Glenn B. Wiggins and John S. Richardson.
Revision of the Onocosmoecus unicolor group (Trichoptera: Limnephilidae, Dicosmoecinae).
Psyche 93:187-216, 1986.

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REVISION OF THE ONOCOSMOECUS UNICOLOR GROUP (TRICHOPTERA: LIMNEPHILIDAE, DICOSMOECINAE) BY GLENN B. WIGGINS' AND JOHN S. RICHARDS ON^ The genus Onocosmoecus, by current definition, comprises the unicolor group and the frontalis group (Schmid 1980, occidentalis group = unicolor group; Wiggins 1977). From a separate study of generic relationships within the Dicosmoecinae (G. B. Wiggins & 0. S. Flint, in prep.), it is clear that Onocosmoecus in this broad sense is not monophyletic. The frontalis group will be considered in a subsequent paper, but in the interim the two western North Ameri- can species of which it is composed, 0. frontalis (Banks) and 0. schmidi (Wiggins), remain nominally under Onocosmoecus. Thus, in final analysis, this study of the unicolor group will constitute a revision of the genus Onocosmoecus s.s., and the generic name is used here in that restricted sense.
Among the genera of the limnephilid subfamily Dicosmoecinae, Onocosmoecus S.S. is one of the most widespread, represented across the whole of northern North America from Newfoundland to Alaska, south in the western mountains to California, and across the Bering Strait to Kamchatka. They are rather large caddisflies, not often found in abundance but by no means rare. Larvae occur in cool lotic habitats, and also in the littoral zone of cool lakes, where they are detritivorous. Seven species have been assigned to the genus in the past but reservations concerning their validity have been expressed by several authors (e.g., Schmid 1955, 1980; Flint 1960; Wiggins 1977). Because no analysis of types or of long series of specimens has been undertaken, identity of the putative species has always been doubtful. The purpose of the present study was to undertake that analysis.
'Department of Entomology, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6.
department of Zoology, University of British Columbia, Vancouver, B.C. Canada. Manuscript received by the editor June 17, 1986.



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Extensive collections in the Department of Entomolgy, Royal Ontario Museum (ROM) provided the main basis for this study and were supplemented by material borrowed from other collections; deposition of all other specimens examined is given below. On the distribution map for 0. unicolor (Fig. 14), not all records in the central part of the range are plotted. Since complete listing of all records for 0. unicolor is too voluminous for inclusion here, an abbreviated citation is used; localities are listed under state or pro- vince and any other identifier, followed by the place of deposition of the material, and the range for adult flight records is given for each state or province. A complete listing of all records compiled is dep- osited in the Library of the Royal Ontario Museum. Records for larvae are included; instars are designated as LV (Larval instar V), LIV, LIII, P (Pupa), PP (Prepupa). Life history data for 0. unicolor are grouped into weekly intervals for plotting (Fig. lo), with each dot representing a collection comprising one or more individuals at a given stage. Larvae were identified to the third instar, although some characters are not as well developed as in the final instar. Observations on food are based on analysis of the contents of the entire gut from 10 LV, following the method of Cummins (1973). Food data were recorded on a percentage area basis using an eye- piece grid, and were classified under four categories: animal frag- ments, vascular plant pieces and filamentous algae, diatoms, and fine particulate organic material (FPOM) unidentifiable as to origin.
Location of specimens examined
CA S California Academy of Sciences, San Francisco CNC Canadian National Collection, Biosysternatics Research Institute, Agriculture Canada, Ottawa
DGD D. G. Denning, Moraga, California
DJB D. J. Burdick, Department of Biology, California State Uni- versity, Fresno
ZNHS Illinois Natural History Survey, Champaign LA CM Los Angeles County Museum
MCZ Museum of Comparative Zoology, Harvard University, Cam bridge




