Why Museums Matter: A Tale of Pinworms (Oxyuroidea: Heteroxynematidae) among Pikas (Ochotona princeps and O. collaris) in the American West [Critical Comment]

Permanent and well-supported museum or natural history collections provide a solid foundation for the process of systematics research through creation of an empirical record which validates our understanding of the biosphere. We explore the role of museums in ongoing studies of the complex helminth fauna characteristic of pikas (Ochotona spp.) in the American west. These studies address the taxonomy for pinworms of the Labiostomatinae and the problems associated with the absence of adequate type series and vouchers and with misidentifications in original descriptions. We demonstrate that the types for Labiostomum (Labiostomum) coloradensis are identical to some specimens in the syntype series representing L. (Eugenuris) utahensis, although the published descriptions are in disagreement. Both are identical to L. (Eugenuris) talkeetnaeuris and, as a consequence, are reduced as junior synonyms. Only 2 species of large pinworms, namely L. (Labiostomum) rauschi and L. (Eugenuris) talkeetnaeuris, are widely distributed in Ochotona collaris and O. princeps. Although this serves to clarify the taxonomy for species in these genera, prior records remain confused, as representative voucher specimens from all major surveys in North America were never submitted to museum collections. We strongly suggest that type and voucher series should not be held in private or personal collections, where such are eventually lost, discarded, or destroyed through neglect due to inattention and the absence of curation. The potential to accumulate meaningful baselines for assessment of environmental change is jeopardized if materials from survey and inventory are not routinely submitted to museum collections. The capacity of museum repositories, as a focus for systematics, ecology, and evolutionary studies and for the development of resources for biodiversity informatics, continues to be undervalued and poorly utilized by a cadre of scientists who are dependant on accurate and definitive information that transcends specific disciplines. In biology and parasitology, confusion over issues of taxonomy and the host and geographic distributions of species are not uncommon. In resolving such challenges, natural history collections and the specimens held in such museum repositories are critical, whether these represent irreplaceable type series or the vouchers that document associations on varying temporal and spatial scales. Specimens, associated data, and permanent collections provide a solid foundation for the process of systematics research through creation of an empirical record, which validates our understanding of the biosphere. Increasingly, collections reside at the core for development of resources for biodiversity informatics, which embody a synoptic understanding or summary of knowledge about the identity, geographic distribution, ecology, phylogeny, population structure, and history of organismal diversity (Brooks and Hoberg, 2000; Wilson, 2000; Hoberg, 2002; Cook et al., 2005; Wandeler et al., 2007). Concurrently, collections serve as historical and environmental baselines with which to assess ecological perturbations and changing faunal structure, including invasive species and emerging diseases, emanating from such processes as global climate warming and other anthropogenic and natural phenomena (e.g., Hoberg et al., 2003; Brooks and Hoberg 2006, 2007; Hoberg et al., 2008). Here, we explore a range of taxonomic (nomenclatural) and biogeographic questions about pinworms and the complex helminth fauna in the American pika (Ochotona princeps [Richardson]) and collared pika (O. collaris [Nelson]), which emphasize the critical nature of specimen-based collections. Taxonomic conclusions that emerge from these evaluations among Received 18 August 2008; revised 4 February 2009; accepted 6 February 2009. the Labiostomatinae Akhtar, 1956 (Oxyuroidea: Heteroxynematidae Skriabin and Shikhobalova, 1948) provide a necessary framework for geographically fine-scale and detailed analyses of population structure and phylogeography for hosts and parasites across the intermountain west of North America (K. E. Galbreath, unpubl. obs.). Our primary focus, however, addresses why and how we choose, as a scientific community, to use specimens-based collections held in museum repositories, as well as the idea that a major cultural change is necessary. Pikas are small