Sonitha libera (Aurivillius, 1914)

Takano, Hitoshi, 2024, Descriptions of three new Sonitha Zolotuhin & Prozorov, 2010 (Lepidoptera: Lasiocampidae: Lasiocampinae: Gastropachini) from West Africa in the collections of the African Natural History Research Trust, with taxonomic notes on the genus, Ecologica Montenegrina 72, pp. 88-98 : 89

Sonitha libera (Aurivillius, 1914) and Sonitha chocolatina Zolotuhin & Prozorov, 2010

The holotype of S. libera in NHMUK has only a single vague locality data label of “W. Africa. / M. Pounds. / 1910–239. [handwritten]” ( Fig. 2 ) but contrary to Zolotuhin & Prozorov (2010) “M. Pounds” does not refer to a locality but a collector. The accession number indicates that 15 specimens of Lepidoptera “collected by Mr M. Pounds” were purchased by NHMUK from Emily Bowdler Sharpe in 1910. The precise provenance of these fifteen specimens remains unclear but based on the distribution of Aurivillius’ species (see below) and speculatively its specific epithet, it is likely to be from the Liberian subregion of the Upper Guinean Forests. Zolotuhin & Prozorov (2010) considered specimens from both West and Central Africa to be conspecific due to their very similar external appearance and a conclusion appears to have been drawn a priori by Prozorov (2016: 1106) that the two populations must be the same despite the evidently different shaped eighth sternite, thus concluding that species identifications based purely on genitalia seemed “impossible”. Although the genital capsule is mounted laterally in the historic slide preparation of the S. libera holotype, the eighth sternite is well presented (see Fig. 2a in Prozorov 2016) and the general outline as well as the distance between the distal processes clearly exceeds the boundaries of intraspecific variation when compared to other congeners. One of the eight new species described by Zolotuhin & Prozorov (2010) was Sonitha chocolatina based on two males from Gabon. In their brief diagnosis, it is stated that this species can readily be identified based on wing colouration and pattern as well as the concave outer margin of the hindwing. There is no mention or comparison of the genitalia but from the figures (rather unfortunately placed on different plates), the difference between the sympatric S. libera sensu Zolotuhin & Prozorov (2010) from Gabon and the holotype of S. chocolatina is minimal (the vesica in Fig. 102 of Zolotuhin & Prozorov (2010) is not fully everted and the tip of the cornutus is broken). Moreover, in Prozorov’s (2016: 1106) later key to the Sonitha species, the differentiating characters are unclear (couplet 16 for S. chocolatina and S. lapa Prozorov, 2016 stating “General coloration [sic] of wings not brown” and couplet 17 for S. chocolatina confusingly starting with “Wings rufous- brown”) due in part to the poor delimitation of the species boundaries. A specimen from Gabon in ANHRT with a slightly concave outer margin matching the holotype of S. chocolatina was dissected and compared to a Gabonese S. libera sensu Zolotuhin & Prozorov (2010) caught in the same collecting event and these two specimens are conspecific ( Figs 4– 5 ). Furthermore, this Central African taxon is clearly distinct from true S. libera (the male genitalia of a modern specimen illustrated here for the first time in Fig. 6 ), which is restricted to the forested regions west of the Dahomey Gap. Below, the male genitalia and the unknown female of S. libera are described, the two species in question are compared and delimited, and differential diagnoses are provided.

Figures

Figures 1–7. Sonitha species. 1. S. libera (Aurivillius, 1915), ♂, Liberia, Nimba Mts. [ANHRTUK 00261556]. 2. Id., holotype ♂ of Stenophatna libera Aurivillius, 1915 [NHMUK 014200366]. 3. Id., ♀, Liberia, Nimba Mts. [ANHRTUK 00056329]. 4. S. chocolatina Zolotuhin & Prozorov, 2010, ♂, Gabon, Mts. de Cristal [ANHRTUK 00204687]. 5. Id., ♂, id. [ANHRTUK 00129611]. 6. Male genitalia of S. libera, Liberia [HT 008]. 7. Male genitalia of S. chocolatina, Gabon [HT 006].