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19861 Wiggins & Richardson- Onocosrnoecus 189 NHA
N. H. Anderson, Department of Entomology, Oregon State University, Corvallis
Oswood M. W. Oswood, Division of Life Sciences, University of Alaska, Fairbanks
SDS S. D. Smith, Central Washington University, Ellensburg UA
Strickland Museum, University of Alberta, Edmonton UBC Spencer Entomological Museum, University of British Colum bia
USNM National Museum of Natural History, Smithsonian Znsti- tution, Washington, D. C.
Vienna Naturhistorisches Museum, Vienna
2.1. USSR
Zoological Institute, Academy of Sciences, Leningrad Genus Onocosmoecus Banks
Dicosmoecus (Onocosmoecus) Banks 1943, p. 357; type-species by original designa- tion D. (0.) tristis Banks 1900.
Onocosmoecus: Schmid 1955, p. 37.
Onocosmoecus: Flint 1960, p. 19.
Onocosmoecus: Wiggins 1977, p. 268.
Onocosmoecus: Schmid 1980, p. 83.
Originally recognized as a subgenus of Dicosmoecus (Banks 1943), Onocosmoecus was later elevated to full generic status by Schmid (1955) on the basis of characters of adults. Larval characters added to the generic diagnosis by Flint (1960) were augmented by Wiggins (1977).
DESCRIPTION. Adults (Fig. 1) over-all light to medium brown colour, legs uniformly light brown; fore wings yellow-brown with variable markings, corneous spots in cells R4 and M variably pig- mented from dark brown to colourless, variable darkish pigmented areas around these spots and along apical and costal margins, rang- ing from complete absence to the condition where most of the wing is medium brown; these corneous points and surrounding pig- mented areas sometimes show a range of expression in a series from a single locality; hind wings paler and without markings. Venation similar to Dicosmoecus except discoidal cell of forewing not more than three times longer than basal radial sector (petiole). Length of fore wing: male 14.5-22 mm; female 15-23 mm. Tibia1 spurs 1, 3,4. Head and thorax with sparse brownish and pale setae; setal warts approximately same colour as surrounding cuticle; pleural setal



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Wiggins & Richardson- Onocosmoecus
warts with pale setae, not as dense or long as in Dicosmoecus spp. (except D. obscuripennis Banks); mesepisternum lacking second setal wart.
Male genitalia (Figs. 2, 4, 1 1, 12). Segment IX broader laterally than in Dicosmoecus, sternum not extended posteromesally. Seg- ment X with external branches broad, flattened, longer than basal segment of inferior appendages, fused to segment IX close to mid- dorsal line dorsad of internal branches; internal branches variably fused together dorsally, inferior branches lacking or occasionally represented by small process, or well developed and prominent; subanal plate cleft mesally, truncate apically. Phallus bearing pair of stout spines ventrally at base of aedeagus; parameres partially and variably fused with aedeagus, each expanded into membranous apex bearing 1-6 stout spines, the arrangement, number and length of these spines extremely variable and in more than 50 per cent of specimens examined spines differ on each paramere of a single individual.
Female genitalia (Figs. 3,5,6,7, 13). Highly variable in structural detail. Segment VIII variably sclerotized ventromesally. Segment IX with massive rounded tergal lobes extending ventrolaterally to sternum IX which is here interpreted as reduced to a very small lobe or fold on each side of flattened vulval lobe; vulval lobe subdivided into three parts apically but continuous basally, median part varia- ble in shape, lateral parts concave mesally and variable in shape. Segment X elongate, forming anal tube, open ventrally, variably cleft dorsomesally; in ventral aspect, basal shoulders of segment X highly variable in shape even within single series, frequently extended into angulate ledge or tooth at each side. LARVA. (Fig. 8).
Broad, light coloured median band extending from coronal suture, over pronotum and mesonotum; sclerites of head, pronotum and mesonotum with dense, minute spines. Prono- turn lacking stout spines along anterior margin, but with row of 12- 16 long, black setae just behind anterior margin, pair closest to mid-dorsal line distinctly shorter, space between these setae and next seta on either side narrower than that between remaining setae of row (character valid at least to LIII); pronotum and mesonotum with sparse, short yellowish and longer dark setae. Metanotal setae confined to setal areas, variable: sal4- 15, sa2 3- 13, sa3 9-26; metep- imera each with approximately 8- 15 setae. Setae on or near ventral



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Figs. 2-3.
Onocosmoecus unicolor (Banks). 2, Male genitalia (specimen from Ontario, Durham Co.): a, lateral; b, dorsal; c, ventral; d, phallus, lateral and ventral. 3, Female genitalia (specimen from Ontario, Durham Co.): a, ventral; b, detail of vulva1 lobe; c, lateral. (anal op., anal opening; gen. op., genital opening; IXt & IXs, tergum and sternum of segment IX; inf. app., inferior appendage; ext. br. X, int. br. X, external and internal branches of segment X; subanal pi., subanal plate).



