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Tardigrada of the West Gulf Coastal Plain, with Descriptions of Two new Species from Louisiana
Harry A. Meyer, Megan N. Domingue, and Juliana G. Hinton

Southeastern Naturalist, Volume 13, Special Issue 5 (2014): 117–130

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117 Tardigrada of the West Gulf Coastal Plain, with Descriptions of Two new Species from Louisiana Harry A. Meyer1,*, Megan N. Domingue1, and Juliana G. Hinton1 Abstract - Fifty-one species make up the known tardigrade fauna of the West Gulf Coastal Plain (western Louisiana, eastern Texas, southeastern Oklahoma, and southern Arkansas). Tardigrade diversity appears low compared to well-sampled areas of North America and Europe. Lichens and mosses collected in southwestern Louisiana during the Spring of 2010 contained ten species of tardigrades. Macrobiotus anemone sp. n. belongs to the hufelandi group. It differs from other species in the group in having egg processes whose terminal disks have 7–10 long, tentacular arms. Murrayon hyperoncus sp. n. differs from other species in the genus in the much larger dimensions of its buccal tube, placoids, and lunules. Echiniscus arctomys, Hypsibius convergens, Mesocrista spitzbergensis, Paramacrobiotus richtersi, and Murrayon pullari are new records for Louisiana. Introduction Tardigrades (Phylum Tardigrada), commonly known as water bears, are microscopic animals found in marine, freshwater, and terrestrial habitats. Terrestrial species occur in mosses, lichens, liverworts, soil, and leaf litter, and are renowned for their ability to enter a cryptobiotic state (anhydrobiosis) in response to desiccation. Terrestrial tardigrades include herbivores as well as carnivorous species that feed on nematodes, rotifers, and other tardigrades (Ramazzotti and Maucci 1983). Over 200 species of freshwater and terrestrial tardigrades are known to occur in North America (Meyer and Hinton 2007). The West Gulf Coastal Plain (WGCP) includes western Louisiana, eastern Texas, southeastern Oklahoma, and southern Arkansas (MacRoberts and MacRoberts 2003) and is characterized by oak (Quercus sp.), hickory (Carya sp.), and pine (Pinus sp.) forests, savanna, and prairie. Maximum elevation is only about 250 m. The WGCP is a region of North America that has only been superficially and unevenly sampled for tardigrades (Hinton and Meyer 2007). In this paper, we review the freshwater and terrestrial tardigrade fauna of the WGCP, including new tardigrade records and species from Acadia Parish, LA. Methods The second author collected four moss and six lichen samples in Crowley, Acadia Parish, LA (30°11'30.23"N, 92°22'23.43"W; elevation 20 m asl), in the spring of 1Department of Biology and Health Sciences, McNeese State University, Lake Charles, LA 70609. *Corresponding author - hmeyer@mcneese.edu. Manuscript Editor: Jerry Cook Proceedings of the 5th Big Thicket Science Conference: Changing Landscapes and Changing Climate 2014 Southeastern Naturalist 13(Special Issue 5):117–130 Southeastern Naturalist H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 118 Vol. 13, Special Issue 5 2010. Sampling was not quantitative. She collected mosses from the ground around the bases of trees. She collected the foliose lichen Parmotrema perforatum (Jacq.) A. Massal. and the fruticose lichen Ramalina stenospora Mull. Arg. from trees and fallen branches. She stored the samples in sealed paper envelopes or paper bags. We soaked samples overnight and inspected them for tardigrades with a dissecting microscope (Nikon SMZ-U Zoom 1:10). We mounted specimens and eggs on slides in polyvinyl lactophenol, examined them using phase contrast microscopy (Nikon Eclipse 50i), and measured them using imaging software (NIS-Elements D 2.30, SPI). We identified Tardigrades using keys and descriptions in Bertolani and Rebecchi (1993), Guidetti (1998), Nelson and McInnes (2002), Pilato and Binda (2010), and Ramazzotti and Maucci (1983). We obtained anatomical terminology, global species lists, and current taxonomic nomenclature from Degma et al. (2013), Degma and Guidetti (2007), and Guidetti and Bertolani (2005). Comments on tardigrade biogeography are based on McInnes (1994). For this study, we consider species to be cosmopolitan if they meet the criterion of Pilato and Binda (2001), namely that they have been found in five or more biogeographical ecozones. The pt index is the ratio of the length of a given structure to that of the buccal tube expressed as a percentage (Pilato 1981). In species descriptions, we have placed pt indices in parentheses in italics. We measured body length from the mouth to the end of the body, excluding hind legs; buccal tube length from the anterior margin of the stylet sheaths to the base of the tube; and stylet insertion point from the anterior margin of the stylet sheaths to the point of insertion on the buccal tube. We measured buccal tube width as the external diameter at the level of stylet support insertion. We measured the lengths of primary branches and secondary branches of external and internal claws (legs I–III) or anterior and posterior claws (leg IV) from the base of the basal section to the apex, including accessory points. We compared the new species with specimens and eggs in the authors’ collection of Macrobiotus hufelandi C.A.S. Schultze, 1834 from North America and Europe, and Murrayon pullari (Murray, 1907) from North America. We based comparisons with species not personally examined on descriptions of these species. We consulted all available published papers, unpublished theses, and dissertations containing data relevant to freshwater and terrestrial tardigrade distribution in the WGCP, and data from an All Taxa Biological Inventory (ATBI) in Big Thicket National Preserve, TX. We accepted authors’ original identifications at face value, unless amended in subsequent literature. Some papers on the Tardigrada of the WGCP were written before the development of rigorous standards of specific diagnosis (Guidetti and Bertolani 2005, Pilato and Binda 2001); the amount of qualitative and quantitative information in older species descriptions varies widely. Some species in older literature regarded as cosmopolitan have proven to belong to complexes of morphologically similar species. Such records must be considered doubtful unless confirmed. Following the recommendations of Michalczyk et al. (2012), we corrected records identified as Milnesium tardigradum in earlier literature to Milnesium tardigradum sensu lato or Milnesium cf. tardigradum. Southeastern Naturalist 119 H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 Vol. 13, Special Issue 5 Results West Gulf Coastal Plain tardigrade fauna Scientific names and authorities of all freshwater and terrestrial Tardigrada known to occur in the WGCP, the locations where each was found and the substrates from which they have been reported are listed in Table 1. Seventy-three tardigrade specimens and 9 eggs from lichens and mosses in Acadia Parish were identified, representing 8 genera and 10 species: Echiniscus arctomys, Milnesium sp., Hypsibius convergens, Mesocrista spitzbergensis, Macrobiotus anemone sp. n., Macrobiotus cf. harmsworthi, Minibiotus cf. intermedius, Paramacrobiotus cf. richtersi, Murrayon hyperoncus sp. n., and Murrayon pullari. All samples contained specimens. Absence of eggs or condition of specimens precluded the identification of four species beyond species complex or genus. Description of Macrobiotus anemone sp. n. (Figs. 1, 2; Tables 2, 3) Material examined. One holotype, 2 paratypes, and 5 eggs: foliose and fruticose lichen from trees and fallen branches in a wooded lot behind Woodlawn Cemetery on South Avenue F, Crowley, Acadia Parish, LA (30°11'30.23"N, 92°22'23.43"W; elevation 20 m asl). Type depository. The holotype (SMLA9562), paratypes (SMLA9563), and eggs (same slides) are