A Systematic Study of Coenia and Paracoenia (Diptera: Ephydridae)

Great Basin Naturalist

Volume 35 Number 1 Article 8

3-31-1975

A systematic study of Coenia and Paracoenia (Diptera: Ephydridae)

Wayne N. Mathis Oregon State University, Corvallis, Oregon

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Recommended Citation Mathis, Wayne N. (1975) "A systematic study of Coenia and Paracoenia (Diptera: Ephydridae)," Great Basin Naturalist: Vol. 35 : No. 1 , Article 8. Available at: https://scholarsarchive.byu.edu/gbn/vol35/iss1/8

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. A SYSTEMATIC STUDY OF COENIA AND PARACOENIA (Diptera: Ephydridae)

Wayne N. Mathis^

iAbstract.— Shore flies of the genera Coenia Robineau-Desvoidy and Paracoenia Cresson are revised, resulting in the description of two new subgenera of Paracoenia, Calocoenia and Leptocoenia, and of four new species, Paracoenia ampla, P. calida, and P. wirthi from California, and Coenia alpina from Labrador, Canada. Biological information on P. turhida and P. calida is given and tlie known distribution for each species is presented. P. paurosoma is reported from the Palearctic Region for the first time based on specimens from Sweden; several new distribution records from North Amer- ica are also included. Characters of the male postabdomen are used, and the male genitalia of each species are illustrated. Keys or references to all known species of these genera are included.

Introduction and Review Naturhistorisches Museum, Wien, Cres- son (1930) reviewed the European species Shore flies of the ephydrid genera Co- of Coenia. He distinguished C. curvicauda enia Robineau-Desvoidy and Paracoenia from C. palustris and designated a lecto- Cresson are common and widely distribu- type for C. curvicauda. Cresson (1935) ted in the Holartic region. Typically, described a new genus, Paracoenia^ that flies of both genera are associated with included two new species, platypelta and semiaquatic or aquatic environments and fumosalis^ in addition to Coenia bisetosa many tolerate a diverse range of seem- and C. turbida, described previously from ingly inhospitable habitats. They are of- North America, and two European species, ten abundant around mineral or hot C. futnosa (Stenhammar) and C. beckeri springs, alkaline lakes, and marginal a- (Kuntze). C. curvicauda and C. palustris quatic areas where the water is highly were left in the geiuts Coenia. Sturtevant saline. This study was initiated to fur- and Wheeler described one additional ther the systematic knowledge of these species, C. paurosoma. in their review of tmique flies and to provide a basis for de- 1954. tailed biological investigations. Cresson delimited Paracoenia from A synoptic series on the North Amer- other genera based dif- ican Ephydridae was started by Ezra T. on comparative ferences noted in the dimensions of Cresson, >. (1942, 1944, 1946, 1949), he whose papers reviewed most Nearctic gen- the head, in the number of dorsocentral bristles (three in four in Para- era of the subfamilies Psilopinae, Noti- Coenia, presence {Paracoenia) philinae, and Parydrinae. His mitimely coenia), and in the well-defined death precluded the completion of this or absence {Coenia) of humeral bristles. specialists have con- series and left the synoptic study of the Most subfamily Ephydrinae largely unfinished tinued to recognize both Coenia and Para- c[S stud- imtil Sturtevant and Wheeler's review in coenia waWA genera. Dahl (1959) ied genitalia of both genera and 1954. This review was the last compre- the male hensive treatment of the genera considered suggested that the marked differences be- here. tween them supported Cresson's view. The also recognized Wirth Prior to Sturtevant and Wheeler's pa- two genera were by of American per, the American species of Coenia or (1965) in the catalog North Paracoenia had not been treated together. Diptera. Sturtevant and Wheeler, how- Coenia, relegating Coquillet (1902) and Curran (1927) de- ever, recognized only to subgeneric status. scribed the first Nearctic species, Coenia Paracoenia bisetosa and C. turhida respectively, and This revision is based primarily upon Johnson (1925) included C palustris (Fal- a comparative study of the male postabdo- len) in his list of Ephydridae from Massa- men and a reevaluation of previously rec- chusetts. Johnson's identification of the ognized characters. From these studies, I latter species as C. palustris is question- generally concur with Cresson's concept able, and Sturtevant and Wheeler include of Coenia and Paracoenia; however, I this citation under C. curvicauda Meigen. now recognize three subgenera in the lat- After studying the Ephydrinae in the ter genus, Paracoenia, Calocoenia, and

'Department of Entomology, Oregon State University, Con-allis, Oregon 97331

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66 GREAT BASIN NATURALIST Vol. 35, No. 1

Leptocoenia. The basis for these proposals Drs. John D. Lattin, Carol A. Musgrave, will be treated in greater detail in the Paul Oman, and Paul O. Ritcher, Oregon sections on ])hylogcny and under the ap- State University, for their technical and propriate generic discussions. Four new editorial assistance and for many stimu- s])ecies are described, three in Parncoenia lating discussions on systematics. The and one in Cocnia. stereoscan electron micrograph was taken by Mr. Alfred Soeldner, Oregon State Uni- Acknowledgments versity. Dr. Willis W. Wirth, USDA- USNM was also kind enough to review This study was initially suggested b}- this study. Dr. Stephen L. Wood while I was an un- dergraduate at Brighani Young University. Methods and Discussion of Characters Many of the preliminary observations were" completed then, although the stud}' All observations were made using a has since been expanded as new species stereomicroscope; a filar micrometer was were discovered and specimens were ex- used for the measurements. Morpholog- amined from a wider geographic area. I ical characters, especially those of the thank Dr. Wood for his encouragement male postabdomen, w^ere illustrated using and for sponsoring two summers of field an ocular grid. All illustrations were work. drawn to the same scale on mylar draft- Special thanks are extended to Dr. Paul ing film. Preparation of the male or fe- H. Arnaud. California Academy of Scien- male postabdomen for study involved its ces, to Dr. Willis W. Wirth, Systematic removal and heating in a 10 percent so- Entomology Laboratory, ARS, USDA-Na- dium hydroxide solution to remove ex- tional Museum of Natural History, Wash- traneous tissue. The abdomen was then ington, D.C., and to Mr. Guy E. Shewell, washed, further dissected, and compared. Canadian National Collection of Insects, For permanent storage the abdomens for their extensive cooperation and assist- were preserved in plastic microvials filled ance. with glycerin and attached to the appro- T^'pe specimens were borrowed from priate specimen. the Academy of Natural Sciences of Phil- During the course of the study, I ex- adelphia (Drs. David C. Rentz and Selw>n amined approximately 4,000 specimens, S. Roback); the National Museum of Na- including the type specimens of all but tural History (Dr. W. W. Wirth); and Cocnia curvicauda. and I did examine the Museum of Comparative Zoology European specimens of this species. The (Mrs. Janice C. Scott and Dr. John F. type specimens examined formed the basis Lawrence) for the species descriptions. purj)osefully In addition to the above, the following Species descriptions are institutions and curators kindly loaned brief; for the most part they summarize specimens, wdthout which this study could specific differences or additions not found not have been completed: LTniversity of in the more detailed generic descriptions. will differentiate the spec- Minnesota (Dr. Philip J. Clausen); Kent The diagnoses rec- State University (Dr. B. A. Foote); Uni- ies from similar taxa. For previously con- versity of California, Riverside (Dr. Saul ognized species, the descriptions also lain any newly acquired information for I. Frommer) ; Los Angeles County Mu- and seum of Natural History (Dr. Charles L. comparative purposes. Polymorphic Hogue); Iowa State University (Dr. Rob- polytypic variations are included under re- ert E. Lewis); Cornell University (Dr. marks. Characters considered in this study are L. L. Pechuman) ; University of Califor- quan- nia, Davis (Dr. R. 0. Schuster); Wash- ffom all bod}^ tagma and have been Ratio values are ington State University (Dr. William J. lifi(>d where appropriate. based on an average of ten specimens se- Turner) ; Florida State Collection of Ar- thropods (Dr. Howard V. Weems, Jr.); lected because of obvious size differences. and Brigham Young UniAorsity (Dr. Ste- Head.— Eye-to-cheek ratio. This is the phen L. Wood). Dr. Marshall R. Wheeler ratio of genal height to^ eye height. Meas- generously loaned specimens from his pri- urements are taken from the head in pro- vate collection. file. This ratio is a convenient character I also wish to gratefully acknowledge for some species groups. March 1975 MATHIS: AMERICAN EPHYDRIDAE 67

