Orseolia javanica Kieffer & Docters van Leeuwen-Reijnvaan

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 : 52

Orseolia javanica Kieffer & Docters van Leeuwen-Reijnvaan

[ Figs 29 a–g]

Orseolia javanica Kieffer & DvLR, 1910: 125 ; Gagné (1985: 145), revision.

Type series. Syntypes, male(s) and female(s), were reared from Imperata cylindrica Beauv. (L.) P.Beauv. ( Poaceae ) in Salatiga, Java in or before 1909. The types are likely lost. Gagné (1985) examined 2 specimens, possibly of this species, reared from I. cylindrica in Bogor , Java, 16-iv-1973, and deposited in BMNH.

Description. Relevant characters from Kieffer & DvLR (1910) are given here followed by Gagné’s (1985) comments on the BMNH specimens (see Remarks). Adult. Size: male 4 mm, female 6 mm. Palpus 4-segmented or 3-segmented in which case last segment made up of two fused segments.

Male. Terminalia [ Fig. 29b ]: generally agrees with Bogor specimens illustrated by Gagné [ Fig. 29g ].

Female. Flagellomeres cylindrical, circumfila positioned in distal 2/3 of segment, consisting of some five transverse bands connected by longitudinal bands [ Figs 29d, e ].

Pupa, larva unknown.

Remarks. The BMNH specimens fit the original description of O. javanica in palpi, male flagellomeres and male terminalia [ Fig. 29g ] but differ in the female circumfila not being reticulate [ Fig. 29f ], a difference which cannot be resolved here. Felt (1917) identified Indian specimens from the same host plant as O. javanica , but the male terminalia as he described them have a short and much broader hypoproct exceeded in length by the aedeagus and thus probably represent a different species ( Gagné 1985 ).

DNA. Purnama Hidayat and Ayu Lestari, IPB University, sequenced COI of one adult specimen of O. javanica from Cianjur, Java, and two of O. oryzae from Bogor and Cianjur – the O. oryzae sequences showed an intraspecific similarity of 99.58% while the interspecific similarity of each of them to O. javanica was 90.31% (unpublished, pers. comm. 8-iv-2019; we compared these three, 717bp-long sequences, in GenBank’s MegaBlast 8-iv-2019). The low level of the interspecific similarity suggests that the two species are indeed discrete. Biology of the population which included the sequenced adult specimen of O. javanica was described in Hidayat et al. (2020a).

Biology. The leaf gall on cogon grass I. cylindrica was described in detail by DvLR & DvL (1926, gall No 60, Fig. II-5 [ Fig. 29a ]) and DvLR & DvL (1910a). The first stage of gall development while larvae are growing is superficially not obvious, but after pupation occurs the gall emerges from the center of the surrounding leaves and develops into a long, often curved, tube which is pointed at the tip. The galls are 4–20 cm long and about 3 mm in diameter, mostly red, seldom white. It is a common and conspicuous gall. The larva lives within a chamber that takes up the whole length of a gall. Pupation takes place at the bottom of the chamber after which the pupa then migrates to the upper part of the gall. Following adult emergence, the pupal exuviae remain attached to the emergence hole. Cogon grass is a weed in several countries of Asia, Africa and USA ( Overholt et al. 2016). The search for a host-specific pathogen triggered an interest in biology of O. javanica , which has been studied extensively ( Loan et al. 2002; Syah & Hidayat 2019; Arini et al. 2017; Hidayat et al. 2020a).

Geographical distribution. This species occurs in West and Central Java (DvLR & DvL 1926; Loan et al. 2002; Hidayat et al. 2020b).

Figures

FIGURES 29a–g. Orseolia javanica: a, gall on Imperata cylindrica (arrow indicates one of two galls; Fig. II-5 of DvLR & DvL (1926)); b, male terminalia; c, 12th male flagellomere; d, 3rd female flagellomere; e, 12th female flagellomere; f, 3rd female flagellomere; g, male terminalia (dorsal). Figs b–e from Kieffer & DvLR (1910) depicting types (now lost), Figs. f, g from Gagné (1985) of specimens in BMNH.