deposited in the W.A.K. Seale Museum, Department of Biology and Health Sciences, McNeese State University, Lake Charles, LA 70609. Figure 1. Macrobiotus anemone sp. n. A) habitus, B) buccopharyngeal apparatus, C) claws of leg II, D) claw of leg IV. Scale bars: A: 100 μm; B: 20 μm; C, D: 10 μm. Southeastern Naturalist H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 120 Vol. 13, Special Issue 5 Table 1. Terrestrial and freshwater tardigrades of the West Gulf Coastal Plain, USA. LA = Louisiana, OK = Oklahoma, TX = Texas; B1 = Beasley 1968, B2 = Beasley 1978, C = Caskey 1971, HM = Hinton and Meyer 2007, HMM = Hinton et al. (this volume), HMS = Hinton et al. 2010, MD = Meyer and Domingue 2011, MDH = this paper, Meh = Mehlen 1969, Mey = Meyer 2001, MH = Meyer and Hinton 2010; C = cryptogam (unspecified lichen, liverwort, or moss), Fw = freshwater, Lc = lichen, Ll = leaf litter or soil, Lv = liverwort, M = moss, N = bird nest. Species Location (reference) Substrate Biogeographical notes Echiniscus arctomys Ehrenberg, 1853 LA (MDH), TX (C) M Cosmopolitan Echiniscus canadensis Murray, 1910 OK (B1, B2) Lc Holarctic Echiniscus cavagnaroi Schuster and Grigarick, 1966 LA (HM, Mey) Lc Americas Echiniscus mauccii Ramazzotti, 1956 TX (HMM) C North America Echiniscus tamus Mehlen, 1969 TX (C, HMM, Meh) Lc North America Echiniscus virginicus Riggin, 1962 LA (HM, HMM, Mey) Lv North America Echiniscus wendti Richters, 1903 TX (HMM) C Cosmopolitan Pseudechiniscus brevimontanus Kendall-Fite and Nelson, 1996 LA (Mey), TX (HMM) C North America Pseudechiniscus juanitae de Barros, 1939 TX (HMM) Lc Americas Pseudechiniscus suillus (Ehrenberg, 1853) TX (HMM) C, Fw Cosmopolitan Milnesium tardigradum sensu lato LA (HM, HMS, MDH, Mey), OK (B1, B2), Lc, Ll, Lv, M TX (B1, Meh) Milnesium jacobi Meyer and Hinton, 2010 TX (HMM, MH) Lc, Ll Texas Milnesium cf. tardigradum Doyère, 1840 TX (C, HMM) C, Ll Cosmopolitan Hypsibius calcaratus Bartoš, 1935 TX (C) C Holarctic Hypsibius convergens (Urbanowicz, 1925) LA (MDH) M Cosmopolitan Isohypsibius schaudinni (Richters, 1909) TX (HMM, Meh) Lc, M Cosmopolitan Pseudobiotus kathmanae Nelson, Marley and Bertolani, 1999 TX (HMM) Fw North America Pseudobiotus longiunguis (Iharos, 1968) TX (HMM) Fw Americas Ramazzottius sp. TX (HMM) M Ramazzottius baumanni (Ramazzotti, 1962) TX (HMM) Ll Americas, Australasia Ramazzottius oberhaeuseri (Doyère, 1840) LA (HM), TX (B1, C, Meh) Lc Cosmopolitan Thulinius saltursus (Schuster, Toftner and Grigarick, 1978) TX (HMM) Fw North America Diphascon (Diphascon) alpinum Murray, 1906 TX (HMM) N Cosmopolitan Diphascon (Diphascon) chilenense Plate, 1888 TX (HMM) Ll Cosmopolitan Diphascon (Diphascon) iltisi (Schuster and Grigarick, 1965) TX (C) C Holarctic Southeastern Naturalist 121 H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 Vol. 13, Special Issue 5 Table 1, continued. Species Location (reference) Substrate Biogeographical notes Diphascon (Diphascon) pingue (Marcus, 1936) LA (HM, HMS) Ll Cosmopolitan Diphascon (Adropion) scoticum Murray, 1905 TX (HMM) Ll Cosmopolitan Astatumen trinacriae (Arcidiacono, 1962) LA (Mey) C Cosmopolitan Itaquascon umbellinae de Barros, 1939 LA (HM, HMM, HMS) Lc, Ll Cosmopolitan Mesocrista spitzbergensis (Richters, 1903) LA (MDH) Lc Holarctic Macrobiotus anemone sp. n. LA (MDH) Lc Southeast USA Macrobiotus coronatus de Barros, 1942 TX (HMM) Fw, Ll Americas, Palearctic Macrobiotus echinogenitus Richters, 1904 LA (HM, Mey), OK (B1, B2), Lc, Ll, M Cosmopolitan TX (B1, C, HMM) Macrobiotus harmsworthi Murray, 1907 OK (B1, B2), TX (C) Lc Cosmopolitan Macrobiotus cf. harmsworthi LA (HMS, MDH), TX (HMM) Lc, Ll, M Cosmopolitan Macrobiotus hufelandi C.A.S. Schultze, 1833 TX (C, Ll, Meh) Lc, Ll, M Cosmopolitan Macrobiotus cf. hufelandi LA (HMS, Mey) Ll Cosmopolitan Macrobiotus islandicus Richters, 1904 TX (C, HMM) Lc, Lv, M Holarctic, Neotropical Macrobiotus cf. liviae Ramazzotti, 1962 TX (HMM) Ll Macrobiotus occidentalis Murray, 