Width-to-height ratio. This ratio is cal- ies. Cresson (1930) mentioned that this culated as head height to head width; character is usually variable and is not measurements are made from a cephalic important as a key character. orientation. Costal vein ratio. This is the ratio of Eye-width-to-foce-length ratio. This distance along the coastal margin between ratio is hased on measurements from the Ri and R:,+,; to the distance between R2+3 head in profile and is calculated as face and Ro+i. All measurements are the maxi- length to eye width. imum straight-line distances. Height-to-length ratio. This is the ra- Mi+2 ratio. This is the ratio of the dis- tio of the height of the head in profile to tance of the Mi+o anterior to the posterior its length, measured from the most ante- cross vein to the distance posterior to the rior surface of the face to the posterior posterior cross vein. margin of the eye. Cresson first used Costal bristles. The presence or absence this character when describing Paracoenia. of costal bristles along the dorsal and/or Aristal -pectinations. The length of the ventral surface is diagnostic of some gen- pectinate branches on the dorsum of the era. Calocoenia is the only taxon of Scatel- arista is compared with the base width lini with prominent bristles on both sur- of the arista. This character is sometimes faces, a character found in many species difficult to use and is best seen in well- of Eph3drini. preserved specimens. Femoral comb. The femoral comb is a Interfoveal hump and marginal bristles. sexually dimorphic character restricted to

This character is correlated with the eye- the males of Paracoenia s. str. to-cheek ratio. It is the comparison of the Abdomen.— Male postabdomen. The hump height to the length of the bristles male genitalia previously have not been along the oral margin. Hump height is used as characters at the species or generic related to genal height. level; I have found them extremely use- Facial color. This character is subject ful at both levels. These characters are to considerable variation in many species, discussed more fully in the generic and especially species of Paracoenia, but it is specific descriptions. of some diagnostic value in others. The Female ventral receptacle. The shape species of Coenia and Calocoenia ha^e rel- of this structure seems to be of consider- atively constant facial color. able diagnostic value, especially at the Postocular bristles. The development generic level. of the dorsalmost postocular bristles is useful in distinguishing Paracoenia from Phylogeny and Classification Coenia. Both Coenia and Paracoenia belong to Thorax.— Acrostichal hairs. The ar- Scatellini as it is presently characterized. rangement and degree of development of The tarsal claws are curved and short, the acrostichal hairs have been overlooked and the pulvilli are developed normally. as a diagnostic character other than at The tribal concepts, however, have not the species level. These characters are been reassessed since Wirth (1948, 1970, important in distinguishing the subgenera 1971), Oliveira (1954a, 1954b, 1957), and of Paracoenia. others (Collin, 1963; Steyskal, 1970) be- Dorsocentral of bristles. The number gan incorporating characters of the male dorsocentral bristles has extensively been postabdomen in their treatments of vari- used as a major character and was ac- ous Ephydrinae genera. This is especially corded significance at the generic level by evident with the annectant genus Austro- Cresson. coenia Wirth from South America as well Humeral bristles. The presence or ab- as several und escribed genera from the sence of well-developed humeral bristles neotropics, which will require further also was used by Cresson to delimit these evaluation before a reliable classification genera. I have followed Cresson in at- of the higher categories can be achieved. tributing generic importance to this char- Biological information and systematic acter as well as to the number of dorso- studies of the immature stages would al- central bristles. so be most useful. Halters. The color of the halters can be Because biological and morphological used to distinguish some groups of spec- data of the larvae are lacking in many re- 68 GREAT BASIN NATURALIST Vol. 35, No. 1 lated genera and in some of the taxa here- ters are apomorphus and define mono- in considered, I have elected to recognize phyletic groups. a conservative classification in this study. On the other hand, the relationships be- Taxa above the species level but within tween subgenera are somewhat obscure the generic limits of Paracoenia as Cres- and the generic concept is not as neatly son described it are given subgeneric stat- circumscribed. More reliance is ])laced on us. But this status is provisional, await- chaetotaxy characters of doubtful signifi- ing the accumulation of additional in- cance. However, coupled with our mea- formation as outlined above and further ger knowledge regarding biology, habitat, assessment. etc., I feel that the genus is convenient The subgenera of Paracoenia are pri- and does reflect a cohesive unit. marily based on characters of the male Coenia has only three species, all of postabdomen and correlated external fea- which are evidently closely related. Ex- tures. The resulting concepts are suffi- cept by association with males and in ciently distinct to be easily recognizable some instances with locality, the females as delimited in the diagnoses and as seen of one species are generally indistinguish- by reviewing the figures. Paracoenia able from those of another. Similarly, the {Paracoenia), for example, is the largest males closely resemble each other, al- subgenus with eight species, yet each though their genitalic characters are con- known taxon belonging to this category sistent and constant, a fact that facilitates can be readily placed without difficulty. identification and classification. This Further, most of the diagnostic charac- group in particular needs biological study.

Taxonomy Key to Coenia and Paracoenia

Four pairs of dorsocentral bristles; humeral bristles well developed; dorsal-

most postocular bristles subequal to verticals .. Paracoenia Cresson Three pairs of dorsocentral bristles; no developed humeral bristles; dorsal postocular bristles much smaller than verticals Coenia Robineau-Desvoidy

Genus Paracoenia Cresson ous with fronto-orbital areas, dull, micro- sculptured. One large pair of proclinate Paracoenia Q-esson, 1935, Trans. Amer. Ent. Soc. 61:356. Type-species, Coenia bisetosa Coquil- diverging ocellar bristles; postvertical lett. by original designation. Sturtevant and bristles various; two pairs of fronto-orbi- Wheeler, 1954. Trans. Amer. Ent. Soc. 79:164- tal bristles; both inner and outer vertical 166 (review of Nearctic species as subgenus of bristles well developed; two pairs of Coenia). Wirth. 1965, USDA Agricultural strong postocular bristles pos- Handbook No. 276, pp. 755-756 (catalog). immediately terior to vertical bristles. Antennae dark Diagnosis. — Members of this genus brown to black, pollinose; second segment are similar to those of Coenia but can be setulose, especially on median and ventral distinguished from the latter as follows: surfaces; dorsum of arista pectinate, pec- Postocular bristles immediately posterior tinate branches up to three times the width to the vertical bristles subequal to verti- of aristal base, sometimes equaling third cals; at least one humeral bristle well de- antennal segment width. Pruinose face veloped, much larger than the surround- (])refrons) protruding, arched with inter- ing setae; foiu- pairs of dorsocentral ])rist- foveal hump, setulose; setae descending les. from hump and along ventral margin Description.— Small to large, length strongest. Eye suboval; gena variously do 2.1 to 4.4 mm, females usually larger veloped with genal bristle toward ventral than males; dark species, often with sub- margin. Mouthparts dark; prementum shining metallic reflections; head with large, bulbous. characteristic arched prefrons. Thorax. Dorsum of mesonotum sub- Head. Front (postfrons) rectangular, shining to dull, generally concolorous, wider than long; margins of mesofrons sometimes with discernible median and directed inward anteriorly; mesofrons lateral stripes. Acrostichal hairs in ap- subshining with metallic reflections, setu- proximately six irregidar rows to two dis- lose; ocellar triangle equilateral, concolor- tinct rows; four pairs of dorsocentral brist- March 1975 MATHIS: AMERICAN EPHYDRIDAE 69

les; one pair of intra-alars; two to three acle in membrane between fifth abdomin- pairs of humeral bristles; two pairs of al tergite and epandrium, all other spira- notopleurals; one pair of presuturals; one cles in ventral margin of respective terg- pair of supra-alars; two pairs of post-alars; ites. Epandrium suboval with scattered dorsum of scutellum convex to flat, setu- setae; dorsum of epandrial plate bearing lose; at least two well-developed pairs of two setulose cerci; ventrally epandrium lateral scutellar bristles; one ])air each terminates at juncture with prominent, of mesopleural and sternopleural bristles. projecting surstyli of various shapes. Hy- Wings transparent to infuscated; costal pandrium extending dorsally and ven- setae weak to strong, on dorsal and/or trally, attaching to epandrium, lateral ventral margins. Legs dark, pollinose to hypandrial process sheathing aedeagus; subshining. aecteagus well sclerotized, pointed apically. Abdomen. Abdomen of males with five Discussion.— For purposes of classifi- visible tergites, females with six to seven, cation the species of Paracoenia are ar- subshining to pollinose; most species with ranged in three subgenera, Paracoenia, pollinose band near the posterior margin Calocoenia, and Lepiocoenia. The latter of each tergite; fifth abdominal tergite of two subgenera might be accorded generic males with anteroventral ])rojection in status by future revisers since the male some species of Paracoenia s. str. Female postabdomens and other characters are postabdomen with three complete seg- fairly distinctive. But before the generic ments, six, seven, eight; ninth segment classification of these taxa is assessed, the with tergite not fused dorsally, with one higher classification of the subfamily pair of long spines on ventral margin; Ephydrinae should be revised on a world- sternite of ninth segment also with one wide basis to insure consistency in generic pair of spines; female abdomen terminat- concepts, especially the distinguishing gap. ing with cerci. Ventral receptacle vari- Such a review will necessarily entail a ously shaped. Male postabdomen sym- great deal of descriptive work because of metrical, reduced; sixth segment with our spotty knowledge of many faunal spiracles only although European species areas, i.e., the Neotropical Region, which of Paracoenia s. str. have a transverse are replete with undescribed species. sclerotized band posterior to fifth sternite The following key works best for male which could represent sixth sternite; specimens and includes both European seventh and eigth segments absent. Spir- species. Illustrations of the male genitalia acles one through six present, sixth spir- will facilitate accurate identification.

