Pyrgulopsis scalariformis (Wolf 1869)

Pyrgulopsis scalariformis (Wolf, 1869)

Pyrgula scalariformis Wolf, 1869:198, pl. 17: fig. 3.—Baker, 1964:176.

Pyrgulopsis scalariformis.—Call and Pilsbry, 1886:14, pl. II: fig. 13.—Walker, 1918:140.—Baker, 1928:138, pl. VII: figs. 24–27.—Burch, 1982: 28, fig. 273.—Hershler and Thompson, 1987:30, fig. 31.—Turgeon et al., 1988:62.

Pyrgula scalariformis mississippiensis Pilsbry, 1886:75.

Pyrgulopsis mississippiensis.—Call and Pilsbry, 1886:13, pl. II: figs. 14–16.—Pilsbry, 1891c:330.—Hinkley, 1906:43.—Walker, 1906:116, pl. 5: fig. 15.—Baker, 1964:174.—Johnson, 1975:142.

Pyrgulopsis wabashensis Hinkley, 1908a:117; 1908b:56.—Goodrich and Schalie, 1944:300.—Baker, 1964:177.—Hershler and Thompson, 1987:30.

DIAGNOSIS.—Shell pupiform to narrowly conic, basally carinate, medium to large-sized, narrowly umbilicate. Penial filament medium length, lobe short. Penial ornament a transverse terminal gland.

DESCRIPTION.—Shell (Figure 30e,f) pupiform-narrowly conic; height, 3.5–4.7 mm; whorls, 5.5–6.0. Early protoconch strongly punctate, later portion with weaker sculpture; protoconch often eroded. Earliest teleoconch with rounded whorls; later whorls near flat; broad peripheral keel (varying from weak to well developed) appearing at middle or end of third whorl and extending to aperture. Aperture ovate, broadly adnate to very slightly separated from body whorl. Inner lip complete, usually thickened; columellar lip slightly reflected. Outer lip similarly thickened, prosocline. Umbilicus near absent to narrowly rimate. Periostracum light brown.

Operculum (Figure 30g,h) ovate, light amber; nucleus slightly-highly eccentric; dorsal surface frilled. Attachment scar margin often thickened all around, sometimes broadly so along inner edge (to nucleus); callus small, but well developed.

Central radular tooth (Figure 42d) with moderately indented dorsal edge; lateral cusps, 4–5; central cusp rounded-pointed, slightly broader and longer than laterals; basal cusps, 1–3 (innermost largest), short, broadly triangular, with weak dorsal support. Basal process narrow, weakly excavated. Lateral margins thickened; neck weak-absent.

Animal completely unpigmented except for black eyespots.

Ctenidial filaments, 22, medium height, narrow. Osphradium large (31%), centered slightly posterior to middle of ctenidial axis. Kidney opening slightly thickened and whitened. Stomach caecum broad, short.

Testis, 1.5 whorls, overlapping stomach to edge of style sac. Prostate gland with large (43%) pallial section; pallial vas deferens with prominent kink considerably distal to edge of prostate gland. Penis (Figure 53b) large; base elongate-rectangular, narrowing distally; filament medium length and width, tapered distally; lobe short, broad. Terminal gland elongate, transverse, borne along distal edge of lobe. Filament unpigmented.

Ovary, 0.5 whorl, abutting posterior edge of stomach. Pallial albumen gland very large (75%). Capsule gland slightly shorter than albumen gland. Genital aperture an elongate, subterminal slit without vestibule. Coiled oviduct of two overlapping, near horizontal loops just behind pallial wall (extending to near posterior edge of albumen gland). Oviduct and bursal duct join well anterior to oviduct coil just anterior to pallial wall. Bursa copulatrix ovoid, short (24%), broad (64%), with 33% of length posterior to gland. Bursal duct broad, very slightly embedded in albumen gland, about twice as long as bursa copulatrix. Seminal receptacle stubby, short, positioned lateral to anterior bursa copulatrix and along ventral edge of albumen gland.

TYPE LOCALITY.—Pyrgulopsis scalariformis: Tazewell shore of the Illinois River, Illinois. Lectotype (Baker, 1964:176), ANSP 27822; paralectotypes, ANSP 375740. Pyrgulopsis mississippiensis: near mouth of Rock River, a few miles below Davenport, Iowa. Lectotype (Baker, 1964:174), ANSP 61606; paralectotypes, ANSP 375747. Pyrgulopsis wabashensis: Wabash River, at The Chains in Posey County, Indiana. Lectotype (Baker, 1964:177), ANSP 27824; paralectotypes, ANSP 96607, ANSP 396953.

DISTRIBUTION.—Ohio, Mississippi, Tennessee River drainages, eastern United States (very incompletely known).