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19861 Wiggins & Richardson- Onocosmoecus 193 edge of femora: profemur 1-3, mesofemur 4-1 1, metafemur 6- 13; tibiae with a single pair of stout spur-like setae; trochanteral brush present on all legs, density variable. Femora flattened and com- pressed, ventral edges blade-like. Abdominal segment VI with 1-4 setae posterodorsally on each side of median line; VII with 1-5, usually 4 setae in this position; VIII with dorsal transverse row of approximately 16-24 setae; dorsal sclerite on segment IX with 12-15 setae; lateral abdominal gills present on segments IV and V; abdom- inal gills: dorsal, I1 1-2,3-4; I11 3,3-4; IV 3,3-4; V 2-3,2-3; VI 2-3, 2-3; VII 2,2-3; VIII 0-2; lateral, I1 0,2-3; I11 2-3,2-3; IV 2-3,2; V 1-2; ventral, I1 2,4; 111 3,4; IV 3, 3-4; V 2-3, 4; VI 2-3, 3-4; VII 2, 2-3. Length of larva up to 25 mm.
CASE (Fig. 9).
Constructed of fragments of leaves, wood and bark, walls rather thin and flexible; length of case up to 27 mm. PUPA.
Generally as in Dicosmoecus with dorsal hook plates on segments 111-VII, dorsal sclerites on segment I with pronounced median notch, and setal tufts present on first two antenna1 seg- ments; dorsum of segment VIII with approximately 30 setae, dor- sum IX with approximately 14; anal processes slightly curved. Onocosmoecus unicolor (Banks)
Anabolia unicolor Banks 1897, p. 27; holotype 9, Washington, Mus. Comp. Zool. Harvard.
Asynarchus tristis Banks 1900, p. 254; cotypes 13,29, Colorado, Mus. Comp. Zool. Harvard. NEW SYNONYMY.
Dicosmoecus coloradensis Ulmer 1905, p. 64, figs. 14-16; cotypes 2 Q, 19, Colorado, Naturhistorisches Mus., Vienna. NEW SYNONYMY. Anabolia quadrinotatus Banks 1908 (Anabolia 4-notata), p. 62, fig. 14; holotype 8, Newfoundland, Mus. Comp. Zool. Harvard. NEW SYNONYMY. Dicosmoecus flavus Martynov 1914, p. 253, cotypes 29, Kamchatka, Zool. Inst., Leningrad. NEW SYNONYMY.
Dicosmoecus (Onocosmoecus) occidentis Banks 1943, p. 362, figs. 104, 116, 124, 125,
128, 132, 136; holotype 3, Idaho, Mus. Comp. Zool. Harvard. NEW SYNONYMY.
Dicosmoecus (Onocosmoecus) alascensis Banks 1943, p. 363, figs. 105, 123, 129; holotype Q, Alaska, Mus. Comp. Zool. Harvard. NEW SYNONYMY. In 1943 Banks reviewed the characters used to distinguish the four Nearctic species then assigned to D. (Onocosmoecus), and at the same time described two additional species, D. (0.) occidentis and D. (0.) alascensis. After studying more than 1000 adult specimens,



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we conclude for reasons outlined below, that all of these names are best treated as synonyms of the original species 0. unicolor; also included in the synonymy is the Palaearctic 0. flaws. In distinguishing species within the unicolor complex, Banks (1943) utilized characters derived from colour of the fore wings and genitalic morphology. The corneous points on the fore wings of most Trichoptera in cells R4 and M (thyridial cell) are usually darkly pigmented in species of Onocosmoecus and contrast strongly with the light to medium brown fore wings. Around these points the membrane often has indefinite darkened areas, and the extent of these "clouds" was used by Banks as a diagnostic character (Fig. 1). Although the darkened areas show some differences among type series, we found that variation prevented their use as effective diag- nostic characters. We have been unable to find in genitalic struc- tures of either males or females throughout the unicolor complex discrete or discontinuous character states signifying genetic groups and taxonomic species. Differences in shape of the branches of segment X or segments of the inferior appendages to which Banks (1943) also referred seem valid for a few male specimens but blend into a seemingly continuously variable range when more series are studied. Particular importance as diagnostic characters was given by Banks to the number and arrangement of spines on the parameres. We found inordinate variability in these spines, ranging from one to six on each paramere throughout the range of the unicolor complex and frequently with a range in number exhibited within a series from one locality; size and arrangement of the spines was equally variable. Frequently on the two parameres of a single individual the spines differed in both number and arrangement, sometimes exhibit- ing conditions said to be diagnostic for two of the putative species. Diagnosis of the females was based mainly on characters of the shape of the tapered posterior extremity of segment X (Banks' sheath of the ovipositor) and presence of a basolateral tooth or ledge, and shape of the three parts of the vulva1 lobe. Using these features Banks characterized the females in rather general terms but not with precise diagnoses. We found, as with the males, that because of many intermediate conditions in the characters proposed we were unable to establish discrete groups for females within the unicolor complex.
We have been cognizant of the possibility that species might be definable within the unicolor complex on the basis of other