Key to Paracoenia subgenera and species

Acrostichal hairs in two rows; dorsum of scutellum slightly convex to flat; posteroventral margin of mesofemora without row of comblike bristles in males 2 Acrostichal hairs in four to six irregular rows; dorsum of scutellum convex; posteroventral margin of mesofemora with dense row of bristles in males subgenus Paracoenia Cresson 3

Length over 3.25 mm; eye-to-cheek ratio 1:0.25 or larger; well-developed costal bristles projecting anteriorly from ventral and dorsal surfaces subgenus Calocoenia, Caloceonia platypelta (Cresson) Length under 3.00 mm; eye-to-cheek ratio 1:0.25 or less; bristles along costal margin not developed subgenus Leptocoenia^ Lepiocoenia paurosoma (Sturtevant and Wheeler)

Fifth abdominal sternite of male deeply U-shaped, Figs. 11, 12; Palearctic .... 4 Fifth abdominal sternite broadly U-shaped, Figs. 1-6; Nearctic 5

Length approximately 5 mm; dorsum of thorax and abdomen grayish-blue to light brown, dull; pleura gray P. beckeri (Kuntze) Length usually less than 4 mm; thorax and abdomen darker, bluish-olive green to greenish-gray; subshining dorsally P. fumosa (Stenhammar) 70 GREAT BASIN NATURALIST Vol. 35, No. 1

5. Postocellars small, no longer than their distance apart at base; facial pruinosity yellowish-gold with greenish-blue metallic reflection showing through around interfoveal hump; ventral projection of fifth abdominal tergite in males blunt, parallel to remainder of ventral margin .... P. fumosalis Cresson Postocellars larger, longer than their distance apart at base, facial pruinosity various; ventral projection of fifth abdominal tergite absent or not as above 6

6. Process of fifth abdominal tergite in males not developed 7 Process of fifth abdominal tergite developed into a projection of various shapes 8

7. Subshining with metallic blue reflections; eye-to-cheek ratio 1:0.45 or larger; associated with hot sulfur springs P. calida n.sp. Subshining with metallic green reflections; eye-to-cheek ratio 1:0.3 or less; associated with thermal or cool water P. turbida (Curran)

8. Process of fifth abdominal tergite of male broadly produced; acrostichal vicin- hairs few; male genitalia as in Fig. 1 ; presently known only from ity of Los Angeles, California P. ampla n. sp. Process of fifth abdominal tergite not as broadly produced; acrostichal hairs stronger; surstyli of male genitalia not pointed distally or bare 9

9. Surstyli thickened basally, at least one-half total length; sheathing projection of hypandrium broadly rounded apically; smaller, length 3.1-3.6 mm; setation less well developed, especially on face and mesonotum; male genitalia as in Fig. 6 P. ivirthi n. sp. Basal expansion of surstyli less than one-third total length; lateral process of hypandrium pointed; length 3.7-4.4 mm; facial and mesonotal hairs well developed P. bisetosa (Coquillett)

Subgenus Paracoenia Cresson hump, strongly arched; eye-to-cheek ra-

. tio 1:0.22-0.45; width-to-height n n ,n:>r- rr t7 . c usually boc. • Paracoenia Cresson, 19i5, Irans. Amer. Ent. ^- a r\ rn ^^^ \ r i ..i : ra- 61:356. Type-species Coenia bisetosa Coquil- ratio 1 0.67; eye-width-to-face-length lett, by original designation. Sturtevant and tio 1:0.45 (1:0.85 in P. callda) ; height- Wheeler, 1954, Trans. Amer. Ent. Soc. 79:164- to-length ratio 1:0.93. Thorax. Dorsum subshining although Diagnosis.— This subgenus is similar subdued in aged specimens, generally to Calocoenia but may be distinguished as shining more posteriorly. Acrostichal follows: acrostichal hairs in several ir- hairs in four to six irregular rows; other- regular rows, no prominent hairs; dor- wise chaetotaxy as in generic description; sum of scutellum convex; costal setae scutellum convex. Costal vein ratio 1:0.2; weak, in a single row; posteroventral mar- Mi+.. vein ratio 1:0.90; costal setae gen- gin of mesofemora with distinct row of erally weak, developed setae on dorsal bristles in males; many species with an margin only. Mesofemora of males with anteroventral projection of the fifth ab- j)osteroventral row of comblike bristles, dominal tergite; epandrium of male with Abdomen. Subshining to pollinose, if an anteromedian triangular projection; shining, reflection somewhat less than aedeagal apodeme subquadrate. dorsum of scutellum. Female ventral re- Description.— Moderately large, ceptacle with operculum, wider than high, length 3.1-5.0 mm; dark species, often extending process not longer than oper- with subshining metallic reflections. cukmi length. Surstyli of male postab- Head. Front rectangular; mesofrons domen projecting from lateral margins subshining to shining with metallic re- <^f epandrium, long, variously shaped; a flections; pectinate branches of arista up triangular process lies between surstyli, to throe times the width of aristal base, ^"me species, with a median groove (see often equaling third antennal segment figures of included species), width. Face with prominent interfoveal Discussion.— The species included in March 1975 MATHIS: AMERICAN EPHYDRIDAE 71 this taxon form a fairly homogeneous graphic account, aside from the general group based mostly on apomorphous char- distributions indicated under the appro- acters (see diagnosis). The joint posses- priate species, will not be possible until sion of these characters dehmits the mono- more collection data become available. phyletic grouping here understood as Para- The paucity of biological studies pre- coenia s. str. and determines the sub- cludes a detailed accounting for the en- generic concept. Two species previously tire subgenus. For the Nearctic region, included here, P. paurosoma (Sturtevant only P. turhida has been studied in any and Wheeler) and P. platypelta Cresson, detail (Brock et al, 1968, 1969). How- are sufficient!}' distinct to fomi the basis ever, Dr. B. A. Foote and associates at for new subgenera. Kent State University and Dr. Karl W.

Paracoenia s. str. is Holarctic, but no Simpson of Cornell University are cur- one species is presently known to occur rently engaged in studies of various eph- in both Eurasia and North America. How- ydrid species that will greatly enhance ever, many species of the subgenus are our biological knowledge. widely distributed, and it is not uncom- Most species can tolerate harsh environ- mon to collect two or more species from ments, especially aquatic habitats with the same general locality-. Other species high concentrations of various salts. These such as the Nearctic P. calida and P. am- shore flies are often abundant, for exam- pla and the Palearctic P. beckeri are ple, along the margin of Great Salt Lake known only from very localized geo- or associated with hot sulfur springs in graphic areas. Yellowstone National Park, Wyoming. Scheiring further re- The subgenus contains eight species; and Foote (1973) port finding larvae in six are Nearctic and two are Palearctic. the shoreline mud of alkaline lakes and in sewage-impreg- All of the Nearctic species except P. fum nated larva of P. osalis are found principally in western mud. The and pupa North Ainerica. A more detailed zoogeo- fumosa. a Palearctic species, were described by Beyer (1939).

Paracoenia (Paracoenia) ampla, n. sp.

