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New Records and Species of Molluscs From Tertiary Cold-Seep Carbonates in Washington State, USA

Posted on: Thursday, 5 January 2006, 06:00 CST

By Kiel, Steffen

ABSTRACT-

Eighteen gastropod and seven bivalve species are reported from Eocene to Oligocene cold-seep carbonates in Washington State, USA. Four species are new (Niso littlei, Turrinosyrinx hickmanae, Xanthodaphne? campbellae, and Lurifax goederti), and 16 are described in open nomenclature. Previously unknown features of protoconch or prodissoconch morphology and/or shell microstructure are provided for Retiskenea statura (Goedert and Benham), Provanna antiqua Squires, Nuculana? aff. N. grasslei Allen, and Bathymodiolus willapaensis (Squires and Goedert). Modiolus (M.) willapaensis is placed within Bathymodiolus based on the elliptical-triangular shape of its juvenile shell, indicating that the divergence between vent/ seep and whale/wood-fall inhabiting bathymodiolines took place at least 40 Ma. The first fossil species of the vent/seep genera Pyropelta (Pyropeltidae), Lurifax (family uncertain), and Catillopecten? (Propeamussidae) are reported. Niso (Eulimidae), Xanthodaphne, Turrinosyrinx, Benthonuingelia (Turridae), Ledella (Nuculanidae), Tindaria? (Tindariidae), and Delectopecten (Pectinidae) are reported for the first time from fossil cold-seep assemblages. Larval developmental strategies are inferred from protoconch and prodissoconch morphologies in 14 species, which largely reflect the species' phylogenetic groups, as in modern vent and seep molluscs. The data presented here indicate that the radiation of toxoglossate turrids (Gastropoda) into deep water took place already in the Oligocene, and not in the Miocene as previously thought. Healed shell injuries and presumed naticid drill holes represent the oldest known fossil evidence of predation at cold- seeps.

INTRODUCTION

TERTIARY COLD-SEEP carbonates on the Olympic Peninsula and adjacent areas in Washington State, USA, contain an unrivaled fossil record of organisms related to those of modern cold-seep environments. They were first described in 1990 and the number of described species has steadily increased, including many first and/ or geologically oldest records of extant vent/seep taxa (Goedert and Squires, 1990, 1993; Squires and Goedert, 1991, 1996; Goedert and Campbell, 1995; Goedert and Kaler, 1996; Saul et al., 1996; Goedert and Benham, 1999; Goedert et al., 2000, 2003 ). The cold-seep nature of several of these carbonates has recently been confirmed by geochemical evidence, and by biomarkers that indicate the past activity of methane-oxidizing Archaea (Peckmann et al., 2002, 2003). The aim of the present study is to provide new data and records of known molluscan species, and to describe 20 species of which four are new and 16 are left in open nomenclature. Additionally, new insights into the ecology and the evolutionary history of these enigmatic organisms are discussed.

MATERIAL

The specimens were collected from five localities in western Washington State and are of mid-Eocene to Late Oligocene age (Figs. 1, 2). Some species are from previously described cold-seep sites in the Humptulips Formation (LACMlP locality 12385), from the Bear River Deposit (LACMIP locality 5802) (Goedert and Squires, 1990; Squires and Goedert, 1991), and from the Lincoln Creek Formation (LACMIP locality 16504) (Squires, 1995). Additional species are from three other cold-seep sites in the Lincoln Creek Formation. At LACMIP locality 17746, a small limestone block was found as float in dark siltstones, and is of Late Oligocene age. It contains a rather diverse fauna. However, the only species that represents previously known Oligocene chemosynthetic fauna is the vent/seep nuculanid Nuculana cf. grasslei Alien, 1993. Therefore, samples from five individual pieces of this block were analyzed for their δ^sup 13^C values. These values range from -35.33 to -41.80[per thousand], indicating that the carbonate has been precipitated under the influence of methane oxidation (see Peckmann et al., 2002 for details), confirming a cold-seep origin. At LACMIP locality 17747 four limestone blocks were found as float, and the fauna of two of them (LACMIP localities 17747a and 17747c) is documented here. Species from these two blocks include known cold-seep species, such as Bathyrnodiolus willapaensis (Squires and Goedert, 1991), Provanna antiqua Squires, 1995, and Depressigyra sp. No isotope analyses were carried out on these blocks. The abbreviation used for catalog and locality numbers is LACMIR Natural History Museum of Los Angeles County, Invertebrate Paleontology section.

METHODS

Fossil extraction and documentation.-The carbonate blocks were first hammered into pieces ≤ 5 cm, and were frequently examined for fossils during this process. They were then cracked up repeatedly using a saturated Glaubers salt solution, a 5%-10% H^sub 2^O^sub 2^ solution, and frost-cracking. The resulting fragments were examined for fossils using a binocular microscope. Specimens for SEM analysis were mounted on stubs, coated with gold, and photographed using a Cambridge Stereoscan 360 and a Leo 1455 VP scanning electron microscope. Analyses show variation of about 3% while using different working distances and virtual rotation, so only approximate values for size are given here. Macrofossils were photographed with an Olympus Camedia C-3040 Zoom digital camera.

Stable isotope analysis of carbonate.-Samples for carbon stable isotopic analyses were taken using a handheld microdrill from the surfaces of small blocks that had not been treated with the chemical methods of fossil extraction outlined above. Carbonate powders were reacted with 100% phosphoric acid (density >1.9, Wachter and Hayes, 1985) at 75C using a Kiel III online carbonate preparation line connected to a ThermoFinnigan 252 mass spectrometer. All values are reported in per mil relative to V-PDB by assigning a δ^sup 13^C value of +1.95[per thousand] to NBS19. Reproducibility was checked by replicate analysis of laboratory standards and is better than 0.11[per thousand].

SYSTEMATIC PALEONTOLOGY

Class GASTROPODA Cuvier, 1797

Subclass COCCULINIFORMIA Haszprunar, 1987

Family PYROPELTIDAE McLean and Haszprunar, 1987

Genus PYROPELTA McLean and Haszprunar, 1987

Type species.-Pyropelta musaica McLean and Haszprunar, 1987, Recent, Juan de Fuca Ridge.

FIGURE /-Index map of western Washington State, USA, showing the five fossil localities and their LACMIP locality numbers.

FIGURE 2-Chronostraligraphic chart showing position of localities for the fossil species described herein.

PYROPELTA sp.

Figure 3.1-3.5

Patelliform limpet GOEDERT AND SQUIRES, 1990, table 1, fig. 2b, c.

Description.-Protoconch oval, about 175 m long; teleoconch limpet- shaped with subcentral apex, outline oval, longer than wide, fine radial growth lines; anterior slope slightly convex, posterior slope slightly concave, sides concave; largest specimen about 1.4 mm long, 1.0 mm wide, and 0.8 mm high. The shell of one specimen (LACMIP 13239) shows alternating layers of simple prismatic, and intersected- crossed-platy microstructure.

Material examined.-One specimen (LACMIP 13239) from LACMIP loc. 17747c, three catalogued specimens (LACMIP 13238) and 17 uncatalogued specimens from LACMIP loc. 12385.

Occurrence.-Early Middle Eocene to Oligocene cold-seep carbonates, Washington, USA.

Discussion.-The species described here is assigned to the Pyropeltidae based on its shell microstructure. An extant species from a whale bone in the Santa Catalina Basin off California, assigned to Pyropelta cf. musaica also has alternating layers of the same structures (Kiel, 2004), whereas other cocculiniforms and the patellogastropods have different shell structures (Hedegaard, 1990). Pyropelta sp. is thus likely to represent the first fossil record of the Pyropeltidae. However, it should be noted that in a specimen of Amphiplica plutonica Leal and Harasewych, 1999, a pseudococculinid from hadal depth in the Cayman Trench, shell layers appear to peel off the shell's surface, similar to Recent Pyropelta species. This might indicate that this species also has alternating layers in its shell, but this remains to be confirmed.

The east Pacific Pyropelta musaica shows morphologic variability from almost round to laterally compressed. The latter are quite similar to the specimens described here. The specimens of P. corymba McLean and Haszprunar, 1987 are more elevated than those of the fossil P. sp., however, the P. corymba specimen figured by Warn and Bouchet (2001) is more similar to P. sp. P. yamato Sasaki, Okutani, and Fujikura, 2003 from Japanese waters, and is known only from the holotype, which differs from the species described by having an almost round aperture. Pyropelta wakefieldi McLean, 1992 from whale- fall off California has an almost round aperture and has a very low profile, and is thus quite different from P. sp. The west Pacific P. bohlei McLean and Haszprunar, 1987 has an elongated shell shape as in P. sp. but differs in having a much lower profile. Thus, the fossil species described here falls within the morphological range of P. musaica and P. corymba. Hence, I refrain from assigning it to any species. It is interesting to note that Pyropelta sp. resembles the two east Pacific species, but not the two west Pacific species.

