Revision of the birch-associated genus Massalongia (Diptera, Cecidomyiidae), with description of a new species from Japan and a taxonomic key to worldwide species Author Elsayed, Ayman Khamis The Botanical Gardens, Graduate School of Science, The University of Tokyo, Tokyo 112 - 0001, Japan & Department of Applied Entomology, Faculty of Agriculture, Alexandria University, Alexandria, Egypt https://orcid.org/0000-0003-0110-543X ayman.khamis77@gmail.com Author Skuhrava, Marcela Bitovska 1227, Praha 4, Czech Republic Author Ohta, Kazuki Laboratory of Systems Ecology, Faculty of Agriculture, Saga University, Saga 840 - 8502, Japan & The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890 - 0065, Japan Author Yoshida, Satoshi Laboratory of Systems Ecology, Faculty of Agriculture, Saga University, Saga 840 - 8502, Japan Author Tokuda, Makoto Laboratory of Systems Ecology, Faculty of Agriculture, Saga University, Saga 840 - 8502, Japan & The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890 - 0065, Japan text ZooKeys 2020 958 1 27 http://dx.doi.org/10.3897/zookeys.958.54300 journal article http://dx.doi.org/10.3897/zookeys.958.54300 1313-2970-958-1 F1D6AF59839A419782766AAB6B3669D8 16CB5344BCCB5E41A5418561334B56A9 Massalongia betulifolia Harris, 1974 Description. Head (Figs 43-45 ). Eyes separated on vertex by diameter of 0.5-1.25 facets. Frons with 7-12 setae (n = 5). Mouthparts: labrum with 6-11 short setae (n = 5), hypopharynx pointed, covered with thick microtrichia; labellum with 5-8 stout setae (n = 4) laterally. Antenna: scape and pedicel with few ventral setae on basal third of segment. Thorax (Figs 46 , 47 ). Wing 2.8-3.0 mm long in males (n = 2), 3.1-3.2 mm in females (n = 2). Anepimeral setae 6-10 (n = 6). Figures 43-47. Massalongia betulifolia . 43 head 44 ventral view of mouthparts (hypopharynx is folded). 45 dorsal view of male flagellomere VIII 46 wing 47 tarsomere V and acromere. Scale bars: 50 µm . Female abdomen (Figs 48 , 49 ). Tergites I-VI bare posteromedially; tergite VII with entire posterior row of setae. Ovipositor: protrusible portion with, ca. 2 times as long as tergite VII, with dorsal sclerite almost along dorsal portion; cerci setose. Figures 48-49. Massalongia betulifolia. 48 terminal part of female abdomen (arrow indicate the dorsal sclerite on the protrusible portion) 49 protrusible portion of ovipositor. Scale bars: 50 µm . Male abdomen . Tergites I-VII as in female; tergite VIII with few setae posteriorly. Terminalia (Figs 50 , 51 ): gonostylus with blunt denticles; cerci base with few setae; cerci with setae apically; hypoproct entire, narrowed at midlength; aedeagus shorter than cerci and hypoproct, cylindrical in dorsoventral view, wide basally in lateral view. Figures 50-51. Massalongia betulifolia . 50 male terminalia 51 ventral view of male hypoproct and aedeagus. Scale bars: 50 µm . Mature larva . Spatula absent. Terminal segment with short conical papillae ( Harris 1974 ). Pupa . Exuviae generally unpigmented. Antennal horns short ( Askew and Ruse 1974 ). Materials examined. Holotype (BMNH): 1♂, emerged on vi.1971, reared by J. Ruse from larva forming lamina and midrib blister galls on Betula pendula leaves, collected on x.1970 from Lindow Common, Cheshire, England. Paratypes : 4♂, 2♀, data same as for holotype. Distribution. Europe: England and Norway ( Gagne and Jaschhof 2017 ). Gall and life history. Massalongia betulifolia forms blister-like leaf galls on B. pendula and B. pubescens . Galls are formed usually between or on veins and are 2.5-3.0 mm wide and 5.0-6.0 mm long. Mature larvae drop to the ground to overwinter in cocoons. Adults emerge probably in May and June, and the galls can be found on the trees between June to October ( Harris 1974 ; Askew and Ruse 1974 ). Remarks. See Remarks under M. bachmaieri and M. nakamuratetsui .