The eastern Nearctic species Rasvena terna ( Frison , 1942 ) ( Plecoptera , Chloroperlidae )

New and prior valid records of the endemic eastern Nearctic species Rasvena terna (Frison, 1942) were compiled and a dot distribution map is provided. Rasvena terna is reported from Canada (Quebec) for the first time. External reproductive morphology of adult males and adult females were studied across this species range. Scanning electron microscopy images of reproductive structures and the larval mandible are presented for the first time.


Introduction
described Chloroperla terna from Vermont, noting similarities with reproductive structures of Chloroperla (Newman, 1836) (sensu Kimmins 1936).Paratypes were also included from New York and Tennessee.Ricker (1952) transferred the species to the new subgenus Rasvena based on the reduced folded anal region of the forewing.Illies (1966) elevated Rasvena to full generic status although Hitchcock (1974) retained the original nomenclature of C. terna without explanation.Fiance (1977) provided the first descriptions and illustrations of the larvae and the first larval key to the eastern North American Chloroperlidae.Surdick (1985) placed R. terna in the new tribe Chloroperlini, with redescriptions and illustrations of adult males, adult females, and larvae.Surdick (1985) hypothesized that Rasvena either has a Beringian tie to an Asian ancestor or a Laurasian origin with a European ancestor.Neither hypothesis has been tested using modern phylogenetic methods.Full descriptions and illustrations of the larva were subsequently included in Stewart andStark (1988, 2002).Descriptions of the larva, plus full descriptions and illustrations of both adult stages, were again presented in Surdick (2004).Little is known about larval biology aside from general associations with stream size, elevation, and when adults have been collected (Stewart and Stark 2002).
Rasvena is still monotypic and R. terna is a widespread Appalachian species (Surdick 2004, DeWalt et al. 2018).NatureServe (2017) has applied a global ranking of G4 (= Apparently Secure).Although R. terna has been included in species lists or noted as new records in several publications at various scales (i.e., state, region, park; Tarter and Kirchner 1980, Kondratieff and Kirchner 1988, Kondratieff et al. 1995, Grubbs 1996, Masteller 1996a, Tarter and Nelson 2006, Parker et al. 2007, Earle 2009, Myers et al. 2011, Beaty 2015) it is uncommonly collected and is reported herein from Canada for the first time.Repeated collecting efforts in western Maryland during the 1990s failed to locate populations of this species (Grubbs 1997).
The intent of this paper was two-fold: (1) study and present scanning electron microscopy (SEM) images of the adult male and adult female external reproductive structures and larval mandible, and (2) provide updated distributional information.An exhaustive search was conducted, providing records from museum holdings, individual collections, and valid literature sources.A dot distribution map is included.

Methods
Specimens or specimen data were obtained from the following collections and institutions: Bill P.  (WKUC).Specimen data were also integrated from valid literature sources.Locality data for all specimen records, in decimal degrees, were obtained either directly on site with GPS units or georeferenced from museum label data using Acme Mapper 2.1 (http://mapper.acme.com).All specimen data accrued and used during this project are archived in Darwin Core Archive file format supported by Pensoft's Integrated Publishing Toolkit (Grubbs 2018) Adult male and female abdominal terminalia and larval mouthparts were prepared for SEM via serial dehydration in 75%, 95%, and 100% ethanol for 10 minutes each and hexamethyldisilizane for 30 minutes.Dehydrated specimens were attached to aluminum stubs with double-stick tape and coated with gold-palladium in an Emscope SC500.Coated specimens were examined using a Jeol JSM-6510LV scanning electron microscope and digital images were captured with an IXRF system.
Diagnosis.The male epiproct of R. terna is consistent in shape and size across its range.The flap of the female subgenital plate exhibits only small differences in form, namely shape (Figs 9,10)      Mountain region of upstate New York east to southern Quebec and Maine.Distribution information inferred from a collection label is insufficient for positive determination.

Discussion
The distribution as plotted herein for R. terna (Fig. 18) was based on material examined and valid literature records, but this should not be considered absolute or finite.For example, specimens from Maine were not immediately available for study but this species has been reported from this state (DeWalt et al. 2018).Only 37 individual vials in total were available for study.This is a sparse amount of material for a species with a broad Appalachian range extending approximately 2400 km along a straight line from northern Georgia to southern Quebec.Comprehensive examination of material housed in museums, state agencies and professional consulting firms, and private collections, together with fieldwork, should slowly expand our understanding of the distribution of this uncommon species.

Figure 18 .
Figure 18.Distribution map of Rasvena terna based on material examined during this study and valid literature data.The red circle refers to the type locality.The three yellow circles refer to the new Canadian province and US state records.