Orseolia oryzae (Wood-Mason)

Kolesik, Peter & Gagné, Raymond J., 2020, A review of the gall midges (Diptera: Cecidomyiidae) of Indonesia: taxonomy, biology and adult key to genera, Zootaxa 4847 (1), pp. 1-82 : 55

Orseolia oryzae (Wood-Mason)

[ Figs 31 a–j]

Cecidomyia oryzae Riley, 1881: 149 , nomen nudum.

Cecidomyia oryzae Wood-Mason (in Cotes 1889: 103) .

Pachydiplosis oryzae (Wood-Mason): Felt (1921a: 16) , new combination.

Orseolia oryzae (Wood-Mason): Gagné (1973: 507) , new combination; Gagné (1985: 148), revision.

Material. Syntypes, female, pupae, pupal exuviae (originally deposited in the National Zoological Collection, Calcutta, India, now presumed lost ( Gagné 1985)), were collected and reared from rice at Kurruckpore , Munger , Bihar, India , x-1880. Previously Gagné (1985) examined specimens from India, China, Thailand and Indonesia .

Description. Both sexes, the pupa and larva were described in Harris & Gagné (1982) and further in Gagné (1985). Some of their drawings are reproduced here. Wing [ Fig. 31h ]: length 2.9–3.3 in male, 3.0– 4.1 in female. Palpus usually 4- but occasionally 3-segmented [ Fig. 31i ]. Tarsal claws as in Fig. 31g . Male flagellomeres as in Fig. 31c . Female flagellomeres [ Figs 31d, i, j ] cylindrical. Male terminalia [ Fig. 31b ]: gonostylus short, tapered, narrowest subapically, almost entirely setulose; hypoproct long, narrow, rounded apically; aedeagus narrow, tapered, conical apically, longer than hypoproct; cerci tapered caudally. Female tergum 10 with few to many lateral setae but absent mesally; cerci ovoid [ Fig. 31e ].

Remarks. The female 10 th tergite in O. oryzae has several lateral setae, that are more numerous in the Indian [ Fig. 31f ] than in the Indonesian population [ Fig. 31e ] ( Gagné 1985). The difference between the Indian and the South East Asian (Indonesian and Thai) populations is evident also in the COI sequence (see below) and it is possible that there are more than one species of Orseolia spp. feeding on rice in Asia. Orseolia oryzae , as defined currently, is the only Orseolia that feeds on rice ( Gagné 1985). It is morphologically similar to O. caulicola , O. difficilis Gagné , O. eragrostisae (Mani) , O. paspali ( Gagné 1985) and O. similis (Mani) .

DNA. Fragments of several genes of O. oryzae have been sequenced, including the taxonomically important COI of which 13 sequences are available from Thailand (GenBank accession numbers KX447431 – KX447443 ) and two verified sequences from India ( KM888183 , KC506565 ) (GenBank, accessed 27-iii-2019). The pairwise difference in COI between the Indian (internal divergence of 0.37%) and the Thai (internal divergence of 0–3.25 %) sequences is 6.22–7.05%, suggesting an existence of two separate species (Janique et al. 2017). Our comparison of two unpublished Indonesian O. oryzae sequences (see more information under O. javanica ) (internal divergence of 0.42%) showed a difference of 0.91–3.57% to the Thailand population and 6.49–7.78% to the Indian population, suggesting that the Indonesian and Thai populations belong to the same species which is different to the nominal Indian species.

Biology. This species is a serious pest of rice Oryza sativa L. ( Poaceae ), causing a leaf sheath gall called a “silver shoot” [ Fig. 31a ] which emerges from the leaves and is white, 5–15 cm long and 2–3 mm in diameter (DvLR & DvL (1926, gall No 61).

Geographical distribution. The range comprises Pakistan, India, Nepal, Sri Lanka, Bangladesh, Myanmar, Thailand, Laos, Vietnam, Cambodia, Malaysia, Indonesia, China and the Philippines ( Plantwise Knowledge Bank 2019). In Indonesia, the last comprehensive report found O. oryzae to be common on all main islands (Java, Sumatra, Kalimantan, Sulawesi) except Maluku and Irian Jaya [now provinces of West Papua and Papua] ( Hidaka & Budiyanto 1984).

Figures

FIGURES 31a–j. Orseolia oryzae: a, gall on Oryza sativa in India (arrow indicates gall; photo from NICRA, 2011); b, male terminalia (dorsal); c, 3rd male flagellomere; d, 3rd female flagellomere; e, female 10th tergite and cerci (dorsolateral; arrow indicates pair of thick setae on cercus; Karawang, Java, Indonesia); f, female 10th tergite (Cuttack, Odisha, India); g, claw and empodium; h, wing; i, female head; j, female flagellomeres 3–12. Fig. b from Harris & Gagné (1982), Figs c–f from Gagné (1985).