lagomorphs that are distributed primarily in alpine–talus habitats and, in western North America, are represented by O. collaris at high latitudes and by O. princeps at boreal to temperate latitudes (Smith et al., 1990). These relatively obscure lagomorphs have received considerable attention as crucial bio-indicators of historical environmental structure across western North America during the late Pleistocene and Quaternary (Hafner, 1993; Hafner and Sullivan, 1995). An understanding of the intricate biogeographic history for pikas has also contributed to interest in documenting the complex nature of the parasite fauna associated with these lagomorphs, both in North America and more broadly in the Holarctic (e.g., Gvozdev, 1956, 1962; Gvozdev et al., 1970; Hoberg, 2005). The pinworm fauna described from pikas is rich and complex. The Herteroxynematidae contains the Labiostomatinae, a putative monophyletic group of genera in lagomorph hosts that includes Ochotonidae and Leporidae; considered here based on the current taxonomy according to Petter and Quentin (1976), are Dermatoxys Schneider, 1866, Labiostomum (Labiostomum) Akhtar, 1941, Labiostomum (Eugenuris) (Schulz, 1948), and Cephaluris Akhtar, 1947. Since inception of the subfamily, proposals for considerable rearrangements have been entertained (reviewed in Akhtar, 1941, 1947, 1953, 1956; Inglis, 1959; SeeCRITICAL COMMENT 491 see, 1973; Quentin, 1975; Grundmann and Lombardi, 1976). For example, Pikaeuris Akhtar, 1953 was reduced as a synonym of Eugenuris by Akhtar (1956), whereas the initially independent Eugenuris was synonymized with Labiostomum by Inglis (1959). Further, Gvozdev (1956, 1962) considered, incorrectly, that Eugenuris was a junior synonym of Dermatoxys. Among this assemblage of hosts and parasites, multi-species infections in single hosts are not uncommon (Hobbs, 1980). This observation, in conjunction with the difficulty in distinguishing among closely related genera and species, particularly for L. (Labiostomum) and L. (Eugenuris), has led to a considerable number of divergent opinions about faunal diversity for pinworms in pikas (e.g., Akhtar, 1956, 1958; Inglis, 1959; Leiby, 1961; Seesee, 1973; Quentin, 1975; Hobbs, 1976; Grundmann and Lombardi, 1976). Additionally, assumptions about host-specificity and extreme geographic isolation for host populations further influenced ideas about biogeography and host associations for parasites in the American pika and the collared pika. THE CAST OF PLAYERS—PINWORMS IN PIKAS Specimens representing pinworms in O. collaris and O. princeps, from localities across western North America, were evaluated. We report taxonomic conclusions that will provide context for broader surveys and analyses of species diversity and the phylogeography of helminth faunas among populations of these host species (K. E. Galbreath and E. P. Hoberg, unpubl. obs.). This does not, however, presume to constitute a formal or synoptic taxonomic revision of this group of oxyurids. Acronyms for specific museum or field collections include: USNPC (U.S. National Parasite Collection), BCP (Beringian Coevolution Project), and KEG (K. E. Galbreath). Where possible, the type specimens or series were examined, and attempts were made to locate catalogued museum materials and vouchers representing prior published field-studies dealing with pinworms in species of Ochotona from North America. Additional specimens were derived from geographically extensive field surveys represented by the BCP and those conducted by KEG for coevolutionary and phylogeographic studies of hosts and parasites (to be reported in detail elsewhere). Nematodes were cleared in phenol-alcohol (80 parts melted phenol crystals and 20 parts absolute ethanol) and studied in temporary whole-mounts under differential interference contrast with a Zeiss Axiophot compound microscope (Carl Zeiss Incorporated, Thornwood, New York). Lip structure, considered by some to be diagnostic in this group at the species-level (e.g., Akhtar, 1956; Grundmann and Lombardi, 1976), was evaluated based on en face views from hand-cut specimens mounted in glycerine jelly. Photomicrographs were prepared using a Nikon DXM 1200F digital camera system (Nikon Instruments Incorporated, Melville, New York); line drawings were prepared using a drawing tube. The comparisons focus primarily on a series of structural attributes in males and females, with lesser emphasis on meristic data due to the limited numbers of specimens available in the respective type series; all measurements