Three further fossil limpets fromthe Pacific realm are of similar general shell shape to Pyropelta sp.; the Eocene to Oligocene lottiid (Patellogastropoda) Erglnus vaderensis (Lindberg, 1979) from Washington State, however, has a very different shell microstructure (Lindberg, 1979; Squires and Goedert, 1994). The internal mold of a limpet from a Pliocene Japanese cold-seep was described as "Patellogastropod" (Nobuhara, 2003), but is of very generalized limpet shape and may not be a patellogastropod. A limpet from a Cretaceous Japanese cold-seep was questionably assigned to the extant acmaeid Serradonta cf. vestimentlfericola Okutani, Tsuchida, and Fujikura, 1992 by Hikida et al. (2003), although its shell microstructure is unknown. The taxonomic positions of the two Japanese fossils, and hence their relationships to Pyropelta sp., remain doubtful.

Subclass UNCERTAIN

Family NBOMPHALIDAE McLean, 1981

Genus RETISKENEA Warn and Bouchet, 2001

Type species.-Retlskenea diploura Warn and Bouchet, 2001, Recent, Aleutian Trench.

FIGURE 3-Pyropeltidae and Neomphalidae from Eocene and Oligocene cold-seep carbonates in Washington State. 1-5, Pyropelta sp.; 1, sample with three specimens, LACMIP 13238, LACMIP loc. 12385, 20; 2, juvenile specimen with preserved protoconch, 60; 3, close-up on the protoconch, arrows indicate transition to teleoconch, same specimen as 2, 200; 4, shell structure, arrows indicate the simple prismatic layers, LACMIP 13239, LACMIP loc. I7747c, 5.000; 5, apical view on largest specimen from Figure 2.1, 40. 6-9, Retiskenea statura (Goedert and Benham, 1999), all specimens from LACMIP loc. 16504; 6, shell structure, LACMIP 13240, 1,000; 7, adult shell with preserved protoconch, LACMIP 13241, 50; 8, close-up on the protoconch, same specimen as 79, protoconch showing well-preserved polygonal pits, LACMIP 13242, 200.

RETISKENEA STATURA (Goedert and Benham, 1999)

Figure 3.6-3.9

"Naticid" GOEDERT AND SQUIRES, 1990, p. 1182, fig. 2g; GOEDERT AND KALER, 1996, p. 67, table 1.

"Hyalogyrinids" GOEDERT AND CAMPBELL, 1995, p. 25, figs. 11, 12.

Depressigyra! statura GOEDERT AND BENHAM, 1999, p. 114, fig. 2.

Emended diagnosis.-Protoconch about half a whorl, initial part large, sculpture of irregularly spaced and sized pits, about 250 m wide. The shell of the teleoconch is about 27 m thick, and consists of an inner layer with simple crossed lamellar structure and a homogenous outer layer.

Material examined.-Three catalogued specimens (LACMIP 13240- 13242) and 12 uncatalogued specimens from LACMIP loc. 16504.

Discussion.-The adult shell of Retiskenea statura has already been described in detail (Goedert and Benham, 1999); here new data on protoconch morphology and shell microstructure is added. The extant R. diploura has a finer reticulation on the protoconch (Warn and Bouchet, 2001, fig. 15j). It has a homogenous and simple crossed- lamellar shell microstructure as found in R. statura, but shows additional simple prismatic layers (Kiel, 2004). The shell thickness of extant R. diploura is about 50 m (Kiel, 2004), about twice as thick as in R. statura.

Family PELTOSPIRIDAE McLean, 1989

Genus DEPRESSIGYRA Warn and Bouchet, 1989

Type species.-Depressigyra globulus Warn and Bouchet, 1989, Recent, Juan de Fuca Ridge.

DEPRESSIGYRA? sp.

Figure 4.1-4.4

Hyalogyrinid GOEDERT AND CAMPBELL, 1995, p. 26, tigs. 9, 10.

Description.-Protoconch orthostrophic, presumably made of half a whorl, oval in shape, 275 |xm in diameter, transition to teleoconch indistinct. Teleoconch low-spired euomphaloid, twoand-a-half whorls; whorls smooth except for prosocline growth lines; diameter 2.1 mm.

FIGURE 4-Peltospiridae and Trochidae from Oligocne cold-seep carbonates in Washington State. 1-4, Depressigyra sp., two specimens showing shape and size of protoconch; 1, 2, LACMIP 13243, LACMIP loc. 16504, adult shell 35, protoconch 120; 3, 4, LACMIP 13244, LACMIP loc. 17747c, adult shell 30, protoconch, arrows indicate presumed margin of protoconch, 100. 5, 6, solariellinid incertae sedis, LACMIP 13245, from LACMIP loc. 16504; 5, 15; 6, shell structure, outer side of shell up, 600.

Material examined.-One specimen (LACMIP 13243) from LACMIP loc. 16504; one uncatalogued specimen from LACMIP loc. 5802; one uncatalogued specimen from LACMIP loc. 17747a; two specimens from LACMIP loc. 17747c, one of them catalogued (LACMIP 13244).

Occurrence.-Oligocene cold-seep carbonates, Washington, USA (Makah and Lincoln Creek fms.).

Discussion.-This species was initially assigned to the Hyalogyrinidae, but the new material shows no initial heterostrophy of the protoconch, as in extant hyalogyrinids (Warn and Bouchet, 1993, fig. 42d-e; Warn and Bouchet, 2001, fig. 37e-g). The species is here only tentatively placed in Depressigyra because the surfaces of the protoconchs are eroded in all available specimens, thus a spiral ribbing on the protoconch that is characteristic for extant peltospirids cannot be observed. The protoconch is otherwise similar to those of peltospirids in size and shape. Shell microstructure was not preserved in any of the specimens.

Subclass VETIGASTROPODA Salvini-Plawen, 1980

Superfamily TROCHOIDEA Rafinesque, 1815

Family TURBINIDAE Rafinesque, 1815

Genus HOMALOPOMA Carpenter, 1864

Type species.-Turbo sanguineaum Linn, 1758, Recent, Mediterranean.

"HOMALOPOMA? Sp. B"

Homalopoma sp. B GOEDERT AND SQUIRES, 1990, fig. 2r.

Material examined.-Five uncatalogued specimens from the Bear River deposit (LACMIP loc. 5802), one uncatalogued specimen from the Lincoln Creek Formation (LACMIP loc. 17747a).

Occurrence.-Late Middle Eocene to Oligocene, cold-seep carbonates, Washington State, USA.

Discussion.-This species was hitherto only reported from the Early to Middle Eocene Humptulips Formation. Due to the poor preservation of the few available specimens, an identification of this species must await better material.

Family TROCHIDAE Rafinesque, 1815

Genus MARGARITES Gray, 1847

Subgenus PUPILLARIA Dall, 1909

Type species.-Trochus pupillus Gould, 1849, Recent, California.

MARGARITES (PUPILLARIA) COLUMBIANA Squires and Goedert, 1991

Margarites (Puplllaria) n. sp. GOEDERT AND SQUIRES, 1990, fig. 2q.

Margarites (Pupillaria) columbiana SQUIRES AND GOEDERT, 1991, p. 412, fig. 2.1-2.3.

Material examined.-One uncatalogued specimen from LACMIP loc. 17747a.

Discussion.-Margarites (Pupillaria) columbiana was first described from Upper Eocene cold-seep carbonates in Washington State, USA. This new record extends the range of this species into the Oligocene.

SOLARIELLINID incertae sedis

Figure 4.5, 4.6

Description.-Protoconch unknown; teleoconch turbiniform, at least three volutions; whorls angulate with tuberculate shoulder and convex periphery; earlier whorls sculptured by thin, slightly oblique ribs that fade near lower suture, and a fine spiral ridge at periphery; in later whorls, the ribs fade just below peripheral ridge. Shell wall consists of three layers, a homogenous outer layer, a simple prismatic central layer, and nacreous inner layer.

