452 Proc. Japan Acad., 51 (1975) [Vol. 51, 96. Definition of Coenomyitidae (Diptera). I Diagnoseso f the Family By Akira NAGATOMI Entomological Laboratory, Faculty of Agriculture, Kagoshima University (Comm. by Sajiro MAKINO, M. J. A., June 3, 1975) The purpose of this paper is to establish the definition of the Coenomyiidae. Hennig (1967) stated that "Fur die Coenomyiidae sind dagegen bisher keine abgeleiteten Merkmale angegeben worden", and Oldroyd (1969) wrote that ".. , a number of primitive genera, in various regions of the world, cannot satisfactorily be allocated to any of the larger families. The simplest solution is to assemble all these genera into one family, Coenomyiidae, while recognizing that this is not necessarily a natural unit." Nagatomi and Saigusa (1970) , who revised the Coenomyiidae of Japan, put the genera Glutops and Pseudoerinna into the Coenomyii- dae, while Tesky (1970a) treated Glutops as one of the Pelecorhyn- chidae and Krivosheina (1971) erected a new family Glutopidae for Glutops. 1t is shown in this series of papers that Bequaertomyia is noth- ing but a synonym of Pseudoerinna; Dialysis is a true member of Coenomyiidae ; and Glutops and Pseudoerinna (=Bequaertomyia) seem to be ancestral among the Rhagionidae. Bequaertomyia was diversely placed in the Tabanidae, Pelecorhynchidae, or Coenomyii- dae, and Dialysis was always placed in the Rhagionidae. It is concluded that the family Coenomyiidae consisting of the genera Coenomyia, Anacanthaspis, Art hropeas, Odontosabula (=Stratioleptis), and Dialysis (= Triptotricha) is homogeneous or monophyletic. This conclusion is based on the result of my study given below. The Coenomyiidae contain the five genera just mentioned and are characterized as follows : Head : (1) mid-lower face roughly triangular in shape, not swollen but flat, and plate-like, that is to say, with the margin more or less turned up and continued around below palpus and proboscis (Fig. 2) ; (2) level of mid-lower face lower than that of eye margin ; (3) eyes contiguous or nearly so in 3' and well separated in ? ; (4) front in becoming broader toward antenna but parallel sided in Dialysis ; (5) face in (as well as in c') becoming broader toward proboscis ; (6) 3rd antennal segment No. 6] Definition of Coenomyiidae (Diptera). I 453 Fig. 1. Head (from antero-lateral view) of Glutops itoi Nagatomi, (Rhagionidae) (proboscis and palpus are omitted) (M: mid- lower face). Fig. 2. Head (from anterior view) of Coenomyia basalis Matsumura, ~ (Coenomyiidae) (proboscis, palpus, antenna, and some of hairs are omitted) (M: mid-lower face). Fig. 3. Antenna (from outer view) of Dialysis iwatai Nagatomi, ci' (Coenomyiidae). Fig. 4. Antenna (from outer view) of Coenomyia basalis Matsumura, d' (Coenomyiidae). 454 A. NAGATOMI [Vol. 51, is annulated (8-segmented in principle) , porrect, and subulate in 4 genera (Fig. 4) or it is conical and with a long arista in Dialysis (Fig. 3) ; (7) palpus 1-segmented, cylindrical, pole-like, and with the dorsal margin not strongly curved downward but almost straight ; (8) proboscis not longer than face. Thorax : (9) in prothorax, basisternum separated from epister- num ; (10) metapleura (=laterotergite or pleurotergite) pilose ; (11) scutellum unarmed in Anacanthaspis, Arthropeas, and Dialysis, but with a pair of spine-like processes in Coenomyia and Odontosabula; (12) subscutellum is absent but in some species of Arthropeas (e, g. A. americana Loew) small one may be present. Leg : (13) tibial spurs 1: 2 : 2, but in some species of Dialysis (e.g. D. disparilis Bergroth and D. kesseli Hardy) fore basitarsus with 2 terminal spurs. Wing : (14) vein C entirely surrounding the wing ; (15) base of vein Rs situated distinctly before base of discal cell, and basal section of vein Rs not conspicuously shorter or sometimes longer than vein between subcostal- and 1st basal cell; (16) apex of vein R2+3 rather closely situated to that of vein R1; (17) 2nd submarginal cell includes wing tip, and apical portion of vein R4 is more or less curved upward ; (18) alula well developed (margin of alula strongly curved) ; (19) thoracic squama undeveloped. Abdomen: (20) sclerotized sternum 1 is well developed and its mid-posterior part is liable to protuberant and may have longer pile; (21) male genitalia : hypandrium absent or entirely confused with basistyle ; basistyle broad, short, and not strongly tapering toward apices ; mid-ventral part of basistyle with a membranous part (that is, transversely elongate "window" expressed by Steyskal, 1953) which appears to be absent in Dialysis, however ; dististyle longer than wide and not tapering toward apex ; epandrium wider than long and its lateral margin rounded ; cerci elongate ; (22) female genitalia : cerci 2-segmented and each segment longer than wide, segment 1 not