A New Species of Docosia Winnertz Fungus Gnat (Diptera: Mycetophilidae) Author(S) :Stephen W
Total Page：16
File Type：pdf, Size：1020Kb
A New Species of Docosia Winnertz Fungus Gnat (Diptera: Mycetophilidae) Author(s) :Stephen W. Taber Source: Southwestern Entomologist, 36(4):451-464. 2011. Published By: Society of Southwestern Entomologists DOI: URL: http://www.bioone.org/doi/full/10.3958/059.036.0407 BioOne (www.bioone.org) is a a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. VOL. 36, NO. 4 SOUTHWESTERN ENTOMOLOGIST DEC. 2011 A New Species of Docosia Winnertz Fungus Gnat (Diptera: Mycetophilidae) Stephen W. Taber Biology Department, Saginaw Valley State University, 7400 Bay Road, University Center, MI 48710 Abstract. A new species of Docosia Winnertz fungus gnat was discovered in western Michigan. Males and females were collected in mid-spring in a Malaise trap in a paper birch-red maple-black cherry woods adjacent to a black ash swamp and cattail marsh. Docosia walpurga Taber resembles Docosia dichroa Loew but male terminalia and female coloration indicate a specific difference instead. A remarkable and yet-unidentified empidid fly that seems to mimic the fungus gnat was found with the new species. Introduction The mycetophilid genus Docosia Winnertz has been long-neglected in the Nearctic region, although in the Palearctic a revival of interest in this and in other fungus gnat genera has been ongoing for the last several decades (Laštovka 1974, .XULQD DQG âHYþtN ). While continuing a study of Boletina Staeger during which two new species were discovered, a small orange and black mycetophilid invited identification because of its attractive appearance that suggested wasp mimicry despite its small size. This fly belonging to the genus Docosia Winnertz proved to be a previously unknown species. Materials and Methods The type locality of the new Docosia species is a narrow ecotone between mostly deciduous second-growth forest and swamp known as “Oxford Swamp”, with GPS coordinates of 43.41° N, 85.44° W, in Manistee National Forest, 7 km east of Brohman, Newaygo County, MI. Forest trees include paper birch (Betula papyrifera Marshall), red maple (Acer rubrum L.), and black cherry (Prunus serotina Ehrhart), whereas the swamp trees are mostly black ash (Fraxinus nigra Marshall). Nearby is a marsh dominated by common cattail (Typha latifolia L.). The flies were collected with a large Malaise trap erected in March as soon as melting snow allowed access to the site, and specimens of the new species were retrieved thereafter on 7, 15, and 21 May, and on 4 June 2011. These adults included 173 males and 13 females. The holotype male was mounted dry and intact on a microscope slide and the allotype female was pointed dry on a pin, with additional paratype males and one paratype female also preserved dry in these ways. Other specimens were mounted dry on microscope slides in their entirety as well as both intact and dissected in polyvinyl alcohol (PVA) mounting medium, with and without clearing 451 overnight and sometimes longer in KOH. Cover slips were not used unless male genitalia were isolated on a slide because it often becomes important to reposition material for examination from different angles by applying additional mounting medium and waiting a few minutes for the previous application to reliquefy. A few males were preserved in formalin/alcohol/acetic acid/glycerine (FAAG), many others were frozen for future DNA analysis, and the same was done for a few females. Because no new species of Docosia have been discovered in the Nearctic in almost 75 years according to the list in Nomina Insecta Nearctica (1998), a recent summary of taxonomic activity (/DãWRYNDDQGâHYþtN), and a search through Biological Abstracts records from 2000 to 2011, the description follows examples provided for newly published Palearctic congeners instead (Kurina 2006; Laštovka DQG âHYþtN ; âHYþtN 2010; âHYþtN DQG /DãWRYND ; Kurina and âHYþtN ), while drawing upon the morphological terminology of the standard reference on Nearctic Diptera (Vockeroth 1981), and excluding certain characters that are either not normally used in identification, or are likely variable, or both. Figure references sometimes indicate dissected specimens although these illustrations are consistent with textual descriptions of type material. The photographs shown here were taken with stereoscopic and high-power compound microscopes (Olympus SZ40 Zoom and Olympus BH-2, respectively), equipped with a digital SPOT idea camera with software. Results Docosia walpurga Taber new species Diagnosis. The transparent basket-like subterminal process of