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Kincaidiana Altman 1936
No full textKincaidiana Altman, 1936 Emended diagnosis (modified from Cook [1971]). Medium-sized to large worms with long, pseudosegmented proboscis (Figs. 1A, 2A–B). Chaetae bifid and enlarged in a few anterior segments (Fig. 1B); simple-pointed posteriorly. No distinct pharyngeal pad (Fig. 2D). One or two pairs of lateral blood vessels, with many blind branches, in posterior segments (Fig. 1C). Nephridia begin on 11/12; postseptal expansion narrow and directed dorsally (Fig. 1D). One pair of testes in IX, one pair of ovaries in X. Male pores on IX, near 9/10, usually paired and slightly inside chaetal lines (Fig. 1A). Pendant penes within shallow sacs when retracted; everted sacs form low porophores (Figs. 2G–H). Atria club-shaped to elongate-cylindrical, ental ¾ or more loosely covered with multicellular, pyriform prostate glands (Figs. 1E, 2G). One pair of male funnels, usually extending back one or more segments in sperm sac (Fig. 1E). Vasa deferentia do not penetrate posterior septum (9/10); they join atria near-medially; muscle coat of atria extends for a short distance along vasa deferentia (Fig. 2I–J). Female pores on chaetal lines at posterior septum of first post-atrial segment. Three pairs of spermathecae, in IX, X, and XI; pores slightly inside ventral chaetal lines, usually in line with or slightly anterior to chaetae (Fig. 1A). Spermathecae with an elongate, thick duct and an elongate-tubular to elongate-pyriform ampulla (Figs. 1E, 2E–F).Published as part of Fend, En. V., 2009, An evaluation of the genus Kincaidiana Altman, 1936, with the designation of Altmanella n. gen. (Annelida, Clitellata, Lumbriculidae), pp. 1-30 in Zootaxa 2077 on page
Altmanella Fend 2009
No full textAltmanella, undetermined western Nearctic species Figure 11 Material examined. Oregon: Lane Co.: Small spring at mouth of Tenmile Creek, 30-Jan-00, coll. S. Fend, 1 whole mount. Washington: Jefferson Co.: small seep along Hoh River, 29-Apr-99, coll. S. Fend, 1 whole mount. Small tributary to Clearwater River at Coppermine Bottom Camp, 25-Apr-04, coll. S. Fend, 1 whole mount. Idaho: Valley Co.: South Fork Salmon River at Shiefer Camp, 25-Aug-05 coll. D. Gustafson, 2 whole mounts. Twin Falls Co.: Salmon Falls Creek, Castleford Branch, 28-Mar-03, coll. D. Gustafson, 3 dissected. Remarks. The three specimens from coastal Oregon and Washington all resemble A. freidris, but have extremely long, extended penes (Fig. 11D–F). As penial extension in preserved worms is highly variable, and related to fixation, this may not be a basis for distinguishing a separate species using such limited material. The few specimens from Salmon Falls Creek in southern Idaho (Fig. 11A–B) appeared somewhat intermediate between A. freidris and A. idahoensis. The atrial ampullae were relatively short, penial structures were narrow and indistinct, and extruded penes narrow and straight. This may represent yet another species, but the poor condition of the limited material does not permit an adequate description. Only two specimens were available from the South Fork Salmon River site in northern Idaho, but both had unusually thin penial structures and very small atria (Fig. 11C).Published as part of Fend, En. V., 2009, An evaluation of the genus Kincaidiana Altman, 1936, with the designation of Altmanella n. gen. (Annelida, Clitellata, Lumbriculidae), pp. 1-30 in Zootaxa 2077 on page 2
Altmanella Fend, 2009, n. gen.
