30 Dorset Street, Blandford Forum, Dorset DT11 7RF, U.K.. ABSTRACT. A new genus and species, Hybomyia oliueri, (Empididae, Empidinae) is described.
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A new genus of Empidinae (Diptera: Empididae) from New Zealand ADRIANR. PLANT 30 Dorset Street, Blandford Forum, Dorset DT11 7RF, U.K.
ABSTRACT A new genus and species, Hybomyia oliueri, (Empididae, Empidinae) is described from specimens collected in the North Island, New Zealand. Keywords: Hybomyia oliveri, Diptera, Empididae, Empidinae, new genus, new species, New Zealand INTRODUCTION Ten genera of Empidinae have been described from the New Zealand region by Miller (1923), Collin (1928), Malloch (1931) and Smith (1964). Since these older works, knowledge of the taxonomy of the Empididae has advanced such that at least one of these genera (Oreogeton Schiner) warrants inclusion in a new subfamily, Oreogetoninae (Chvda 1976, 1983) while the generic assignments of others (e.g. Empimorpha Coquillet) require critical appraisal. Forms allied with Hilara Meigen account for more than 80% of the Empidinae described from New Zealand whereas Empis L. and Rhamphomyia Meigen, which are major components of the northern hemisphere fauna, are poorly represented. Closer affinities exist between the Empidinae of southern South America and New Zealand and the distribution of EmpidadeIpha Collin, which occurs in both Chile and New Zealand, suggests that it is a relict Gondwanan genus originating on the southern supercontinent during the Jurassic or lower Cretaceous period (Plant 1991). Gynatoma Collin is apparently endemic to New Zealand and this paper describes a second endemic empidinine genus, Hybomyia n. gen., from the North Island of New Zealand; it is characterized by unusually reduced venation and poorly developed axillary lobes of the wings.
DESCRIPTIONS Hybomyia n.gen. Length: small, 2.0 mm Head: globular, eyes prominent, occupying much of head; upper facets slightly enlarged in male, not conspicuously larger than lower facets in female. Male holoptic, eyes closely approximated on frons, diverging on face so as to accomodate mouth opening (Fig. 1). Female dichoptic, with frons parallel-sided and rather more widely separated than on face (Fig. 2). Both sexes with a few minute hairs on frons; ocellar triangle prominent, protuberant, with a group of fine forwardly directed bristles (not shown in Fig. 1 or Fig. 2). Occiput convex. Vertical bristles contiguous with, and apparently undifferentiated from, a row of occipital bristles which runs from the vertex around occiput immediately posterior of eye-margin. Lower occiput with scattered fine bristles. Proboscis shorter than head is high, directed slightly forwards; tip pointed and highly sclerotized. Palpi with minute hairs at tip and about 3 strong bristles ventrally. Antennae (Fig. 3) with basal two segments short and with fine bristles terminally; third segment pilose, narrowed apically; arista with basal article and style as wide as tip of third segment but terminating in a fine bristle. Thorax: arched; prosternum consisting of a single plate occupying the whole area between front coxae, without bristles. Mesonoturn strongly convex anteriorly but rather more flattened posteriorly where there is a slight median depression. Dorsocentral bristles uniserial; acrostichals consisting of two widely separated rows of short bristles, each row being virtually uniserial or very slightly biserial. One large and one small notopleural,
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Figs 1-7: liybomyia oliveri n.sp. 1, male head, anterior aspect; 2, female head, anterior aspect; 3, antenna; 4, wing; 5-7, male genitalia- 5, side lamella; 6,ventral lamellae: 7, dorsal lamellae.
one postalar, and one supraalar bristle; a line of fine bristles between notopleural depression and the supraalar bristle. Metapleurae bare, without a fan of bristles; humeri with a few hairs but not bearing strong bristles. A pair of strong bristles on prothoracic "collar". Posterior margin of scutellum with a pair each of strong (inner) and weaker (outer) bristles. Legs: simple, without obvious raptorial modifications and without conspicuously swollen segments in either sex. Generally rather short-haired but a ventral row of hairs on femora is outstanding and conspizuous on anterior and posterior femora (especially so in the male where the hairs are as long as femur is wide). A comb of tiny bristles behind posterior tibia at tip. Tarsi with fourth segment obviously shorter than segments three and five. Wings (Fig. 4): Axillary lobe weakly developed and axillary excision very obtuse. Costa running around margin to just beyond end of cubital vein. Mediastinal vein fading out before costa. Subcostal vein reaching costa well beyond level of end of first basal cell. Discal cell absent. All veins unforked with radial vein merging with costa well over 0.5 from base of wing. Anal cell shorter than first or second basal cells; postical vein closing anal cell strongly recurrent, forming virtually no angle with anal vein. Track of axillary and anal vein beyond end of anal cell virtually indistinguishable from wing membrane.