are reported in micrometers unless specified otherwise. Type specimens examined: (1) L. coloradensis Leiby, 1961, holotype male and alloptype female in O. princeps from Colorado, under USNPC 39443, re-determined as L. (E.) talkeetnaeuris; (2) E. utahensis Grundmann and Lombardi, 1976, syntype males (6 specimens) and females (3 specimens) in O. princeps from Utah, under USNPC 73259, re-determined as L. (E.) talkeetnaeuris; (3) L. (Eugenuris) sp., from Grundmann’s syntype females (2 specimens) for E. utahensis, re-determined under USNPC 101091. Other specimens examined: (1) L. (Labiostomum) rauschi Akhtar, 1956 voucher specimens: USNPC 101096 (BCP 9737) in O. collaris, Lake Clark National Park, Alaska; USNPC 101097 (BCP 49536) in O. collaris, Yukon-Charley National Park, Alaska; USNPC 101093 (KEG 377) in O. collaris from Northwest Territories, Canada; USNPC 101095 (KEG 433) in O. princeps from Grande Cache, Alberta, Canada; USNPC 101092 (KEG 337) in O. princeps from Gifford-Pinchot National Forest, Washington State. (2) D. veligera, voucher females (2 specimens) in O. collaris from Alaska, under USNPC 26485, re-determined as L. (L.) rauschi. (3) L. (Eugenuris) talkeetnaeuris Akhtar, 1956 voucher specimens: USNPC 101103 (KEG 377) and 101102 (KEG 375) in O. collaris from Jawbone Lake, Northwest Territories, Canada; USNPC 101099 (BCP 9737) and 101104 (BCP 9635) in O. collaris from Lake Clark National Park, Alaska; USNPC 101100 (BCP 49518) and 101101 (BCP 49340) in O. collaris from Yukon-Charley National Park, Alaska; USNPC 101105 (KEG 488) in O. princeps from Mackenzie Pass, Oregon; and USNPC 101098 (BCP 7687) in O. hyperborea from Yttgran Island, Chutkhotka, Russia. COMPARISONS AMONG SPECIMENS We examined and compared the types for L. (L.) coloradensis and L. (E.) utahensis and representative vouchers of L. (E.) talkeetnaeuris and L. (L.) rauschi during the current study (Figs. 1–22). Further, we compared these observations with the original descriptions attributable to respective species (Akhtar, 1956; Leiby, 1961; Grundmann and Lombardi, 1976). The type series for the latter 2 species, originally deposited by Akhtar (1956) in the collections of the Pakistan Zoological Survey, Karachi, Pakistan, were not immediately available. Type specimens for L. (Labiostomum) coloradensis: Leiby (1961) apparently described this species based on 3 male and 8 female nematodes in O. princeps from Gunnison, Colorado, but only deposited 2 specimens in the USNPC. These ‘‘type specimens,’’ a presumptive male holotype and female allotype, were not clearly designated in the original description; other specimens were not deposited. The male was represented by a tail in ventral orientation, mounted permanently in glycerine jelly (Fig. 19). Length of the tail in this specimen is 597 (355 in the original description) and ventral crests initiate near 416 anterior to the cloaca. Caudal papillae include 6 pairs, and 2 massive median or double papillae form a ventral cushion on the posterior margin of the cloaca (Fig. 19). The anterior-most pair, or first, have prominent elongate bases, with tips turned ventrally along the margin of the cloaca. The third pair is bilobed in appearance, each with a prominent inflated base. The female allotype is large, about 19 mm in length and 356 in width at the vulva. The cephalic extremity lacks an inflation, and prominent cervical alae are present laterally (Fig. 1). The esophagus, including the bulb, is 1,249 in length. The prominent, beak-like vulva is situated at 8,979 from the cephalic ex492 THE JOURNAL OF PARASITOLOGY, VOL. 95, NO. 2, APRIL 2009 FIGURES 1–6. Labiostomum (Eugenuris) talkeetnaeuris and L. (Labiostomum) rauschi showing structure of the cephalic region (1–3) and vulva in female specimens (4–6); same scale bars for all figures. (1) Cephalic extremity, lateral view of allotype for L. (L.) coloradensis, USNPC 39443 in O. princeps showing tapering head without inflated capsule. (2) Cephalic extremity, dorsal view of voucher specimen of L. (E.) talkeetnaeuris, USNPC 101105 in O. princeps, showing tapering head with prominent cervical alae and without capsule. (3) Cephalic extremity of voucher specimen of L. (L.) rauschi, USNPC 101092 in O. princeps, showing well-developed capsule. (4) Vulva, lateral view in allotype for L. (L.) coloradensis, USNPC 39443, noting prominent beak-like structure. (5) Vulva, lateral view in syntype female of L. (E.) utahensis, USNPC 73259 in O. princeps, showing beak-like form and variation in size. (6) Vulva, lateral view in voucher