No full textAltmanella n. gen. Diagnosis. Small worms without a proboscis. Dorsal pharyngeal pad present. All chaetae simple-pointed. No lateral blood vessels in posterior segments. First pair of nephridia pre-clitellar, on 6/7. A single testicular segment, with testes paired in VIII or IX, ovaries paired in IX or X. Male pores one pair, behind ventral chaetae in VIII or IX; spermathecal pores one pair, behind ventral chaetae in the first post-atrial segment. Atria elongate and tubular to petiolate; male pores either on short porophores or on penes formed by extrusion of elongated lining cells from a muscular penial structure. A single pair of male funnels on the posterior septum of the atrial segment; one posteriorly-directed vas deferens per atrium; vasa deferentia do not penetrate posterior septum. Female pores on chaetal lines at posterior septum of first post-atrial segment. Spermathecal ducts narrow-elongate; ducts may terminate in vestibules; spermathecal ampullae globular to ovate with large, vacuolated cells entally. Type species. Altmanella freidris (Cook, 1966) n. comb. Other species. Altmanella idahoensis n. sp., Altmanella lenati n. sp. Etymology. The genus is named for L.C. Altman, whose early work (including the description of Kincaidiana) provided the basis for subsequent studies of northwestern Nearctic oligochaetes. Remarks. Altmanella species differ from Kincaidiana s. str. in many respects, and should be assigned to a separate genus. All Altmanella species are small worms (Figs. 2A–B, 13A), and lack a proboscis; chaetae in anterior segments are not enlarged or bifid, pre-clitellar nephridia are present on 6/7, and lateral blood vessels are absent from posterior segments. Altmanella has a single pair of spermathecae in the first post-atrial segment (a common condition in lumbriculid genera), but spermathecae are absent in the less-common atrial and second postatrial segments. In addition to differences in arrangement, there are basic structural differences between the reproductive organs of Altmanella and Kincaidiana. The western Altmanella species have petiolate atria, and penes are formed by extrusion of elongated lining cells from a distinct penial structure (Figs. 6J, 10L–M). The single eastern species has tubular atria and male ducts terminating in short porophores (Fig. 15I). None has pendant penes within an eversible sac (Fig. 2H). Altmanella has narrow spermathecal ducts (Figs. 4, 8, 14), in contrast to the thick ducts seen in Kincaidiana (Fig. 1E). The spermathecal ampullae of Altmanella are globular, with large cells (apparently with sorptive vacuoles) in the ental portion, in contrast to the narrow, more uniform ampullar walls of Kincaidiana. The unusual extension of atrial muscle onto the vasa deferentia is seen only in Kincaidiana. See also Remarks at A. freidris.Published as part of Fend, En. V., 2009, An evaluation of the genus Kincaidiana Altman, 1936, with the designation of Altmanella n. gen. (Annelida, Clitellata, Lumbriculidae), pp. 1-30 in Zootaxa 2077 on pages 6-
Altmanella lenati Fend, 2009, n. sp.
No full textAltmanella lenati n. sp. Figures 13–15 Holotype. USNM 1122780. A whole mounted worm, stained in borax carmine. Type locality. North Carolina, Carteret Co.: Pettiford Creek at Millis Road, 8-Jan-08, collected by D. Lenat. Paratypes. USNM 1122781-1122784. From the type locality, 8-Jan-08, collected by D. Lenat. 1 whole mount, 1 sagittally sectioned, 1 transversely sectioned. North Carolina, Richmond Co.: Drowning Creek at SR 1004, 28-Mar-08, 1 whole mount. Other material. North Carolina: The type locality, 17-Feb-08, 1 whole mount. 8-Jan-08, 5 whole mounts, 1 dissected, 1 sagittally sectioned. Halifax Co.: Beech Swamp, 17-Mar-07, 1 whole mount. Montgomery Co.: Cedar Creek on River Road, 18-Mar-07, 2 whole mounts. Little River at Star, 18-Mar-07, 2 whole mounts, 2 sagittally sectioned. Unnamed tributary to Little River at Star, 18-Mar-07, 1 whole mount. Richmond Co.: Drowning Creek at SR 1004, 15-Mar-07, 1 whole mount. 