dilated outward or downward, and in segment 2 apex rather rounded and not so broader than in base ; sternum 8 is large and strongly chitinous, and its mid-apical part is deeply incised but may not be so developed as a pair of fins ; (23) ovipositor including abdomonal segment 5. Hairs on body and leg: (24) Pile is not stiff. Dialysis is unusual among the known Coenomyiidae and differs from other genera by having the 3rd antennal segment conical and with a long arista (Fig. 3) and mid-ventral part of basistyle without a membranous part. One of the characters of the Coenomyiidae except for Dialysis No. 6] Definition of Coenomyiidae (Diptera). I 455 is the mesonotum strongly arched as seen in the suborder Nematocera but this feature is found also in the Chiromyzinae of Stratiomyidae and some genera of Rhagionidae, e, g. Glutops, Bolbomyia, Ptiolina, Spania, etc. Two features, the annulated antennal segment 3 and the strongly arched mesonotum, might be thought essential to the Coenomyiidae and this misled the position of Dialysis. The Coenomyiidae thus defined are at once separated from other related families besides the structure of d~ and genitalia by the characters (9), (13), (14), (15), (17), (23), etc, from the Stra- tiomyidae, by (1), (2), (3), (9), (13), (14), (16), (23), etc, from the Solvidae (=Xylomyidae), by (3), (5), (6), (14), (17), (18), (23), etc, from the Rachiceridae, by (3), (6), (7), (17), (18), (23), etc. from the Xylophagidae, by (13) , (15) and probably (1) , (2), (7) , etc. from the Pantophthalmidae which I have not seen, by (1), (2), (3), (7), (10), (16), (23), etc. from the Vermileonidae which will be proposed as a new family in the forthcoming paper, by (1), (2), (7), (10), (13), (16), (19), etc, from the Pelecorhynchidae, by (1), (2), etc. from the Rhagionidae and Athericidae (whose defini- tion was given by Stuckenberg, 1973), by (1), (2), (7), (13), (16), (19), etc. from the Tabanidae. Among the characters mentioned above, (1) is present in the Rachiceridae, Xylophagidae, and some of the Stratiomyidae, e. g. Clitellariinae, Pachygasterinae, the genera Actina, Allognosta, Chorisops, Exodontha of Beridinae (in Beris mid-lower face swollen) but is not found in the Pelecorhynchidae, Rhagionidae, Athericidae, and Tabanidae, although in Atherix ibis Fabricius (especially in a) and Atherix basilica Nagatomi (in d') the mid-lower face is nearly flat and its level is lower than that of eye margin being never "plate- like." The genitalia in both sexes will distinguish the Coenomyiidae from all other related families including the Rhagionidae, when the careful studies or comparisons are made. The larva is known only in Coenomyia and Arthropeas. Accord- ing to Krivosheina (1967 and 1971) the larval characters are in com- mon in several principal respects in these 2 genera. Further studies on the immature stages of Anacanthaspis, Odontosabula, and Dialysis will support their assignment to the Coenomyiidae. My papers, "Genera of Coenomyiidae" and "Genera excluded from Coenomyiidae" will be published shortly. Acknowledgment. I wish to express my sincere thanks again to the persons mentioned in the paper, Nagatomi and Saigusa (1970). Many thanks are also extend to Dr. I. M. Mackerras, CSIRO, Can- 456 A. NAGATOMI [Vol. 51, berra, for the gift of the specimens of Pelecorhynchus and to Dr. L. L. Pechuman, Cornell University, Ithaca and Dr. W. J. Turner, Washington State University, Pullman, for the loan of the specimens of Art hropeas and Bequaertomyia. I am also much indebted to Professor Emeritus S. Makino and Professor Emeritus C. Watanabe, Hokkaido University, Sapporo, for reading through this manuscript. References Hennig, W. (1967) : Die sogenannten „niederen Brachycera" im Baltischen Bernstein (Diptera: Fam. Xylophagidae, Xylomyidae, Rhagionidae, Tabanidae). Stutt. Beitr. z. Naturk., 174, 1-51. Krivosheina, N. P. (1967) : Comparative characteristics of the larva of Arthro- peas sibilica Loew (Diptera, Xylophagidae). Zool. Zhurnal, 46, 954-956 (in Russian). -- (1971) : The family Glutopidae, Fam, n. and its position in the system of Diptera Brachycera Orthorrhapha. Ent. Obozr., 50, 681-694 (in Russian). Nagatomi, A., and Saigusa, T. (1970) : The Coenomyiidae of Japan ( Diptera) . Mem. Fac. Agr. Kagoshima Univ., 7, 257-292. Oldroyd, H. (1969) : Handbooks for the identification of British insects. Diptera Brachycera, section (a) Tabanoidea and Asiloidea. 132 p. London. Steyskal, G. C. (1953) : A suggested classification of the lower Brachycerous Diptera. Ent. Soc. Amer. Ann., 46, 237-242. Stuckenberg, B. R. (1973) : The Athericidae, a new family in the lower Brachy- cera ( Diptera) . Ann. Natal Mus., 21, 649-673. Tesky, H. J. (1970a) : The immature stages and phyletic position of Glutops rossi ( Diptera : Pelecorhynchidae). Can. Ent., 102, 1130-1135..