MATERIAL EXAMINED.—FSM 91725, Meramec River, 2.9 km north-northwest of Steeleville, Crawford County, Missouri; FSM 91726, ibid., 12.0 km southeast of Leesburg.

Cladistic Analysis

The “m*” option produced a single tree of consistency index of 0.26 and retention index of 0.61. Branch and bound (“bb*”) search based on this tree yielded more than 1559 trees of equal length. The “nelsen” option then was used to obtain a strict consensus tree for these solutions, which is shown in Figure 53. Lists of character-state transformations supporting clades of interest are in Table 2.

The consensus tree provides support for monophyly of Pyrgulopsis (referred to as Clade 1 in Table 2) in that our genus is differentiated from the outgroup by 15 character-state transformations, including six non-homoplasious synapomorphies: densely pitted protoconch (character 3-1), broad operculum attachment scar (8-1), narrow basal process on central radular tooth (16-1), well developed lateral angles of central tooth (17-1), simple anterior vas deferens (25-1), and horizontally oriented bursa copulatrix (55-1).

Within Pyrgulopsis, four large clades are reasonably supported and may merit recognition as species groups. The nine eastern American species (Clade 2), comprising all species allocated to Marstonia by Thompson (1977) plus P. scalariformis, are defined by 10 character-state transformations, including non-homoplasious synapomorphies of coarse protoconch microsculpture (3-2) and anterior junction between oviduct and bursal duct (49-1). Homoplasious characters supporting this clade include a banded pattern of mantle pigmentation (18-1; reversed in one eastern species), narrowly vertical oviduct coil (50-1; reversed or transformed in two eastern species), elongate bursal duct (58-1; paralleled in a western species), and bursal duct deeply embedded in albumen gland (59-2; reversed in one eastern species). Other characters uniquely, but not universally, found in this clade are an incomplete inner shell lip (2-1), indented outer edge of operculum (7-1), strongly oblique penial lobe (29-1), and narrow, sac-like bursa copulatrix (53-3). Members of this clade have ovate-conic shells and relatively simple penes usually ornamented by a terminal gland and, in some cases, a ventral gland.

The other three clades are comprised of subsets of the western American fauna. Six species from southern Nevada and southeastern Arizona form a clade (Clade 3) defined by three transformations, including unique synapomorphies involving loss of penial lobe (30-3) and terminal gland (32-3). Other unique synapomorphies defining sub-clades within this group are an enlarged ventral gland (43-2) and superficial position of ventral gland (44-1). Members of this clade usually have globose shells, and their penes are ornamented by a ventral gland, sometimes accompanied by a large dorsal gland.

A second western clade (Clade 4) is comprised of 10 species from eastern California, northern Arizona, and Snake River environs of Wyoming, Idaho, and Oregon; and includes all members of the subgenus Natricola sensu Gregg and Taylor (1965). This group is defined by five synapomorphies, of which only one, presence of a dot-like Dg1 penial gland, is unique; this character is transformed in advanced members of this clade. Other defining characters are homplasious, and include a strong ventral callus on the operculum (10-1), and three features relating to Dg1 (37-1, 38-2, 40-1). There is extensive parallelism in penial and female genitalic character transformations between this clade and that discussed below. Members of this group often are large, have ovate-conic shells, and have penes ornamented by terminal gland, Dg1, and sometimes Dg2 and/or Dg3.

A third western clade (Clade 5), comprised of 18 species from various drainages, closely approximating the “F[ontelicella]. californiensis series” of Taylor (1987), is defined by five character-state transformations. Three of these (33-1, 34-1, 35-1) are associated with the unique occurrence of a penial gland (Pg) in this clade. The other two, involving a strong ventral callus on operculum (10-1) and loss of anterior capsule gland vestibule (48-0), are homoplasious. Within this group, sub-clades are defined by the following unique or near-unique character-state transformations: proximally bifurcate penial gland (35-2, one parallel within this clade), Dg1 a short strip (36-2), multiple minor dorsal glands (42-2, paralleled by two species), posterior position of ovary (46-1, parallel by one species within this clade), multiple ventral glands (43-2), and elongate bursa copulatrix (52-1, two parallels and one reversal). Members of this group have globose to elongate-conic shells and penes ornamented by a terminal and penial gland, often accompanied by one or more dorsal glands.

The 17 Western American species having a relatively simple penis (ornamented solely by terminal gland) do not comprise a monophyletic group and, in general, are poorly resolved on the cladogram. Four globose-shelled species from southern Nevada (carinifera, nanus, fairbanksensis, isolata) are basally placed on the cladogram, but are not a well-defined group; and an assemblage of eight species scattered throughout the West, approximating the “F[ontelicella]. stearnsiana series” of Taylor, 1987), forms an unsupported polytomy. On the other hand, two small groups of species are more strongly supported. One pair from Gila River drainage of Arizona (bacchus, sola) is defined by a small penis (26-1, unique synapomorphy), bifurcate penial lobe (paralleled in one species), and simple terminal gland on penis (32-0, a homoplasious reversal). A second group, comprised of three highly disjunct species from internal drainage of northern Mexico (brandi), Amargosa River drainage (amargosae) and lower Snake River drainage (bruneauensis); is defined by three character-state transformations: weak ventral operculum attachment scar (9-0, homoplasious), penial filament (28-1, paralleled in one species), and bursal duct positioned lateral to albumen gland (59-0, homoplasious).

