Hardy, D. Elmo

Kaneshiro, K.Y.

Proceedings of the Hawaiian Entomological Society

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Vol. XXII, No. 1, August, 1975 51Studies in Hawaiian Drosophila, Modified Mouthparts SpeciesNo. 1: Mitchelli Subgroup1D. Elmo Hardy and K. Y. KaneshiroUNIVERSITY OF HAWAII, HONOLULU, HAWAIIA large number of Hawaiian Drosophila species have the mouthpartsof the male variously modified for grasping the female's genital area during courtship. These modifications consist of dense hairs, bristles, orprocesses on the lobes of the labella, or a sclerotization of the apicalmargin of the labellum into a heavy black rim (Carson, et al., 1970:453,fig. 4b; Spieth, 1966:281-288). Only preliminary studies of these flies havebeen done to date (Hardy, 1965). The species are known to breed in awide assortment of media, such as rotting leaves, stems, flowers, fruits ofnative plants, and in fungi (Heed, 1968:389) and their nutritional andsubstrate requirements are at present poorly understood. The majoremphasis in the studies of Hawaiian drosophilids to date has been on thepicture-winged species of Drosophila. Since field and laboratory technicshave been worked out for dealing with these species, most of them canbe readily cultured under laboratory conditions and are therefore idealfor evolution and genetic studies. By comparison the modified mouthparts and other large groups of species have been almost totally neglectedand it is now necessary that attention be given to these rather poorlyknown groups. A detailed investigation of the ecology and nutritionalrequirements of these species is obviously necessary as there has beenlittle success in maintaining modified mouthpart species in laboratorycultures. It has been mainly through the efforts and perseverance of MissKathleen Resch, University of Texas, that a number of species are nowbeing reared successfully in artificial media. J. S. Yoon, K. Resch, andM. R. Wheeler (1972a and 1972b) have published preliminary paperson the cytological and genetic relationships, including polytene chromosomes and metaphase karyotypes, among the Drosophila having modifiedmouthparts. The present paper is to clarify the taxonomy in the mitchelli("hystricosa") subgroup.The Mitchelli SubgroupMembers of this subgroup are characterized by having prominentblack spines or reddish brown bristles (fig. 4) on the labellum of themale and the development and arrangement of these spines seem to bethe best diagnostic features for separating species. Also the front basitarsushas numerous long anterodorsal cilia extending entire length, arrangedin two or three irregular rows and the posterior surface of front tibia is1 Published with the approval of the Director of the Hawaii Agricultural ExperimentStation as Journal series no. 1736.52 Proceedings, Hawaiian Entomological Societydensely covered with short, erect cilia (asketostoma Hardy is an exception, see discussion below) . The thorax and abdomen are entirely brownto black in ground color and usually the femora are brown to blackish.The palpi are thickly setose and the apical bristle is rather small, usuallynot over two times longer than other setae.Because of the strong black spines on the labellum (fig. 1) and thelong cilia on the basitarsus, asketostoma Hardy from Maui would fithere. The front tibiae are not ciliated, however, and the flies look quitedifferent, are densely gray pollinose, usually with brown pollinose markings on mesonotum. The aristae are more sparsely haired, the oral vi-brissae are much stronger and three rather prominent pairs of dorso-central bristles are developed. It is questionable whether or not thisspecies belongs in the mitcheUi subgroup but these seem to show relationship. Further studies are needed to determine the true position ofasketostoma.Yoon, et al. studied three species of this subgroup: biseriata Hardy,hystricosa Hardy and Kaneshiro and "mitchelli-like" (equals nigrocirrusHardy) . They discussed in detail the metaphase chromosome configurations and gave an analysis of polytene chromosomes of these three species.Interspecific hybridization studies demonstrated that all hybrid F-l maleswere sterile.Key to Species1. Dorsum of thorax and abdomen subshining, lightly pollinose, thepollen not obscuring the ground color. Crossvein not infuscated. Fronttibia of male with dense, erect cilia over posterior surface 2Entire thorax and upper half of front densely gray pollinose, obscuringground color. Mesonotum often marked with brown pollen. Crossveinr-m infuscated. Front tibia lacking erect cilia on posterior surface.Labellum as in figure 1. Maui asketostoma Hardy2. Wings with upper apical portion brown 3Wings evenly infuscated, lacking distinct brown markings 43. Five thick black spines on labellum arranged in two sets (figure 2).Femora brown. Hawaii mitcheUi HardyOnly three strong spines in one set (figure 3) . Legs yellow. Hawaiinigrocirrus Hardy4. Only two strong humeral bristles. With heavy black spines on