CORE Metadata, citation and similar papers at core.ac.uk Provided by University of Minnesota Digital Conservancy J. N. Am. Benthol. Soc., 1993, 12(4):438-443 © 1993 by The North American Benthological Society A new species and new records of Oxyethira (Trichoptera:Hydroptilidae) from Minnesota MARGOT P. MONSON AND RALPH W. HOLZENTHAL Department of Entomology, University of Minnesota, St. Paul, Minnesota 55108 USA Abstract. Males of a new species of microcaddisfly, Oxyethira (Holarctotrichia) itascae, (Trichoptera: Hydroptilidae) from the Lake Itasca region of northern Minnesota are described and illustrated. This represents the first new species of Trichoptera described from the State in nearly twenty years. Fifteen other Oxyethira species are known from the State, including 0. (Dampfitrichia) verna Ross and 0. (Oxyethira) ecornuta Morton, new records for Minnesota and the United States, respectively. Key words: Oxyethira (Holarctotrichia) itascae, caddisflies, endemic, biome. Fifty-eight of the 280 species of Trichoptera Methods known from Minnesota are members of the Trichoptera were trapped with 15-watt D.C. family Hydroptilidae and, of these, 16 are spe­ black lights suspended over pans containing cies of Oxyethira Eaton. Oxyethira species have 80% ethanol and placed at water's edge. Col­ been reported from all the major faunal regions lections were made every two weeks from May of the world, with species records throughout to October, 1988 and 1989. Specimens were the North American continent. The larvae are cleared in 10% KOH solution (Ross 1944). Due typically encountered in standing waters or in to their small size, they were examined under lotic habitats where the current is slow. They compound and dissecting microscopes for iden­ commonly are located on submerged aquatic tification; illustrations were made with the aid plants, where they feed on filamentous algae of a drawing tube attachment on an Olympus and diatoms. Some species have been discov­ BH-2 compound microscope. Terminology for ered in faster-flowing waters on rocky, moss­ genitalic structures follows that of Kelley (1984). covered substrates (Marshall 1979). Larvae of Type material is deposited in the University of North American Oxyethira may be identified by Minnesota Insect Collection, St. Paul (UMSP), their exceptionally long, slender meso and me­ the National Museum of Natural History, tathoric legs, which are at least 2 1h times longer Smithsonian Institution, Washington, D.C. than their prolegs, a long distoventral lobe on (NMNH), and the Illinois Natural History Sur­ the fore tibiae, and very long antennae relative vey, Champaign, Illinois (INHS), as indicated to most other genera in the family. In the final below. instar, larvae are found within flattened, bottle­ shaped cases constructed entirely of silk (Wig­ Oxyethira (Holarctotrichia) itascae gins 1977). Monson and Holzenthal, new species Lake Itasca, headwaters of the Mississippi Fig. 2 River, is in a region of Minnesota where the northern coniferous forest, eastern deciduous Diagnosis. Oxyethira itascae is assigned to the forest, and tallgrass prairie biomes meet (Fig. subgenus Holarctotrichia Kelley because of pos­ 1). During 1988 and 1989, adult caddisflies were session by the males of long dorsolateral pro­ collected at the edge of three creeks and one cesses on segment VIII, convergent but separate small lake near Lake Itasca, as part of a study subgenital processes, and an elongate titillator on the phenology and diversity of the Trichop­ on the phallus (Kelley 1984). Oxyethira itascae tera of the region. During the study, a new spe­ bears some resemblance to 0. distinctella Mac cies of Oxyethira was discovered, which we de­ Lachlan and 0. araya Ross, both in the subgenus scribe here. Holarctotrichia, in the shape of segments VIII 438 This content downloaded from 134.84.28.154 on Wed, 21 Jun 2017 14:45:57 UTC All use subject to http://about.jstor.org/terms 1993] NEW SPECIES OF 0XYETHIRA 439 ··:----Lf ........ _}·.Nor .. , thern Conferous Fore~t: ;--- -; !~~~~-·-~~~?-- ', . < I ....... I :·----·--·- · ~-"' ··· -- - i~~1ern~L-tq..KXr.io F-;Cf"' ! ·--. ·\, l_ ___ )-·.-·.( ' Northern II Coniferous Forest Eastern D Deciduous Forest D Tallgrass Prairie FIG. 1. The three major biomes of Minnesota and the distribution of 0. itascae, n. sp. Inset: Approximate extent of the same biomes in the Great Lakes region. and IX. In 0. araya and 0. distinctella the pos­ Blickle's (1979) key to Oxyethira species with terior margin of segment VIII possesses a tri­ slight modifications to his first couplet and the angular configuration similar to 0. itascae, and addition of a third choice. the dorsolateral processes are similar to the me­ 1. 8th tergite produced into a single process dial pair of processes in the new species; also, on the apicolateral margin . 2 in 0. araya and 0. distinctella the truncate dorsal - 8th tergite not produced into processes margin of segment IX resembles that of 0. itas­ on apicolateral margin .............. 