the male gonostylus distinguished the new species from all those known to occur in the eastern United States. Male specimens of Docosia walpurga might be confused with those of Docosia dichroa Loew by reliance upon their similar orange and black abdominal coloration. However, the female D. walpurga shares that condition of an abdomen black at the tip and orange elsewhere, and so resembles the male of both species, whereas the female D. dichroa reportedly lacks black on the tip of the abdomen which is thus entirely orange (Loew 1870). Type Material. Holotype. Adult male, Manistee National Forest, 7 km east of Brohman, Newaygo Co., MI, 7 May 2011, S. W. Taber, Saginaw Valley State University Insect Collection, University Center, MI. Allotype. Adult female, 21 May 2011. Paratypes. 10 adult males and 4 adult females, all from the same locality on 15 May 2011. Total number of type specimens = 16. Description. Holotype. Adult male (Fig. 1). Total dried length = 3.3 mm. Head: black, palps orange, although some specimens have palps with mixtures of both black and orange, antennae black. Thorax: black with pale setae and blackish bristles, laterotergite bare; coxae orange, trochanters with several blackish spots, femora orange, tibiae and basitarsi light brownish, remainder of tarsomeres darker, increasing in intensity through 5th tarsomere which is blackish, tarsal claws with each of the two tips bifid, tibial spines yellow-brown, mesotibia and metatibia bearing several small black spines near the base of a longer and paler tibial spine, protibia lacking these smaller, darker structures. Wing (Fig. 2): length 3.7 mm, membrane hyaline, Sc intersects R1 approximately half the distance between h and Rs although commonly extending a little farther than halfway in other specimens, 452 Fig. 1. Male holotype of Docosia walpurga; length = 3.3 mm. Fig. 2. Wing of male Docosia walpurga; length = 3.4 mm. 453 r-m longer than but not quite twice as long as the faintly-colored Mp (petiole of M), although in some specimens r-m is much longer than that of the holotype, fork of Cu located posteriorly between fork of r-m/Mp and fork of M although often opposite to or even basal to the fork of r-m/Mp in other specimens, C continues past confluence with R4+5 by a distance between 1/4 and 1/3 the distance between that confluence and the terminus of M1; halteres orange. Abdomen: mostly orange but much of segment 6 and all segments posterior to 6 blackish (Fig. 3); tergite 9 strongly Fig. 3. Terminal abdominal segments of male Docosia walpurga. rounded in outline, with distinct apical notch (Fig. 4). Genitalia (Figs. 5-9) (illustrations from paratypes to retain holotype intact): posterior of hypopygium with median comb of black spines (Fig. 5); gonostylus tri-partite with a dorsal, median, and ventral lobe (Fig. 6), the dorsal lobe bearing a peculiar, largely transparent basket-shaped structure (Fig. 7), the median lobe a smooth blade, the ventral lobe with a row of black spines, the cercus black and strobilus-shaped with 10 rows of spines (Fig. 8), though in some specimens there appeared to be nine rows instead, aedeagus and parameres as illustrated (Fig. 9), aedeagus/paramere complex 0.32 mm in length, 0.23 mm in width. 454 Fig. 4. Tergite 9 of male Docosia walpurga, dorsal view. Fig. 5. Hypopygium of Docosia walpurga, posterior view with elements removed. 455 Fig. 6. Two gonostyli of Docosia walpurga; DL = dorsal lobe, ML = median lobe, VL = ventral lobe. Fig. 7. Dorsal lobe of gonostylus of Docosia walpurga. 456 Fig. 8. Cercus of male Docosia walpurga. Fig. 9. Docosia walpurga aedeagi in ventral, lateral, and dorsal view (left to right). 457 Female Allotype. Total dried length = 3.7 mm. Coloration, including the darkened tip of the abdomen, and wing (length = 3.9 mm), like that of the male but antennae much shorter. Terminalia evident as paired cerci (as shown for the paratype of Figs. 10, 11). Distribution. The new species is known only from the type locality in Manistee National Forest, 7 km east of Brohman, Newaygo County, MI. Remarks. Docosia walpurga will almost key out to Docosia dichroa using the three existing non-genitalic keys to the eastern U.S. species of this genus (Johannsen 1912, Fisher 1937, Shaw and Fisher 1952). However, remarkable contradictions exist between keys and accompanying text. The first of these keys requires that the abdomen, presumably of both genders, be reddish yellow (Johannsen 1912, p. 299). Yet on the same page, the male D. dichroa is said to have its last two segments and the hypopygium blackish instead, whereas the female abdomen is by implication devoid of blackish coloration.