Dirioxa pornia
Common name
Island fruit fly, boatman fly, South Sea flyDescription
Dirioxa pornia is not the only species in its genus, but it is the only species of Dirioxa with available larval morphological data, so the diagnosis (taken from Carroll et al. 2006), contains both genus- and species-level characters. It can be distinguished from other fruit flies by the following specific characteristics for the third instar:
Body. Larvae medium-sized. Body length 5.5–8.5mm; slender, elongate, tapering anteriorly, or stout, elongate, tapering anteriorly. Integument unsclerotized, entirely whitish to yellowish.
Head. Head of normal shape; cephalic lobes well developed, or moderately developed. Antenna 2-segmented. Stomal organ: primary lobe small, round; number of peg sensilla one (small); peg sensilla unbranched; other peg-sensilla-like structures absent. Stomal region: secondary lobes present, medial ones elongate, like oral ridges (5–6, long, resembling small oral ridges); margins of secondary lobes more than one lobe with serrate margins; sclerotized stomal guards absent. Oral ridges present; number of oral ridges 13–18 (very long); margins scalloped (long, parallel sided, bluntly rounded teeth;deep). Accessory plates present (long, interlocking with outer edges of oral ridges); number of accessory plates 10–11; margins serrated (deeply serrated). Elongate, finger-like lobes arising above mandibles absent. Median oral lobe absent or not protruding (bilobed, but not like P. poeciloptera). Labium broad.
Cephalopharyngeal skeleton. Mandibles: subapical teeth absent; base elongate, forming a more oblique angle. Parastomal bars elongate, free from hypopharyngeal sclerite. Dental sclerites present, posterior to mandibles.
Anterior spiracles. Anterior spiracle concave medially, appearing bilobed (broad, fan-shaped). Anterior spiracular tubules 9–13; in a single uniform row, or in a single irregular row.
Spinules and creeping welts. Dorsal spinules on segments T1.
Caudal segment (a8) and anal lobes. Ventral caudal sensilla absent or visible only with great difficulty, or obvious, not on a papilla or tubercle. Anal lobes plainly visible, but not protuberant; bifid ("unequally bilobed").
Posterior spiracles. Posterior spiracular area not distinctly set off from caudal segment. Posterior spiracles: slits 2.5x longer than wide (about). Dorsal spiracular processes with numerous trunks arising from a short or semicircular base (long processes). Number of dorsal spiracular processes 10–15. Number of ventral spiracular processes 10–15. Number of lateral spiracular processes 6–9. Area between posterior spiracles smooth.
Host plants
| Family | Genus |
| Anacardiaceae | Mangifera |
| Ebenaceae | Diospyros |
| Moraceae | Morus |
| Myrtaceae | Feijoa |
| Passifloraceae | Passiflora |
| Rosaceae | Cydonia, Malus, Prunus, Pyrus |
| Rutaceae | Citrus, Poncirus |
| Sapotaceae | Chrysophyllum, Planchonella, Sideroxylon |
Part of plant attacked: fruit.
Biogeographic region and distribution
AustralasianAustralia (n. Qld. to e. cent. NSW), New Caledonia; New Zealand, Fiji, American Samoa, French Polynesia?
Adult taxonomy
Dirioxa pornia (Walker)Trypeta pornia Walker 1849: 1039.—Australia. New South Wales: Port Stephen [Port Stephens]. LT ♀ BMNH. Lectotype designation by inference of holotype by Hardy 1959: 219.
Trypeta musae Froggatt 1899: 501.—New Hebrides [Vanuatu; error, Australia. Queensland]. STANSWA.Type data (Tryon 1927: 216, Permkam and Hancock 1995: 1085).
Rioxa confusa Hardy 1951: 183.—Australia. Queensland: Atherton Tableland. HT ♂ USNM.
References
Carroll, L. E., A. L. Norrbom, M. J. Dallwitz, and F. C. Thompson. 2004 onwards. Pest fruit flies of the world – larvae. Version: 8th December 2006. http://delta-intkey.com.
White, I. M., and M. M. Elson-Harris. 1992. Fruit flies of economic significance: their identification and bionomics. CAB International; Wallingford, UK. 601 p.