1910 LA (Mey), TX (C, HMM, Mey) Lc, M Cosmopolitan Macrobiotus cf. spectabilis Thulin, 1928 TX (HMM) Ll, M Minibiotus acadianus Meyer and Domingue, 2011 LA (HM, MD), TX (HMM) Lc Louisiana, Texas Minibiotus furcatus (Ehrenberg, 1859) LA (HM), OK (B1, B2), TX (B1, C, Meh) Lc Cosmopolitan Minibiotus intermedius (Plate, 1888) LA (HM, HMS, Mey), TX (C, HMM) Lc, Ll, Lv, M Cosmopolitan Minibiotus cf. intermedius LA (MDH) Lc Cosmopolitan Paramacrobiotus areolatus (Murray, 1907) OK (B1, B2), TX (B1, C, HMM, Meh) Lc, Lv, M Cosmopolitan Paramacrobiotus richtersi (Murray, 1911) TX (HMM) Ll, M Cosmopolitan Paramacrobiotus cf. richtersi LA (MDH) Lc Cosmopolitan Paramacrobiotus tonollii (Ramazzotti, 1956) TX (HMM) Lc, Lv, M North America Murrayon sp. TX (HMM) Fw Texas Murrayon hyperoncus sp. n. LA (MDH) M Louisiana Murrayon pullari (Murray, 1907) LA (MDH), TX (HMM) Fw, M Cosmopolitan Southeastern Naturalist H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 122 Vol. 13, Special Issue 5 Figure 2. Macrobiotus anemone sp. n. A) egg, B) egg process. Scale bars: A: 20 μm; B: 5 μm. Table 3. Morphometric data of selected structures in eggs of Macrobiotus anemone sp. n. Ranges are in micrometers. Range refers to the smallest and largest structure found among all measured specimens. Character Range Diameter without processes (5 eggs) 75.0–94.3 Diameter with processes (5 eggs) 83.7–99.7 Height of process (5 eggs, 25 processes) 3.6–5.2 Diameter of process base (5 eggs, 25 processes) 3.5–5.5 Length of distal arm of process (5 eggs, 25 processes) 1.1–2.9 Distance between processes (5 eggs, 25 processes) 4.3–7.3 Number of processes around circumference (5 eggs) 25–30 Approximate number of processes in hemisphere (5 eggs) 35–60 Table 2. Morphometric data of selected structures of the type specimens of Macrobiotus anemone sp. n. All lengths in micrometers. Range refers to the smallest and largest structure found among all measured specimens. See description of holotype for claws not listed here. n = number of specimens measured, SD = standard deviation, n.a. = not applicable, pt = pt index. Range Mean SD Character n Length pt Length pt Length pt Body 3 349.0–499.7 n.a. 399.9 n.a. 86.4 n.a. Buccal tube 3 33.2–43.2 n.a. 37.1 n.a 5.3 n.a. Stylet support insertion 3 25.9–34.2 78.0–79.2 29.2 78.6 4.4 0.6 Buccal tube external diameter 3 4.5–6.1 12.9–14.1 5.0 13.5 0.9 0.6 First macroplacoid 3 6.9–10.7 20.8–24.8 8.5 22.7 2.0 2.0 Second macroplacoid 3 4.0–6.8 13.0–15.7 5.3 14.3 1.4 1.4 Macroplacoid row 3 12.0–17.7 36.1–41.0 14.5 38.8 2.9 2.5 Microplacoid 3 1.4–2.0 4.0–5.7 1.8 4.8 0.3 0.9 Placoid row 3 14.5–20.4 44.0–47.2 17.0 45.1 3.0 1.6 Primary claw branch, internal, leg III 2 9.2–11.1 25.7–27.7 10.2 26.7 1.3 1.4 Secondary claw branch, internal, leg III 2 7.7–8.8 20.3–23.2 8.3 21.8 0.8 2.0 Southeastern Naturalist 123 H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 Vol. 13, Special Issue 5 Species diagnosis. Colorless; cuticle smooth, without pores; eyes absent; no leg granulation; simple buccal armature with 3 dorsal and ventral transverse ridges but no teeth; narrow buccal tube; stylet supports inserted at pt 78.0–79.2; two macroplacoids and small microplacoid present. Claws of hufelandi type with smooth lunules and strong accessory points. Eggs with short conical processes terminating in a disk with seven to ten long, tentacular arms; egg surface smooth. Description of holotype. Body length 499.7 μm, colorless (Fig. 1A). Cuticle smooth without any pores. Eyes absent. No granulation on legs. Buccal armature in oral cavity simple: 10 peribuccal lamellae and a system of 3 thin dorsal and 3 thin ventral transverse bands present; no bands of teeth evident. Buccal tube 43.2 μm long and 6.1 μm (14.1) wide (Fig. 1B). Ventral lamina present but not oriented properly for measurement. Stylet supports inserted on buccal tube at 34.2 μm (79.2). Round pharyngeal bulb (41.0 μm long, 39.8 μm wide) with apophyses, 2 rod-shaped macroplacoids