DANIEL J. BICKEL Australian Museum, Sydney, NSW, Australia AUSTRALIAN, MELANESIAN AND MICRONESIAN ACROPSILUS MIK (DIPTERA: DOLICHOPODIDAE) Bickel, D. J, 1998. Australian, Melanesian, and Micronesian Acropsilus Mik (Diptera: Dolichopodidae).– Tijdschrift voor Entomologie 141: 1-17, figs. 1-21. [ 0040-7496]. Pub- lished 30 November 1998. The Australian, Melanesian, and Micronesian species of the genus Acropsilus Mik (Diptera: Dolichopodidae) are revised, and comprise eleven species: Acropsilus protractus Robinson (Solomon Islands, New Guinea, trop. Australia), and ten newly described species: A. albitibia (trop. Australia, New Guinea, Solomon Islands, Vanuatu), A. boharti (Irian Jaya, Solomon Is- lands) A. colmani ( Papua New Guinea), .A. kuranda (Queensland), A. malaita (Solomon Is- lands), A.. maprik (Papua New Guinea), A. nigricornis ( Solomon Islands, New Guinea, Queens- land), A.. putosa (Papua New Guinea), A. toma (Papua New Guinea), and A. udot (Micronesia: Truk). Some species are widely distributed in the Australasian tropics. Acropsilus is known only from the Old World, and is particularly rich and often abundant in moist tropical habitats. The entire genus is reviewed and redefined, and its phylogenetic posi- tion is discussed. Acropsilus is close to the Oriental genus Griphomyia and both genera are ten- tatively referred to the Peloropeodinae, a subfamily which requires redefinition. D.J. Bickel, Entomology Section, Australian Museum, 6 College Street, Sydney, 2000 Australia. E-mail: [email protected] Key words. – Diptera, Dolichopodidae, Acropsilus, Australia, Melanesia, Micronesia. The genus Acropsilus Mik comprises small-sized cited follows, and I thank the respective curators and dolichopodids. Although this genus initially appears support staff for the loan of specimens. to be rather nondescript, males of many species are Australian Museum, Sydney – M. Moulds; easily recognised by their elongate ivory-white cerci, Australian National Insect Collection, , which project out from a pedunculate hypopygium. Canberra – P. Cranston; Closer examination reveals a number of uniquely de- Bernice P. Bishop Museum, Honolulu – N. rived features which define the genus, and it has not Evenhuis; been readily placed in any of the traditional California Academy of Sciences, San Francisco dolichopodid subfamilies. – P. Arnaud; Previously six species had been described from wi- Carnegie Museum of Natural History, Pitts- dely separated locales in Europe, Tadzhikistan, West burgh – C. Young; Africa, the Seychelles, Sumatra and the Solomon Is- Biosystematics Research Institute, Agricul- lands. However, mass trapping methods, particularly ture Canada – J. Cumming; malaise and water traps, reveal the genus to be abun- National Museum of Wales, Cardiff. – J. dant and rich in the Indo-Malayan and Australasian Deeming; wet tropics. This paper considers the fauna of Aus- National Museum of Natural History, tralia, Melanesia and Micronesia, and treats eleven Smithsonian Institution, Washington, D. C species, ten of which are newly described. Two – F. C. Thompson; species, Acropsilus protractus and A. albitibia are wide- Zoological Museum, University of Copen- spread throughout Melanesia and northern Australia hagen – V. Michelsen. (figs. 20, 21). S. Bullock drew the genitalic figures. C. E. Dyte provided notes and specimens. P. Grootaert provided valuable comments on an early draft of the manu- M script. This research was supported by Australian Bi- This study is based on material from major world ological Resources Study (....) grants 85/0921 collections. Institutional abbreviations for material and 87/5905. 1 Downloaded from Brill.com10/02/2021 03:56:50AM via free access T E, 141, 1998 M clypeus; eye facets enlarged anteriorly and ventrally; clypeus usually with four setae: pair midcentral short- Drawings of genitalia were made with a camera lu- er setae, and pair of stronger distal setae (as in fig. 15); cida attached to a compound microscope. The left strong verticals and strong diverging ocellars present; lateral view of the hypopygium or male genital cap- postverticals represented by 4-5 short setae, continua- sule is illustrated for most species. In describing the tion of postorbitals; first flagellomere variably covered hypopygium, ‘dorsal’ and ‘ventral’ refer to morpho- in microtrichia; arista apical, and varies from arising logical position prior to genitalic rotation and flexion. on entire outer curvature of first flagellomere (fig. 15) Thus, in figures showing a lateral view of the hypopy- to arising within distinct indentation on the outer gium, the top of the page is morphologically ventral, curvature (fig. 4); arista with tiny pubescence, and while the bottom is dorsal. Morphological terminolo- longer