Appendices

Appendix 1

Recent Species Incorrectly Described As or Allocated to Pyrgulopsis or Its Junior Synonyms

(Unless otherwise stated, all Central American species of Ancey were allocated to Pyrgophorus by Hershler and Thompson, 1992.)

Pyrgulopsis conoidea Ancey, 1888:196. Nicaragua.

Pyrgulopsis coronatus Ancey, 1888:197. Vera-Cruz, Mexico.

Amnicola (Marstonia) greenensis Baker, 1928:113. Holocene, off Sherwood Forest Hotel, Green Lake, Green Lake County, Wisconsin. Generic status of this extinct species is uncertain.

Pyrgulopsis hydrobioides Ancey, 1888:201. Lago de Coatepeque, El Salvador.

Pyrgulopsis newcombiana Ancey, 1888:196. Nicaragua.

Pyrgulopsis nicaraguanus Ancey, 1888:194. Nicaragua.

Pyrgulopsis nicaraguanus costulifera Ancey, 1888:195. Nicaragua.

Pyrgulopsis nicaraguanus duplicata Ancey, 1888:195. Nicaragua.

Pyrgulopsis nicaraguensis Ancey, 1888:194. Nicaragua.

Pyrgulopsis patzcuarensis Pilsbry, 1891b:9. Lake Patzcuaro, West Mexico. Allocated to Tryonia by Taylor (1966).

Amnicola pilsbryi Walker, 1906:116. Rockford, Illinois. Allocated to Marstonia by Walker (1926). Transferred to Lyogyrus by Thompson (1968).

Pyrgulopsis producta Ancey, 1888:197. Nicaragua.

Amnicola sheldoni Pilsbry, 1890:52. Lake Michigan, at Racine, Wisconsin. Allocated to Pyrgulopsis by Walker (1918:140). Is the type species of Hoyia F.C. Baker, 1926 (monotypic).

Pyrgulopsis spinosus Call and Pilsbry, 1886. Comal Creek, New Braunfels, Texas. Transferred to Pyrgophorus by Martens (1899).

Pyrgulopsis spinosa brevispira Ancey, 1888:193. Comal Creek at New Braunfels, Texas.

Amnicola walkeri Pilsbry, 1898:43. Lake Michigan at High Island Harbor, Beaver Islands [Michigan]. Allocated to Marstonia by Baker (1926). Transferred to Lyogyrus by Thompson (1968).

Amnicola (Marstonia) walkeri foxensis Baker, 1928:116. Fox River, 1 mile (1.6 km) north of Portage, Columbia County, Wisconsin. Generic status uncertain; probably a Lyogyrus as above.

Amnicola winkleyi Pilsbry, 1912:1. Saco, Maine. Allocated to Marstonia by Baker (1926). Placed in synonymy with Marstonia lustrica by Thompson (1977). Transferred to Cincinnatia by Davis and Mazurkiewicz (1985).

Pyrgulopsis wrighti Ancey, 1888:199. Lago de Coatepeque, El Salvador.

Pyrgulopsis wrighti minima Ancey, 1888:201. Lago de Coatepeque, El Salvador.

Pyrgulopsis wrighti obesa Ancey, 1888:201. Lago de Coatepeque, El Salvador.

Pyrgulopsis wrighti oblonga Ancey, 1888:200. Lago de Coatepeque, El Salvador.

Pyrgulopsis wrighti plicosa Ancey, 1888:199. Lago de Coatepeque, El Salvador.

Pyrgulopsis wrighti transitans Ancey, 1888:200. Lago de Coatepeque, El Salvador.

Appendix 2

Fossil Species Described As or Allocated to Pyrgulopsis or Its Junior Synonyms.

Lithasia antiqua Gabb, 1866:13. Tertiary (Pliocene-Pleistocene; Taylor 1966), on Snake River, Idaho Territory, on the road from Fort Boisé to the Owyhee mining country. Allocated to Pyrgulopsis by Hannibal (1912b:189). Transferred to Lithoglyphus (= Fluminicola) by Taylor (1966a; as synonym of L. occidentalis (Hall, 1845)).

Pyrgulopsis blakeana Taylor, 1950:30. Subfossil, shore of Salton Sea by Fish Springs, Imperial County, California. Allocated to Tryonia by Taylor (1975).

