Puncturella, Lowe, 1827

Kiel, Steffen, Campbell, Kathleen A. & Gaillard, Christian, 2010, New and little known mollusks from ancient chemosynthetic environments, Zootaxa 2390 (1), pp. 26-48 : 29-31

Puncturella (sensu lato) mcleani sp. nov.

( Fig 2 )

Diagnosis: Tall Puncturella with foramen on lower half of anterior slope; apex bent posteriorly and situated directly above posterior margin; apparently no external sculpture.

Holotype: UCMP 55740 , L = 7 mm, H = 6 mm, W = 4 mm.

Paratypes: UCMP 557041 , L = 8 mm, H = 5 mm, W = 5.5 mm, from NW Berryessa limpet [ UCMP loc. A-4500, loc. 10 in Kiel et al. (2008)] ; UCMP 557042 , L = 6 mm, H = 4.5 mm, W = 3 mm, from the type locality ; LACMIP 13558 , L = 6 mm, H = 5 mm, and LACMIP 13559 : L = 5 mm, H = 3.5 mm, both from Paskenta [loc. 2 in Kiel et al. (2008)] .

Further material examined: Two further specimens from Wilbur Springs and Rocky Creek [locs. 5 and 7 in Kiel et al. (2008)] are deposited in the CAS.

Type locality: The Bear Creek seep site, California, USA, 39°03'14"N, 122°24'40" W; Crack Canyon formation of the Great Valley Group; Early Cretaceous, Valanginian (Kiel et al. 2008) .

Description: Tall limpet, aperture elongate-oval in outline; apex bent posteriorly, situated vertically above posterior margin of aperture; posterior slope slightly concave, anterior slope gently convex; outer surface apparently smooth; foramen on lower half of anterior slope, about four-and-half times longer than wide.

Remarks: The absence of sculpture is unusual for Puncturella and fissurellids in general; however, only a single specimen with fragments of shell material was available. If the absence of sculpture is confirmed this species might be better placed in a new genus. The record from the Tithonian (Late Jurassic) site at Paskenta makes this the oldest slit limpet at fossil cold seeps. Species of Puncturella found at modern vents and seeps are quite different from Puncturella (s.l.) mcleani: they are not as tall, have a more centrally located apex and radial sculpture ( Okutani et al. 1993; Beck 1996; Warén and Bouchet 2009). Vent-inhabiting fissurellids without radial sculpture belong to the genus Cornisepta McLean & Geiger, 1998 ; however, they are not smooth but rather have tuberculate sculpture. They are quite different from Puncturella (s.l.) mcleani in being tall, and having a centrally located apex and foramen ( McLean and Geiger 1998).

Two further fissurellids are known from the Cretaceous of California, which differ from Puncturella (s.l.) mcleani by being lower and having radial sculpture. They include Fissurella (sensu lato) bipunctata Stanton, 1895 from “near Stephenson’s, on Cold Fork of Cottonwood Creek, Tehama county, California ”; this is a seep deposit of Albian age [the Cold Fork of Cottonwood Creek site of Kiel et al. (2008)]. The holotype is figured here (USNM 23065; Fig. 2G ); it is worth noting that this species has a seemingly rectangular apical opening and that the two central radial ribs on the anterior slope are stronger than the other radials; Stanton’s (1895) drawing does not show this. These two strong radials, however, do not mark the edges of a slit. The other species is Fissurella gabbi Stewart, 1927 , from the Chico Formation (Coniacian-Campanian) and has, according to Stewart (1927), 20 radial ribs while Fissurella (sensu lato) bipunctata has 27. We have one specimen of a tall limpet resembling Puncturella (s.l.) mcleani in general shape from the Bear Creek seep deposit. But in contrast to Puncturella (s.l.) mcleani, this specimen has radial ribs and shows no sign of a slit or foramen.

Distribution: Late Jurassic (Tithonian) to Early Cretaceous (Valanginian), Great Valley Group, California, USA.

Etymology: For James H. McLean, Los Angeles.

Figures

FIGURE 2. Fissurellids from Cretaceous seep carbonates in California. A-F. Puncturella (sensu lato) mcleani sp. nov. A-C. Paratype (UCMP 557041) from the site at NW Berryessa in California, USA. D-F. Holotype (UCMP 557040) from the early Cretaceous Bear Valley site in California, USA. G. Holotype of Fissurella (sensu lato) bipunctata Stanton, 1895 from the Albian Cold Fork of Cottonwood Creek site, California, USA (USNM 23065).