Fig. 1, Map 1

Diagnosis. — Although this species is quite similar to P. hisetosa, it can be readily distinguished from the latter by comparing male postabdomens. The surstyli of P. ampla are sinuate, bare, and strongly narrowed apically. Further, the shape of the lateral hypandrial process is distinctive, especially the clavate extension. This species is larger than most P. bisetosa and in general is less setulose. The acrostichal hairs, in particular, are weak and widely scattered. Description.— Length approximately 4.0 mm (the abdomen was removed for dissection before measurements were taken); generally subshining with bluish- green metallic reflections. Head. Width-to-height ratio 1:0.7; height-to-length ratio 1:1; eye-width-to-

face-length ratio 1 : 0.44; facial pruinosity brownish-gold. Thorax. Setae generally weak, scattered; costal vein ratio 1:0.17; Mi+o ratio 1:1. Map 1. Distribution of Paracoenia wirihi, — Abdomen. Fifth tergite ventrally pro- filled stars; Paracoenia platypelta, filled circles; Paracoenia ampla, open circle; and Paracoenia duced into broadly based processes that calida, open star. extend anteriorly to basal margin of fused 72 GREAT BASIN NATURALIST Vol. 35, No. 1

U-shaped fourth and fifth abdominal rior margin of the fifth abdominal stern- | sternites, processes pointed apically; fifth ite is sclerotized and of uniform thickness abdominal sternite thin, weak, deeply U- throughout. The Aentral process of the shaped with parallel arms; epandrium fifth abdominal tergite is well developed subquadrate; medial triangular projection and pointed. Basally, the surstyli are en- proportionately small to epandrial size; larged but narrow quickly, making the surstyli directed inward, apically nar- lateral margin sinuate. The hypandrial rowed, sinuate, bare; hypandrium in pro- process usually tapers evenly to a rounded file almost rectangular, with extending point. Outwardly, this species might be process slightly clavate; aedeagus broad confused with P. ampla, but the male basally, tapering rapidly, curved and genitalia of P. hisetosa differ sufficiently pointed apically. Male genitalia as in from the latter that recognition of either Fig. 1. species should not be difficult. Distribution.— Los Angeles, Cali- Description.— Length 3.7-4.4 mm; fornia. dark greenish-brown dorsally; laterally Types.— Male holotype with the fol- quite pollinose. lowing label data: Los Angeles, Cal., Apr Head. Mesofrons with bronze metallic 29th, 1915, M. VanDuzee; a determina- reflections. Eye-to-cheek ratio 1:0.34; tion label, Coenia hisetosa Coq., 1919, width-to-height ratio 1:0.69; height-to- Cresson; a blue M C VanDuzee collection length ratio 1:0.9; eye-width-to-face- label. The type will be deposited with length ratio 1:0.5. the California Academy of Sciences, type Thorax. Dorsum with pollinose an- number 12032. terior, becoming subshining posteriorly; pleural areas largely pollinose. Wings Remarks.— This species is known only infuscated with light brown. from the unique male holotype. Recogni- Abdomen. As in diagnosis and Fig. 4. tion of the specimen as representing a new species is justified in view of the Specimens examined.— 1881. very distinctive male postabdomen. Un- Distribution.— Like P. turhida, this fortunately, P. ampla inay already be ex- species is primarily a western North tinct due to the tremendous and rapid American taxon, although collecting data urban growth in the Los Angeles area indicate eastern extensions to New York since 1915. I have examined several Para- (5 miles W Cardiff), Pennsylvania (Phil- coenia specimens from Los Angeles adelphia), Delaware (Bombay Hook), and County but none were ampla. Virginia (Saltville). The Northwest Ter- ritories (Nyarling River), Canada, is the northernmost collection site, and the spec- Paracoenia {Paracoenia) hisetosa ies ranges from there southward through (Coquillett) most of the Midwest to Texas (Buffalo

Fig. 4, Map 3 Spring Lake) and into Mexico (Guada- lupe Can., B. Calif.). Westward, speci- Coenia hisetosa Coquilllett. 1902. J. N. Y. Ent. collected in every state Soc. 10:183 mens have been of the 100th Caenia [sic] hisetosa: Aldrich, 1905, Smithson. and Canadian pro\ince west Misc. Coll. 66(1444): 631 ])arallel. Paracoenia hisetosa: Cresson, 1935, Trans. Amer. Remarks.^— This is the most common Ent. Soc. 61:356 species of the genus and among the most Coenia {Paracoenia ) hisetosa: Sturtevant and widespread. It is also one of the most Wheeler, 1954, Trans. Amer. Ent. Soc. 79:164 variable. Facial pruinosity color runs Types.— Male holotype, Salt Lake, from bright brownish-orange to silver, Utah, 25 June, E. A. Schwarz collector. and the general body color varies from The type is deposited with the National shining greenish-brown to a subdued, Museum of Natural History, Washington, grayed green. Age polymorphism is also D.C., type number 6644. This specimen apparent; older specimens are often more is in relatively good condition, although brownish and are worn. the wings are ragged and torn. Dr. Willis W. Wirth has made several Diagnosis. — P. hisetosa is similar to P. collections of P. hisetosa from aquatic turhida. but the former is larger, more habitats with varying concentrations of setulose, and more brownish. The poste- both alkaline and saline salts. March 1975 MATHIS: AMERICAN EPHYDRIDAE 73

Map 2. — Distribution of Paracoenia fumosalis, filled circles; Paracoenia turbida, filled stars; and Coenia alpina, enclosed stai-s.

Paracoenia {Paracoenia) calida, n. sp. of uniform thickness and has a noticeable

Fig. 3, Map 1 taper just before the apices. Additionally, the fifth abdominal tergite does not have Diagnosis.— This is the most distinc- a ventral extension, although the margin tive Nearctic species and is easily separa- is pointed. P. calida and P. bisetosa are ted from all others of the genus. Exter- approximately the same size. nally, the blue metallic reflections from the dorsum, the protruding prefrons, and Description.— Length 3.4-4.3 mm, the eye-to-cheek ratio are diagnostic. The holotype male 3.9 mm, generally dark, male postabdomen resembles that of P. gray pollinose on head and thoracic plurae bisetosa but differs in the shape of the with subshining blue metallic reflections hypandrial process, which is more or less dorsally. 74 GREAT BASIN NATURALIST Vol. 35, No. 1

Head. Eye-to-cheek ratio 1:0.45; height- be collected in great numbers. The adults to-length ratio 1:1; width-to-height ratio are also abundant and were often ob-

1 : 0.71 ; eye-width-to-face-length ratio served to congregate in large clumps near 1:0.85. Fronto-orbital and ocellar triangle the spring source where shaded or pro- areas blackish-gray, concolorous with mar- tected areas could be found. Empty pu- gins of frons; postocellar bristles weak in paria that are scattered on the surface of some specimens; pruniose face grayish- the effluent and along its margins are tan. often utilized as oviposition sites. Figure Thorax. Pleural areas dull, pollinose; 13 is a stereoscan electron micrograph of dorsmn subshining to shining, brownish- the egg of P. calida. blue; halters dark, reddish-bro\^^l to black; The effluent of the spring emptied into wings completely infuscated, brown to a small creek around which swarming smoky. Tarsal claws well developed, as numbers of other ephydrids were encoun- long as third or fourth tarsomere; pulvil- tered on emergent grasses and in quieter lar pads proportionately small to claw size. eddies on the water's surface. P. calida, however, was not common there, and only Abdomen. Dorsum of all segments with an occasional collection was distinct blue to purplish-blue reflections, made away from the hot springs. It is also of interest reflections stronger in general than else- that a new saldid species was recently where on body; ventral margin of fifth described from the same locality (J. T. abdominal tergite broadly pointed, with- Polhemus, 1967). out lobelike projection; fifth abdominal sternite broadly U-shaped, narrow pro- The specific name, calida, is descriptive jecting arms forming obtuse angle; setae of the habitat. along posterior margins of tergites much larger than rest of setae, at least twice Paracoenia {Paracoenia) fumoscdis as long, in some female specimens three Cresson to four times as long. Surstyli of male Fig. 2, Map 2 genitalia with more or less gradual taper, Paracoenia fumosalis Cresson, 1935, Trans. Amer. not sinuate or pedunculate; aedeagus Ent. Soc. 61:356 short; hypandrial process as described in Coenia {Paracoenia) fumosalis: Sturtevant and diagnosis. Wheeler, 1954, Trans. Amer. Ent. Soc. 79:164 Distribution. — Wilbur Hot Springs, Types. — Male holotype, Rockport, Colusa Co., California. Massachusetts, 28 August 1913, C. W. Types. — Male holotype, allotype, and Johnson collector. The type is deposited all paratypes are from the type locality. with the Boston Natural History Society Two male and 9 female paratypes, H. J. (Museum of Comparative Zoology, Har- Jacob; 1 male and 1 female paratype, 27 vard University, Cambridge, Massachu- June 1950, L .W. Quate; holotype, allo- setts), type number 31759. One male and type, and 205 male and 96 female para- two female paratypes are topotypical. types, 25 June 1974, W. N. Ma this. Pri- Four female paratypes were collected on mary types will be deposited with the U. Nantucket Island, 13 July 1926 by C. W. S. National Museum of Natural History, Johnson. All paratyj)es are deposited with type number 72975. Male and female the Academy of Natural Sciences of Phil- paratypes will be deposited with the Cali- adelphia. fornia Academy of Sciences, Canadian Diagnosis.— Cresson (1935) stated that National Collection, Academy of Natural this species is similar to P. hisetosa and P. Sciences of Philadelphia, Kent State Uni- funiosa, which is Palearctic. My observa- versity, Washington State University, and tions agree with Cresson's, although in Oregon State University. The remaining many respects P. fumosalis is unique paratypes are in my collection. among Paracoenia species. The males Remarks.— Of all the Nearctic species are most easily distinguished from similar of Paracoenia s. str., P. calida is perhaps taxa by the rounded, fingerliko projection the most remarkable. Its known distribu- of the fifth abdominal tergite. This pro- tion is limited to a hot sulfur spring in the cess is parallel to the ventral margin of foothills just east of Clear Lake, California. the tergite that is deeply incised and of The larvae develop and mature in all but uniform thickness before the slightly en- the hottest water where they can easily larged, rounded apex. The fifth abdomin- March 1975 MATHIS: AMERICAN EPHYDRIDAE 75

stars; Co- Map 3.— Distribution of Paracoenia bisetosa, filled stars; Coenia paurosoma, open and enia curvicauda, filled circles.