Marstonia bucciniformis Youlou, 1978:42. Early Tertiary, Bohai Coastal Plain, China.

Pyrgulopsis cahuillarum Taylor, 1950:31. Subfossil, fifty yards northeast of the so-called Fish Traps, 7.9 miles (12.6 km) west of Mecca, Riverside County, California. Allocated to Tryonia by Taylor (1975).

Pyrgulopsis carinata Yen, 1944:103. Pliocene, Idaho Formation, Hammett, Elmore County, Idaho.

Amnicola crybetes Leonard, 1952:38. Pleistocene, Blanco Formation, 15 miles (24 km) east of Liberal, Seward County, Kansas. Allocated to Marstonia by Taylor (1960b).

Nematurella euzona Hanna, 1923:33. Miocene, Sonoma County, California. Allocated to Savaginius by Taylor (1975).

Pyrgulopsis imminens Taylor, 1950:28. Subfossil, shore of Salton Sea by Fish Springs, Imperial County, California.

Marstonia inflata Wang in Yu and Wang, 1977:21. Late Cretaceous/Cenozoic, China.

Amnicola (Marstonia) leightoni Baker, 1920:125. Pleistocene, near Rush Lake, Logan County, Ohio. Described as subspecies of Amnicola winkleyi; elevated to full species status by Baker (1928).

Fontelicella (Natricola) melina Taylor in Taylor and Smith, 1981:350. Pliocene, Honey Lake, Lassen County, California.

Amnicola micra Yen, 1946:488. Late Tertiary, 9 miles (14.4 km) northwest of Montpelier, Bear Lake County, Idaho. Allocated to Fontelicella by Gregg and Taylor (1965).

Paludestrina nanna Chamberlain and Berry, 1933:28. Pliocene, Collinston, Utah. Allocated to Savaginius by Taylor (1966).

Fluminicola percarinata Pilsbry, 1934:16. Late Pliocene-Early Pleistocene, Lost Hills Oil Field, California. Allocated to Savaginius by Taylor (1966).

Fluminicola perditicollis Pilsbry, 1934:16. Late Pliocene-Early Pleistocene, Lost Hills Oil Field, California. Allocated to Savaginius by Taylor (1966).

Fluminicola pilula Pilsbry, 1934:15. Late Pliocene-Early Pleistocene, Lost Hills Oil Field, California. Allocated to Savaginius by Taylor (1966).

Pyrgulopsis polynematicus Pilsbry, 1934:15. Pliocene, Buttonwillow Gas Field, California.

Amnicola (Marstonia) precursor Baker, 1928:116. Pleistocene, Green Lake, Green Lake County, Wisconsin.

Amnicola puteana Pilsbry, 1935b:559. Pliocene, Buttonwillow Gas Field, California. Allocated to Savaginius by Taylor (1966).

Pyrgulopsis? satilla Dall, 1913:236. Pliocene, near Alexandria, Louisiana.

Fluminicola siegfusi Pilsbry, 1934:16. Late Pleistocene-Early Pliocene, Lost Hills Oil Field, California. Allocated to Savaginius by Taylor (1966).

Fluminicola spiralis Pilsbry, 1934:16. Late Pliocene-Early Pleistocene, McKittrick Front Oil Field, California. Allocated to Savaginius by Taylor (1966).

Marstonia stenothyroides Youlou, 1978:42. Early Tertiary, Bohai Coastal Plain, China.

Pyrgulopsis tectoformis Youlou, 1978:37. Early Tertiary, Bohai Coastal Plain, China.

Pyrgulopsis tropidogyra Pilsbry, 1935b:555. Late Pliocene-Early Pleistocene, Santa Clara Lake beds, west side of Santa Clara Valley near Los Gatos, California.

Hydrobia truckeensis Yen, 1950:186. Pliocene, Truckee Formation, Nevada. Allocated to Fontelicella by Gregg and Taylor (1965).

Pyrgulopsis vincta Pilsbry, 1934:15. Pliocene, [basal] Tulare Formation, Kettleman Hills, California. Pyrgulopsis williamsi Hannibal, 1912b:189. Pliocene, Kettleman Lake beds, California.

Amnicola yatesiana Cooper, 1894:171. Late Pliocene-early Pleistocene, Santa Clara Lake beds, San Jose Mission, California. Allocated to Pyrgulopsis by Hannibal (1912b).

Fluminicola yatesiana utahensis Yen, 1947:273. Pliocene, Salt Lake Formation, near Logan, Utah. Allocated to Savaginius by Taylor (1966).

Marstonia xinminensis Youlou, 1978:43. Type locality, Early Tertiary, Bohai Coastal Plain, China.

Appendix 3

Data Matrix of 64 Characters for 60 Species of Pyrgulopsis and a Single Outgroup.

Figures 31–53