Material examined.-One specimen (LACMIP 13245) from LACMIP loc. 16504.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

FIGURE 5-Provanna antiqua Squires, 1995 from Oligocene cold-seep carbonates in Washington State, all specimens from LACMIP loc. 16504. 1, Protoconch showing fine spiral striation and intimations of axial sculpture, LACMIP 13246, 100; 2, same as 1, juvenile specimen, 60; 3, 4, isolated protoconch, LACMIP 13247, 100; 5, apical view on protoconch, same as 1; 6, shell structure, LACMIP 13248, 700; 7, adult shell, arrow indicates shell injury, LACMIP 13249, 20; 8, apical portion of the shell injury, same as 7, 100.

Discussion.-This specimen shows some similarities with solariellins, but is too imperfectly preserved for a more precise placement.

Subclass CAENOGASTROPODA Cox, 1959

Family PROVANNIDAE Warn and Ponder, 1991

Genus PROVANNA Dall, 1918

Type species.-ITrichotropis (Provanna) lomana Dall, 1918, Recent, off California, USA.

PROVANNA ANTIQUA Squires, 1995

Figure 5.1-5.8

Provanna n. sp. GOEDERT AND CAMPBELL, 1995, p. 25, figs. 4-7.

Provanna antiqua SQUIRES, 1995, p. 32, figs. 3-18; PECKMANN ET AL., 2002, p. 860-861, table 1, fig. 3e.

Emended diagnosis.-Protoconch blunt, rather flat-topped, about one whorl, first-quarter whorl sculptured by very fine pits and wrinkles, and by three or four fine spiral lines; after a quarter volution fine, undulating growth lines and fine spiral lirae commence; transition to teleoconch indistinct, presumably marked by small constrictions of the whorl; protoconch 410 m wide, 340 m high. Shell wall of teleoconch about 33 m thick, composed of simple prismatic, complex crossed lamellar, and homogenous structure (from outside to inside).

Material examined.-Four catalogued specimens (LACMIP 13246- 13249) and numerous uncatalogued specimens from LACMIP loc. 16504; one uncatalogued specimen from LACMIP loc. 17747a; 11 uncatalogued specimens from LACMIP loc. 17747c.

Occurrence.-Eocene to Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-The teleoconch of this species and the variability of its sculpture have already been described and discussed (Squires, 1995). Detailed descriptions of its protoconch and shell structure are provided here. Whereas most Recent provannids have slender high- spired protoconchs with strong collabral ribs that reflect planktotrophic development (Warn and Bouchet, 1993), the protoconch of Provanna antiqua is blunt and almost smooth, and indicates lecithotrophic development. It resembles to some extent the protoconch of P. variahilix Warn and Bouchet, 1986 from the Juan de Fuca Ridge just offshore of Washington State (Gustafson and Lutz, 1994), but differs from that by having a flatter top and faint spiral threads.

Certain deepwater rissoids of the genus Onoba H. and A. Adams, 1852 secrete very similar proto- and teleoconchs (see Warn, 1996, figs. 23, 24, and 27). Provanna antiqua ma\y be distinguished from these by its more lenticular aperture, which is apically more pointed, and has a more prominent siphonal notch than Onoba species, which have a more rounded aperture.

Squires (1995) considered Provana antiqua to be most closely related to P. variabilis, but differing in its tabulate whorls and more closely spaced ribbing. Its shell characters suggest that extant P. variabilis evolved gradually from P. antiqua. Two further Recent species fall within the morphologic range of P. antiqua and P. variabilis. These are Provanna sp. A and P. sp. B described from New Zealand (Lewis and Marshall, 1996, p. 183, fig. 3d, e), who considered them "closely related to species already reported from [. . . ] other parts of the world." In addition, P. laevis Warn and Ponder, 1991 from the Guyamas Basin is similar, but seems to differ from P. antiqua in having no umbilical slit early in ontogeny (see Warn and Ponder, 1991, fig. 20h, i). Provanna glabra Okutani, Tsuchida, and Fujikura, 1992 is another very similar species but its whorl flanks are less convex than in P. antiqua (Okutani et al., 1992).

One keeled specimen of Provanna antiqua from LACMIP loc. 16504 shows a healed shell injury on the upper part of the last whorl's flank (Fig. 4.7, 4.8). Specimens of the extant P. sculpta Warn and Ponder, 1991 off Louisiana frequently have the outer lip damaged by crustaceans (Warn and Bouchet, 2001).

FIGURE 6-Cerithiopsid incertae sedis from Oligocene cold-seep carbonates in Washington State, all specimens from LACMIP loc. 16504. 1, Early teleoconch with three spirals on the whorl's flank, LACMIP 13250, 20; 2, specimen showing internal features, LACMIP 13251, 20; 3, specimen showing four to five spirals on the whorl's flank, LACMIP 13252, 15; 4, same specimen as 3, basal view showing growth lines, 20.

FIGURE 7-Eulimidae from Oligocene cold-seep carbonates in Washington State. 1-3, Niso littlei n. sp., holotype LACMIP 13260, LACMIP loc. 17746; 1, teleoconch, 16; 2, 3, details of the protoconch, 100. 4, Eulimid sp. 1, LACMIP 13261, LACMIP loc. 16504, 70. 5, Eulimid sp. 2, LACMIP 13262, LACMIP loc. 16504, 45.

Family CERITHIOPSIDAE H. and A. Adams, 1853

CERITHIOPSID incertae sedis

Figure 6.1-6.4

Description.-Protoconch unknown; teleoconch of very generalized "Cerithiella" appearance, slender turriform, up to six slightly convex whorls; sculpture of three to five equally sized and spaced spiral lines and about 20 slightly opisthocyrt ribs; aperture roundish with pointed apical end, siphonal canal apparently short but wide; basal thread lacking. Shell wall about 37 m thick, composed of complex crossed lamellar structure. Largest shell is about 4.1 mm high and 1.7 mm wide.

Material examined.-Three specimens (LACMIP 13250-13252) from LACMIP loc. 16504.

Occurrence.-Oligocene cold-seep carbonates, Washington, USA.

Discussion.-Due to the lack of data on protoconch morphology and the aperture, a more precise treatment is not currently possible.

Family EULIMIDAE Philippi, 1853

Genus NISO Risso, 1826

Type species.-Niso eburnea Risso, 1826, Pliocene, France.

NISO LITTLEI new species

Figure 7.1-7.3

Diagnosis.-Protoconch paucispiral, one whorl, initially smooth, on latter half with four weak spiral lines. Teleoconch turriculate, umbilicate, whorls smooth, with basal angulation, early whorls almost straight, later ones slightly convex.

Description.-Protoconch paucispiral, about one whorl, about 330 m high and about 430 m wide; first-half whorl smooth, second-half with four very weak spiral lines; transition to teleoconch indistinct or not visible. Teleoconch turriform, at least six smooth whorls; whorls straight to little convex, with sharp angulation near lower suture, growth lines relatively strong, slightly opisthocyrt; base broadly conical, umbilical slit with keeled margin. Holotype 5.3 mm high and 2.4 mm wide at base.

FIGURE 8-Turridae from Oligocene cold-seep carbonates in Washington State. 1-3, Turrinosyrinx hickmanae n. sp., holotype, LACMIP 13253, LACMIP loc. 17746; 1, 20; 2, close-up on lirst onc- and-half teleoconch whorls, showing anal sinus and onset of teleoconch, 30; 3, close-up on last whorl of protoconch, showing rhomboid sculpture, 100. 4, 5, Xanthodaphne campbellae n. sp., from LACMIP loc. 17746; 4, holotype, LACMIP 13254, 25; 5, paratype, LACMIP 13255, 11.

Etymology.-After Crispin T. S. Little, Leeds.

Type.-LACMIP 13260, type locality LACMIP loc. 17746.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-The large initial whorl of the protoconch indicates lecithotrophic development. This makes a precise placement of this species difficult, because similar adult shells occur, for example, in the pyramidellid genus Eulimella Forbes and MacAndrew, 1846. The placement of this new species in Niso is based on its general eulimid shape and its narrow umbilicus. Eulimids have not yet been described from Recent vents and seeps. However, as they are parasites on echinoderms, which occur at some Recent cold-seeps (Sibuet and Olu, 1998), they may be expected. Among the Recent eastern Pacific species of Niso, N. excolpa Bartsch, 1917 has a similar, but less developed basal angulation. All other Niso species differ from N. littlei in lacking the angulation or by having a more rounded whorl profile (Emerson, 1965).

