Melanostoma, Schiner, 1860

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 : 27-29

Key to Australasian and Oceanian species of Melanostoma

1. Face with a distinct tubercle ( Fig. 7C, E ); male genitalia small ( Fig. 7A, C )..........................4

– Face with only a trace of a tubercle, almost straight ( Figs 4D , 7D , 9A ); male genitalia greatly enlarged, usually visible externally ( Figs 6G , 7B, D , 9B ).............................................................2

2. Abdominal terga entirely black ( Figs 4A , 6 F–G); legs partly black in both male and female ( Figs 4C , 6 F–G). Male genitalia: surstylus curved towards dorsal part ( Fig. 9D ) ( French Polynesia) ................................................................................................... M. polynesiotes sp. nov.

– Abdominal terga with large orange or yellow abdominal markings; male abdomen almost entirely orange with apical margins narrowly black and genitalic segments black ( Figs 7B, D , 9B ); female abdomen with pairs of large, narrowly separated pale maculae ( Figs 7F , 8A ); legs all orange, rarely metatibia with an indistinct medial brown band ( Fig. 7B, E ). Male genitalia: surstylus curved towards ventral part ( Fig. 9G, I ).........................................................3

3. Male surstylus club-shaped apically ( Fig. 9I ). Female: frons extensively pollinose, with two small shiny areas above lunule and ventrad to anterior ocellus; shiny areas do not reach eye margin ( Fig. 8B ) ( India, Sri Lanka, Thailand, Taiwan, Philippines, Borneo, Java, Central Moluccas: Buru) .................................................. M. univittatum (Wiedemann, 1824)

– Male surstylus tapers to slender acute apex ( Fig. 9G ). Female: frons mainly shiny with two large lateral pollinose maculae; shiny areas reach eye margin ( Fig. 8C ) (New Guinea, Australia, New Caledonia, Solomons, Fiji, Tonga, Samoa) ....................................... M. apicale Bigot, 1884

4. Abdominal terga with yellow maculae on terga 2–4, sometimes very large, but always with a medial continuous black vitta ( Fig. 7A ) ( New Zealand) .................... M. fasciatum (Macquart, 1850)

– Abdominal terga entirely black, sometimes extensively dark pollinose (New Guinea) ................. ....................................................................................................... M. fumivenosum Doesburg, 1966

Figures

Fig. 7. A, C, E. Melanostoma fasciatum (Macquart, 1850), ♂ (AM_K407062). A. Dorsal view. C. Lateral view. E. Head and thorax, lateral view. B, D. Melanostoma univittatum (Wiedemann, 1824), ♂ (ZFMK-DIP-00019737). B. Dorsal view. D. Lateral view. F. Melanostoma apicale Bigot, 1884, ♀ (ZFMK-DIP-00019781), lateral view. Scale bars: A–D, F = 1 mm; E = 0.5 mm.

Fig. 4. A, C–D. Melanostoma polynesiotes Mengual & Ramage sp. nov., holotype, ♂ (ZFMK- DIP-00019707). A. Lateral view. C. Lateral view. D. Head, lateral view. B, E. Ornidia obesa (Fabricius, 1775), ♂ (ZFMK-DIP-00019747). B. Dorsal view. E. Frontal view. F. Syritta aenigmatopatria Hardy, 1964, ♀ (ZFMK-DIP-00019739), frontal view. G. Palpada vinetorum (Fabricius, 1798), ♀ (ZFMK- DIP-00019738), frontal view. Scale bars = 1 mm.

Fig. 9. A–B. Melanostoma apicale Bigot, 1884, ♂ (from Ôhara & Kusigemati 1985, as M. univittatum (Wiedemann, 1824)). A. Head, lateral view. B. Abdomen, dorsal view. C. Melanostoma mellinum (Linnaeus, 1758), ♂, metasternum, ventral view (from Vockeroth & Thompson 1987; mtst = metasternum, cx3 = metacoxa). D–F. Melanostoma polynesiotes Mengual & Ramage sp. nov., holotype, ♂ (ZFMK-DIP-00019707), genitalia. D. Epandrium with surstylus and cercus, lateral view. E. Hypandrium, lateral view. F. Hypandrium, ventral view. G–H. M. apicale Bigot, 1884, ♂, genitalia, lateral view (from Ôhara & Kusigemati 1985, as M. univittatum (Wiedemann, 1824)). G. Epandrium with surstylus and cercus. H. Hypandrium. I. Melanostoma univittatum (Wiedemann, 1824), ♂ (ZFMK- DIP-00019737), surstylus and part of epandrium and cercus, lateral view. Scale bars = 0.5 mm.

Fig. 6. A. Ischiodon scutellaris (Fabricius, 1805), ♂ (ZFMK-DIP-00019713), metacoxa and metatrochanter. Arrow indicates the ventral spine-like process. B. Simosyrphus grandicornis (Macquart, 1842), ♂ (ZFMK-DIP-00019736), metacoxa and metatrochanter. C–E. Allograpta jacqui Mengual & Ramage sp. nov., holotype ♂ (ZFMK-DIP-00026906). C. Lateral view. D. Dorsal view. E. Frontal view. F–G. Melanostoma polynesiotes Mengual & Ramage sp. nov., paratype, ♂ (ZFMK-DIP-00026902). F. Dorsolateral view. G. Lateral view. Scale bars = 0.5 mm.

Fig. 8. A, C. Melanostoma apicale Bigot, 1884, ♀ (ZFMK-DIP-00019781). A. Posterior view. C. Head, frontal view. B. Melanostoma univittatum (Wiedemann, 1824), ♀ (ZFMK-DIP-00019740), head, frontal view. D–F. Allograpta jacqui Mengual & Ramage sp. nov., holotype, ♂ (ZFMK-DIP-00019707), genitalia. D. Epandrium with surstylus and cercus, lateral view. E. Hypandrium, lateral view. F. Hypandrium, ventral view. Scale bars: A–C = 1 mm; D–F = 0.5 mm.