Robinsonia marginata Rothschild, 1909

Laguerre, Michel, 2021, Partial revision of the genus Robinsonia Grote 1866: description of five new species for the Neotropical fauna (Lepidoptera, Erebidae, Arctiinae, Phaegopterina), Zootaxa 4990 (1), pp. 65-80 : 77-78

Note on Robinsonia marginata Rothschild, 1909 and Robinsonia flavicorpus Dognin, 1910

Beside R. simulans Laguerre sp. nov., another very common species in French Guiana is indisputably R. marginata Rothschild, 1909 . Its habitus is similar to R. simulans except that the termen is bordered by a black denticulated narrow band. This species has been described from two females collected in Guyana. In the original description ( Rothschild 1909), it is claimed that they were received from Rev. M. Whitford, who in turn had bought them in Georgetown but they were certainly collected by the miners at Omai ( Rothschild 1910 p.3). This species is abundant in French Guiana, especially along the Kaw Road, but I have never found it outside this country. Beside this species one can find an enigmatic entity: R. flavicorpus Dognin, 1910 , described based on a single male coming from the French dealer E. Le Moult and collected in August at St. Jean du Maroni also in French Guiana. The male type is housed in Washington (USNM) and it has been illustrated along with its genitalia by Alan Watson in 1971 (plate 25e and genitalia 120c–d). The two species are very close and the habitus difference is very slight. Moreover R. flavicorpus seems especially scarce: the type is unique in Washington, in the NHMUK (ex British Museum) there is only a picture pinned in the corresponding drawer and no specimen is present in MNHN in Paris! I was lucky to collect a small series of four males in the Venezuelan Guiana, all coming from the same road: El Dorado—Sta. Elena, either at PK 13 (5-VIII-1995) or at PK 38 (16–17-VIII-1996), so at a close distance of the southern Guyana border. Three are in my collection and one is in the Jean Aimé Cerda collection in Patawa (French Guiana). It is interesting to note that its absence in MNHN implies that nobody has collected this species in French Guiana during the years between 1980 and the beginning of the XXIst century. Dissection of one of these males shows that these specimens are referable to R. flavicorpus as illustrated by Watson.

At the habitus level there are some minor differences: for R. marginata the forewing apex is pointed and the termen is concave whereas the apex is rounded and the termen is straight in R. flavicorpus . In R. flavicorpus the coastal dark brown line displays a tooth inward after cell, this indentation being absent in marginata . The dark brown border along termen is more denticulated in R. flavicorpus and there are a few brown stains on disk and at the lowest part of the cell extremity (see Fig. 18 , present in the four males).

Male genitalia show some clear differences: the valvae are longer in R. flavicorpus and narrower near extremity (not spatulate as in marginata ), the translucent lobe of the valva is rounder and shorter in R. marginata , in R. flavicorpus the junction between vinculum and saccus is clearly narrowed, the two vesica are different (see Fig. 19 ).

Finally, even if the specimens were old, we got a small fragment of the barcode (289 bp) which shows already a 2.8% difference with the dozen or so of R. marginata sequenced from French Guiana (see tree in Fig. 3 ). So it is now clear that R. marginata and R. flavicorpus , despite very similar habitus, are distinct species but, up to now, no specimen of R. flavicorpus has been collected in French Guiana since its original description as opposed to R. marginata which proved to be a very common species throughout the territory.

Figures

FIGURE 3. Neighbour-Joining tree of 17 selected COX1 sequences of the studied group, distances in % are given below each branch and bootstrap supports are given above each branch in bold (only if larger than 70 %) (obtained with MEGA7, see Ku- maR et al., 2016). The newly described species are highlighted in bold.

FIGURE 18. Upper side on the left and ventral view on the right, A and B, male of R. marginata—C and D, female of R. marginata—E and F male of R. flavicorpus. A–D, from French Guiana; E–F, from Venezuela. Scale = 10 mm.

FIGURE 19. A–E: male genitalia of R. marginata, A ventral view, B dorsal view, C lateral view, D valva view from inside, E aedeagus with everted vesica. F–J: male genitalia of R. flavicorpus, F ventral view, G dorsal view, H lateral view, I valva view from inside, J aedeagus with everted vesica.