EULIMID? sp. 1

Figure 7.4

Description.-Protoconch unknown. Teleoconch slender turriculate, at least two-and-a-half whorls; whorls convex, smooth; growth lines slightly sinuous to slightly opisthocyrt; suture distinctly incised; height 1.0 mm.

Material examined.-One specimen (LACMIP 13261) from LACMLP loc. 16504.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-Eulimid? sp. 1 and 2 have very generalized eulimid shapes, but lack protoconch and apertural details, and a more precise placement must await further material.

EULIMID? sp. 2

Figure 7.5

Description.-Protoconch unknown. Teleoconch slender turriculate, at least four-and- a-half whorls; whorls little convex, smooth, growth lines slightly opisthocyrt; sutures indistinct; height 1.7 mm, width 0.76 mm.

Material examined.-One specimen (LACMIP 13262) from LACMIP loc. 16504.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Family TURRIDAH Swainson, 1840

Genus TURRINOSYRINX Hickman, 1976

Type species.-Turns packardi Weaver, 1916, Oligocene, Oregon and Washington, USA, and British Columbia, Canada.

TURRINOSYRINX HICKMANAE new species

Figure 8.1-8.3

?'Admele" n. sp. GOEDERT AND CAMPBELL, 1995, p. 25, fig. 8.

Diagnosis.-A Turrinosyrinx with apical angle of 450 -50; sculpture of fine axial ribs on subsutural ramp of early whorls; 13- 14 spiral cords on periphery and basal slope; protoconch with rhomboid pattern on last whorl.

Description.-Last whorl of protoconch with strong rhomboid pattern, width approximately 500 m. Teleoconch fusiform, at least four whorls, apical angle 450 -50; subsutural ramp of the whorls sculptured by fine axial ribs on the early whorls, these ribs disappear later; periphery and basal slope sculptured by 13-14 spirals, these are irregularly strong and spaced in one specimen, and almost equally strong and spaced in the other specimen; about four spirals can be seen when the lower part of the whorl is enclosed by the succeeding one. Holotype 2.9 mm high, paratype 2.5 mm high.

Etymology.-After Carole S. Hickman, Berkeley.

Types.-Holotype LACMIP 13253, paratype LACMIP 13273, type locality LACMIP loc. 17746.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-What was figured by Goedert and Campbell (1995) as "Admete" n. sp. from the early Oligocene Makah Formation, Washington State, differs slightly from Turrinosyrinx hickmanae in having a narrower subsutural ramp and a respectively broader peripheral zone with spiral sculpture. However, that species shows some variability in these characters and might well belong to T. hickmanae (K. A. Campbell, personal commun., 2003). Turrinosyrinx hickmanae differs from the type species T. packardi by having a narrower subsutural ramp and a convexly rounded basal slope, while that of T. packardi is straight or slightly concave. The same features distinguish T. hickmanae from the three other species of Turrinosyrinx figured by Hickman (1976). These species also have a narrower apical angle than T. hickmanae. Hickman (1976) placed Turrinosyrinx in the Turriculinae based on teleoconch characters. However, T. hickmanae shows a rhomboid pattern on its last protoconch whorl, which is typical for the deepwater turrid subfamily Daphnellinae. The holotype of T. hickmanae shows a healed shell injury on the upper half of the whorl's flank, near the beginning of the second whorl (Fig. 6.1).

Genus XANTHODAPHNE Powell, 1942

Type species.-Pleurotoma membranacea Watson, 1886, Recent, bathyal of New Zealand.

XANTHODAPHNE? CAMPBELLAE new species

Figure 8.4, 8.5

Diagnosis.-Teleoconch fusiform, whorls convex, sutures deep, sculpture of fine, undulating spirals, anal sinus situated subsuturally, shallow but deep for the genus.

Description.-Protoconch unknown. Teleoconch fusiform, at least three whorls, last whorl large; whorls convex and well rounded, sutures clearly demarcated; sculpture of fine, undulating, incised spirals that are subequally distributed over the shell; growth lines sinuous, anal sinus below the suture. Shell wall about 50 m thick; height of holotype 8.0 mm, width 6.0 mm.

Etymology.-After Kathleen A. Campbell, Auckland.

Types.-Holotype LACMIP 13254, paratype LACMIP 13255, type locality LACMIP loc. 16504.

Other material examined.-Ten uncatalogued specimens from LACMIP loc. 16504.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-This species is tentatively placed within Xanthodaphne, as it resembles members of this genus in having incised spirals, similar shell shape, and an anal sinus of similar strength in a similar pos\ition. However, most North Atlantic species of Xanthodaphne have a more or less well-developed angulation on the shoulder (Bouchet and Warn, 1980), but this is absent in X.I campbellae. In this respect it resembles species of Lusitanops Nordsieck, 1968; however, that genus differs in having no distinct sinus zone. Although superficially similar to the extant vent and seep turrid Phymorhynchus DaIl, 1908 in shell shape and characters of the anal sinus (Warn and Bouchet, 2001), X.? campbellae differs from Phymorhynchus in having incised spirals rather than spiral cords. Similarly shaped shells are seen in the vent and seep buccinids Bayerius Olsson, 1971, Eosipho Thiele, 1929, and Buccinum thermophilum Haraswych and Kantor, 2002 (Warn and Bouchet, 2001; Harasewych and Kantor, 2002), but X.? campbellae differs from these taxa by having a sinuous growth line. Protoconch and siphonal canal characters of X.? campbellae are still unknown, and a more precise placement of the species must await additional material.

Genus BENTHOMANGELIA Thiele, 1925

Type species.-Surcula trophonoidea Schepman, 1913, Recent, Indo- Pacific.

BENTHOMANGELIA? sp.

Figure 9.1-9.3

Description.-Protoconch broadly conical, three and a quarter whorls; about 1.07 mm wide and about 1.41 mm high, including the siphonal canal; embryonic shell about half a whorl, smooth, about 180 m wide; first one-and-half whorls of larval shell smooth, followed by the development of opisthocyrt ribs, onset of spiral sculpture starts a quarter whorl later; opisthocyrt ribs sinuous below lower suture, more closely spaced near the end of the protoconch; transition to teleoconch marked by the onset of the shouldered whorl profile. Two whorls of teleoconch preserved; whorls shouldered, subsutural ramp narrow, sculptured by approximately 18 slightly sinuous axial ribs; these ribs form spines at the shoulder which is marked by two keels. Whorl flanks almost straight to slightly convex, axial ribs weaken towards the basal margin, where they disappear and are replaced with about nine spiral cords. Growth lines sinuous, maximum depth at second spiral. Aperture unknown. Height of teleoconch 2.1 mm, width 1.7 mm.

FIGURE 9-Benthomangelia? sp. from Oligocene cold-seep carbonates in Washington State, both specimens from LACMIP loc. 17746. 1, Fragment of the teleoconch, LACMIP 13256, 20. 2, 3, Juvenile specimen with protoconch, LACMIP 13257, 30. Arrows indicate the transition from proto- to teleoconch.

Material examined.-Two specimens (LACMIP 13256, 13257) from LACMIP loc. 17746.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-This species is tentatively placed in Benthomangelia due to its opisthocyrt ribs on the last whorl of the protoconch and its shouldered and axially ribbed teleoconch whorls (see Bouchet and Warn, 1980). Some doubt remains, however, because the aperture is unknown. Benthomangelial sp. resembles two species described from Recent vents and seeps off Japan that were assigned to Oenopota Mrch, 1852 (Okutani and Fujikura, 1992; Okutani et al., 1993).

Family UNCERTAIN

Genus LURIFAX Warn and Bouchet, 2001

Type species.-Lurifax vitreus Warn and Bouchet 2001, Recent, Mid- Atlantic Ridge.

Discussion.-Warn and Bouchet (2001) placed Lurifax in the heterobranch family Orbitestellidae lredale, 1917 based solely on radula characters, although they noted that the genus differs in several features from other orbitestellids, including having an orthostrophic (not heterostrophic) protoconch. Because a heterostrophic protoconch (when built by a planktotrophic larva) is characteristic for heterobranchs (Haszprunar, 1985), the placement of Lurifax among the Heterobranchia (and Orbitestellidae) is questioned here, and it is instead placed among the Caenogastropoda due to its orthostrophic protoconch. No attempt is made here, however, to place it more precisely in a caenogastropod family.