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19861 Wiggins & Richardson- Onocosmoecus 195 Figs. 4-6.
Onocosmoecus unicolor (Banks). 4, Male genitalia (specimen from Alaska, Admiralty Is.): a, dorsal; b, ventral. 5, Female genitalia (specimen from Alaska, Admiralty Is.), ventral. 6, Female genitalia (specimen from Oregon, Baker Co.), ventral.
characters, including those from other body structures, but we have not been able to recognize discontinuities in any other characters. Thus we conclude from our study of this material that the entire unicolor complex is best treated as a single, variable taxonomic species. Conclusions from study of the type specimens of the species placed in synonymy follow.
0. unicolor (Banks).
We have examined the holotype female
(Skokomish R., Washington) in the Museum of Comparative Zool- ogy. The wings are torn and the apical lobes of segment X broken. The two corneous points on the fore wing are only lightly pig- mented, and the surrounding membrane only slightly darker than



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196 Psyche [vo~. 93
the rest of the wing. Banks (1943) stated that the apical lobes of segment X are longer in 0. unicolor than in the other species; in females of the unicolor complex that we have examined these lobes are elongate but variable, and discontinuously longer in none. In the holotype there is a distinct tooth or ledge at the base of each lobe of segment X on the lateral margin (e.g. Fig. 6); expression of this character also shows continuous variability in our material and the ledge is lacking in most specimens (e.g. Fig. 3a). The median and lateral vulval lobes of the holotype taper to rounded points, which blend continuously with a range of conditions in our material. The male has not been clearly identified in the literature. The illustration of male genitalia labeled as unicolor by Ross (1938, fig. 48) was given only the status of the "supposed male of bunicolor"' by Banks (1943); and although no locality data were given for the specimen illustrated by Ross, Banks (1943: 364) stated that it came from Inyo Co., California. Banks himself (1943) referred to speci- mens from Banff and Alaska that "may be males of this species," offering as a diagnostic character that the third and fourth spines of the paramere are not widely separated. Our material shows such a very wide range of variation in arrangement of the spines of the parameres that this character cannot be regarded as distinctive. 0. tristis (Banks). We have examined the three specimens (South Park, Colorado) in the type series from the Museum of Comparative Zoology. From these specimens Ross (1938) desig- nated a lectotype male (17 Aug. 1899) and lectoallotype female (20 Aug. 1899); the remaining female (20 Aug. 1899) is identical to the lectoallotype. Ross (1938) placed 0. tristis in synonymy with 0. unicolor, but Banks (1943) maintained that the two were distinct species. Although the females in the type series were characterized by a pronounced basolateral tooth or ledge on segment X (Banks 1943), there seems little difference between these specimens and what remains of this character in the holotype of 0. unicolor (see above). The apices of the posterior lobes of segment X are closely appressed in both females of the type series, and all three parts of the vulval lobe are truncate. This latter character contrasts with somewhat more rounded lobes in the holotype of 0. unicolor, but we have many specimens showing intermediate conditions. The male in the type series of 0. tristis was distinguished by narrower external branches of segment X (superior appendages of Banks), but



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19861 Wiggins & Richardson- Onocosmoecus Fig. 7. Onocosmoecus unicolor (Banks), female genitalia (specimen from Kam- chatka, U.S.S.R.; Syntype of 0. flavus (Martynov)): a, ventral; b, lateral. we find little distinction in this character and considerable variation in our material generally (cf. Figs. 2 and 4). The five spines of the parameres, offered as a diagnostic character for 0. tristis by Banks, have little value in view of the wide variability in number, size and arrangement in our material of the unicolor complex. The three specimens in the type series show slightly different degrees of pig- mentation of the corneous points of the fore wing. Although Ross (1938) designated both lectotype male and lectoal- lotype female for 0. tristis, there is no male specimen bearing a lectotype label, and it must be concluded either that the specimen was not labelled, or that the label or labelled specimen has been lost. Since among the three remaining specimens of the type series there is only one male, that specimen is here designated lectotype, an assignment which would of course lapse should Ross' lectotype be found.
0. coloradensis (Ulmer). In the original description Ulmer offered no diagnostic characters for separating 0. coloradensis from closely related forms, but he later commented in a re-description of 0. flaws (Ulmer 1927: 6) that his 0. coloradensis was the same as Asynarchus tristis Banks, the genital appendages resembling in turn those of 0. flavus Martynov. Diagnosis on the basis of only two spines on each paramere was later proposed by Banks (1943), who



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unicolor
Figs. 8-9.
Onocosmoecus unicolor (Banks), larva (specimen from British Colum- bia). 8a, larva with detail of mesofemur, lateral; b, abdominal segments VII, VIII, IX, dorsal; c, head and thorax, dorsal. 9, case, detail of posterior end.