28-Mar-08, 1 whole mount. Seep at Drowning Creek, SR 1004. 17-Apr-08, 4 whole mounts. All specimens collected by D. Lenat. Etymology. Named for David R. Lenat, who has discovered several new species of Lumbriculidae, in addition to other freshwater invertebrates in southeastern North America. Description. Histological details are based on sectioned worms from Pettiford Creek and Little River. Measurements in the text are means and ranges for all sites. Small, thin, tapered worms (Fig. 13A); length (preserved) 14 (11–16) mm; diameter 0.28 (0.20–0.35) mm in IX (at male pore); maximum diameter to 0.32 (0.24–0.40) mm (usually in X–XII), anterior and posterior segments thinner, less than 0.2 mm. Prostomium rounded or rounded-conical (Fig. 13C). Chaetae paired, in four bundles per segment, beginning in II. All chaetae simple-pointed, moderately sigmoid, with nodulus 0.33–0.41 of the total length from the tip (Fig. 13B). Chaetal length 88 (70–103) µm anteriorly and in clitellar region, 85 (55–99) µm posteriorly; somewhat shorter in II–III. Secondary segmentation variable, usually a few anterior segments posterior to II have a narrow anterior ring up to 1/4 length of segment (Fig. 13C), occasionally to IX or more (Fig. 13A). Segmentation obscured by clitellum in external view, often weak in posterior segments. Epidermis in anterior segments 7–12 µm thick; many epidermal cells appear enlarged and granular, particularly in middle of some anterior segments. Clitellum distinctly glandular in mature specimens, from mid-IX to mid-XI; absent between and around male pores. Clitellar epidermis thickest (23–33 µm) ventrally in X, anterior to the spermathecal pores (Figs. 13D, 14B); more dorsally, clitellum 12–24 µm thick. Circular muscle of body wall 1–2 µm thick; longitudinal muscles 8–12 µm thick. Septa indistinct at 1/2–2/3. Pharynx with ventral wall thin; a thickened dorsal pad in II–III (Figs. 13D, 15A); everted in many preserved specimens. Pharyngeal glands usually in V–VII (Fig. 13D). Dorsal blood vessel divides beneath the brain, and the two ventral trunks rejoin near septum 2/3 to form the ventral blood vessel. Highly sinuate, lateral commissural vessels usually visible in II–VIII; they join the dorsal vessel anterior to the chaetae, and join the ventral vessel either near the posterior margin of the originating segment or in the anterior to middle part of the following segment. Lateral vessels difficult to see posterior to VIII, but visible as far back as XI in some specimens; those in IX–X may loop back through several segments within the sperm and egg sacs. Lateral vessels were not visible in posterior segments. Perivisceral blood vessels may form a conspicuous plexus in VII–VIII. Chloragogen begins around VIII. First nephridia paired on 6/7, second pair on 11/12, then sporadic (approximately every fifth segment) and usually unpaired posteriorly. Nephridia with granular postseptal expansions 40–80 µm long, diameter about 20 µm, followed by a convoluted duct, which may penetrate several posterior segments ventral to the gut (Fig. 13E). Nephropores with or without a weak terminal vesicle, just anterior to ventral chaetae. All genital pores paired, on ventral chaetal lines. Male pores in IX, each on a short porophore within a shallow concavity, about midway between ventral chaetae and 9/10 (Fig. 13D). Spermathecal pores paired in X, inconspicuous, just behind ventral chaetae. Female pores intersegmental on 10/11. Testes paired on anterior septa in IX, ovate, extending to mid-IX; ovaries paired in X, narrow and elongate, often extending into XI within egg sacs. Sperm sacs confluent with egg sacs, extending