Allograpta amphotera ( Bezzi, 1928 )

Ramage, Thibault, Charlat, Sylvain & Mengual, Ximo, 2018, Flower flies (Diptera, Syrphidae) of French Polynesia, with the description of two new species, European Journal of Taxonomy 448, pp. 1-37 : 5-6

Allograpta amphotera ( Bezzi, 1928)

Figs 2A , 3 A–B

Xanthogramma amphoterum Bezzi, 1928: 74 (holotype: ♂, BMNH; type locality: Cook Islands, Rarotonga).

Differential diagnosis

Species with yellow face with a medial black vitta, scutum black with a continuous lateral yellow vitta from postpronotum to scutellum, scutellum yellow with a median black macula, terga 2 and 5 with two lateral yellow maculae and terga 3 and 4 with a broad yellow fascia. It differs from A. nigripilosa only in the wing microtrichia, as stated in the key.

Material examined

Holotype FIJI: ♂, “Holo- // type” [round, red margin], “ Rarotonga 9 // 1920. // H.W. Simmonds ” “ Xanthogramma // amphoterum // Type Ƌg n.sp.” [red ink], “Fiji Is. // Pres.by // Imp.Bur.Ent. // Brit. Mus . // 1929–1.” ( BMNH).

Paratypes FIJI: 1 ♂, Movua, Nov. 1920, H.K. Simmonds leg. ( BMNH); 1 ♀, Lautoka, Aug. 1919, R. Veitch leg. ( BMNH) .

Other material

FRENCH POLYNESIA: 1 ♂, Austral Islands, Rurutu , Mar. 1925, St. George Expedition ( BMNH) .

COOK ISLANDS: 1 ♂, Rarotonga, Avatiu Valley , 28 Mar. 1999, C. Wilkinson leg. ( BMNH); 1 ♀, Rarotonga, Avarua , 0–200 m a.s.l., Nov.–Dec. 1979, N.L.H. Krauss leg. ( BMNH) .

Geographical distribution

Cook Islands, Fiji, French Polynesia (Marquesas Islands (?), Society Islands(?) and Austral Islands), Samoa.

Status in French Polynesia

Present.

Flowers visited

No records (ferns?, see Aubertin & Cheesman 1929).

Genetics

There are five DNA barcodes for Fiji specimens of this taxon with the following BOLD Process ID numbers: CNCDB1923-11, CNCDB1924-11, CNCDB1925-11, CNCDB1926-11 and CNCDB1927-11 (all by J.H. Skevington). The Barcode Index Number ( BIN) for them is BOLD:AAZ6685 (https://doi.org/10.5883/BOLD:AAZ6685).

References

Aubertin & Cheesman 1929: 172 (records); Hull 1937: 83 (catalogue); Vockeroth 1969: 129 (list); Thompson & Vockeroth 1989: 441 (catalogue); Mengual et al. 2009: 15 (list).

Remarks

Aubertin & Cheesman (1929) recorded this species for the first time from French Polynesia (Tahiti, Raiatea and Bora-Bora) and mentioned that it was abundant on fern-covered slopes. Hull (1937) listed this species from Fiji, the Marquesas Islands and Tahiti, while Vockeroth (1969) mentioned it from Samoa. We were not able to collect specimens during any field expeditions, even though it might be abundant. The only studied specimen from French Polynesia that has the same wing microtrichia pattern as the holotype of A. amphotera is a male from Rurutu in the BMNH.

This species and A. nigripilosa are extremely similar, and after the study of the type material by XM, it is still not clear whether they are the same taxon or two different species, one located in the western and southern parts of the south Pacific Ocean ( A. amphotera ) and the other ( A. nigripilosa ) restricted to the central part. In the BMNH, there is a male ( Cook Islands: Rarotonga, Avatiu Valley, 28 Mar. 1999, C. Wilkinson leg.) with the cell bm bare on the basal ¼. This male does not match the type of A. amphotera , indicating a potential intraspecific variability or some damage during preservation of this specimen. This specimen might also be a male of A. nigripilosa that reached the Cook Islands, broadening the distribution range of this species. At this point, we should consider the records from French Polynesia by Aubertin & Cheesman (1929) as doubtful, since they were reported prior to the description of A. nigripilosa by Hull (1944). More specimens are needed to understand the variability of these Oceanic species of Allograpta , but the analysis of the available DNA barcodes, including the specimens of Allograpta from Fiji mentioned above, resolved Fijian and Polynesian specimens in the same cluster, with a bootstrap support value of 100 in the Neighbour-Joining analysis. Moreover, BOLD groups all of these specimens in the same Barcode Index Number (BIN), BOLD:AAZ6685 (https://doi.org/10.5883/BOLD:AAZ6685). Although resolved in the same clade, the barcodes of Fijian and Polynesian specimens form two different clusters. In further studies we will try to collect more individuals of Allograpta to test the molecular variability of these two species; at the current stage, the synonymy of A. amphotera and A. nigripilosa seems plausible.

Figures

Fig. 2. A. Allograpta amphotera (Bezzi, 1928), holotype, ♂, dorsal view. B. Allograpta jacqui Mengual & Ramage sp. nov., holotype, ♂ (ZFMK-DIP-00019707), dorsal view. C. Allograpta nigripilosa (Hull, 1944), ♂, dorsal view (photograph by F. Jacq). D. Ischiodon scutellaris (Fabricius, 1805), ♂ (ZFMK- DIP-00019713), dorsal view. Scale bars = 1 mm.

Fig. 3. A–B. Allograpta amphotera (Bezzi, 1928), holotype, ♂. A. Lateral view. B. Frontal view. C–D. Allograpta jacqui Mengual & Ramage sp. nov., holotype, ♂, (ZFMK-DIP-00026906). C. Lateral view. D. Frontal view. E–F. A. nigripilosa (Hull, 1944), ♂ (photographs by F. Jacq). E. Lateral view. F. Frontal view. G–H. Ischiodon scutellaris (Fabricius, 1805), ♂ (ZFMK-DIP-00019713). G. Lateral view. H. Frontal view. Scale bars = 1 mm.