al sternite is subrectangular without ex- Further, the tannish-bronze color of the tending arms from the posterolateral mar- pruinose face seems to be constant. gins. The surstyli are narrowly S-shaped, Description.— Length 3.5-4.0 mm; and the median triangular process often dark brown, lightly pollinose to subshin- has a median groove that is cleft apically. ing dorsally; some greenish-blue metallic The hypandrial process is much longer reflections. than the aedeagus, and apically it is trun- Head. Mesofrons shining with bluish cate. Externally, P. fumosalis differs reflections; fronto-orbital areas subshining from all others in the length of the post- brown; face concolorous with mesofrons, ocellar bristles, which are usually shorter pruinose, tannish-bronze. Eye-to-cheek than their distance apart at the base. ratio 1:0.3; width-to-height ratio 1:0.64; 76 GREAT BASIN NATURALIST Vol. 35, No. 1 height-to-length ratio 1:0.87; eye-width- Paracoenia turbida: Wirth, 1965, USDA Agri. to-face-length ratio 1:0.41. Handbk. No. 276:756 Thorax. Dorsally subshining, purplish- Types.— Male holotype and allotype, blue reflections, dark brown. Pleural areas Old Faithful, Yellowstone National Park, pollinose except dorsal margin. Wings in- Wyoming, 30 September 1924, N. Crid- fuscated \\dth brown. dle. Two male and one female paratype Abdomen. Concolorous with dorsum of have the saine label data as the type. All thorax. Male postabdomen as in diagno- types are deposited with the Canadian Na- sis and Fig. 2. tional Collection, type number 2370. Specimens examined. 368. Diagnosis. — Externally, this species re- Distribution.— P. fumosalis is pre- sembles P. ivirthi and is sometimes con- dominately a nothern and eastern North fused with P. hisetosa. However, it differs American species. I have examined ma- from both in the shape of the hypandrial terial from Alaska (Matanuska and Eagle process, which apically narrows more River flats) and from all of the Canadian abruptly although the apex is rounded. provinces except British Columbia and Also, the lateral margins of the surstyli the Yukon Territory. In the continental do not taper apically as rapidly as P. hi- United States, P. fumosalis ranges west- setosa nor are they enlarged basally as in ward to Montana (Libby), eastward P. wirthi. Outwardly, P. turbida is smal- through the Great Lake states, some mid- ler than P. bisetosa but of approximately western states (Nebraska, Iowa), and in- the same length as P. ivirthi. However, to the Northeast. It has also been col- the acrostichal hairs are weaker in turbi- lected as far south as Florida (Archbold da. The fifth abdominal sternite is more Biological Station, Lake Placid), and it similar to that of bisetosa, although the presumably occurs between Florida and more sclerotized posterior margin is not the Northeast. Wirth (1965) lists Cali- as wide nor as uniform in thickness as it fornia as the westernmost extension of P. is in bisetosa. fumosalis, but I have not seen specimens Description. — Length 3.25-3.75 mm; from California. dark greenish-brown, subshining dorsally. Remarks.— Examination of over 350 Head. Fronto-orbital areas dark brown, specimens of this species from a wide pollinose to subshining. Eye-to-cheek ratio selection of localities within its distribu- 1:0.3; width-to-height ratio 1:0.65; height- tion revealed very little morphological to-length ratio 1:0.93; eye-width-to-face- variation. This species is very uniform length ratio 1:0.44. except for slight artificial size differences Thorax. Anterior area of dorsum slight- reflecting the mode of preservation. The ly pollinose, becoming subshining to shin- facial coloration seems to be a consistent ing posteriorly; pleural areas in general diagnostic character unlike other wide- more subdued than dorsum, especially spread species of Paracoenia. I suspect along margins. Wings nearly transparent that the species is quite vagile and that to light brown. the apparent uniformity is due to exten- Abdomen. As in diagnosis and Fig. 5. sive genetic exchange. Specimens examined.— 674. Although I do not know of any locali- Distribution.— The majority of col- ties in which this species is associated with lection localities are west of the Rocky hot springs, it has been collected around Mountains, although they do extend east alkaline and saline habitats. Scheiring to Nebraska (Cherry Co., Big Alkali and Foote (1973) reared specimens and Lake), Iowa (Ames), and Ohio (Kent, report finding larvae in mud impregnated 5.6 miles SE). Specimens have been col- with organic sewage. lected as far north as Alaska (Circle Hot Springs) and southward through Canada (British Columbia to Manitoba) and the turhida Paracoenia {Paracoenia) western United States into Mexico (60 (Curran) km S Tijuana).

Fig. 5, Map 2 Remarks.— Strength of setation, gen- oral body color, especially the facial pru- Caenia [sic] turbida Curran, 1927, Can. Ent. 59:91 inosity, and overall size show considerable Coenia {Paracoenia) turbida: Sturtevant and Wheeler, 1954, Trans. Amer. Ent. Soc. 79:165 variability. Polymorphism within a sin- March 1975 MATHIS: AMERICAN EPHYDRIDAE n

Figs. 1-5. — Male and female genitalia. 1 a,b Paracoenia ampla, 2 a,b,c Paracoenia funiosalis; 3 a,b,c,d Paracoenia calida; 4 a,b,c Paracoenia bisetosa; 5 a,b,c Paracoenia turbida. Fig. a, ventral view of cerci, epandrium, and surstyli; Fig. b, lateral view of cerci, epandrium (epn), surstyli (sur), aedeagal apodeme (aeg ap), hypandrial process (hyp pr), and aedeagus (aeg); Fig. c, ventral view of male fifth abdominal steniite; Fig. d, lateral view of female ventral receptacle. gle population of P. turbida seems to var}^ and adults feed on blue-green algae and as greatly as the total species variance. the filamentous bacteria of mucilaginous Character displacement was not apparent mats, which develop under a variety of in areas where turbida occurs sympatri- hot spring flow conditions. Fly activity cally with other Paracoenia species. is generally restricted to cooler mats Brock, et al. (1968, 1969) have studied (from 30-35C), where most egg laying the biology of turbida from near the type occurs. Above 40C the eggs fail to hatch locality in Yellowstone National Park, and first instars die. At 35C the life cycle Wyoming. They found that both larvae takes approximately 14 days (egg to egg), 78 GREAT BASIN NATURALIST Vol. 35, No. 1 and mature females can produce 100 or Abdomen. Metallic reflections green to more eggs a day. Turbida can exploit olive green. Male genitalia as in diagnosis transient islands of available resource and Fig. 6. quickly, and the lar^'ae soon decimate the Distribution.^— This species is found optimum habitat (Weigert and Mitchell, in the Sonoran desert from southern Cali- 1973). Wiegert and Mitchell also an- fornia and northern Baja California east- alyzed the interactions between the algal ward into Arizona. It extends south into mats and turbida and between turbida Mexico (Distrito Federal, Mixquic). and a mite parasite Partnuniella thermalis Types.— Male holotype, allotype and de- Viets. Mitchell and Redmond (1974) 21 paratypes (7 males, 14 females), Cali- scribe the egg of turbida (several stereo- fornia, Inyo Co., 1 mile N Tecopa Hot scan electron micrographs) and suggest Springs, 24 June 1974, Wayne N. Mathis. inechanisms of respiration under varying Thirty-nine paratypes as follows: Cali- conditions. Paracoenia environmental fornia, Inyo Co., Tecopa Hot Springs, 16 turbida, however, is not endemic to hot May 1965, W. F. Barr, 1 male; Inyo Co., springs, and the details of their feeding Shoshone, 24 June 1974, W. N. Mathis, 1 habits and habitat preferences under dif- male, 5 females; Inyo Co., Shoshone, 1 ferent conditions could vary considerably. October 1935, A. J. Basinger, 1 male, 3 this species More notes on the biology of females; San Diego Co., Mtn. Palm be found in Scheiring and Foote may Springs, Anza Desert, 2 March 1964, 1 (1973). male. Arizona, Pima Co., Lowell Ranger Station, 6-20 June 1916, 32° 18.5' N, 110° Paracoenia {Paracoenia) wirthi, n. sp. 49' W, ca. 2,700', 1 male, 1 female; Bill Fig. 6, Map 1 Williams Forest, August, F. H. Snow, 1 male, 1 female. Mexico, Baja California, Diagnosis.— This species resembles Guadalupe Canyon, 19 May 1957, F. X. both P. bisetosa and P. turbida and in Williams, 1 male, 3 females; Distrito Fed- many respects is intermediate. As in P. eral, Mixquic, 9 km SW Chalco, 4 August bisetosa, the ventral margin of the fifth 1965, K. R. Valley, 4 males, 16 females. abdominal tergite is produced into a The type, allotype, and 8 paratypes will pointed extension, but the projection is be deposited in the California Academy not as long as that of P. bisetosa. The of Sciences, type number 12033. The re- general coloration and setal characters maining paratypes will be deposited with more resemble P. turbida; however, males the U. S. National Museum of Natural of P. wirthi are destinct from either spec- History, Cornell University, the Canadian ies in the shape of the surstyli, the hy- National Collection, The Academy of Na- pandrial process, and the fifth abdominal tural Sciences of Philadelphia, and my sternite. Basally, the surstyli are wide, a collection. condition that extends to about one-half their total length. The hypandrial pro- Remarks.— Although P. wirthi ap- charac- cess is broadly produced apically with a pears to be intermediate in many bluntly rounded apex. The fifth abdomin- ters, their consistency, especially the male al sternite is broad, and the projecting genitalia, justifies recognition as a new arms are subparallel and short. species. As with other species of the genus, P. wirthi is sometimes associated Description.— Length 3.1-3.6 mm; with hot springs, usually along the mar- subshinning with bluish-green to green gins of the effluent. metallic reflections. P. wirthi is named to honor Dr. Willis Head. Mesofrons greenish-blue, shin- W. Wirth for his contribution to the ing; pruinose face grayish-tan; eye-to- systematics of the Ephydridae and for his cheek ratio 1:0.22; width-to-height ratio helpful, encouraging responses to my 1:0.6; height-to-length ratio 1:0.87; eye- many questions. width-to-face-length ratio 1:0.44. Thorax. Acrostichal hairs in three to Calocoenia, n. subgen. four rows anteriorly, becoming irregular with five to six rows posteriorly. Pleural Type-species: Paracoenia plalypelta Cresson, 1935, areas although subdued not grayed. Wings monobasic in many specimens almost transparent, in Diagnosis.— Although similar to Para- others smoky infuscate. coenia s. str. and Leptocoenia, Calocoenia March 1975 MATHIS: AMERICAN EPHYDRIDAE 79