back to XI– XVII; anterior sperm sacs almost always absent, but in one specimen protruding into VIII. Egg sacs extend to XIV–XX. Spermathecal ampulla irregularly ovate, length 290 (210–420 µm), width 140 (80–180 µm) (Fig. 14); in X or XI. A very thin muscle layer surrounds the epithelium; epithelial cells small (5–7 µm) near ectal end of ampulla, but larger and vacuolated entally, to 19–31 µm in some mated specimens (Fig. 15C). Sperm heads may be directed towards ectal duct within ampulla, remainder of ampulla sparsely filled with unordered sperm or tails; no obvious sperm was present in vacuolated cells of epithelium. Spermathecal duct distinct, tubular, length 260 (205–310) µm; diameter at middle 21 (17–25) µm. Duct formed of tightly packed, regular epithelium, surrounded by a very thin muscle layer (Fig. 15B). Ectally, the duct may widen slightly, but does not form a distinct vestibule. Female funnels simple, cup-shaped, posterior lip about 70–120 µm high, with thick anterior lip. Male funnels directed posteriad, extending back into X within the sacs (Fig. 14). Funnels simple, conical to spoon-shaped, about 60–90 µm long by 30–50 µm wide, histologically distinguished from vasa deferentia by cuboidal cells with dense nuclei. Vasa deferentia relatively short and thick; length of free portion 250 (210–275) µm; width in free portion 24–34 µm; ciliated. Vasa may loop posteriorly, but do not penetrate 9/10 or enter X (Fig. 14); instead, they enter IX directly from the sperm sacs, becoming appressed to the atrium near the ectal end of the atrium (about 30 µm from the male porophore) (Fig. 15H–I); vas somewhat flattened, but remains histologically distinct from atrium (Fig. 15D); width of appressed portion about 20 by 30 µm. The lumen of the vas joins the atrial lumen apically (Fig. 14B–C). Vasa deferentia with thick (10–12 µm) epithelium having a fibrous appearance and indistinct cell boundaries; nuclei sparse and uneven near the atrium, but denser as the vas approaches the sperm funnel; lumen narrow (5–7 µm) and ciliated. Atria usually entirely in IX, but may pass through septum 9/10 into X. Total atrium length 290 (200–390) µm. Atria tubular to slightly club-shaped, not divided into distinct duct and ampulla (width in ectal part 17–29 µm; width in ental part 24–34 µm); main (ental) part mostly distinguished by presence of prostate glands. Atrial epithelium of cuboidal to slightly columnar cells; in the main (ental) part these cells appear vacuolated with basal nuclei in mature specimens; lumen narrow, to 5–8 µm wide, and ciliated (Fig. 15D, F). Muscle layer of atrium thin, (1–2 µm). Prostate glands in irregular, petiolate bundles of up to 20–30 granular cells, loosely covering the ental 2/3 to 3/4 of the atrium; prostate bundles about 40–60 µm long. Atrial duct protrudes within a short, rounded porophore, 31 (22–43) µm high by 36 (28–46) µm wide (Fig. 15G–I). Porophores may be conical, dome-shaped, or slightly turbinate, and are present (protruded) in all mature, preserved specimens. Remarks. Altmanella lenati superficially resembles the western Altmanella species; its small size, and thin, tapered form is distinctive within southeastern Nearctic worm samples. The male porophores are usually visible on unmounted, mature specimens. The position of the male pores on IX is anterior to that of most other lumbriculids (usually in X), but posterior to that of its congeners (VIII). Internally, the tubular atria with thick vasa deferentia (approximately the atrial diameter) separate this species from all other Nearctic lumbriculids.Published as part of Fend, En. V., 2009, An evaluation of the genus Kincaidiana Altman, 1936, with the designation of Altmanella n. gen. (Annelida, Clitellata, Lumbriculidae), pp. 1-30 in Zootaxa 2077 on pages 20-2
Altmanella idahoensis Fend, 2009, n. sp.