specimen of L. (L.) rauschi, USNPC 101092, showing structure of small ventral flap. CRITICAL COMMENT 493 FIGURES 7–10. Labiostomum (Eugenuris) talkeetnaeuris and L. (Labiostomum) rauschi showing variation in structure of the vulva; same scale bars for all figures. (7) Vulva, lateral view in syntype female of L. (E.) utahensis, USNPC 73259 in O. princeps. (8) Vulva in lateral view of voucher of L. (E.) talkeetnaeuris, USNPC 101105 in O. princeps. (9) Vulva in lateral view of voucher of L. (E.) talkeetnaeuris, USNPC 101103 in O. collaris. (10) Vulva in latero-ventral view of voucher of L. (L.) rauschi, USNPC 101093 in O. collaris, noting prominent ventral flap. 494 THE JOURNAL OF PARASITOLOGY, VOL. 95, NO. 2, APRIL 2009 FIGURES 11–13. Labiostomum (Eugenuris) talkeetnaeuris and L. (Labiostomum) rauschi showing structure of tail in female, in lateral view. (11) Allotype for L. (L.) coloradensis, USNPC 39443 in O. princeps showing elongate filiform tail. (12) Syntype female of L. (E.) utahensis, USNPC 73259 in O. princeps. (13) Voucher of L. (L.) rauschi, USNPC 101092 in O. princeps showing inflated tail. CRITICAL COMMENT 495 FIGURES 14–17. Labiostomum (Eugenuris) talkeetnaeuris showing structure of male tail and distribution of caudal papillae. (14) Caudal extremity in syntype male of L. (E.) utahensis, USNPC 73259 in O. princeps. (15) Caudal papillae, ventral view, in syntype male of L. (E.) utahensis USNPC 73259 showing distribution of 6 paired papillae (1–6) and massive double papillae (dbl) on posterior margin of cloaca. (16) Caudal extremity of voucher specimen of L. (E.) talkeetnaeuris USNPC 101105 in O. princeps. (17) Caudal papillae, ventral view, in voucher specimen of L. (E.) talkeetnaeuris USNPC 101103 in O. collaris. 496 THE JOURNAL OF PARASITOLOGY, VOL. 95, NO. 2, APRIL 2009 FIGURES 18–22. Labiostomum (Eugenuris) talkeetnaeuris and L. (Labiostomum) rauschi showing structure and distribution of caudal papillae in male specimens; drawn at same scale. Shown is ventral view at level of cloaca, bordered by body wall and lateral caudal alae. (18) Voucher specimen of L. (E.) talkeetnaeuris, USNPC 101103 in O. collaris showing 2 preanal pairs, 1 adanal pair with inflated bases, 3 postanal pairs, and massive double papillae forming ventral cushion on median line. (19) Holotype male for L. (L.) coloradensis, USNPC 39443 in O. princeps. (20) Syntype male of L. (E.) utahensis, USNPC 73259 in O. princeps. (21) Voucher specimen of L. (L.) rauschi, USNPC 101093 in O. collaris, showing 2 preanal pairs and 3 postanal pairs, and massive double papillae on midline forming ventral cushion posterior to cloaca. (22) Voucher specimen of L. (L.) rauschi, USNPC 101095 in O. princeps. CRITICAL COMMENT 497 tremity (Fig. 4). The tail is elongate and filiform, 2,574 in length (Fig. 11). Eggs have a single operculum and measure 107–109 long and 52–57 wide. The range of diagnostic characters demonstrated in the male and female type specimens contrasts considerably from the original description presented by Leiby (1961) and is incompatible with species of L. (Labiostomum), according to Petter and Quentin (1976). Type specimens for L. (Eugenuris) utahensis: Grundmann and Lombardi (1976) described this species based on 17 male and 15 female specimens in O. princeps from Utah; only 6 males and 5 females were deposited in the syntype series in the USNPC; specimens were not deposited in other museum collections. Among males, 6 specimens largely conform to the original description and include relatively large worms to near 11 mm in total length, with the tail being 575–615 long (Fig. 14). Caudal papillae include 6 pairs, and massive double papillae form a ventral cushion on the posterior margin of the cloaca (Figs. 15, 20). Ventral crests initiate at 588–594 anterior to the cloaca. Among females, 3 specimens conform to the original description and are represented by large worms, near 16– 18 mm in total length, lacking a cephalic capsule but with an elongate filiform tail exceeding 2 mm in length (Fig. 12) and with a prominent beak-like vulva (Figs. 5, 7). The remaining 2 specimens (not shown), including a fully gravid female, are considerably smaller, 8.6 and 9.1 mm in total length and with a filiform tail 910 and 1,080 long; the vulva is smooth and lacking a prominent beak-like protuberance. Voucher specimens for L. (Eugenuris) talkeetnaeuris: Akhtar (1956) described this species based on specimens collected by Robert L. Rausch in O. collaris from the Talkeetna Mountains, Alaska. Our specimens in O. collaris from