Figs. 6-10.— Male and female genitalia. 6 a,b,c,d Paracoenia ivirthi; 7 a,b,c,d,e Paracoema plaly- Fig. e, pelta; 8 a,d,e Coenia curvicauda; 9 a,h,c4,e Paracoenia paurosoma; 10 a,b,c,d,e Coenia alpina. lateral view of internal genitalia; otliers as in caption of 1-5.

may be distinguished from either as fol- specimens is more noticeably narrowed lows: Externally, Calocoenia differs from apically. The most apparent difference is Paracoenia s. str. in the arrangement of between Calocoenia and Lcptocoenia acrostichal hairs, which are in two dis- size; Calocoenia is nearly twice the length tinct rows, by the absence of a postero- of most Leptocoenia. Further, the eye-to- ventral comb of bristles along the male cheek ratio of Calocoenia is at least 1:0.2 mesofemora, by the flattened scutellum, and the M1+2 vein ratio is under 1:0.8. by the prominent costal bristles project- The male postabdomen is symmetrical; ing anteriorly from both dorsal and ven- the epandrium is subeUiptical with closely tral margins, and by the generally uni- fused surstyli ventrally and with a median form, concolorous abdomen which in male groove. The hypandrial process and aede- 80 GREAT BASIN NATURALIST Vol. 35, No. 1 agus are tusklike, long, and well sclero- costal bristles on dorsal and ventral mar- tized. The aedeagal apodeme is crescent gins; costal vein ratio 1:0.2. shaped. Abdomen. Subshining to shining, brown Description.— Length 3.4-4 mm; sub- metallic reflections; fifth abdominal ter- shining to shining, metallic brown to gite of male more or less truncate, with- greenish-brown; pollinose, gra^' ventrally. out anteroventral process; fifth abdominal Head. Mesofrons shining, bronze-gold sternite with three posteriorily oriented metallic reflections; pectinate branches of prongs. Female postabdomen similar to arista not more than twice aristal width Paracoenia s. str. Male postabdomen as in at base; pruinose face tan; interfoveal diagnosis. Fig. 7. Ventral receptacle with operculum wider than high, extending hump not as prominent as Paracoenia s. str., dorsally sloping; eye large, subcircu- process considerably longer than opercu- lar, width in profile double the length of lum. projecting face in profile; eye-to-cheek Discussion. — Calocoenia is a mono- ratio 1:0.25; width-to-height ratio 1:0.66; typic subgenus known only from the No- height-to-length ratio 1:0.9. Chaetotaxy arctic Region. Nothing is known about of head and thorax like Paracoenia s. str. the biology of the included species. except acrostichal hairs. Although the type-species of Calocoejiia Thorax. Acrostichal hairs in two rows; was originally described in Paracoenia s. dorsum pollinose to subshining; pleural str., its inclusion with the latter subgenus areas concolorous with mesonotum cen- would form a paraphyletic grouping since trally, becoming pollinose, grayed mar- the sister group of Calocoenia is Lepto- ginally; halters yellow. Male mesofemora coenia. The sister-group relationship with without comb of bristles. Wings with Leptocoenia is deduced from the joint pos-

Figs. 11-13.— Male genitalia and egg. 11 a,b,c Paracoenia beckeri; 12c Paracoenia fumosa; 13 stereoscan electron micrograph of Paracoenia calida egg, 100 X. Figures as in caption of 1-5. March 1975 MATHIS: AMERICAN EPHYDRIDAE 81 session of the following apomorphous fea- process between them, which is very simi- tures not found in Paracoenia s. str.: eye- lar to a comparable structure in Para- to-cheek ratio less than 1:0.3; interfoveal coenia s. str. rhe triangular process in hump not as pronounced as in Paracoenia Paracoenia s. str., however, is better de- s. str.; and the fifth abdominal tergite veloped in comparison with the lateral lacking an anteroventral process. surstyli. Externally, Leptocoenia is similar to Calocoenia. and both share the fol- Paracoenia (Calocoenia) platypelta lowing character states: The acrostichal hairs are in two distinct rows; the scutel- (Cresson) Imn is slightly flat; the ventral margin Fig. 7, Map 1 of the fifth abdominal tergite is not pro- Paracoenia platypelta Cresson, 1935, Trans. Amer. duced into a lobe; and the posteroventral Ent. Soc. 61:356 surface of the mesofemora does not bear Coenia {Paracoenia) platypelta: Sturtevant and a row of comblike bristles. Wheeler, 1954, Trans. Amer. Ent. Soc. 79:165 Description.— Length 2.1-2.6 mm; Types. — Male holotype, Pine Lake, So. dark brown, pollinose. Cal., Johnson. The type specimen also Head. Fronto-orbital areas, mesofrons has a small label with the male sex sym- nearly concolorous, the later subshining; bol, Cresson' s pink type label, and a red pectinate aristal branches at most two and USNM type label, number 51110. The one-half times aristal width at base; in- type is deposited with the U. S. National terfoveal hump not prominent, without Museum of Natural History. Cresson's pronounced dorsal indentation; pruinose original description also lists a topotypi- face light tan; longest bristles along ven- cal female paratype. I have examined tral margin of face approximately three- this latter specimen, presently with the fourths length of interfoveal himip height; Academy of Natural Sciences of Philadel- genal bristle weak, subequal to humeral phia, and determined it as Paracoenia bristles. Eye-to-cheek ratio 1:0.175; turbida. width-to-height ratio 1:0.65; height-to- Diagnosis and Description.— See length ratio 1:0.93; eye-width-to-face- generic description. length ratio 1:0.3. Specimens examined.— 516 Thorax. Lightly pollinose dorsally. Acrostichal setae in two rows; four pairs Distribution.— This species is known of dorsocentral bristles; humeral bristles only from the West (US). I have ex- present; halters yellowish-brown to amined specimens from Washington to brown. Costal setae weak, developed only Alberta (Laggan) and southward to New on dorsal margin. Mexico, Arizona, and California. I have not seen specimens from Montana or Abdomen. Male postabdomen as in Fig. Wyoming, although collection attempts 9; ventral receptacle as in Fig. 9d. have been made. Discussion.— In many respects, this is Paracoenia Remarks.— C. platypelta is a very subgenus pivotal, linking homogeneous species exhibiting little with Coenia. This is evident in characters morphological variation. There is some associated with size and dimension, but color polymorphism, but this could repre- the annectant role of Leptocoenia is best sent age polymorphism. As mentioned evidenced by the shape of the female ven- previously, nothing is known regarding tral receptacle. The ventral receptacle the biology or larvae of this species. closely resembles those of Coenia species and is probabl}^ less likely to be affected by selective pressure, which would bring Leptocoenia. n. subgen. about convergence in dimension and size Type-species.— Coenia paurasoma Sturtevant of external characters except by pleio- and Wheeler, monobasic trophy. I attribute considerable import- Diagnosis.— Leptocoenia resembles ance to this feature and the relationship Calocoenia but the body size is much with Coenia that it demonstrates. smaller, length 2.1-2.6 mm, and the male The internal male genitalia of Lepto- postabdomen of Leptocoenia differs con- coenia also reflect the intermediate posi- siderably. The surstyli are well separated tion of this subgenus with Coenia. This apically with a small median triangular is best seen by comparing Figs. 9e and lOe. . ;