decreasing in length, and a small, rod-shaped microplacoid (Fig. 1B). First macroplacoid 10.7 μm (24.8) long, with a central constriction. Second macroplacoid 6.8 μm (15.7) long, with subterminal constriction. Microplacoid 2.0 μm (4.6) long. Macroplacoid row 17.7 μm (41.0) long, entire placoid row 20.4 μm (47.2) long. Claws robust, of hufelandi type (Figs. 1C, D). Claw lengths: leg I external claw primary branch 10.5 μm (24.3), secondary branch 8.7 μm (20.1); leg II external claw primary branch 11.7 μm (27.1), secondary branch 8.8 μm (20.4); leg II internal claw primary branch 11.6 μm (26.9), secondary branch 9.1 μm (21.1); leg III external claw primary branch 12.0 μm (27.8), secondary branch 9.1 μm (21.1); leg III internal claw primary branch 11.1 μm (25.7), secondary branch 8.8 μm (20.4); leg IV anterior claw primary branch 13.4 μm (31.0), secondary branch 9.8 μm (22.7); leg IV posterior claw primary branch 14.2 μm (32.9), secondary branch 10.5 μm (24.3). Other claws not oriented properly for measurement. Primary branches of all claws with well-developed accessory points. Smooth-edged lunules present on all claws. Lunule widths: leg I external 2.6 μm (6.0), leg II external 3.5 μm (8.1), leg III external 3.4 μm (7.9), leg IV anterior 5.0 μm (11.6). No cuticular bars visible on legs. Description of eggs. Eggs white or transparent, laid freely. Surface smooth (Fig. 2A). Short, conical processes ending in broad terminal disk with 7–10 long, tentacular arms (Figs. 2A, B). The presence of an embryo with buccal tube and placoids in 1 egg makes the assignment of these eggs to Macrobiotus anemone sp. n. definitive. Remarks. Summary morphological data for the holotype and 2 paratypes are presented in Table 2. Because of specimen orientation, ventral laminae and most claws were not measured in paratypes. Table 3 presents summary morphometric data for 5 eggs. Differential diagnosis. Macrobiotus anemone sp. n. belongs to the hufelandi group of species. The egg is commonly used for species determination in this group because its features show the greatest inter-specific variability (Bertolani and Rebecchi 1993, Kaczmarek and Michalczyk 2004). Six species within the hufelandi group have smooth egg surfaces (i.e., without reticulation, pits, or dots): Southeastern Naturalist H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 124 Vol. 13, Special Issue 5 Macrobiotus ramoli Dastych, 2005; M. marlenae Kaczmarek and Michalczyk, 2004; M. kazmierskii Kaczmarek and Michalczyk, 2009; M. patagonicus Maucci, 1998; M. persimilis Binda and Pilato, 1972; and M. polonicus Pilato, Kaczmarek, Michalczyk and Lisi, 2003. Macrobiotus anemone sp. n. differs from M. marlenae in lacking buccal teeth, in the absence of dentate lunules on leg IV, and in having more egg processes (25–30 along the circumference in the new species, 16 in M. marlenae) with much longer arms on terminal disks. Macrobiotus anemone sp. n. differs from M. kazmierskii in lacking buccal teeth and in having eggs with indented, rather than smooth, terminal disks. The new species differs from M. patagonicus in lacking brown-pigmented spots on its caudal surface and in having egg processes with much longer arms on terminal disks. It differs from M. persimilis in lacking buccal teeth and dentate lunules on leg IV and in having egg processes with much longer arms on terminal disks. The new species differs from M. polonicus in lacking buccal teeth and dentate lunules on leg IV, in the absence of hemispherical gibbosities on leg IV and in having egg processes with much longer arms on terminal disks. Macrobiotus anemone sp. n. differs from M. diversus Murray in having cuticle without pores and granules (M. diversus has cuticular pores, and cuticle is granulated caudally and on legs), in having three dorsal ridges in third band of buccal armature (M. diversus has only one joined ridge), in having smooth lunules also on fourth legs (fourth lunules are dentated in