FIGURE 10-Lurifax goederti n. sp. from Eocene and Oligocene cold- seep carbonates in Washington State. 1, 2, Paratype, LACMIP 13259, LACMIP loc. 16504, 25; 3, holotype, close-up on protoconch, LACMIP 13258, LACMIP loc. 5802, 110; 4, paratype, close-up on sculpture, 150; 5, 6, holotype, 28.

LURIFAX GOEDERTI new species

Figure 10.1-10.6

Diagnosis.-Protoconch of one-and-a-half helicoidal, smooth whorls, about 265 m wide. Teleoconch vitrinelloid, three whorls, last whorl large; early whorls with strong angulation at shoulder, later ones strongly convex; shell covered by strongly sinuous growth lines; spiral sculpture more prominent on earlier whorls, on periphery only.

Description.-Protoconch helicoidal, smooth, about one-and-a-half whorls, with terminal thickening; diameter about 265 m. Teleoconch vitrinelloid, three whorls; first two whorls with strong angulation at shoulder, three well-developed spiral cords at periphery, lower one may be covered by the succeeding whorl; growth lines highly sinuous: opisthocline on shoulder, prosocyrt on periphery, opisthocyrt on base. Final whorl shows the same sculpture and growth lines but have more evenly convex flanks. Aperture and umbilicus unknown. Holotype 1.58 mm wide, largest specimen 1.7 mm wide.

Etymology.-After James L. Goedert, Seattle.

Types.-Holotype LACMIP 13258, type locality LACMIP loc. 5802; paratype LACMIP 13259, from LACMIP loc. 16504.

Occurrence.-Late Eocene to Oligocene cold-seep carbonates, Washinton State, USA.

Discussion.-This species is very similar to the extant vent/ seep gastropod Lurifax vitreus from which it differs in its more rounded whorl profile, especially the more rounded basal margin, and in its smaller protoconch (that of L. vitreus has a diameter of 300-310 m, Warn and Bouchet, 2001). Warn and Bouchet (2001) included IPterolabrella sp. described by Lewis and Marshall (1996, fig. 3) from a methane seep off New Zealand in Lurifax. That species differs from L. goederti by its lower and more angular whorls. This is the first fossil record of this genus. The highly disjunct geographic occurrences of the two extant Lurifax species (northern Mid- Atlantic Ridge and New Zealand), the occurrence of a fossil species in Washington State, and the long geological history of this genus (~35 Ma) make it likely that additional species, extant and fossil, will be discovered in the future.

Subclass HETEROBRANCHIA Gray, 1840

Family HYALOGYRINIDAE Warn and Bouchet, 1993

Genus HYALOGYRINA Marshall, 1988

Type species.-H. glabra Marshall, 1988, Recent, bathyal, on sunken driftwood off New Zealand.

HYALOGYRINA? sp.

Figure 11.1, 11.2

Description.-High-spired, turbiniform shell, at least three convex whorls, suture deep; whorls smooth except for prosocline growth lines; last whorl slightly angulate, with weak subsutural constriction; height 3.2 mm, diameter 2.8 mm.

Material examined.-One uncatalogued specimen from LACMIP loc. 16504, one specimen (LACMIP 13263) from LACMIP loc. 12385; two uncatalogued specimens from LACMIP loc. 5802.

Occurrence.-Early Mid-Eocene to Oligocne cold-seep carbonates, Washington, USA.

Discussion.-Neither protoconch nor shell structure are preserved in the available specimens, and its placement among Hyalogyrina is speculative. It is similar to the extant H. umbellifera Warn and Bouchet, 2001 from the Aleutian Trench, but H.? sp. seems to differ in its somewhat angulate last whorl, and its weak subsutural constriction.

Order OPISTHOBRANCHIA Milne-Edwards, 1848

Family ACTEONIDAE d'Orbigny, 1842

Genus ACTEON Montfort, 1810

Type species.-Valuta tornatilis Linn, 1758, Recent, Mediterranean.

ACTEON sp.

Figure 11.3-11.5

Description.-Protoconch globular, with a blunt lateral projection, height about 235 m, width about 190 m. Teleoconch egg- shaped, at least three convex whorls, last whorl sculptured by 16 incised spiral lines, the first five of them more narrowly spaced than the lower ones; columella undulating, with weak plication at base; inner lip of aperture calloused. The specimens are 2.6 mm high and 1.9 mm wide (LACMIP 13265), and 3.3 mm high and 2.0 mm wide (LACMIP 13264).

Material examined.-Three specimens from LACMIP loc. 17746, two of them catalogued (LACMIP 13264, 13265).

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-The globular protoconch suggests a lecithotrophic ontogeny.

Family SCAPHANDRIDAE Montfort, 1810

Genus CYLICHNA Lovn, 1846

Type species.-Bulla cylindracea Pennant, 1777, Recent, North Atlantic.

FIGURE 11-Heterobranchia from Eocene and Oligocene cold-seep carbonates in Washington State. 1, 2, Hyalogyrina sp., LACMIP 13263, LACMIP loc. 12385; 1, side view, 16, 2, apical view, 25. 3, 4, Acteon sp.; 3, specimen showing sculpture on the whorl's surface, LACMIP 13264, LACMIP loc. 17746, 20; 4, specimen showing internal features, arrow indicates the weak basal columellar fold, LACMIP 13265, LACMIP loc. 17746, 24; 5, same as 4, close-up on the protoconch, 200. 6, Cylichna sp., LACMIP 13266, LACMIP loc. 17746, 16.

CYLICHNA sp.

Figure 11.6

Description.-Teleoconch convolute, flanks evenly convex, surface sculpture of about 20 subequally spaced, pitted spirals. Largest specimen 6.8 mm high, 3.0 mm wide.

Material examined.-Two specimens from LACMIP loc. 17746, one of them catalogued (LACMIP 13266).

Occurrence.-Oligocene cold-seep related carbonates, Washington State, USA.

Discussion.-Determination of this species must await better- preserved material.

Class BIVALVIA Linn, 1758

Subclass PROTOBRANCHIA Pelseneer, 1889

Order NUCULOIDA Dall, 1889

Family NUCULANIDAE H. and A. Adams, 1858

Genus NUCULANA Link, 1807

Type species.-Area rostrata Brugire, 1789, Recent, Indopacific.

NUCULANA? sp. aff. 'N.' GRASSLEI Allen, 1993

Figure 12.1-12.4

'Nuculana' sp. aff. 'N.' grasslei PECKMANN ET AL., 2002, p. 860- 861, fig. 3.

non 'Nuculana' sp. aff. 'N.' grasslei GOEDERT ET AL., 2003, p. 226, pl. 43, fig. 8.

Description.-Prodissoconch oval, posterior side more pointed than anterior side, hinge line unknown, s\culpture of eight to nine concentric ridges, about 10 wrinklelike radial ribs, and fine wrinkles in the interspaces; 220 m long, at least 160 m high. Juvenile dissoconch elongate-oval, posterior side more pointed than anterior side, umbo anterior (position at approx. 45% total length), dorsal margin well rounded, sculpture of broad concentric rings and fine growth lines; length 2.6 mm, height 1.7 mm.

Material examined.-Two specimens (LACMIP 13267, 13268) from LACMIP loc. 17746.

Occurrence.-Eocene to Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-The specimen described here resembles juveniles of N. grasslei (Allen, 1993, fig. 2). A figure of an adult shell of 'Nuculana' sp. aff. 'N.' grasslei from cold-seep related carbonates of the Lincoln Creek Formation (LACMIP 12980) showing the posterior ridge has been published earlier (Peckmann et al., 2002, fig. 3a). The protoconch with its conspicuous sculpture is almost identical to that of the recent N. grasslei. The hinge dentition of the fossil specimens is yet unknown, and the assignment to the extant species is only preliminary. The extant N. grasslei has a smooth surface, whereas the Eocene specimen figured by Goedert et al. (2003) as 'Nuculana' sp. aff. 'N.' grasslei has concentric ribs that fade on the posterior side. In that respect it resembles the Nuculana sp. figured by Goedert and Campbell (1995) from an early Oligocene chemosynthetic community in the Makah Formation. It was suggested that extant N. grasslei, along with its fossil representatives, might not belong to Nuculana but might be related to Ledella Verrill and Bush, 1897 (Peckmann et al., 2002, 2003), due to features of the ligament. However, these uncertainties remain and the fossil specimen is hesitantly assigned to Nuculana. One specimen shows a sediment-filled, round hole of approximately 0.75 mm diameter in dorsocentral position, which might be interpreted as a naticid drill hole.

NUCULANA sp.