14 cae (Kelley 1986). The presence of two pairs of - 8th tergite produced into two processes elongate dorsolateral processes on segment VIII on the apicolateral margin .. itascae, n. sp. distinguishes the new species from all others in the subgenus in North America. Description. Males. Length 2.8-3.0 mm. The new species can be determined using Brown in alcohol. Antennae with 25-32 seg- This content downloaded from 134.84.28.154 on Wed, 21 Jun 2017 14:45:57 UTC All use subject to http://about.jstor.org/terms 440 M. P. MONSON AND R. W. HOLZENTHAL [Volume 12 A ,, (~ \\ '···-~< B E FIG. 2. Oxyethira itascae, new species, male genitalia. A. Segments VII-X, lateral; B. Segment IX, lateral; C. Segment VIII, dorsal; D. Segments VIII and IX, ventral, inset: details of inferior appendages, subgenital processes, and bilobed processes; E. Phallus, dorsal. Abbreviations: bp = bilobed process; ia = inferior ap­ pendage; sg = subgenital process; sl = setal lobe. ments. Genitalia as in Figure 2. Abdominal ster­ gent digitate apices; setal lobes and bilobed pro­ num VII with apicomesal process. Segment VIII cesses each with single seta. Segment X entirely roughly triangular in lateral view, with taper­ membranous. Phallus simple with spiralled ing posterior margin; dorsally, with squared titillator. posteromesal excavation and two pairs of elon­ Females and immatures. Unknown. gate dorsolateral processes: lateral pair elon­ Holotype. Male. Minnesota: Clearwater gate, extending beyond apex of segment IX, County: Itasca State Park, Nicollet Creek at Wil­ slender, acute apically, curved mesally; medial derness Drive, 47.194°N, 95.230°W, el. 1500 ft., pair about 1h length of lateral pair, setose, with 19.viii.1988, col. M. Monson (UMSP). apicomesal serrations. Segment IX roughly tri­ Paratypes. Minnesota: Hubbard County: angular in lateral view, retracted within VIII; LaSalle Creek at Co. Rd. 40, 47.349°N, 95.165°W, in lateral view, dorsal margin truncate, dorsal el. 1394 ft., 25.vi.1988, col. M. Monson, 29 males and lateral edges semimembranous, except for (UMSP); same, except 02. vii.1988, 2 males sclerotized region on posterior margin. Inferior (INHS); same, except 24.vii.1988, 2 males appendages fused to IX with U-shaped config­ (NMNH); same, except 26.vii.1988, 4 males uration in ventral view, mesally setose, tapered (UMSP); same, except 13.viii.1988, 12 males to acute apex, slightly curved mesally. Subgen­ (UMSP); same, except 22.viii.1988, 20 males ital plate prominent, sclerotized, with conver- (UMSP). This content downloaded from 134.84.28.154 on Wed, 21 Jun 2017 14:45:57 UTC All use subject to http://about.jstor.org/terms 1993] NEW SPECIES OF OXYETHIRA 441 Etymology. Named for Lake Itasca, the head­ currence in Minnesota represents a western limit waters of the Mississippi River. The name Itasca of its range, it may be a species associated pri­ was derived from ver(itas ca)put after the ex­ marily with the eastern deciduous forest, which plorer Henry R. Schoolcraft, who in 1832 found meets its western limit near the Itasca area. the lake to be the true source of the Mississippi Ross (1967) states that the ecological charac­ River. teristics of many caddisflies found only in small Distribution. Known from the type locality streams are a result of the complex interrela­ and the edge of LaSalle Creek, Hubbard Coun­ tionships with the terrestrial communities bor­ ty, in northern Minnesota; flight period is from dering them. The caddisfly faunas in these hab­ early June through mid September. itats are influenced by shade, leaf-fall, precipitation, the climax community, and the Discussion relationship between these variables. Correla­ tions have been made between caddisfly phy­ Oxyethira itascae is the first caddisfly to be logenetic and distributional information and the described from Minnesota since Wiggins' (1975) dispersal patterns of some plant groups with description of Chilostigma itascae (Limnephili­ which caddisflies have an ecological association dae) and Etnier's (1968) descriptions of Ceraclea (Ross 1967). brevis (Leptoceridae, as Athripsodes) and Polycen­ The state of Minnesota is at the cross roads tropus milaca (Polycentropodidae), all believed of three major biomes, the northern coniferous to be endemic species. The discovery of 0. itas­ forest, the eastern deciduous forest, and the tall­ cae at the edge of Nicollet Creek in Itasca State grass prairie, which offer habitat variety more Park is especially interesting because this is also diverse than the surrounding states (Coffin and the type locality for Chilostigma itascae, which is Pfannmuller 1988). The Itasca region in partic­ known only from adults and represents the sin­ ular is even more closely associated with this gle record for that genus outside of Scandinavia merging of biomes, because the coniferous and and Finland (Wiggins 1977). Nicollet Creek, deciduous forests intermingle in the area, grad­ with its silty bottom and many spring seepage ually giving way to tallgrass prairie just west areas, meanders through a wetland meadow of the Itasca region. As a result of ongoing stud­ surrounded by coniferous forest on its way to ies and the county biological survey of plants join Lake Itasca.