Andronymus fontainei Larsen & Congdon

Larsen, Torben B., 2012, The genus Ampittia in Africa with the description of a new species (Hesperiinae; Aeromachini) and three new species in the genera Andronymus and Chondrolepis (Hesperiinae, incertae sedis) (Lepidoptera; Hesperiidae), Zootaxa 3322, pp. 49-62 : 54-56

Andronymus fontainei Larsen & Congdon sp.nov.

Background: An important source of data for the Hesperiidae project has been the Royal Africa Museum in Tervuren (MRAC), where the curator for many years was Lucien A. Berger, who upon finishing his book on the butterflies of Zaïre (excluding Hesperiidae ) was planning a revisional work on all African Hesperiidae . Because of the planned book he published only a minor part of his finding along the way, before his death. It is unclear what stage his manuscript had reached at the time, but his wife had apparently done excellent line drawings (now lost) of most of the 1,400 genitalia preparations of his in both the British Museum (Natural History) and MRAC. However, some of Berger’s findings are clear from the arrangement of the Hesperiidae in the collection.

While Larsen perused the MRAC collections a single male and two females of a very small Andronymus Holland bearing the manuscript name A. fontainei were located; his first thought was that they were simply dwarf specimens of A. caesar philander Hopffer , possibly with some minor genital differences. However, the well-prepared genitalia of the male proved quite distinct from those of other known members of the genus. The genus Andronymus is currently considered to include nine species, some of which are very similar, but usually with stable and clearly differentiated male genitalia.

When visiting Robert Ducarme in Brussels in 2011 to discuss Chondrolepis ducarmei (described below), Larsen went through the Ducarme collection and encountered another dwarf male Andronymus . Its genitalia proved identical with those of Berger’s A. fontainei , substantiating it as a valid species that is described below.

Description: Forewing 12.5–13.0 mm—the smallest known member of the genus. The forewing upperside has three well-defined subapical spots, the middle of which recessed. There is a small, round upper spot at the very end of the cell and a longer streak below it. A white spot is present in space 3 with a much larger, almost quadrate spot at the base of space 2, just below the lower cell-streak, though somewhat shorter than the latter. There is a white spot also in space 1b. The hindwing upperside has a white discal area composed of a large spot filling the outer half of the cell with an adjacent spot at the base of 3. A quadrate white spot in spaces 2 and 1c connects the discal patch with a white streak in 1b that is separated by the finely blackened vein 1b. The tornal cilia is only slightly whitened. The male has the usual black androconial hair tuft entering a fold in space 7. The forewing underside is almost like the upperside, with some additional white markings on the inner edge of the spot in space 1b. The hindwing underside is mainly white. The inner half of the costa is brown as is the margin from the apex to space 1c, where a white streak separates the margin from a larger tornal brown area. As in most of the genus, sexual dimorphism is slight, the lack of the androconial tuft apart; thus the above description also covers the female.

Male genitalia: The valve is proportionately short and the cucullus of the new species is cut off at a nearly 90o angle at its distal end, at the dorsal edge ending in a large triangular tooth. Only the upper half of the distal edge is lightly serrated. There is a fultura with two long narrow branches. The penis is 1.64 the length of the valve with the typical shape of the genus. The paratype from Biakatu is illustrated (SCC 705 (ABRI ex tbl BJI)) (figure 7)) rather than the holotype because the penis and fultura is free rather than overlapping with one valve, but the preparation in Tervuren is effectively identical (MRAC H.592 Holotype).

Holotype: 3 DRC, Uele, Paulis (02o52’N 27o40’E), 20.x.1959 (M. Fontaine leg.) ( MRAC; genitalia H.592). Paratypes: 2 ƤƤ Uele, Paulis, 16.viii.1959, 2.vii.1959 (M. Fontaine leg.) ( MRAC); 3 DRC, Biakatu (Orientale Prov.), iv.2008, (R. Ducarme leg.) (genitalia SCC 705 ABRI (ex tbl BJO)).

Diagnosis: The upperside is like a miniature version of A. caesar philander (two-thirds of the normal forewing length). We have seen no A. caesar as small as any in the A. fontainei type series (many hundred collected by us or inspected in collections). The underside pattern is also similar to A. caesar but with all light markings on both wing surfaces having no trace of cream tones or of ochreous-brown shading of the margins of the white discal area of the hindwing (see figure 6). The white area separating the marginal band from the tornal patch is wider in A. caesar than in A. fontainei . If the genitalia of both the holotype and the paratype were not clearly different from those of A. caesar it could not have been described from such a limited material. As shown in figure 7 the valve of A. caesar is proportionately longer than in A. fontainei and the almost squared off distal end of the cucullus is very different from the oblique shape in A. caesar . Very small specimens from central Africa are likely to be A. fontainei , but examination of the genitalia would be advisable in any specimen where the tornal white band on the hindwing underside is not noticeably obscured by dark scaling (figure 6).

Range, habitat and habits: The species is known only from the type series from Paulis (now Isiro) in the Haut-Uele province of the northeastern DRC and from an additional male collected at Biakatu (near Beni in North Kivu but in the Orientale Province), some 240 km to the southeast. The habitat is presumably forest of good quality; though Isiro is in the forest/savannah transition zone there are patches of closed evergreen forest; the Biakatu locality is evergreen forest with a rich mostly lowland butterfly fauna. Isiro is on the western boundary of the Albertine Rift while Biakatu is in the centre of this biogeographical zone. This area has a significant degree of endemicity and those that are not submontane often extend to Isiro. We are fairly sure that we never saw additional material of the species in collections, and nor did S. C. Collins (pers. comm.), and it is possibly limited to the western Albertine Rift area of the DRC. Like most members of the genus it probably stays inside forested areas and has a rather inconspicuous life style. However, it must genuinely be very rare; experienced collectors in the Albertine Rift area such as V.G.L. van Someren, T.H.E. Jackson, and J. Kielland all took long series of Andronymus on the eastern side of the Albertine Rift and would have collected any such tiny specimens.

Etymology: L. A. Berger at MRAC had planned to name the species after Dr Maurice Fontaine, who worked as a medical doctor in many parts of the then Belgian Congo, where he collected large numbers of butterflies, several of which already bear his name. We respect Berger’s wish, which is doubly appropriate since Dr. Fontaine was a good friend of Robert Ducarme who captured the only other known specimen.