M. diversus), and in having long teeth on discs of egg processes. Macrobiotus anemone sp. n. differs from M. hyperboreus in having cuticle without pores and granules (M. hyperboreus has cuticular pores and cuticle is granulated caudally and on legs), in having developed only third band of buccal armature (M. hyperboreus Biserov has also both anterior and posterior bands of small teeth, although the first band can be very slight) and in having much longer arms on terminal discs of its eggs. Moreover, Macrobiotus anemone sp. n. differs from all the above species in having cuticle without pores. Therefore, having a cuticle without pores, a smooth egg shell surface, and terminal egg processes with long arms is a unique combination of characters for the new species. Etymology. The specific epithet is a noun in apposition referring to the resemblance of the egg processes to a sea anemone. Description of Murrayon hyperoncus sp. n. (Figs. 3, 4; Table 4) Material examined. One holotype and 3 paratypes: dry moss collected from ground in a wooded lot behind Woodlawn Cemetery on South Avenue F, Crowley, Acadia Parish, LA (30°11'30.23"N, 92°22'23.43"W; elevation 20 m asl). Five additional juvenile or contracted specimens from the same location. These specimens were excluded from morphometric analysis to minimize allometric effects (Bartels et al. 2011). Type depository. The holotype (SMLA9570) and 3 paratypes (SMLA9570, 9571) are deposited in the W.A.K. Seale Museum, Department of Biology and Health Sciences, McNeese State University, Lake Charles, LA 70609. Species diagnosis. Colorless; cuticle with pillars, without pores; eyes absent; no leg granulation; buccal armature with anterior and posterior bands of teeth and 3 Southeastern Naturalist 125 H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 Vol. 13, Special Issue 5 dorsal and ventral transverse bands; very broad buccal tube (10.8–12.2 μm); stylet supports inserted at pt 82.4–83.2; two large macroplacoids and large microplacoid present. Claws large, robust, of Murrayon type with very broad lunules (7.1–11.9 μm) and thin accessory points. Eggs unknown. Description of holotype. Body length 642.5 μm, colorless (Fig. 3A). Cuticle smooth, with pillars, without pores. Eyes absent. No granulation on legs. Peribuccal lamellae evident (at least 5; total not discernable with certainty). Oral cavity Figure 3. Murrayon hyperoncus sp. n. A) habitus; B) oral cavity, with arrows indicating locations of anterior and posterior bands of teeth; C) oral cavity and buccal tube; D) pharynx and placoids. Scale bars: A: 100 μm; B: 10 μm; C, D: 20 μm. Figure 4. Murrayon hyperoncus sp. n. A) claws of leg III, B) claw of leg IV. Scale bars: 20 μm. Southeastern Naturalist H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 126 Vol. 13, Special Issue 5 with anterior band of fine, circular teeth; and posterior band of coarser, round teeth, and 3 dorsal and 3 ventral posterior transverse ridges (Fig. 3B). Buccal tube 57.5 μm long and 11.4 μm (19.8) wide (Fig. 3C). Ventral lamina 33.8 μm (58.8) long. Stylet supports inserted on buccal tube at 47.4 μm (82.4). Oval pharyngeal bulb (66.1 μm long, 58.1 μm wide) with apophyses, 2 elongated rod-shaped macroplacoids decreasing in length, and elongated rod-shaped microplacoid (Fig. 3D). First macroplacoid 20.6 μm (35.8) long, with pronounced central constriction. Second macroplacoid 11.4 μm (19.8) long, with subterminal constriction. Microplacoid 6.4 μm (11.1) long. Macroplacoid row 34.2 μm (59.5) long, entire placoid row 42.9 μm (74.6) long. Claws large, stout, of Murrayon (also called pullari) type (Figs. 4A, B). Claw lengths: leg II external claw primary branch 23.2 μm ( 40.3), secondary branch 16.5 μm (28.7); leg II internal claw primary branch 19.8 μm (34.4), secondary branch 15.9 μm (27.7); leg IV anterior claw primary branch 25.0 μm (43.5), secondary branch 16.0 μm (27.8); leg IV posterior claw primary branch 26.5 μm (46.1), secondary