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19861 Wiggins & Richardson- Onocosrnoecus 199 cited an illustration by Ross (1938, fig. 48) as an example. It is not clear what basis there was for this character; no reference was made to it in Ulmer's original description (no genitalic preparations had been made from the type series), and Ross' figure actually shows a third small apical spine on the paramere. Origin of the specimen on which Ross' figure 48 was based was not given, although Banks (1943: 364) stated that it came from Inyo Co., California; further- more, although designated as 0. unicolor by Ross, the specimen was not accepted by Banks as the male of that species (see above), evi- dently because he regarded it as 0. coloradensis. We have examined the three co-types (23, 19, S. Colorado, 1879) in the collection of the Naturhistorisches Museum, Vienna. The parameres of one male each have three spines and those of the other, four spines. We find no other features of these males that are dis- tinctive. In the female of the type series, the apical lobes of segment X are rather long and slender, lacking the basal ledge or tooth of the holotype of 0. unicolor or the females in the type series of 0. tristis. The two corneous points in the fore wing are dark in all specimens, which in the males particularly are surrounded by a relatively large dark area.
0. quadrinotatus (Banks). We examined the holotype male (Grand Lake, Newfoundland, 28 July 1906) in the Museum of Comparative Zoology. This is the only name based on material from eastern North America, and was distinguished from the west- ern forms by uniformly dark fore wings (Banks 1943). The holotype displays this character, but in some eastern populations there is a tendency for slighty darkening around the spot in cell R4 (Fig. lb). Moreover, some specimens from western North America also have uniformly dark fore wings, e.g. Fig. Id. Some of these have several spines on the parameres (e.g., California, Nevada Co., Sage- hen Cr., 4 Aug. 1985, 18, ROM), but in others the spines are reduced to one or two (Utah, Summit Co., E. Fork Bear R., ca. 2 mi. above confluence with Bear R., 4-5 Aug. 1985, 7 3, ROM; Idaho, Teton Co., Darby Cr., 6-7 Aug. 1985,6S, ROM). The holo- type male has five and six spines respectively on the two parameres, distinguished by the basal spine being little longer than the others and not reaching the tip of the paramere (Banks 1943). Within the eastern part of North America where no western species has ever been recorded in the literature, we found spines of the parameres



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200 Psyche [VOI. 93
ranging from three to six, with the basal spine in some extending to the end of the paramere; and within a single series (Province of Quebec, Wacouno R., n. Sept. Iles, 10 Aug. 1973, ROM) all conditions from three to six are represented. No precise diagnosis was offered for the female by Banks, but only the general characters of rather short apical lobes (Banks' sheath of the ovipositor) and absence of a basal ledge on segment X, and a broad median vulval lobe (Fig. 3). Our sample of females from eastern populations comprises only six specimens (Ont., P.Q., N.H., Mich.), but genitalic structures differ considerably among them: shape of the vulval lobes, and on segment X, the length and taper of the apical lobes and development of the basolateral ledge. These variations concern the same characters proposed by Banks for diagnosis of the western species of Onocosmoecus, and we find no other basis for identification of 0. quadrinotatus as a separate species.
0. occidentis (Banks). We examined the holotype male (Wal- lace, Idaho, l October) in the Museum of Comparative Zoology. Diagnosis was based solely on genitalic characters. In the male the internal branch of segment X (Banks' superior plate) was said to be broadened toward the base and to have a median separation extend- ing to the basal fourth; our examination of the holotype reveals no distinctive broadening in the shape of these combined internal branches and the median separation extends no more than half the length, which is generally characteristic of males of the unicolor complex. Spines of each paramere are four in number as stated, but the arrangement attributed to them holds true only for one para- mere of the holotype, spines of the other being quite different. The female was distinguished by characters of segment X-short apical lobes with slightly divergent tips and lacking the basolateral tooth or ledge; over the range of characters in 0. unicolor s.l.. none of these characters is unique as described, and we find nothing that would serve to distinguish this species. 0. alascensis (Banks). We have examined the holotype male (1 Aug. 1917) and single male paratype (29 July 1917), both from