No full textAltmanella idahoensis n. sp. Figures 7–10 Holotype. USNM 1122773 A whole mounted worm, stained in borax carmine. Type locality. Idaho, Oneida Co.: Deep Creek above Stone Canal, 11-Jul-04, collected by D. Gustafson. Paratypes. USNM 1122774-1122779. From the type locality, 11-Jul-04, 3 whole mounts, 2 sectioned. Idaho: Bonneville Co: Fisher Bottom lower spring, 27-Jun-00, 1 whole mount. Other material. California: Tehama Co.: Sacramento River at Bend, coll. S. Fend, 13-May-01, 19 whole mounts, 5 dissected, 2 sectioned. 26-May-02, 2 whole mounts, 1 dissected. Idaho: Bear Lake Co.: Bue Pond Spring, 4-Sep-00, 3 whole mounts. St Charles Spring, 4-Sep-00, 2 dissected, 1 whole mount. Bonneville Co: Fisher Bottom lower spring, 27-Jun-00, 1 dissected, 3 sectioned. 2-Sep-00, 7 whole mounts, 3 dissected. Clearwater Co.: North Fork Clearwater River at Dworshak Ramp, 1-Apr-05, 11 whole mounts, 2 sectioned. Idaho Co.: Meadow Creek at Selway Falls, 1-Jul-02, 1 whole mount. Oneida Co.: Deep Creek above Stone Reservoir, 25-Apr-04, 7 whole mounts. Deep Creek above Stone Canal, 11-Jul-04, 11 whole mounts, 3 sectioned. Power Co.: American Falls Hatchery outlet at Snake River, 27-Mar-00, 5 whole mounts. Batiste Springs, 28-Feb-02, 7 whole mounts, 2 dissected. Nevada: Elko Co.: Marys River, 28-Apr-04, 4 whole mounts. Bruneau River at Cottonwood Creek, 15-Jul-04, 1 whole mount. Oregon: Klamath Co.: Spring Creek at Williamson River, 23-Jun-08, coll. J. Carter, 6 whole mounts,12 dissected. Wasco Co.: Deschutes River at South Junction Road, 26-Oct-95, coll. S. Fend, 10 whole mounts, 3 dissected, 2 sectioned. Utah: Cache Co.: Logan River at Wood Camp, 17-Apr-97, coll. R. D. Kathman, 5 whole mounts. Logan River at Beaver Creek, 29-Aug-03, 1 whole mount. Utah Co.: American Fork, 28-Aug-03, 10 whole mounts. All specimens collected by D. Gustafson, unless otherwise noted. Etymology. Named for the type locality. Description. Histological details are based primarily on sectioned worms from Deep Creek, Fisher Bottom spring, Clearwater River, and Sacramento River. Measurements in the text are means and ranges for all sites; measurements by region are given in Table 1. Length of preserved worms 12 (7–22) mm; segments 62 (36–104); diameter 0.36 (0.25–0.56) mm in X. Prostomium rounded to nearly conical (Fig. 7). Chaetae paired, in four bundles per segment, beginning in II. All chaetae simple-pointed, moderately sigmoid, with nodulus 0.35 (0.28–0.43) of the total length from the tip (Fig. 7E). Chaetal length 89 (70–106) µm in clitellar region, 87 (60–110) µm posteriorly. Secondary segmentation begins in III, with a narrow anterior ring; segmentation obscured by clitellum, often weak in posterior segments. Epidermis in anterior segments 10–14 µm thick; in clitellum 12–22 µm. Clitellum distinctly glandular in mature specimens, surrounding entire segment from VIII to X. Circular muscle of body wall 1–2 µm thick; longitudinal muscles 10–15 µm thick. Septa indistinct at 1/2 and 2/3; prominent elsewhere. Pharynx with ventral wall thin; a thickened dorsal pad in I–II (Fig. 7C); everted in many preserved specimens (Fig. 7D). Pharyngeal glands usually IV–VI, may extend into VII (Fig. 7C). Nephridia as described above for A. freidris; postseptal expansion 50–60 µm long, diameter 25–30 µm; terminal vesicle 30–50 µm long by 17–20 µm wide (Fig. 10D). Blood vessels as described above for A. freidris. Ventral blood vessels separate through III, join in IV; the dorsointestinal blood vessel begins in about VII. All genital pores paired, on ventral chaetal lines. Male pores in VIII, about midway between chaetae and 8/9. Spermathecal pores paired in IX, near 9/10, often on slight papillae. Female pores intersegmental on 9/10. Testes paired on anterior septa in VIII, ovaries paired in IX. Sperm sacs confluent with egg sacs, extending back to about XII–XIV; anterior sperm sacs usually absent. Egg sacs