Figure 12.5-12.8

Description.-Prodissoconch oval, hinge line unknown, sculpture of at least six sharp-crested concentric ribs, length about 200 m. Dissoconch elongate oval, weakly rostrate posterior, umbo anterior (position at approx. 40% total length), surface smooth except for faint concentric growth rings. Growth rings with fine indentation on posterodorsal side of both valves. Length 3.87 mm, height 2.57 mm.

FIGURE 12-Nuculanidae from Oligocene cold-seep carbonates in Washington State, all specimens from LACMIP loc. 17746. 1-4, Nuculana? cf. grasslei Allen, 1993; 1, 2, juvenile shell, LACMIP 13267, 20; 3, close-up on ribbed prodissoconch, same as 1, 200; 4, specimen with hole, LACMIP 13268, 15. 5-8, Nuculana sp., LACMIP 13269; 5, 6, 15; 7, close-up on ribbed prodissoconch, 320; 8, close- up on posterior side of left valve, arrows indicate the indentation, 80. 9-12, Ledella sp., LACMIP loc. 17746, LACMIP 13274; 9, 10, view on right valve and apical view, 25; 11, close-up on prodissoconch, 40; 12, close-up on left valve of prodissoconch I, 300.

Material examined.-One specimen (LACMIP 13269) from LACMIP loc. 17746.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-This Nuculana sp. differs from 'Nuculana' sp. aff. W.' grasslei in being slightly rostrate and in having strong, sharp- crested concentric ribs on the prodissoconch.

Genus LEDELLA Verrill and Bush, 1897

Type species.-Ledella bushae Warn, 1978, Recent, northwest Atlantic.

LEDELLA sp.

Figure 12.9-12.12

Description.-Prodissoconch I convex, with granulate surface, 125- 135 m long; prodissoconch II oval, posterior side slightly pointed, beak moderately pointed, growth lines fine and narrowly spaced, 500 m long, 423 m high. Transition to teleoconch marked by a reinforced margin and by the onset of the posterior rostrum. Dissoconch oval, rostrate posteriorly, not gaping; umbo anterior (approx. 45% total length), ventral margin almost straight, transition to rounded anterior margin slightly angulate, dorsal margin well rounded; posterodorsal ridge prominent; shell margin sculptured by strong wrinkles. Length 2.5 mm, height 1.75 mm, width of articulated shell 1.4 mm. Prodissoconch yellow-brown, dissoconch whitish in one specimen.

FIGURE 13-Tindaria? sp., (LACMIP 13270) from Oligocene cold-seep carbonates in Washington State, specimen from LACMIP loc. 17746. 1, 2, Left valve and apical view, 16; 3, close-up on ribbed prodissoconch, 350; 4, close-up on posterodorsal margin, arrows indicate indentation, 50.

Material examined.-Thirteen specimens from LACMIP loc. 17746, one of them catalogued (LACMIP 13274).

Occurrence.-Oligocene cold- seep carbonates, Washington State, USA.

Discussion.-All specimens are articulated. To observe features of the hinge, one specimen was cut vertically along the hinge line and the surface of the cut was polished. This revealed that the dentition is taxodont, but no additional details.

Family TINDARIIDAE Sanders and Allen, 1977

Genus TINDARIA Bellardi, 1875

Type species.-Tindaria arata Linn, 1758, Pliocene, Italy.

TINDARIA? sp.

Figure 13.1-13.4

Description.-Prodissoconch oval, sculptured by more than 14 fine concentric ribs and numerous slightly finer, somewhat irregular radial ribs; about 108 m long. Dissoconch equivalve; umbo anterior (position at approx. 43% total length); beaks prominent; posterodorsal margin more or less straight, angulate about half-way between umbo and posterior end; ventral margin broadly arcuate; anteroclorsal margin straight to slightly concave; sculpture of strong commarginal lamellae. Lamellae on posterodorsal side with indentation on both valves, increasing in depth towards shell margin. Length 2.7 mm, height 2.2 mm, width of articulated valves 2.0 mm.

Material examined.-One specimen (LACMIP 13270) from LACMIP loc. 17746.

Occurrence.-Oligocene cold- seep carbonates, Washington State, USA.

Discussion.-The specimen is articulated so that the hinge dentition and pallia] line could not be observed, and is thus only tentatively assigned to Tindaria. The Nuculana sp. described from cold- seep carbonates of the early Oligocene Makah Formation (Goedert and Campbell, 1995, fig. 2) is more elongate, has broader and less numerous ribs, and has a rather smooth posterior area in contrast to Tindarial sp., which has numerous fine ribs that cover the entire outside of the shell, and does not have a smooth posterior area. Nuculana (Lamellinucula) exigua (Sowerby, 1833) figured by Moore (1983, pi. 1, fig. 13) from the Pliocene of California is less elongate than the species described here. If the identification as Tindaria is correct, the posterodorsal indentation (Fig. 12.4) probably relates to the point of attachment of the gill axis to the mantle margin (J. A. Allen, personal commun., 2004).

Subclass ISOFILIBRANCHIA Iredale, 1939

Order MYTILOIDA Frussac, 1822

Family MYTILIDAR Rafinesque, 1815

Subfamily BATHYMODIOLINAE Kenk and Wilson, 1985

Genus BATHYMODIOLUS Kenk and Wilson, 1985

Type species.-Bathymodiolus thermophilus Kenk and Wilson, 1985, Recent, Galapagos Rift Zone.

BATHYMODIOLUS WILLAPAENSIS (Squires and Goedert, 1991)

Figure 14.1-14.6

Modiolus n. sp. GOEDERT AND SQUIRES, 1990, fig. 2m, n.

Modiolus (Modiolus) willapaensis SQUIRES AND GOEDERT, 1991, p. 413, fig. 2.4-2.6; GOEDERT ET AL., 2003, p. 226, 228-229, table 1, pl. 43, fig. 4.

Emended diagnosis.-Prodissoconch I D-shaped, with long straight hinge line and strongly pitted surface, 107 m long, 81 m high; prodissoconch II almost round, anterior side slightly pointed, beak moderately pointed, growth lines fine and narrowly spaced, 470 m long, 430 m high, 160 m wide. Transition to dissoconch marked by a conspicuous, broad, and smooth groove. Juvenile dissoconch (1.7 mm length) of elliptical-triangular shape, anterior end rounded, dorsal margin slightly convex, posterior end rounded, posterodorsal corner angular, ventral margin nearly straight.

Material examined.-Two specimens (LACMIP 13271, 13272) from LACMIP loc. 16504; three uncatalogued specimens from LACMIP loc. 5802.

Occurrence.-Eocene to Oligocene cold- seep carbonates, Washington State, USA.

Discussion.-The dissoconch of this species has already been described in detail (Squires and Goedert, 1991). This description is complemented here with descriptions of the prodissoconch and the juvenile shell. The species is transferred to Bathymodiolus based on the shape of its juvenile shell. Juveniles of Modiolus (Modiolus) Lamarck, 1799, where B. willapaensis was initially placed (Squires and Goedert, 1991), are of arcuate modioliform shape, whereas juveniles of Bathymodiolus have a rather elliptical-triangular shape (Kenk and Wilson, 1985; R. von Cosel, personal commun., 2003). The prodissoconch of B. willapaensis is similar in size and shape, including the pitted sculpture on P I, to those described for extant Bathymodiolus species (Turner et al., 1985; Cosel et al., 1999).

Subclass PTERIOMORPHIA Beurlen, 1944

Order OSTREOIDA Frussac, 1822

Family PROPEAMUSSIDAE Abbott, 1954

Genus CATILLOPECTEN Iredale, 1939

Type species.-Pecten murrayi Smith, 1885, Recent, Australia.

FIGURE 14-Bathymodiolus willapaensis (Squires and Goedert, 1991) from Oligocene cold-seep carbonates in Washington State. 1-3, Juvenile specimen, LACMIP 13271; 1, 2, view on left valve and apical view, 30; 3, close-up on prodissoconch, 75; 4-6, isolated prodissoconch, LACMIP 13272; 4, close-up on the two valves of prodissoconch I, showing its polygonal sculpture, 300; 5, 6, view on left valve and apical view, 80.

CATILLOPECTEN? sp.

Figure 15.1-15.3, 15.6

Description.-Prodissoconch unknown; imprint of prodissoconch on dissoconch almost round, diameter 160 m, inner margin thickened, keyholelike denticles (length 6 m) around entire margin, except for a posterodorsal outlet. Dissoconch small, disk roundish, sculpture of regularly, widely spaced concentric rings and irregular, sometimes bifurcating radial riblets. Transitionsfrom auricles to disk gradual. Shell composed of foliated calcite. Length 1.0 mm, height 1.2 mm.