82 GREAT BASIN NATURALIST Vol. 35, No. 1

Paracoenia {Leptococnia) pawosoma well-developed humeral bristles; two pairs (Sturtevant and Wheeler) of dorsocentral bristles; halters brownish- yellow to dark brown; and fifth abdomin- Fig. 9, Map 3 al sternite of males longer than wide. The Coenia paurosoma Sturtevant and Wheeler, 1954, size of Leptocoenia is within the dimen- Trans. Amer. Ent. Soc. 79:165 sions of Coenia^ and superficially they ap- Paracoenia paurosoma: Wirth, 1965, USDA Agri. pear very similar. However, the chaeto- Handbook No. 276, p. 567 taxy characters readily distinguish either Types.— Female holotype, three para- and set the Coenia species apart from any types (one male, two females), Lander, Paracoenia subgenus. Wyoming, 16 August 1950. The holo- Description.— Length 2.2-2.8 mm; type also bears a collector label, M. R. dark brown, pollinose to subshining. Wheeler, and type number 6696. A fourth Head. Mesofrons subshining with me- paratype (female). Rainbow Lake, Colo- tallic reflections; postocular bristles weak, rado, ^elev. 10,200', 50 hi. The original at most slightly larger than their distance description indicates that K. W. Cooper apart as base; postorbital bristles usually the collector was of the fourth paratype, weak; pectinate aristal branches various; but collector no label accompanied the bristles of face comparatively large, specimen. is The holotype deposited with bristles along ventral margin subequal in the Academy of Sciences Natural of Phil- length to interfoveal hump height; facial adelphia, two paratypes with the U.S. pruinosity various; chaetotaxy of head National Museum of Natural History, similar to Paracoenia except as noted. Eye and paratypes two with M. R. Wheeler. relatively large, subcircular although Di.\GNOsis AND Description.— See higher than wide; width-to-height ratio generic description. 1:0.62; height-to-length ratio 1:0.95; eye- Specimens examined.— 41 width-to-face-length ratio 1:0.3. Distribution.— Paurosoma has been Thoj-ax. Dark brown, generally con- collected from Colorado north through colorous; strength of pollinose covering Wyoming, Alberta (Laggan), and into various. Acrostichal hairs in two rows, in- Alaska (Matanuska Flats). I have also distinct in some species. Three or four examined five specimens from Sweden pairs of dorsocentral bristles; humeral (Norrbotten, 3 km N Messaure). bristles various; otherwise chaetotaxy as in Although paurosoma is Holarctic, it was Paracoenia. Wings without prominent the most recently discovered species. costal bristles, at most weakly developed ratio Moreover, nothing is known about its bi- on dorsal margin; costal vein 1:0.3; 1:0.7. ology. The habitat of this species is mon- Mi+_. vein ratio Legs uniformly tane; at lower latitudes it is found at ele- dark brown; male mesofemora without vations up to 10,500 feet (Rainbow Lake, posteroventral comb. Halters as in diag- Colorado) nosis. Abdomen. Subshining to shining dark brown; male five visible tergites; Genus Coenia Robineau-Desvoidy with female with six to seven; male with i\\e Coenia Robineau-Desvoidy, 1830, Essai sur les sternites; fifth sternite narrowed to small Myodaires 2:800. Type-species caricicola Coenia strip; spiracle arrangement as in Para- Robineau-Desvoidy i = Ephydra palusiris Fal- coenia. with surstvli len), by monotypy; Sturtevant and Wheeler, Male postabdomen 1954, Trans. Amer. Ent. Soc. 79:164-166 (re- closely apposed basally, becoming well view of Nearctic species as subgenus of Coenia) se])arated on apical 2/3; aedeagal apo- Wirth. 1965, USDA Agri. Handbook No. 276, deme broad to narrowly crescent-shaped; pp. 755-756 (catalog) aedeagus curved, pointed apically. Ven- Caenia emendation: Walker, 1853, Insecta Britan- tral operculum, ex- nica Diptera ?:259 (preoccupied-Newman, receptacle with small 1853, Entomological notes. Art X. Ent. mag., tending process C-shaped. pp. 372-402, Coleoptera) Discussion.-— Of the three known Co- Diagnosis.— Coenia species resemble enia species, one is aj)parently endemic those of Paracoenia^ especially the sub- to the Nearctic Region, a second is limited genus Leptocoenia. but they are differen- to the Palearctic, and a third species is tiated as follows: Dorsalmost postocular Holarctic. Cresson's comments regarding bristles not subcqual to the verticals; no the European species and their distinguish- March 1975 MATHIS: AMERICAN EPHYDRIDAE 83 ing characteristics should bo consulted for tions of various salts. Dahl (1959) and species separation from that fauna. Scheiring and Foote (1973) report on as- Species of Coenia are not usually asso- sociations of Coenia curvicauda (Meigen) elated with aquatic environments that are with mud shore habitats and to a lesser contaminated or contain high concentra- extent with the limnic wrack.

Key to Coenia species

1. Male genitalia large, exposed ventrally; epandrium over twice as long as

wide, with median suture - C. curvicauda (Meigen) Male genitalia more compact, not exposed; epandrium less than twice as long as wide, without median suture --.. C. alpina n. sp.

Coenia alpina, n. sp. 1955, E. E. Sterns; 1 male, 12 August

Fig. 10, Map 2 1955. The type, allotype, and 32 paratypes will be deposited wdth the Canadian most closely re- Di.'\GNosis. — C. alpina National Collection, type number 13435. Palearctic species. sembles C. palustris, a A male and female paratype also will be the latter by dif- It is distinguished from deposited with the California Academy of genitalic structures. The ferences in male Sciences, the U.S. National Museum of proportionately shorter to surstyli are Natural History, and in my collection. epandrial length, the aedeagus is the In addition to the type series, I have Aentrall}' rounded, the aede- deeper and examined 31 specimens of this species agal is longer, and the hypandri- apodeme from the following localities: 9 males, 17 thinner and project mesad al processes are females, Aklavik, Northwest Territories, connection with the to the hypandrial May-August 1930 and 1931; 2 males, 3 of both species are aedeagus. The females females, Rabbit Ears Pass, Colorado, 11 very similar. June 1968, S. L. W. Description.— Length 2.1-2.6 mm; Remarks.— This species is alpine, purplish metallic dark brown with some which accounts for the specific name. Al- reflections dorsally. though the known distribution is based Head. Interfoveal hump more or less on minimal data that is rather disjunct, I prominent; pruinose face brown; pectin- feel that C. alpina is distributed through- branches of arista long, approximately ate out the Rocky Mountains at higher ele- aristal width at base; post- three times vations and across northern Canada. orbital setae not developed dorsally. Eye- From my study, I liaAe found very ratio 1:0.12; width-to-height ra- to-cheek httle variation except for minor size dif- height-to-length ratio 1:0.96; tio 1:0.6; ferences as indicated in the description. eye-width-to-face-length ratio 1:0.33. Otherwise, C. alpina seems to be a very Thorax. Acrostichal setae weak, in two uniform species. rows; three pairs of dorsocentral bristles; humeral bristles absent; halters dark Coenia curvicauda (Meigen) brown. Fig. 8, Map 3 Abdomen. Subshining to shining with some purplish reflections; ventral recep- Ephydra curvicauda Meigen, 1830, Syst. Beschr. tacle as in Fig. lOd; male genitaha as in 6:116 Coenia curvicauda: Macquart, 1835, Hist. Nat. Fig. 10. Ins. Dipt. 2:530 Distribution.— C. alpina has been collected in Colorado (Rabbit Ears Pass), Types. — Cresson (1930) designated a in the Northwest Territories (Aklavik), lectotype for this species from material and in Labrador (Cartwright). in the Naturhistorisches Museum, Wien. Types.— Male holotype, allotype, and According to Cresson, the male lectotype "curvicauda 21 paratypes (8 males, 13 females). Cart- has the following label data: wright, Labrador, 29 June 1955, E. F. Coll. Winth," "curvicauda." A second Cashman; 17 paratypes with same data male specimen with similar data was de- as type except as follows: 5 males, 3 fe- signated a parat3^pe b}' Cresson. males, 3 July 1955; 4 males, 2 females, 2 Diagnosis.— C. curvicauda is similar to July 1955, E. E. Sterns; 1 male, 6 August C. alpina and to C. palustris but differs .

