Amegilla ( Glossamegilla ) amymone ( Bingham, 1896 )

Carion, Frédéric, Gérard, Maxence, Ghisbain, Guillaume & Wood, Thomas J., 2025, Unravelling Amegilla (Glossamegilla) diversity across the Wallace Line: new species, wing morphometrics, and biogeographic boundaries (Hymenoptera, Apidae), ZooKeys 1256, pp. 1-79 : 1-79

Amegilla ( Glossamegilla) amymone ( Bingham, 1896)

Anthophora amymone Bingham, 1896: 196, ♀ [ Indonesia: Sumatra, NHMUK, examined] (Fig. 12)

Anthophora bouwmani Lieftinck, 1944: 103, ♀ [ Indonesia: Sumatra, RMNH, examined] (Fig. 13) syn. nov.

Remarks.

In the material donated to the RMNH collection in 2008 from R. Desmier de Chenon were 24 specimens of “ A. bouwmani ”, all identified by R. Desmier de Chenon as A. amymone , from Sumatra that were collected at the same time and place as another ten specimens of A. amymone (see map, Fig. 25 ). Only males of A. bouwmani were found by R. Desmier de Chenon while he collected both sexes of A. amymone at the same place. The sympatry of these two taxa, the collection of only males of A. bouwmani but both sexes of A. amymone led to the hypothesis that A. amymone and A. bouwmani may be conspecific. Indeed, A. bouwmani was originally described from a single female specimen, with the male unknown.

The comparison of these males of A. bouwmani with the holotype of A. bouwmani hosted at the RMNH showed similarities in terms of pilosity and structure but also a difference in its clypeal mark; this level of difference is similar to the one characterising both sexes of A. amymone .

However, when morphology was compared between the males of the two species, no clear differences were observed, with the clearly overlapping range. Indeed, most of the specimens have shared distributions with shared altitudes (both seem to be mountain species) as visible on the map (Fig. 25 ). The males have the same habitus but a paler pilosity is observed in A. bouwmani (Fig. 14 A, B, E, F ), the clypeal marks are approximately the same (same colour, approximately the same surface is covered, Fig. 14 C, D ), the labra are very similar (Fig. 14 C, D ), the punctation shows no clear differences and the genitalia are the same in both species (Fig. 14 G, H ). Concerning the females, similarly to the males, only the colour of the pubescence changes with a paler pubescence for A. bouwmani . Lieftinck (1944: 103–105) gave a full description of A. bouwmani as the original description but A. amymone was not considered in this paper. Later, Lieftinck (1956: 9) described A. bouwmani as “ The female […] resembles that of amymone fairly closely in texture and colour of the body, but the pubescence is much lighter. ”, suggesting that these two species are closely related (Lieftinck also put them as “ near allies ” in his paper of 1956). This is interpreted here as an additional argument to their synonymy.

Contrarily to most of the other species assessed, A. amymone and A. bouwmani cannot be differentiated based on wing size and shape. Concerning wing size, a substantial overlap occurs between both species when the distribution of size is examined. Wing size in A. amymone overlaps at 100 % the size of the wing of A. bouwmani , the latter being more variable than the former (Fig. 15 ). However, differences in wing size is not statistically significant (p-value = 0.495; Table 6 ). Concerning wing shape, the PCA plot shows a complete overlapping between both species, without any distinct group differentiating. This absence of differentiation is confirmed by the result of the Procrustes ANOVA, the shape of the wing being indeed not significantly different (Fig. 16 ; p-value = 0.494; Table 7 ).

Evidence from all these arguments demonstrates that A. amymone and A. bouwmani are most likely the same species, as they only have colouration differences and no significant structural differences nor significant biogeographic differences. Amegilla bouwmani syn. nov. is therefore considered here as a pale form of A. amymone .

Figures

Figure 12. Holotype of Amegilla amymone (Bingham, 1896), initially published as Anthophora amymone Bingham, 1896 (NHMUK). A. Labels of the specimen; B. Habitus in profile view; C. Face in frontal view; D. Terga in dorsal view.

Figure 13. Holotype of Amegilla bouwmani (Lieftinck, 1944), initially published as Anthophora bouwmani Lieftinck, 1944 (RMNH). A. Labels of the specimen; B. Habitus in profile view; C. Face in frontal view; D. Terga in dorsal view.

Figure 14. Morphological comparison between the males of Amegilla (Glossamegilla) bouwmani (Lieftinck, 1944) and Amegilla (Glossamegilla) amymone (Bingham, 1896) (RMNH). A, C, E, G. Amegilla amymone male. B, D, F, H. Amegilla bouwmani male. A, B. Habitus in profile view. C, D. Face in frontal view. E, F. Terga in dorsal view. G, H. Genitalia in dorsal view.

Figure 15. Distribution of the centroid sizes for the wings in the males of A. bouwmani and A. amymone. No significant differences.

Figure 16. Ordination of A. bouwmani and A. amymone along the two first axes of the Principal Component Analyses (PCA) (explaining 20.87 % and 14.54 % of the variance, respectively).

Figure 25. Distribution map for A. amymone (Bingham, 1896) in the Indo-Australian Archipelago. This map contains both colour forms of A. amymone with the dark form (true amymone) represented by the blue points and the pale form (A. bouwmani (Lieftinck, 1944) syn. nov.) represented by the red points. The empty points represent specimens collected before and in 1950 while the full points represent specimens collected in 1951 and thereafter.