Material examined.-Two left valves (LACMIP 8337, 8338) from LACMIP loc. 17746.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-Catillopecten has previously only been reported from Recent bathyal and abyssal depth (Bernard, 1978; Dijkstra and Gofas, 2004). The extant Bathypecten Schein-Fatton, 1985 that occurs at hydrothermal vents (Schein-Fatton, 1985) was considered synonymous with Catillopecten (Dijkstra and Gofas, 2004). Catillopectenl sp. described here may represent the first fossil record of this extant vent-inhabiting genus. Prodissoconchs that are similar to the prodissoconch imprint figured here were described from the Late Jurassic of England, but are about twice as large: 300 m in the Jurassic specimens (Malchus, 2004) compared to 160 m for Catillopecten? sp. The Jurassic prodissoconchs could not be assigned to any known taxon due to the lack of corresponding adult shells.

Family PECTINIDAE Rafinesque, 1815

Genus DELECTOPECTEN Stewart, 1930

Type species.-Pecten (Pseudamusium) vancouverensis Whiteaves, 1893, Recent, Vancouver Island, Canada.

DELECTOPECTEN sp.

Figure 15.4, 15.5

Description.-Prodissoconch unknown. Only left valve of dissoconch preserved, disk presumably higher than long, transition from posterior auricle to disk gradual, sculpture of fine, somewhat irregular radial riblets, and faint, concentric growth increments. Byssal notch unknown, anterior auricle and anterior part of disk incomplete. Length 4 mm, height 4.2 mm.

Material examined.-One left valve (LACMIP 13275) from LACMIP loc. 17746.

Occurrence.-Oligocene cold-seep carbonates, Washington State, USA.

Discussion.-Members of Delectopecten occur throughout the Tertiary of the Pacific slope of North America (Moore, 1984). Delectopecten sp. is the first record of Pectinidae from Tertiary cold-seeps.

ECOLOGICAL AND EVOLUTIONARY SIGNIFICANCE OF THE FAUNA

Hickman (1976) proposed that the radiation of toxoglossate turrids into the deep water took place during the late Cenozoic, because the turrids she described from Oligocene deepwater sediments in Oregon, including Turrinosyrinx, were all placed in nontoxoglossate turrid subfamilies. New data on the protoconch morphology of Turrinosyrinx hickmanae n. sp. indicate that this genus more likely belongs to the toxoglossate turrid subfamily Daphnellinae. Also, Xanthodaphnel catnpbellae n. sp. most probably belongs to the Daphnellinae. This new information indicates that toxoglossate turrids radiated into deep water earlier than previously considered.

Three nuculanoid species described here have concentric reticulation on the prodissoconch, and two of them show additional radial reticulation. Similar sculpture on the prodissoconch is hitherto only known from two extant nuculanids from hydrothermal vents (Lutz et al., 1986; Alien, 1993). This reticulation was suspected to have little evolutionary advantage (Alien, 1993). Nevertheless, this character has persisted for at least 30 Ma. The wrinklelike appearance of the reticulations suggests that they are at least in part the result of shrinkage of the uncalcificd shell prior to its final calcification. This is supported by observations on extant protobranch bivalves. For Solemya reidi Bernard, 1980 no calcification of the prodissoconch during its free swimming (but nonfeeding) larval stage was observed (Gustafson and Reid, 1986, 1988), and the prodissoconch of S. velum Say, 1822 shows wrinkles before it is fully calcified (Gustafson and Lutz, 1992). The cause of the suggested shrinkage, however, remains unknown.

Based on 18S rRNA analysis, Distel et al. (2000) showed that mytilids (bathymodiolins) inhabiting vents and seeps (e.g., Bathymodiolus and Tamu Gustafson, Turner, Lutz, and Vrijenhoek, 1998) form a monophyletic group together with mytilids that live at whale- and woodfall in the deep sea (e.g., Adipicola Dautzenberg, 1927, Idas Jeffreys, 1876, etc.), and suggested that vents and seeps were only recently invaded by modern mylilid taxa. These molecular data place the origin of the Bathymodiolinae sometime between 22 Ma (Distel in Little and Vrijenhoek, 2003) and 56-94 Ma before present (Little and Vrijenhoek, 2003). The presence of Bathymodiolus in Mid- Eocene to Oligocene cold-seep carbonates shows that the split between the vent/seep and the wood/whale-fall Bathymodiolinae (sensu Distel et al., 2000) took place at least 40 Ma.

FIGURE 15-Propeamussidae and Pectinidae from Oligocene cold-seep carbonates in Washington State, all specimens from LACMIP loc. 17746. 1-3, Catillopectenl sp.; 1, outline of left valve, LACMIP 8337, 40; 2, same as 1, close-up on sculpture, 200; 3, left valve of juvenile specimen showing the almost round imprint of the prodissoconch, LACMIP 8338, 250. 4, 5, Delectopecten sp., LACMIP 13275; 4, outline of left valve, 15; 5, close-up on posterior ear and sculpture, 70. 6, Catillopectenl sp., same specimen as 3, upper arrow indicates regularly foliated shell structure, lower arrow points to the prodissoconch outlet, 800.

Previous studies suggested that the developmental strategies of vent and seep mollusc species largely reflect the strategies of the phylogenetic group to which they belong (Turner et al., 1985; McHugh, 1989; Le Pennec and Beninger, 2000). This hypothesis is supported by the new fossil data. Most of the species with known early ontogenetic shells studied here can be assigned to extant families or genera, and in 10 species (Pyropelta sp., Retiskenea statura, Turrinosyrinx hickmanae, Benthomangelial sp., Lurifax goederti n. sp., the four nuculanids, and Bathymodiolus willapaensis) the reproductive strategy reflects that of its corresponding higher taxon. In the remaining four species (Provanna antiqua, Niso littlei n. sp., Acteon sp., and Catillopecten sp.), dispersal strategies are variable in the phylogenetic group to which they belong.

Two specimens belonging to Provanna antiqua and Turrinosyrinx hickmanae show healed shell injuries, in both cases on the upper part of a whorl. The shape of these injuries and the presence of decapods in cold-seep sites of the Lincoln Creek Formation (Peckmann et al., 2002) suggest that they have been caused by crabs. Two specimens belonging to Nuculana cf. grasslei and an as yet undescribed bivalve show round holes of about 0.75 mm diameter in a central position on the valves, which resemble naticid drill holes. Naticids are absent from the cold-seep carbonates described here, but Natica sp. was listed from some sites by Peckmann et al. (2002), and Cryptonatica aff. C. pittsburgensis Moore, 1976 occurs in another Oligocene cold-seep locality in Washington State (personal data). The first evidence for predation on fossil cold-seep molluses were drill holes in species of Calyptogena DaIl, 1891 and Conchocele Gabb, 1866 from the Japanese Miocene (Amano, 2003). The injured shells from the Oligocene Lincoln Creek Formation documented here represent the oldest known record of predation in fossil cold-seep assemblages.

ACKNOWLEDGMENTS

First of all, I would like to thank J. L. Goedert, Seattle, who made this material available for study and Simpson Timber Company, Shelton, for allowing access to sites on their land; I also thank J. A. Alien, Millport; A. G. Beu, Lower Hut; P. Bouchet, Paris; K. A. Campbell, Auckland; R. von Cosel, Paris; H. H. Dijkstra, Amsterdam; H. Filkorn, Los Angeles; R. N. Kilburn, Pietermaritzburg; C. T. S. Little, Leeds; N. Malchus, Barcelona; H. Sahling, Bremen; T. R. Waller, Washington DC; and A. Warn, Stockholm for their help during the course of this study. I am indebted to M. Joachimski, Erlangen, for carrying out the isotope analyses; to C. T. S. Little, Leeds, and J. H. McLean, Los Angeles, for their critical reviews of the manuscript, and to P. J. Harries and L. Vermaas, for their editorial work.

REFERENCES

ABBOTT, T. A. 1954. American Seashells. Van Nostrand Reinhold, New York, xiv + 541 p.

ADAMS, H., AND A. ADAMS. 1852. On a new arrangement of British Rissoae. Annals and Magazine of Natural History, series 1, 10:358- 359.