than head height; proboscis (fig. 18) with 6 gy follows McAlpine (1981) and Cumming et al. geminate pseudotracheae; epipharyngeal armature (1995). Common features are listed in the introduc- with 2 prongs, and dorsal projection with is weakly tory descriptions and are not repeated in species de- sclerotised, and adjacent to which are three thorn-like scriptions unless needing clarification. Measurements setae. are in millimeters and were made on representative Thorax. – Usually rather short, and ratio of length/ dry specimens. Body length is measured from the width about 1.3 (fig. 17); proepisternum with some base of the antennae to the tip of the seventh abdom- short setae near posterior margin, and strong seta just inal segment. Wing length is the perpendicular dis- dorsad of CI; posterior slope of mesonotum slightly tance to the apex from an imaginary extension of the flattened but not depressed; ac absent; 5 dc present, humeral crossvein; wing width is measured from the comprising 4 stronger posterior dc which decrease in junction of R1 with the costa to the opposite side of size anteriorly, and with additional very weak dc an- the wing, perpendicular to the wing’s long axis. The teriormost, on anterior slope of thorax; 1 pa, 2 sa, an- CuAx ratio is the length of the m-cu crossvein/distal terior much shorter than posterior, 2 sr, 2 npl, 1 hm, section CuA. The position of features on elongate 1 pm present; posterior mesonotum with distinct structures such as leg segments are given as a fraction transverse fold just anteriad of scutellum; median of the total length, starting from the base. The relative scutellar seta strong, lateral present as weak tiny hair; lengths of the podomeres should be regarded as repre- postscutellum with distinct median longitudinal sentative ratios and not measurements. The ratios for mound. each leg are given in the following formula and punc- Legs. – Mostly yellow; CI and CII with short pale tuation: trochanter + femur; tibia; tarsomere 1/ 2/ 3/ anterior hairs; CII and CIII each with short lateral 4/ 5. seta; leg I usually without distinctive setation; FII The following abbreviations and terms are used: without distinct true subapical anterior seta, although – Male secondary sexual character(s), the non- sometimes some subapical setae many appear slightly genitalic characters found only on the male body; I, stronger; FII with subapical pv seta; TII with strong II, III: pro- , meso-, metathoracic legs; C, coxa; T, ad-pd pair at ¼, strong ad at ³⁄₅, and with strong ven- tibia; F, femur; ac, acrostichal setae; ad, anterodorsal; tral apical, and with coronet of short setae; FIII with- av, anteroventral; dc, dorsocentral setae; dv, dorso- out subapical anterior seta, but with weak subapical ventral; hm, postpronotal setae; np, notopleural setae; pv seta; TIII with short ad-pd pair at ¼, and often pa, postalar setae; pd, posterodorsal; pm, presutural with dorsal setae on distal half; male IIIt1 sometimes supra-alar setae; pv, posteroventral; sa, postsutural somewhat swollen with ventral row of hairs (). supra-alar setae; sr, presutural intra-alar setae; t, tar- Wing (fig. 16). – Membrane hyaline; R2+3 ends in ⁵⁄₆ sus; t1-5, tarsomeres 1 to 5. anterior margin at ; R4+5, just anterior to apex; R4+5 and M subparallel; M without flexion or “bosse alaire”; anal vein absent; anal angle weak; CuAx ratio S near 0.3. Abdomen. – Usually dark brown; tergal setae not Genus Acropsilus Mik strongly developed; male tergum 1 wide (fig. 17), and Acropsilus Mik (1878: 6). Type species: Chrysotus niger Loew distinctly wider than thorax, especially noticeable in 1869: 298, monotypy. dried specimens; hypopygium pedunculate (fig. 1); segment 7 prolonged with distinct elongated tergum Description and sternum separated by membrane; sternum 8 with Male. – Body length ranges from 1.0-2.3 mm, but distinctive inverted Y-shaped carina ; hypopygial fo- most species about 1.3-1.6. ramen left basolateral; hypandrium and aedeagus Head. – Dorsal postcranium flat to slightly con- both short and emerging at angle near base of epan- cave; male eyes distinctly separated by face and drium; hypandrium broad and apically upcurved, 2 Downloaded from Brill.com10/02/2021 03:56:50AM via free access B: Australasian Acropsilus (Dolichopodidae) and basally fused with epandrium; aedeagus rather Males of many species have bright ivory-white cer- short and slightly curved, and often with notched ci, which may function in sexual signalling. Here it phallus; ventral margin of epandrium with 2 epandri- should be noted that Acropsilus albitibia has ivory- al setae; epandrial lobe raised from ventral margin white tibiae I and II (), which possibly augment and externally overlapping digitiform surstylar arms; the function of the