branch 17.5 μm (30.4). Other claws not oriented properly for measurement. Primary branches of all claws with slender accessory points. Large lunules present on all legs (leg II: external 7.6 μm (13.2) wide, internal 7.1 μm (12.4) wide; leg IV: anterior 9.5 Table 4. Morphometric data of selected characters of four specimens of Murrayon hyperoncus sp. n. All lengths in micrometers. Range refers to the smallest and largest structure found among all measured specimens. n = number of specimens measured, SD = standard deviation, n.a. = not applicable or not available, pt = pt index. Range Mean SD Character n Length pt Length pt Length pt Body 4 500.0–642.5 n.a. 579.2 n.a. 59.4 n.a. Buccal tube 4 54.3–57.5 n.a. 55.7 n.a. 1.4 n.a. Stylet support insertion point 4 44.8–47.6 82.4–83.2 46.4 82.8 1.8 0.4 Buccal tube external diameter 4 10.8–12.2 19.8–21.7 11.6 20.7 0.6 1.0 First macroplacoid 4 17.2–20.6 30.9–35.8 18.7 33.4 1.5 2.4 Second macroplacoid 4 11.3–13.9 19.8–25.3 12.4 22.2 1.3 2.4 Macroplacoid row 4 30.1–34.2 55.4–59.6 32.6 58.1 1.7 2.0 Microplacoid 4 5.0–6.4 9.1–11.1 5.5 9.8 0.6 0.8 Placoid row 4 38.8–42.9 69.9–76.3 40.9 73.0 2.2 3.0 Primary claw branch, external, leg I 2 19.1–19.5 33.5–35.9 19.3 34.6 0.3 1.4 Secondary claw branch, external, leg I 2 16.1–16.5 28.8–29.7 16.3 29.3 0.3 0.6 Primary claw branch, external, leg II 2 23.2–23.9 40.3–41.8 23.6 41.1 0.5 1.1 Secondary claw branch, external, leg II 2 16.0–16.5 28.0–28.7 16.3 28.4 0.4 0.5 Primary claw branch, internal, leg II 1 19.8 34.4 n.a. n.a. n.a. n.a. Secondary claw branch, internal, leg II 1 15.9 27.7 n.a. n.a. n.a. n.a. Primary claw branch, external, leg III 1 18.9 34.8 n.a. n.a. n.a. n.a. Secondary claw branch, external, leg III 1 16.7 30.8 n.a. n.a. n.a. n.a. Primary claw branch, internal, leg III 2 19.8–20.1 34.6–36.6 20.0 35.6 0.2 1.4 Secondary claw branch, internal, leg III 2 16.4–18.1 28.7–33.0 17.3 30.9 1.2 3.0 Primary claw branch, anterior, leg IV 3 22.6–25.0 39.5–45.7 24.1 42.9 1.3 3.1 Secondary claw branch, anterior, leg IV 3 16.0–16.7 27.8–30.8 16.5 29.3 0.4 1.5 Primary claw branch, posterior, leg IV 1 26.5 46.1 n.a. n.a. n.a. n.a. Secondary claw branch, posterior, leg IV 1 17.5 30.4 n.a. n.a. n.a. n.a. Southeastern Naturalist 127 H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 Vol. 13, Special Issue 5 μm (16.5) wide, internal 11.9 μm (20.7) wide). Lunules of first three legs smooth edged, lunules of leg IV finely dentate. No cuticular bars visible on legs. Remarks. No eggs were found. Murrayon has been collected from both freshwater and terrestrial habitats (Guidetti 1998). Like M. hibernicus (Murray, 1911) and M. stellatus Guidetti, 1998, Murrayon hyperoncus sp. n. is known only from terrestrial substrates. Morphometric data and summary statistics for the holotype and three paratypes are given in Table 4. Differential diagnosis. Guidetti (1998) and Pilato and Binda (2010) identified 3 distinctive characteristics of Murrayon: pillars in the cuticle, Murrayon-type claws, and a hook on the ventral margin of the strengthening bar of the buccal tube. Murrayon hyperoncus sp. n. has all 3 features. Murrayon currently consists of M. ovoglabellus (Biserov, 1988), M. dianeae (Kristensen, 1982), M. hastatus (Murray, 1907), M. hibernicus, M. nocentiniae (Ramazzotti, 1961), M. pullari, and M. stellatus. Murrayon hyperoncus sp. n. differs from the other 7 species in the exceptional length of its macroplacoids and width of its buccal tube and lunules (first macroplacoid length: mean of 18.7 μm and pt 34.4 in the new species, largest values among other species are 10.7 μm and pt 24.2, in M. ovoglabellus; buccal tube width: mean of 11.6 μm and pt 20.7 in the new species, maximum values among other species are 4.5 μm, in M. hastatus and M. pullari, and pt 14.0, in M. stellatus; lunule width: 7.1–11.9 μm in the holotype of the new species, maximum recorded value in other species is 6.8 μm, in M. ovoglabellus). Only M. ovoglabellus