E, 17 October 2011, leg. M. Hirschfeld; ZMB 82902 (GenBank MK318892), Gosner stage 25, Cameroon, Mt Manengouba, Pola, 1788 m, 5°3'26.6"N, 9°50'10.2"E, 20 October 2011, leg. M. Hirschfeld; ZMB 82828 (GenBank MK318893), Gosner stage 25, Cameroon, Mt Manengouba, near Abdou, 2012 m, 5°2'24"N, 9°51'39.3"E, 26 September 2011, leg. M. Hirschfeld; ZMB 79241, Gosner stage 25, Cameroon, Mt Manengouba, near summit, 2042 m, 5°2'26.3"N, 9°51'18.9"E, 4 August 2011, leg. M. Hirschfeld.

All tadpoles were collected from streams in gallery forest and very degraded forest fragments. The description is mainly based on ZMB 82892 and ZMB 82901. The genotyped tadpoles have been compared with an adult from the Tchabal Mbabo, Cameroon (ZFMK 75632; GenBank MK318894). The uncorrected pairwise p-difference between tadpoles and between tadpoles and the adult ranged from 0-0.2% (0-1 bp).

Description.

Long robust tadpole with almost parallel flanks and long, muscular tail (Fig. 15); body bullet-shaped in dorsal view, oval but slightly flattened in lateral view; back with a longitudinal medial depression; snout rounded in dorsal view, more narrowly rounded in lateral view; body length 32.8 ± 1.7% of total length; body height 42.2 ± 4.5% of body length; body width 55.3 ± 5.5% of body length; eyes positioned dorsolaterally, eye diameter 10.8 ± 1.0% of body length; nostrils positioned dorsolaterally, closer to snout tip than to eyes; inter-nostril distance 82.8 ± 5.5% of interorbital distance; tail fins narrow, dorsal and ventral fin originating from tail base; ventral fin height 79.9 ± 6.8% of dorsal fin height; highest part of tail approximately in the middle of the tail; body height 98.4 ± 9.6% of maximum tail height; tail axis width 46.5 ± 6.9% of body width; tail axis height 71.2 ± 9.9% of maximum tail height; tail tip narrow and pointed; vent tube dextral; body with large lateral sacs, extending from spiracle to end of body; short spiracle, sinistral; mouth ventral, near snout, in almost terminal position, narrower than interorbital distance; keratodont formula 1:2+2/2+2:1; anterior lip with large rostral gap, short, round papillae restricted to corner of mouth; posterior lip with 2 or 3 rows of about 20-30 uniform, slender, triangular papillae; massive, black and serrated jaws, upper jaw arched with a big medial fang, lower jaw narrowly V-shaped, without visible notch.

The largest specimen at Gosner stage 25, as well as the largest specimen at Gosner stage 36, were the two largest tadpoles in our samples, both reaching about 80 mm total length.

Coloration in preservation.

Body light to dark brown, lateral sacs and ventral surfaces lighter, more grayish; fine brown speckling on tail axis, fading from dorsal to ventral parts; fins largely beige transparent, with tiny brown dots along the margin of the last third of dorsal and ventral fin.

Variation.

Except the large size range of tadpoles all in Gosner stage 25, tadpoles were very uniform in color ation, body and mouth part proportions and characteristics. The tadpole of A. rheophilus was already described by Channing et al. (2012). These authors give an additional keratodont formula as 1:2+2/1:1+1:1.