extend to about XIV–XV (as far as XVII). Spermathecal ampulla irregularly ovate, length 240 (120–410) µm, width 120 (40–200) µm (Fig. 8). A very thin muscle layer surrounds the epithelium; histology of ampulla as described (see above) for A. freidris (Fig. 10B–C). Spermathecal duct distinct, tubular, length 169 (59–310) µm; diameter at middle 20 (14–31) µm. Duct formed of tightly packed, regular epithelium, surrounded by a prominent layer of transverse-circular muscles, about 2– 4 µm thick (Fig. 10A). The duct terminates in a vestibule, 115 (75–160) µm tall by 43 (24–62) wide; epithelium somewhat columnar, surrounded by a 2–5 µm layer of circular-transverse muscle fibers. Female funnels simple, tubular, about 80 µm high, with thick anterior lip. Male funnels on 8/9, directed forward into VIII or posterior margin directed back into sperm sacs; occasionally extending back to mid-IX. Funnels about 60–100 µm wide, not very convoluted. Vasa deferentia relatively short and thick; length 460 (300–640) µm; width 22 (15–28) µm at most sites, but to 40 µm in Spring Creek, Oregon; ciliated. Vasa may enter IX slightly, but do not form a distinct loop in IX (Fig. 8); in most specimens they appear to enter VIII directly, penetrating atrial muscle layer ental to the midpoint of the atrium, and entering atrial lumen subapically (thus usually embedded for a short distance, about 30–70 µm). Atria usually entirely in VIII, but may pass through septum 8/9 into IX. Total atrium length 230 (97–400) µm at most sites (Table 1), but to 625 µm in Spring Creek, Oregon. Atria consist of a short duct (mean length 68 µm, mean width 18 µm) and ental, club-shaped ampulla (length 189 [70–500] µm, width 45 [34– 67] µm) (Figs. 8, 9); ampulla mostly distinguished from indistinct duct by presence of prostate glands (Fig. 10E–F). Ampullar epithelium of cuboidal to slightly columnar, ciliated cells; lumen variable, often less than 10 µm wide, but mean diameter 22 µm, and up to 57 µm when ampulla is expanded (Fig. 10G). Muscle layer of atrial ampulla thin, 1.6 (1–3) µm (to 7 µm at Spring Creek) with most fibers arranged more or less longitudinally. Prostate glands, in pyriform bundles of up to about 20 cells, loosely cover the atrial ampullae; prostates about 40–80 µm long; histology as described for A. freidris (see above). Atrial duct expands abruptly at ectal end, forming a pyriform to cask-shaped penial structure, 130 (60–280) µm tall by 76 (40–125) µm wide (not including the irregular peritoneum); length about 2 times width (varies among populations) when penes are not extended (Figs. 8, 9, 10H–K). Penial structure surrounded by a muscle layer 2.5 (1–6) µm thick; mostly transverse-circular muscle in specimens from the type locality, but in some other material a distinct longitudinal layer surrounds the circular layer. Epithelium of penial structure produced into irregular lamellae, forming an irregular lumen with thin cuticle (Fig. 10I–M). Epithelial cells elongate, with basal nuclei and indistinct boundaries. Extruded penes of preserved worms 75 (up to 160) µm long, usually short and blunt (Figs. 9, 10L–M). Ectal end of penial structure may extend a short distance out of the body, forming base of penis, but penis mostly formed by extrusion of epithelial cell extensions into a narrow tube; nuclei mostly remaining inside the penial structure; internal dimensions of the penial structure may be considerably reduced after extension. Remarks. Altmanella idahoensis is distinguished from A. freidris by the shorter, thicker penial structures, the short atria with a thin muscle layer, and the more ental junction of the vasa deferentia with the atria. In contrast to A. freidris, in which the penial structures taper gradually, those of A. idahoensis narrow abruptly to form the base of the atrial duct. The penial structure of A. idahoensis has a wide, irregularly convoluted lumen, in contrast to the