has claws of comparable size. Murrayon hibernicus and M hyperoncus sp. n. are the only two species in the genus with microplacoids; M. hibernicus lacks the first two bands of buccal armature bound in M. hyperoncus n. sp. Etymology. The specific epithet is a masculine adjective derived from the Greek adjective “hyperonkos” (immense) and refers to the large dimensions of the buccal tubes, placoids, claws, and lunules. Discussion The tardigrade fauna of the WGCP includes 51 taxa identified to species, species complex, or genus. Of these, 21 (41.2%) are considered cosmopolitan in distribution (Table 1). The proportion of WGCP species with cosmopolitan distributions is relatively high—Pilato and Binda (2001) characterized 53 (6.8%) of global freshwater and terrestrial tardigrade fauna as cosmopolitan. Four species: Echiniscus tamus, Milnesium jacobi, Minibiotus acadianus, and Murrayon hyperoncus sp. n. are not known to occur outside the region. Freshwater and terrestrial tardigrade biodiversity in the WGCP appears to be lower than in well-sampled areas of North America and Europe. Dastych (1980) found 54 terrestrial species in a smaller area, Tatra National Park, in Poland; he did not collect aquatic samples. An ATBI in Great Smoky Mountains National Park (GSMNP) has found at least 73 species, and estimated a total species richness of approximately 100 (Bartels and Nelson 2007). Two studies of tardigrades in the WGCP employed sampling efforts sufficient to allow comparison with other areas of North America. Estimated species richness found in an ATBI conducted in Big Southeastern Naturalist H.A. Meyer, M.N. Domingue, and J.G. Hinton 2014 128 Vol. 13, Special Issue 5 Thicket National Preserve, TX is markedly lower than in GSMNP (Hinton et al. 2014 [this issue]). Quantitative sampling by Hinton et al. (2010) found lower tardigrade species richness and abundance in Louisiana leaf litter and soil than a similar study found in Italy and Tennessee (Guidetti et al. 1999). Altitudinal variation in the WGCP is much less than in the mountainous regions sampled in Italy, Poland, Tennessee, and North Carolina. Some studies have shown that the number of tardigrade species increases with altitude (Dastych 1987, Rodriguez-Roda 1951). The lack of altitudinal variation may contribute to low tardigrade diversity in the WGCP. Alternatively, lower diversity may reflect a lower diversity of available mic rohabitats. Only 1 species of water bear, Milnesium cf. tardigradum, has previously been found in Acadia Parish (Hinton and Meyer 2007). Seven species (Echiniscus arctomys, Hypsibius convergens, Mesocrista spitzbergensis, Macrobiotus anemone sp. n., Paramacrobiotus cf. richtersi, Murrayon hyperoncus sp. n., and Murrayon pullari) found in this collection are new to the fauna of Louisiana, bringing the number known to occur in the state to 20. Meyer (2008) reported the widespread occurrence of an undescribed Macrobiotus of the hufelandi group (designated in that paper Macrobiotus cf. hufelandi sp. 2) in Florida. This taxon has not been reported from Alabama or Mississippi (Hinton and Meyer 2009), but Hinton and Meyer (2007) recorded its presence in Louisiana. We now attribute these specimens to Macrobiotus anemone sp. n. Hinton and Meyer (2007), and Meyer and Domingue (2011) hypothesized that this species and 4 others (Echiniscus cavagnaroi; E. kofordi Schuster and Grigarick, 1966; Minibiotus acadianus; and Minibiotus fallax Pilato, Claxton, and Binda, 1989) constitute a distinctive regional tardigrade fauna within North America. Whether this region includes areas of the WGCP outside Louisiana remains to be determined. Acknowledgments Denise Domingue and Richard Doss assisted with the field collection of lichens and mosses. Roberto Guidetti provided invaluable advice on the Macrobiotus hufelandi group and Murrayon. Literature Cited Bartels, P.J., and D.R. Nelson. 2007. 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