Review of the Canadian Eustrophinae (Coleoptera, Tetratomidae)

Currently, the Canadian fauna of Eustrophinae consists of 7 species in 5 genera, as follows: Pseudoholostrophus impressicollis (LeConte), P. discolor (Horn); Holostrophus bifasciatus (Say); Eustrophus tomentosus Say; Eustrophopsis bicolor (Fabricius), E. confi nis (LeConte); Synstrophus repandus (Horn). None of these 7 species is restricted to Canada; each has a wider distribution in the United States. Each species (adult stage only) is diagnosed and described with selected morphological features illustrated. A key to Nearctic genera, and Canadian species of Eustrophinae is presented, as well as a checklist of all Nearctic species of the subfamily. Lectotypes are designated for Holostrophus discolor Horn and Eustrophus confi nis LeConte. Neotypes are designated for Eustrophus bifasciatus Say and Eustrophus tomentosus Say. Th e Canadian distribution of each species is mapped in detail, as well as a general indication of distribution in the United States. Aspects of the natural history of all species, where known, are included.


Introduction
Th e Eustrophinae are a relatively small, structurally and ecologically homogenous group of tenebrionoid beetles.Like many other taxa of the superfamily, these beetles have not had a stable family placement until recently.Th is instability is due at least partly to the over-reliance on adult characters, which suggested to some authors a relationship between the Eustrophinae and Melandryidae (e.g.Arnett 1968).Other non-North American authors (e.g.Crowson 1964;Hayashi 1975;Viedma 1971) suggested a relationship between Eustrophinae and Tetratomidae, based on both adult and larval characteristics.Indeed, due to the popularity of Arnett (1968), most North American coleopterists were unfamiliar with the family Tetratomidae, since Arnett chose to incorporate its constituents into a very broad concept of Melandryidae.In the most recent comprehensive family/subfamily-level classifi cation of Coleoptera, Lawrence and Newton (1995) placed the Eustrophinae again within Melandryidae.However, the eustrophines seem to have found a stable family placement within the Tetratomidae, as outlined by Nikitsky (1998).Earlier, Chantal (1985) also placed the eustrophines in Tetratomidae, without giving any detailed explanation.Nikitsky (1998) treated the genera of Tetratomidae worldwide, and combined larval and adult characters into the classifi cation.He also created several new taxa within the subfamily, notably the new tribe Holostrophini and a new subgenus Holostrophinus, and synonymized the name Eustrophinus Seidlitz with Eustrophopsis, the latter of which was formerly restricted to mainly tropical species with a notched prosternal process.No phylogenetic analysis accompanied the treatment of Nikitsky (1998) but placement within Tetratomidae seems well supported.
Like most groups of Coleoptera, relatively little is known about the ecology and habits of members of Eustrophinae, although they are associated with various fungi found in and on coarse woody debris in forest habitats.Most fungal host records are within the Polyporales (e.g.Polyporus, Fomes, Trametes, Meripilus, Panus, Spongipellus, and Laetiporus), with several genera of Agaricales also (e.g.Pleurotus and Omphalotus).Specimens have also been taken from fungi on isolated trees, for example, in urban areas.Host records and habitat associations are given in Chantal (1985), Lawrence (1991) and Majka and Pollock (2006).When observed and/or collected in situ, adult eustrophines are most often found on fruiting bodies of the fungi, or adjacent wood.Larvae are often found deeper within the substrate, where there is a mixture of fungal hyphae and rotting wood.Adult eustrophines are uncommonly collected in long series, except when they are trapped (e.g. in Lindgren funnel traps) or sought at night on fungusy wood.Th e fact that there are gaps in the distributions of species such as Eustrophus tomentosus Say and Synstrophus repandus (Horn) may be due more to lack of eff ective collecting methods than to unsuitable habitat or other barriers.Details of natural history are given below, for individual species; most data are taken directly from specimen labels.
Th ere is presently no comprehensive treatment of any genus of Eustrophinae or of the entire subfamily; for North American components of the group, all that has been published are checklists (e.g.LeSage 1991) or keys to genera (e.g.Arnett 1968;Young and Pollock 2002).Nothing specifi c has been published regarding the Canadian eustrophines, although Chantal's (1985) "Tetratomidae of Quebec" included six of the seven species of Eustrophinae found in Canada.In fact, southern Quebec is the area of highest diversity of Canadian Eustrophinae.In this work, species are keyed, described briefl y, and distributions mapped.Also, data on biology and natural history were presented for each species.Th e present study, while overlapping considerably at the species level, is an extension of the excellent work done by Chantal (1985), as it enlarges the coverage to the entire country, and also updates the taxonomy, notably at the genus and subgenus levels.
No species of Eustrophinae are restricted to Canada; rather, the Canadian distribution of each represents the northern range limit of an otherwise fairly widespread USNM National Museum of Natural History, Smithsonian Institution, Washington, DC UWEM University of Wisconsin, Madison, WI Standard methods of examination and description of specimens were used.Published lists of localities for Canadian Eustrophinae (e.g.Chantal 1985) were used to construct the distribution maps, but specifi c locality data are not given under the section "material examined".
Due to the regional aspect of this paper and because it is not meant to be a taxonomic revision, full descriptions are not given for genera or species; rather, descriptions are diagnostic in nature, with emphasis on characteristics that will facilitate rapid determination of species.Complete descriptions (of genera and species) will be published elsewhere, as part of a comprehensive review of the entire subfamily Eustrophinae.
Because of the relative rarity of specifi c life history data, all known information is given for each species, even if taken from specimens collected outside of Canada.Th e geographic origin of such extralimital information is indicated by the standardized, two-letter postal abbreviation following each datum.
In the descriptions, TL = length from anterior margin of pronotum, to elytral apex along midline.Th e length of the head was not used, since the head is defl exed and therefore does not contribute to body length.GEW = greatest width across both elytra.
For type specimens, complete verbatim label data are given, enclosed within quotation marks; individual labels are separated by a slash (/).
Figures 1-14 were taken with a JVC digital camera KY-F775U attached to a Leica Z16 APO stereoscope.Images were then modifi ed using Auto-Montage Pro version 5.01.0005.Figures 15-16 were taken through a Leica MZ95 stereoscope, using a Nikon CoolPix digital camera; they were not modifi ed further.were produced using a camera lucida attached to a Wild stereoscope.