ADAMS, H., AND A. ADAMS. 1853-59. The Genera of Recent Mollusca Arranged According to their Organization. John Van Voorst, London, l:vi-xl, 1-484; 2:485-661 p.

ALLEN, J. A. 1993. A new deep-water hydrothermal species of Nuculana (Bivalvia: Protobranchia) from the Guaymas Basin. Malacologia, 35(1):141-151.

AMANO, K. 2003. Predatory gastropod drill holes in Upper Miocene cold seep bivalves, Hokkaido, Japan. The Veliger, 46(1):90-96.

BARTSCH, P. 1917. A monograph of the West American melanellid mollusks. Proceedings of the U.S. National Museum of Natural History, 53:295-356.

BELLARDI, L. 1875. Monograiia delle nuculidi trovate finora nei terreni terziari del Piemonte e della Liguria. Il R. Liceo Gioberi nell'Anno scolastico 1874-1875, Torino, 32 p.

BERNARD, F R. 1978. New bivalve molluscs, subclass Pteriomorphia, from the northeastern Pacific. Venus, 37(2):61-75.

BERNARD, F. R. 1980. A new Solemya s. str. from the northeastern Pacific (Bivalvia: Cryptodonta). Venus, 39:17-23.

BEURLEN, K. 1944. Beitrage zur Stammesgeschichte der Muscheln. Bayerische Akademie der Wissenschaften, Sitzungsberichte, 1-2:133- 145.

BOUCHET, P., AND A. WAREN. 1980. Revision of the north-east Atlantic bathyal and abyssal Turridae (Mollusca, Gastropoda). Journal of MoIluscan Studies, supplement, 8:1-119.

BRUGIRE, J. G. 1789-1816. Encyclopdic Mthodique ou par Ordre de Matires. Histoire naturelle de Vers, des Mollusques, Paris, 758 p.

CARPENTER, P. P. 1864. Supplementary report on the present state of our knowledge with regard to the mollusca of the West Coast of North America. Reports of the British Association to the Advancement of Science, 33:517-686.

COSEL, R. v., T. COMTET, AND E. M. KRYLOVA. 1999. Bathymodiolus (Bivalvia: Mytilidae) from hydrothermal vents on the Azores Triple Ju\nction and the Logatchev hydrothermal field, Mid-Atlantic Ridge. The Veliger, 42(3):218-248.

COX, L. R. 1959. Thoughts on the classification of the Gastropoda. Proceedings of the Malacological Society of London, 33:239-261.

CUVIER, G. L. C. F. D. 1797. Table lmentaire de l'Historie Naturelle des Animaux. Baudouin, Paris, 710 p.

DALL, W. H. 1889. Reports on the results of dredging, under the supervision of Alexander Agassiz, in the Gulf of Mexico (1877-78) and in the Caribbean Sea (1879-80), by the U.S. Coast Survey steamer "Blake" XXIX. Report on the Mollusca. Pt. 2, Gastropoda and Scaphopoda. Bulletin of the Museum of Comparative Zoology, Harvard University, 18:1-492.

DALL, W. H. 1891. On some new or interesting west American shells obtained from the dredgings of the U.S. Fish Commission steamer Albatros in 1888, and from other sources [Albatros Report]. U.S. National Museum Proceedings, 14:173-191.

DALL, W. H. 1908. Descriptions of new species of mollusks from the Pacific coast of the United States with notes on other mollusks from the same region. Proceedings of the U.S. National Museum of Natural History, 34:245-257.

DALL, W. H. 1909. Contributions the Tertiary paleontology of the Pacific Coast. I. The Miocene of Astoria and Coos Bay, Oregon. U.S. Geological Survey Professional Paper, 59:1-278.

DALL, W. H. 1918. Description of new species of shells chiefly from Magdalena Bay, Lower California. Proceedings of the Biological Society of Washington, 31:5-8.

DAUTZENBERG, P. 1927. Molluscques provenant des campagnes scientifiques du Prince Albert Ier de Monaco dans l'Ocean Atlantique et dans le Golfe de Gascogne. Resultats des Campagnes Scientifiques accomplies par Albert Ier, 72:1-400.

DUKSTRA, H. H., AND S. GOFAS. 2004. Pectinoidea (Bivalvia: Propeamussiidae and Pectinidae) from some northeastern Atlantic seamounts. Sarsia, 89(1):33-78.

DISTEL, D. L., A. R. BACO, E. CHUANG, W. MORRILL, C. CAVANAUGH, AND C. R. SMITH. 2000. Do mussels take wooden steps to deep-sea vents? Nature, 403:725-726.

DORBIGNY, A. 1842-1843. Palontologie Franaise, terrains Crtacs. Vol. 2. Gastropodes. Author, Paris, 645 p.

EMERSON, W. K. 1965. The eastern Pacific species of Niso (Mollusca: Gastropoda). American Museum Novitates, 2218:1-12.

FRUSSAC, J. B. L. 1822. Tableau systmatiques des animaux molluscques. J. B. Bailliere, Paris, 111 p.

FORBES, E., AND R. MACANDREW. 1846. Notes on new and rare animals observed during cruises in the British seas since the last meeting. Athenaeum, 988:1027.

GABB, W. M. 1866-1869. Cretaceous and Tertiary fossils. California Geological Survey, Paleontology, 2:1-299.

GOEDERT, J. L., AND S. R. BENUAM. 1999. A new species of Depressigyra? (Gastropoda: Peltospiridae) from cold-seep carbonates in Eocene and Oligocene rocks of western Washington. The Veliger, 42(2): 112-116.

GOEDERT, J. L., AND K. A. CAMPBELL. 1995. An Early Oligocene chemosynthetic community from the Makah Formation, northwestern Olympic Peninsula, Washington. The Veliger, 38(1):22-29.

GOEDERT, J. L., AND K. L. KALER. 1996. A new species of Abyssochrysos (Gastropoda: Loxonematoidea) from a Middle Eocene cold- seep carbonate in the Humptulips Formation, western Washington. The Veliger, 39(1):65-70.

GOEDERT, J. L., AND R. L. SQUIRES. 1990. Eocene deep-sea communities in localized limestones formed by subduction-related methane seeps, southwestern Washington. Geology, 18:1 182-1185.

GOEDERT, J. L., AND R. L. SQUIRES. 1993. First Oligocene Records of Calyptogena (Bivalvia: Vesicomyidae). The Veliger, 36(1):72-77.

GOEDERT, J. L., J. PECKMANN, AND J. REITNER. 2000. Worm tubes in an allochthonous cold-seep carbonate from lower Oligocene rocks of western Washington. Journal of Paleontology, 74(6):992-999.

GOEDERT, J. L., V. THIEL, O. SCHMALE, W. W. RAU, W. MICHAELIS, AND J. PECKMANN. 2003. The late Eocene 'Whiskey Creek' methane-seep deposit (western Washington State) Pt. I: Geology, palaeontology, and molecular geobiology. Facies, 48:223-240.

GOULD, A. A. 1849. On the shells collected by the United States exploring expedition. Boston Society of Natural History Proceedings, 3: 89-92.

GRAY, J. E. 1840. Synopsis of the Contents of the British Museum. London.

GRAY, J. E. 1847. A list of the genera of Recent Mollusca, their synonyma and types. Proceedings of the Zoological Record of London, 15: 129-219.

GUSTAFSON, R. G., AND R. A. LUTZ. 1992. Larval and early post- larval development of the protobranch bivalve Solemya velum (Mollusca: Bivalvia). Journal of the Marine Biological Association of the U.K., 72:383-402.

GUSTAFSON, R. G., AND R. A. LUTZ. 1994. Molluscan life history traits at deep-sea hydrothermal vents and cold methane/sulfide seeps, p. 336. In C. M. Young and K. J. Eckelbarger (eds.), Reproduction, Larval Biology and Recruitment of the Deep-Sea Benthos. Columbia University Press, New York.

GUSTAFSON, R. G., AND R. G. B. REID. 1986. Development of the pericalymma larva of Solemya reidi (Bivalvia: Cryptodonta: Solemyidae) as revealed by light and electron microscopy. Marine Biology, 93:411-427.

GUSTAFSON, R. G., AND R. G. B. REID. 1988. Larval and post- larval morphogenesis in the gutless protobranch bivalve Solemya reidi (Cryptodonta: Solemyidae). Marine Biology, 97:373-387.

GUSTAFSON, R. G., R. D. TURNER, R. A. LUTZ, AND R. C. VRIJENH

Source: Journal of Paleontology

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