labellum as in figures 5 and 6 and not with a row of erect cilia on posteriorsurface of front tarsus 5Three strong numerals; armature of labellum made up of reddishbrown bristles, the uppermost pair rather spine-like (fig. 4) ; fronttarsus with a row of erect posterior cilia, six on basitarsus. MauLn. sp.5. Spines of labellum arranged in one set of four, each spine bifid oninner surface (fig. 6) 6Spines arranged as in figure 5, with three upper spines close togetherVol. XXII, No. 1, August, 1975 53\fig. 2fig. 3 fig.4fig.7Labellae of mouthparts: fig. 1. Drosopliila nsketostoma Hardy; fig. 2, mitchelli Hardy;fig. 3, nigrocirrus Hardy; fig. 4, nsp. Maui; fig. 5, hystricosa Hardy and Kaneshiro;fig. 6, biseriata Hardy; fig. 7, furvifacies Hardy.54 . Proceedings, Hawaiian Entomological Societyand a large, well spaced, lower spine which curves at about right angle.Maui hystricosa Hardy and Kaneshiro6. Legs entirely yellow. Labellum truncate below spines, shaped as infigure 6. Oahu biseriata HardyFemora dark colored, brown to blackish. Labellum rather stronglyproduced beyond spines as in figure 7. Kauai furvifacies HardyDrosophila nigrocirrus Hardy (fig. 3)Drosophila nigrocirrus Hardy, 1965, Insects of Hawaii 12:392, figs. 153a-d.This species was not correctly associated in the original description.It fits in the mitchelli complex and closely resembles that species. It isdifferentiated by the ciliation of front legs of male and the armature ofthe male labellum (figs. 2 and 3). Only one set of strong black spines isdeveloped on the labellum. The longest cilia of the front basitarsus aresubequal to the length of that tarsomere and 11-15 cilia are arranged intwo irregular rows over its entire length. D. mitchelli has the basal ciliaabout equal in length to the basitarsus and has 18-20 long hairs arrangeddown anterodorsal surface arranged in three incomplete rows. The setaeon the posterior surface of the front tibia are shorter, much less conspicuous than in mitchelli, not much longer than the recumbent setae overthe remaining portions of the tibia, and less than half as long as preapicaldorsal bristle. In mitchelli the posterior surface is densely covered withlong conspicuous erect setae; these are more than two times longer thanrecumbant setae and two-thirds to three-fourths as long as preapical dorsalbristle. No host information is available to date.The metaphase chromosome configuration, polytene chromosome analysis, and hybridization studies have been discussed by Yoon, et al. underthe name "mitchelli-like." They made comparisons with two other speciesof this subgroup, hystricosa Hardy and Kaneshiro and biseriata Hardy,but did not have an opportunity to make comparisons with mitchelli.This species is widespread over the Island of Hawaii: collected at numerous localities on the slopes of Mauna Loa, Mauna Kea, Hualalai andthe Kohala Mts.Drosophila n. sp. (fig. 4)One male specimen on hand from Waikamoi, Maui, July 8, 1964 (W.B. Heed) fits in the mitchelli complex because of the strong bristles onthe labellum of male and by having abundant long cilia over the dorsalsurface of the front tarsus. Further specimens will be needed before it canbe described. It is differentiated from other members of this subgroup bythe arrangement and development of the bristles on the labellum; onlythe uppermost pair are thickened spine-like (fig. 4), and the bristles aredark reddish brown rather than black. It also differs by having threestrong humeral bristles and by having a row of moderately long erectcilia down posterior surface of front tarsus. The wings are evenly in-Vol. XXII, No. 1, August, 1975 55fuscated, lacking brown markings, the thorax is entirely dark brown toblackish and the femora are entirely brown.REFERENCES CITEDCarson. H. L.. D. E. Hardy, H. T. Spieth and W. S. Stone. 1970. The evolutionarybiology of the Hawaiian Drosophilidae. In Essays in Evolution and Genetics, a suppl.to Evolutionary Biology. Appleton-Century-Crafts, New York. pp. 437-543.Hardy, D. E., 1965. Diptera: Cyclorrhapha 11, Series Schizophora, Section Acalypterae1, Family Drosophilidae. Insects of Hawaii 12: 814 pp.Heed, W. B. 1968. Ecology of the Hawaiian Drosophilidae. Univ. Texas Publ. 6818:387-419.Spieth, H. T., 1966. Courtship in Hawaiian Drosophilidae. Univ. Texas Publ. 6615:245-313.Yoon, J. S., K. Resch and M. R. Wheeler, 1972a. Cytogenetic relationships in HawaiianDrosophila I. The Drosophila 'hystricosa subgroup of the modified mouthpartsspecies group. Univ. Texas Publ. 7213: 179-199.Yoon, J. S., K. Resch and M. R. Wheeler, 19721). Cytogenetic relationships in HawaiianDrosophila II. The Drosophila mimica subgroup of the modified mouthparts speciesgroup. Univ. Texas Publ. 7213: 201-212.

Studies in Hawaiian Drosophila, Modified Mouthparts Species No. 1: Mitchelli Subgroup

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Studies in Hawaiian Drosophila, Modified Mouthparts Species No. 1: Mitchelli Subgroup

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