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Abdomen: Cylindrical, rather weakly bristled. Male with hypopygium unrotated, symmetrical, of a type similar to that found in local Hilara spp, with ventral lamella somewhat keel-shaped and produced apically (Fig. 6) to form an elongate process into which the aedeagus is apparently located. Side lamella (Fig. 5) with a narrow finger-like projection dorsally. Dorsal lamellae (Fig. 7) connected anteriorly. Female abdomen with a pair of short and weakly bristled apical papillae. Included species
Hybomyia oliueri n.sp. (Figs 1-7): Length 2.0mm. Head with eyes red, antennae brown, occiput black. Thorax rather paler, brownish-black, tending to reddish-brown particularly on pleurae. Legs brownish-yellow with apical 0.6 of all femora and apical tarsal segments slightly darker. Abdomen brown with posterior margins of all tergites paler and rather less strongly sclerotized. Male genitalia as in Figs 5-7. Description otherwise as under generic diagnosis. Material examined New Zealand, WO, N.Is., Malaise trap by Wainui Stream, Mt Karioi, Holotype: 0 , Raglan, 22-31 .iii. 1986, H.A.Oliver. Paratypes: 1 0 , same data as holotype. 1 0 , 6 Q Q , same data as holotype but date of capture given as May 1987. The holotype, one male paratype and all female paratypes are deposited in the NZ Arthropod Collection, Mt Albert Research Centre, Auckland. One male and one female paratype are deposited in the collections of the National Museum of Wales, Cathays Park, Cardiff, Wales, U.K. Additional material: 17 00 , 28 Q Q , same data as holotype but various dates from late February- early June, 1986, 1987. 1 Q , Pukerimu Reserve, Tokoroa, T O , 20.ii. 1988, A.R.Plant, swept.
Remarks Although Hybomyia n.gen. is probably allied with the Hilara group of genera, it is very distictive and unusual amongst the Empidinae. The poor development of the axillary angle in the wing, combined with absence of discal cell and all veins running to the wing margin without forking readily distinguish this genus from all other Empidinae. The holoptic condition of the male suggests a relationship with Gynotoma. Hybomyia is provisionally placed in the Hilarini but the affinities with Gynotoma suggest that a Gondwanan complex of genera may exist in the southern hemisphere. A phylogenetic analysis of Hybomyia and related genera may provide a better understanding of their systematic position.
Biology and ecology The type locality for the only known species is an area of mixed forest with regenerating understorey close to a small stream. The emergence period extends from late summer into autumn. Nothing is known of the life history but the mouth parts of the adult are seemingly adapted for a predatory habit. Sexual dimorphism of the eyes, in which the males are holoptic and have the upper ommatidia enlarged, suggests that Hybomyia (like many other Empidinae) indulge in epigamic swarming activity.
ACKNOWLEDGEMENTS I would like to thank Hugh Oliver for providing most of the specimens on which this study is based. His support, enthusiasm and friendship are gratefully acknowledged. Milan Chvda, Bradley Sinclair and Hans Ulrich are gratefully acknowledged for examining specimens and commenting on an earlier draft of this paper.
REFERENCES Collin, J . E . , 1928: New Zealand Empididae. London, British Museum (Natural History), 1lOpp. Chvhla, M., 1976: Swarming mating and feeding habits in Empididae (Diptera), and their significance in evolution of the family. Acta entomologica bohemoslovaca 78: 353-366.
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Chvdla, M., 1983: Empidoidea (Diptera) of Fennoscandia and Denmark 11, General Part, Families
Hybotidae, Atelestidae and Microphoridae. Fauna entomologica scandinavica 12, 279 pp. Malloch, J.R., 1931: Notes on New Zealand Empididae (Diptera). Records ofthe Canterbury Museum 4: 423-429. Miller, D., 1923: Material for a mo ograph on the Diptera fauna of New Zealand: Part I11 family Empididae. Transactions of the w Zealand Institute 54: 437- 464. Plant, A.R., 1991: A revision of th genus Ceratomerus (Diptera: Empididae: Ceratomerinae) of
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New Zealand. Journal of natural history 25: 1313-1330. Smith, K.G.V., 1964: Insects of Campbell Island. Diptera: Empididae. Pacific insects mono~raph 7: 325-328