84 GREAT BASIN NATURALIST Vol. 35, No. 1 from either by the well-developed male Diptera from North America. Jour. N. Y. 10:177-191. postabdomen which })rotrudes from the Ent. Soc. Cresson, E. T., Jr. 1930. Studies in the Dip- venter of the abdomen. The epandrium terous Family Ephydridae. III. Trans. Amer. plus surstjdi are over twice as long as Ent. Soc. 56:93-131. the epandrial width, and the epandrium . 1935. Descriptions of genera and species of the dipterous family Ephydridae. Trans. is divided by a median groove. The sur- Amer. Ent. Soc. 61:345-372. styli arms are longer than their base, the . 1942. Synopses of North American aedeagal apodeme is slender and C-shaped Ephydridae (Diptera). I. Trans. Amer. Ent. in profile, and the aedeagus is broadly Soc. 68:101-128.

. of North American developed basally and curves forming a 1944. Synopses Ephydridae (Diptei-a). la and II. Trans. J-shaped structure. Amer. Ent. Soc. 70:227-240.

Description.— Length 2.3-2.8 mm; . 1946. Synopses of North American (Diptera). III. The tribe Noti- dark brown, subshining to shining. Ephydridae philini of the subfamily Notiphilinae. Trans. Head. Mesofrons shining, dark brown; Amer. Ent. Soc. 72:227-240. fronto-orbital areas subshining; pectinate 1949. A systematic annotated arrange- of and species of the North aristal branches subequal to third anten- ment the genera American Ephydridae. IV. The subfamily width; face lightly pollinose, nal segment Napaeinae. Trans. Amer. Ent. Soc. 74:225- mostly dark brown; chaetotaxy as in C. 260. alpina; eye-to-cheek ratio 1:0.11; width- Curran, C. H. 1927. Descriptions of nearctic to-height ratio 1:0.6; height-to-length ra- Diptera. Canad. Ent. 59:79-92. D.\HL, R. G. 1959. Studies on Scandinavian tio eye-W'idth-to-face-length 1:0.3. 1:1; Ephydridae (Diptera. Brachycera). Opusc. Thorax and abdomen as in C. alpina Ent.^ (Soc. Ent. Lund.). Sup. 25:1-225. except as given in diagnosis. H.\LiD.\Y, A. H. 1839. Remarks on the generic distribution of the British Hydromyzidae Specimens examined.— 150 (Diptera). Ann. Nat. Hist. 3:217-224. of England. Distribution. — Coenia cwvicauda is Johnson. C. W. 1925. Fauna New List of the Diptera or two-winged flies. a Holarctic, boreal species. In the Nearc- Occas. Papers Boston Soc. Nat. Hist. 7(15) :1- tic region it is found in Montana (Big- 326. fork) and east through the Midwest to LoEW, H. 1860. Die Europaeischen Ephydrini- the Northeast. It extends north to Alaska dae und die Bisher in Schlesien Beobachteten Arten Derselben. Neue Beitrage zur Kennt- (Tonsina) and east to Quebec (Cross nis der Diptereu. part 7. Mittler und Sohn, Point) Berlin. Remarks.— Although I did not ex- M.\CQU.\RT, J. 1835. Histoire Naturelle des In- sectes Dipteres. vol. 2. Roret. Paris. amine the lectotype, I have studied Euro- Meigen, J. W. 1830. iSj-stematische Beschrei- pean specimens of this species. The bung der bekannten europaischen zweiflugel- aedeagus in some specimens does not igen Insekten. vol. 5. Hamm. curve apically to the extent found in Ne- Mitchell, R. M. ,\nd B. L. Redmond. 1974. Fine structure and respiration of the eggs of arctic specimens, but I did not find any two ephydrid flies (Diptera: Ephvdridae). I consider all other major differences. Trans. Amer. Micros. Soc. 93:113-118. specimens I examined to be conspecific. Newm.\n, E. 1838. Entomological notes. Art. XL. Ent. Mag., pp. 372-402. Oliveir.\, S. J. 1954a. Contribuicao para o con- Literature Cited hecimento do genero ''Dimecoenia" Cresson. 1916. I. ''Dimecoenia lenii" sp. n. encontrada Chile (Diptera, Ephydridae). Rev. Brasil. Aldrich, J. M. 1905. A catalogue of Nortli no American Diptera. Smithsn. Inst.. Smithsn. Biol. 14:187-194.

. 1954b. Contribuigao para o conheci- Misc. Collect. 46(2-pub. 14-44) : 1-680. Beyer, A. 1939. Morphologische, Okologische mento do genero ''Dimecoenia'" Cresson, 1916, und Ph3-siologisc.hc Studion an den Larven II. Sobre 3 especies novas do Brasil (Diptera. Biol. 14:269-278. del- Fliegen: Ephydra riparia Fallen. E. mi- Ephydridae). Rev. Brasil. cans Haliday und Cacnia jiauosa Stenhani . 1957. Contribuigao para o conhecimen- mar. Kieler Meereforschungen 3:265-320. to do genero ''Dimecoenia' Cresson, 1916. III. Brock, T. D. .^nd M. L. Brock. 1968. Life in Sobre uma especie nova do Estado de Sao a hot-water basin. Nat. Hist. 77:47-54. Paulo. Brasil (Diptera. Ephydridae). Rev. Brock, M. L., B. G. Wiegert, and T. D. Brock. Brasil. Biol. 17:305-308. 1969. Feeding by Paracoenia and Ephydra PoLHEMUs, J. T. 1967. A new saldid from (Diptera: Ephydridae) on the microorgan- California (Hemiptera: Saldidae). Proc. Ent. isms of hot springs. Ecologj- 50:192-200. Soc. Wash. 69:346-348. Coi.i.iN. J. E. 1963. The British species of Rorineau-De-svoidy. a. J. "B. 1830. Essai sur Ephydra (Dipt., Ephydridae). Entomol. Mon. les Myodaires. Memoires da I'Academie Mag. 99:147-152. Rovale des Sciences de ITnstitut de France. CoQUiLLETT, D. W. 1902. Now acalyptrate 2:1-813. March 1975 MATHIS: AMERICAN EPHYDRIDAF. 85

ScHEiRiNG. J. F. AND B. A. FooTE. 1973. Hab- WiEGERT, R. G. and R. Mitciiei.e. 1973. Ecol- itat distribution of the shore flies of north- ogy of Yellowstone thermal effluent systems: eastern Ohio (Diptear: Ephydridao). Ohio intersects of blue-green algae, grazing flies Jour. Sri. 7^:152-166. (Paiaroenia, Ephydridae) and water mites

Stenh.\mm.\r. C. 18-H, Forsok till gruppering {Part/iuniclla, Hydrachnellae). Hydrobiol- och revision af de svenska Ephydrinae. K. ogia M: 25 1-271. Vetensk. Akad. Handl. 1843:75-272. WiRTir, W. W. 1948. A taxonomic study of Hawaiian Ephydridae (Diptera) related to Steyskal, George C. 1970. The species of the Scalclla Robineau-Desvoidy. Proc. Hawaiian genus Dimecoenia (Diptera: Ephydiidae) in Ent. Soc. 13:277-304. America north of Panama, with the descrip- — -. 1965. Ephydridae. Pages 734-759 in tion of a new species. Ann. Ent. Soc. Amer. Alan Stone, C. Sabrosky, Wirth, 63:462-465. W. W. W. R. H. Foote, and J. R. Coulson, eds. A catalog R. SxURTEyANT, A. H. AND M. WlIEEI.ER. 1954. of the diptera of America north of Mexico. Synopses of nearctic (Diptera). Ephydridae U. S. Dep. Agr. Handb. No. 276. Trans. Amer. Ent. Soc. 79:151-261. . 1970. A new genus and species of shore Walker, F. 1849. List of the specimens of dip- fly (Diptera. Ephydridao) from southern Pata- terous insects in the collection of the British gonia. Act. Zool. Lill. 26:1-8.

Museum. Vol. 4. pp. 689-1172. . 1971. The brine flies of the genus

. 1853. Insecta Britannica. Diptera. Vol. Ephydra in NoiUi America (Diptera: Eph- II, 297 pp. ydridae). Ann. Ent. Soc. Amer. 64:357-377.