1
Outer faces of meso-and metathoracic tibiae with numerous oblique, comblike ridges (as in Fig. 16) ...  -Innermost margins of eyes more narrowly separated (Fig. 12), in some specimens virtually contiguous; if slightly separated, then gap less than length of fi rst antennomere; body dark dorsally, with legs, much of venter and antennomere 11 distinctly contrasting ..

Species accounts
Tribe Holostrophini Nikitsky, 1998 Pseudoholostrophus Nikitsky, 1983 Pseudoholostrophus Nikitsky, 1983: 37.-Type species: Hallomenus klapperichi Pic, 1954 (orig. des.);Nikitsky, 1998: 40;Young and Pollock, 2002: 416.Th is genus was described by Nikitsky (1983) on the basis of examination of Hallomenus klapperichi Pic, which is now included in, and type species of Pseudoholostrophus.According to Nikitsky (1998), Pseudoholostrophus diff ers from Holostrophus in its smaller and more weakly emarginate eyes, and the prosternal process not extending behind the posterior edge of the procoxae.Th ere are four species in Pseudoholostrophus (Nikitsky, 1998), two of which are Nearctic (including Canada) in distribution.Th e other two species, P. klapperichi (Pic) and P. chinensis Nikitsky, are known from China.Nikitsky (1998) divided the genus into two subgenera; all species other than P. discolor (Horn) are placed in the nominate subgenus.Holostrophus discolor (Horn) was transferred to Pseudoholostrophus (Holostrophinus) by Nikitsky (1998).
Distribution (Fig. 26) Th is species is restricted to extreme western North America.In Canada, all known records are from Vancouver Island and the adjacent mainland of British Columbia, north to the Queen Charlotte Islands.Th is is seemingly one of the rarest, or most infrequently collected, species of Nearctic Eustrophinae; most localities are represented by a single specimen.US distribution: WA (Hatch 1965), OR, CA.
Natural history Little is known regarding the habits of P. impressicollis.Label data indicate the following: under bark of pine; in rotten log; fungus.
Natural history Given that specimens of P. discolor are rarely collected, there are very few data available on its habits or biology.Label data include the following: in polypore fungus; malaise trap (NH); intercept trap (PA).According to Chantal (1985) specimens are known from small polypores on trees, notably cherry (Prunus) and maple (Acer).A single specimen from New Brunswick (CNC) bears a label stating "on or near fl eshy polypore fungi on beech log".Hatch (1965) 1965: 66; LeSage, 1991: 246;Poole and Gentili, 1996: 299;Nikitsky, 1998: 48;Young and Pollock, 2002: 416.According to Nikitsky (1998), this genus comprises 17 species worldwide, distributed in the Russian Far East, Korea, China, Japan, the Orient, and Nearctic regions.In North America, there is the single species H. bifasciatus (Say).In further justifying his separation of the genera Pseudoholostrophus and Holostrophus, Nikitsky (1998: 40) stated that "it seems noteworthy that species of Pseudoholostrophus display the elytra either one-color but not black or with a light humeral spot only, or with a clarifi ed diffused transverse fascia in basal part.A more clearly evident reddish-yellow or red spotty pattern of the elytra is characteristic of Holostrophus, not Pseudoholostrophus".
Distribution (Fig. 30) Although specimens are seemingly rarely collected, E. confi nis exhibits one of the broadest west-east ranges.Th e species is known from western British Columbia to Nova Scotia.Th e single record from Saskatchewan is the most northerly known specimen of Eustrophinae in North America.US distribution: ID, MI, ME, NE, NH, SD, WI.