narrow, indistinct lumen of A. freidris (Figs. 10I–M vs. 6H–K). The structure appears to partially evert with penis extension, rather than simply extruding cell extensions, as indicated by the deeply folded lumen and by an inverse relationship between length of extruded penis and size of the internal penial structure (cf. Figs. 8A vs. 8B). The atrial ampulla is distinguished from the atrial duct only by the presence of prostates, and does not have a thickened muscle layer (Figs. 10E–G vs. 6C–F). Unlike A. freidris, the ampulla often is expanded, with thin epithelium and a wide lumen (Fig. 10G); this is variable among specimens, and is likely related to reproductive state. Other lumbriculids have been described as going through a similar process, i.e. erosion and thinning of atrial epithelium and general loss of structure at a late stage of maturity (e.g. Timm 1998). The vas deferens of A. idahoensis joins the ampulla near the ental end, rather than near the base (Figs. 8, 9 vs. 4, 5). Although most of these characters appear variable when quantified (Table 1), examination of over 100 specimens from the sites where both morphotypes occurred (the Sacramento River, California and Spring Creek, Oregon) did not produce any intergrades (Figs. 4A, 5E–F vs. 8D, 9L–M and 5L vs. 9O). There appear to be minor morphological differences among regions. Worms from the type locality and nearby sites (central Idaho) generally had relatively small, compact penial structures, somewhat tapered towards the ental end. Specimens from northern Idaho (Clearwater River) and California (Sacramento River) tended to have larger, more ovate penial structures with a more distinct lumen, and more abrupt transition to the atrial duct. However, due to differences in fixation protocol, almost all of the specimens from the latter collection were in a much more relaxed state, with penes (and pharynx) retracted. Because the A. idahoensis penes are extruded by eversion of the penial structures, some of this apparent difference may be an artifact. The atria were highly variable among populations, although there did not appear to be a large-scale clinal trend. The Marys River worms had the shortest atria; these were shorter than the penial structures in the few available specimens (Fig. 9I). The Spring Creek (Oregon) population was the most anomalous; all representatives in a good series of specimens had exceptionally elongate atria (Fig. 9O). Other aspects of the male ducts also were enlarged in these specimens; the vasa deferentia were unusually thick (to 40 µm, versus up to 28 µm at other sites), and the atrial muscle layer was as thick as 6 or 7 µm (1–3 µm at most other sites). The Deschutes River (also Oregon) worms also appeared to have a thicker atrial muscle than specimens from other sites, although this appeared to be a general thickening of the entire structure, rather than a distinctly thickened ampulla. Poor histological fixation may have been a factor here, as these specimens were fixed in straight formalin without prior relaxation; consequently the tissues appeared shriveled and distorted. Although inclusion of the Spring Creek population within idahoensis creates overlap in atrial measurements with A. freidris (Table 1), these specimens had typical idahoensis -like penial structures, and the vasa deferentia entered the atrial ampullae subapically (Fig. 9O). Additionally, they differed sharply from A. freidris collected at this site (Fig. 5L).Published as part of Fend, En. V., 2009, An evaluation of the genus Kincaidiana Altman, 1936, with the designation of Altmanella n. gen. (Annelida, Clitellata, Lumbriculidae), pp. 1-30 in Zootaxa 2077 on pages 14-2
Going Beyond Counting First Authors in Author Co-citation Analysis
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counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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