Afrixalus osorioi (Ferreira, 1906) Photo

Sánchez-Vialas, Alberto, Calvo-Revuelta, Marta, Castroviejo-Fisher, Santiago & De, Ignacio, 2020, Synopsis of the Amphibians of Equatorial Guinea based upon the Authors’ Field Work and Spanish Natural History Collections, Proceedings of the California Academy of Sciences 66 (8), pp. 137-230 : 160

Afrixalus osorioi (Ferreira, 1906) Photo figures 14B–C

TYPE LOCALITY.— “Quilombo”, northern Angola .

DISTRIBUTION.— Afrixalus osorioi occurs from northern Angola and Gabon to Kenya and Uganda throughout Democratic Republic of Congo. There are no previous published records of this species in Equatorial Guinea ( Map 15C ).

COMMENTS.— We report for the first time the presence of A. osorioi in Equatorial Guinea. Specimens were found in southeastern Río Muni (see list of specimens examined) and in Monte Alén (IDlR photographic records: Fig. 14B–C ). We tentatively assign the examined specimens to this taxon based on external morphological characters. However, these specimens differ slightly from the species’ typical pattern ( Schiøtz 1999; Amiet 2012). Recently, Jongsma et al. (2017) discovered this species in Gabon, providing three photographs: the figured specimen GFMJ1356 shows the typical pattern (see also Schiøtz 1999), whereas the other two figured specimens, CAS 258270 and CAS 258161, present a more uniform dorsal pattern where the dark dorsal rectangle is absent. Jongsma et al. (2017) stated that their specimen’s identifications were confirmed by molecular data. Later, Dewynter et al. (2018) provided an additional record for Gabon, and some specimens were figured, showing a pattern similar to the ones observed by us from Equatorial Guinea. This suggest that the typical pattern of A. osorioi (a well-defined dark rectangular mark on dorsum) in Gabon and Equatorial Guinea might be uncommon or absent. Instead, these populations have irregular and smaller spots, often arranged in two areas: between the eyes and over the neck region

(see Fig. 14B–C and pictures in Dewynter et al. 2018). However, a closely related species and morphologically similar, A. equatorialis (Laurent, 1941) , is distributed in Cameroon and Democratic Republic of Congo ( Amiet 2012; Portik et al. 2019). The dorsal pattern of A. osorioi is sometimes very similar to that of A. equatorialis from Cameroon. Although Jongsma et al. (2017) stated that the identification was confirmed by comparing DNA sequence data of the specimens from Gabon to another previously identified sample from Uganda, additional phylogenetic studies including samples from the type localities of each species will be necessary for resolving the taxonomy and distributional limits of the species in this group.

SPECIMENS EXAMINED.— Eight specimens. Engong (Aconibe-Asoc), 01 May 1987 ( EBD 25094–25101 ) .

Figures

MAPS 15A–C. Distribution maps for Equatorial Guinean records of (A) Afrixalus fulvovittatus; (B) Afrixalus laevis; (C) Afrixalus osorioi.

FIGURE 14. A. Afrixalus fulvovittatus (Monte Alén National Park, Río Muni). Photo IDlR.; B–C. Afrixalus osorioi (Monte Alén National Park, Río Muni). Photos IDlR.; D. Afrixalus paradorsalis (Caldera de Luba, Bioko Sur, Bioko). Photo IM.; E. Afrixalus paradorsalis (Monte Alén National Park, Río Muni). Photo IDlR.