Discussion
Th e Eustrophinae, like many groups of "little brown beetles", are rather obscure, infrequently encountered by general collectors, and without much detailed knowledge of their biology.Th eir somewhat cryptic habits and habitats, and predominantly nocturnal activity have allowed this obscurity to continue.However, in preferred habitats (i.e.dead trees with wood-rotting fungi), individuals of some species (e.g.E. bicolor and S. repandus) can be very abundant.One must be willing to visit these habitats after dark, and examine dead wood surfaces and/or associated fungi.
Eustrophines are a small part of the entire group of saproxylic Coleoptera, which includes species that are wood and bark feeders, fungal feeders, and predators (Jonsell, 1999).In forest habitats, saproxylic Coleoptera represent a large component of the beetle fauna (Hammond et al., 2004;Siitonen, 2001).For example, about 25% of Swedish beetles are saproxylic (Jonsell, 1999); these species are partly responsible for the breakdown of coarse woody material, through direct feeding action and transferring fungi among individual logs, snags and stumps (Hammond et al., 2004).Most studies on the importance of saproxylic Coleoptera to forest ecology and management were done in Europe, notably in Scandinavia (e.g.Martikainen, 2001;Siitonen, 2001).European Coleoptera are better known, both taxonomically and ecologically, with habitat associations generally well understood for most species.Studies on saproxylics in North America have lagged somewhat behind, although they have become better known through increased awareness of their importance in forest habitats in Canada and the United States.Indeed, according to Hammond et al. (2004: 16) "in North America, saproxylic assemblages are poorly understood and woefully understudied".
Forest management practices can signifi cantly aff ect diversity and abundance of saproxylic Coleoptera (Majka and Pollock, 2006), although most considerations of the eff ects of forest practices focus on vertebrates (Hammond et al., 2004).Some recent studies in Canada (e.g.Hammond, 1997;Hammond et al., 2001;Majka and Pollock, 2006) have revealed a rich fauna of saproxylic Coleoptera, although there is much more to learn about these ecologically important beetles.Although the Canadian Eustrophinae are relatively few in species, they are occasionally very abundant in wood-rotting fungal habitats, and are undoubtedly an integral component of the "coarse woody debris" insect assemblage.As suggested by Majka and Pollock (2006), further work is required to initially identify the saproxylic beetle assemblages, determine their role in forest communities, and then to recommend silvicultural practices that minimize impact on these insects.For the Canadian eustrophines specifi cally, very little is known about their feeding preferences, life histories, immature stages and other bionomic parameters.Perhaps once these are better known, the ecological importance of these historically obscure beetles will be shown to be greater than previously thought.