the Northwest Territories and Alaska, those in O. princeps from Oregon, and those in O. hyperboea from Chukhotka conform to the original description (Figs. 2, 8, 9, 16, 17, 18). Male specimens are relatively large worms measuring about 9–10 mm in total length, with the tail 554–742 long (Fig. 16). Caudal papillae include 6 pairs, and massive double papillae form a cushion on the posterior margin of the cloaca (Figs. 17, 18). Ventral crests initiate at 693–861 anterior to the cloaca. Female specimens are represented by large worms, from 18–21 mm in total length, with prominent cervical alae but lacking a cephalic capsule (Fig. 2); an elongate filiform tail is 2,445–2,908 in length. The vulva is prominent and beak-like (Figs. 8, 9) and situated at 8,563–9,553 from the cephalic extremity. Eggs measure 96–111 long by 47– 52 wide. Voucher specimens for L. (Labiostomum) rauschi: Akhtar (1956) described this species based on specimens collected by Robert L. Rausch in O. collaris from the Talkeetna Mountains, Alaska. Our specimens in O. collaris from the Northwest Territories and Alaska, and those in O. princeps from Washington and Alberta, conform to the original description (Figs. 3, 6, 10, 13, 21, 22). Males and females have a prominent cephalic capsule (Fig. 3). Males are relatively large worms, measuring 10– 11 mm in total length and with a tail 514–569 long. Caudal papillae include 5 pairs, and prominent double papillae form a ventral cushion on the posterior margin of the cloaca (Figs. 21, 22). Ventral crests initiate at 539–630 anterior to the cloaca. Among females, total length ranges from 16–20 mm, the tail is 1,831–2,336 long and inflated with a relatively blunt tip (Fig. 13), and the vulva with ventral flap is 8,959–9,256 from the cephalic extremity (Figs. 6, 10). Eggs measure 94–101 long by 44–49 wide. TAXONOMIC CONCLUSIONS The holotype and allotype for L. (L.) coloradensis were found to be identical to some specimens in the syntype series representing L. (E.) utahensis, although the figures and written descriptions of the 2 species do not agree (Leiby, 1961; Grundmann and Lombardi, 1976). Both lots of type specimens represent L. (Eugenuris), and neither is compatible with L. (Labiostomum) as demonstrated by comparisons to L. (L.) rauschi. Further, we examined ‘‘unequivocal voucher specimens’’ attributed to L. (Eugenuris) talkeetnaeuris in both O. collaris and O. princeps and found these to be identical with the type specimens for L. (L.) coloradensis and L. (E.) utahensis. Additionally, the syntypes deposited by Grundmann and Lombardi (1976) clearly contained 2 species, a large form (on which the description was based) that represents L. (E.) utahensis and a small form that remains undescribed (USNPC 101091). The term ‘unequivocal voucher’ is introduced here for materials such as those representing L. (E.). talkeetnaeuris for which the original types, possibly still held in Pakistan, were simply not available. This concept relates to the idea that specimens referred to this species, from multiple and geographically widespread localities, were identical in all critical morphological details to those in the original description; genetic variation demonstrated among these parasites was further consistent with a single species (K. E. Galbreath and E. P. Hoberg., unpubl. obs.). Although not collected specifically from the type locality, all specimens examined by us were derived from the type host across a range of localities at high latitudes which geographically bracket the Talkeetna Mountains, where the original specimens were collected by R. L. Rausch. Consequently, we consider the identification to be unequivocal and feel that these current voucher specimens can serve as a basis for comparison. Therefore, due to the identity of these 3 nominal species, L. (L.) coloradensis and L. (E.) utahensis are reduced as junior synonyms of L. (E.) talkeetnaeuris through application of priority (Article 23, ICZN, 1999). In this case, although the description by Leiby (1961) refers to a species of L. (Labiostomum) for L. coloradensis, it is the ‘‘name bearing type specimens’’ representing L. (Eugenuris) that determines the identity (Article 72, ICZN, 1999). Additionally, the large syntype specimens and description of E. utahensis provided by Grundmann and Lombardi (1976) apply to L. (E.) talkeetnaeuris, although the syntype series represents a composite; the small forms of L. (Eugenuris) sp. (USNPC 101091) are a putative, undescribed species that should be dealt with in a separate study.