Squiresica knapptonensis ( Amano and Kiel, 2007 ) Hybertsen & Goedert & Kiel, 2022

Hybertsen, Frida, Goedert, James L. & Kiel, Steffen, 2022, A new genus of chemosymbiotic vesicomyid bivalves from the Oligocene of western North America, Acta Palaeontologica Polonica 67 (3), pp. 703-709 : 705-707

publication ID

https://doi.org/ 10.4202/app.00992.2022

publication LSID

lsid:zoobank.org:pub:C706ED1A-0393-4414-9BDA-CC0AF38FCF56

persistent identifier

https://treatment.plazi.org/id/5265676A-F92C-FF9B-FCC6-4C69F99CF979

treatment provided by

Felipe

scientific name

Squiresica knapptonensis ( Amano and Kiel, 2007 )
status

comb. nov.

Squiresica knapptonensis ( Amano and Kiel, 2007) View in CoL comb. nov.

Figs. 2 View Fig , 3 View Fig .

1993 Calyptogena (Calyptogena) chinookensis Squires and Goedert, 1991 View in CoL ; Goedert and Squires 1993: 74, fig. 4.

2007 Archivesica knapptonensis View in CoL sp. nov.; Amano and Kiel 2007: 284, figs. 30–43.

Type material: Fragment of right valve with preserved hinge dentition, length 13.5 mm +, height 7.0 mm, USNM 534954 About USNM .

Type locality: LACMIP loc. 5843, beach terrace of the Columbia River near Knappton, Washington State, USA .

Type horizon: Upper Oligocene part of the Lincoln Creek Formation .

Material.— Numerous specimens (figured: NRM PAL Mo 195149–195155) from the West Fork Satsop seep deposit, lower Oligocene , Lincoln Creek Formation, western Washington, USA .

Description. —Elongated, weakly inflated, small shell, reaching little over 20 mm in length, H/L-ratio 0.46–0.60, W/H-ratio 0.61–0.65; umbo slightly elevated and moderately coiled, positioned at anterior 20–25% of shell length; external ligament opisthodetic, occupying>60% of postero-dorsal margin; anterior adductor scar D-shaped, its posterior margin thick; posterior adductor scar nearly round; pallial line impressed anteriorly, commarginal, forming a small indentation right beneath posterior adductor scar.

Remarks.— Goedert and Squires (1993) reported Calyptogena chinookensis Squires and Goedert, 1991 from the Pysht and Makah formations along the northern coast of Washington state, and from the upper Oligocene part of the Lincoln Creek Formation on the southern side of Washington state. Among their illustrated specimens, that from the Lincoln Creek Formation ( Goedert and Squires 1993: fig. 4) shows a lunular incision and a different hinge morphology than C. chinookensis and instead belongs to Squiresica knapptonensis (i.e., Amano and Kiel 2007). The newly collected material from the West Fork of Satsop River shows all characters possessed by specimens from the upper Oligocene type locality of S. knapptonensis and thus extends the stratigraphic range of this species down into the lower Oligocene.

The second species assigned here to the new genus, Squiresica marincovichi ( Kiel and Amano 2010: 80–81, figs. 17–25) from the Oligocene Kulthieth Formation in Alaska, differs from S. knapptonensis by being less elongated, having a broader escutcheon, lacking irregular growth lines on the outer surface, and a less distinct subumbonal pit (see Fig. 4 View Fig for a re-illustration of the type material). Squiresica marincovichi reaches almost 40 mm in length and it thus notably larger than S. knapptonensis .

Stratigraphic and geographic range.—Oligocene, Lincoln Creek Formation, western Washington State, USA.

NRM

Swedish Museum of Natural History - Zoological Collections

Kingdom

Animalia

Phylum

Mollusca

Class

Bivalvia

Order

Venerida

Family

Vesicomyidae

Genus

Squiresica

Loc

Squiresica knapptonensis ( Amano and Kiel, 2007 )

Hybertsen, Frida, Goedert, James L. & Kiel, Steffen 2022
2022
Loc

Archivesica knapptonensis

Amano, K. & Kiel, S. 2007: 284
2007
Loc

Calyptogena (Calyptogena) chinookensis

Goedert, J. L. & Squires, R. L. 1993: 74
1993
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