Pseudomohnia rogerclarki, Strong & Sirenko & McLean, 2021
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publication ID |
https://dx.doi.org/10.3897/zookeys.1055.68911 |
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publication LSID |
lsid:zoobank.org:pub:EDAA550D-C7AB-4C4D-8CA9-1D988F4F3940 |
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persistent identifier |
https://treatment.plazi.org/id/B7AAEBD1-6DD5-4680-8B6F-71CD3754838E |
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taxon LSID |
lsid:zoobank.org:act:B7AAEBD1-6DD5-4680-8B6F-71CD3754838E |
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treatment provided by |
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scientific name |
Pseudomohnia rogerclarki |
| status |
sp. nov. |
Pseudomohnia rogerclarki View in CoL sp. nov.
Figs 1E-I View Figure 1 , 3C, D, F View Figure 3 , 6 View Figure 6
Type material.
Holotype. Aleutian Islands • 17.53 mm in length; Near Islands, north of Attu Island; 53°5.55'N, 173°43.46'E; 114 m; 4 August 1997; R/V Dominator stn 23-971-218; RN Clark leg.; LACM 3776 (ex LACM 1997-174) (Figs 1E View Figure 1 , 3C, D, F View Figure 3 , 6 View Figure 6 ).
Other material.
Aleutian Islands • 2 spms; Near Islands , north of Attu Island ; 53°5.55'N, 173°43.46'E; 114 m; 4 August 1997; R/ V Dominator stn 23-971-218; RN Clark leg.; LACM 1997-174 (Fig. 1F, G View Figure 1 ); • 1 spm; Near Islands , south of Attu Island ; 52°29.30'N, 172° 57.50'E; 166 m; 2 August 1997; R/ V Dominator stn 23-971-210; RN Clark leg.; LACM 1997-163.21 (Fig. 1H View Figure 1 ); • 1 spm; Near Islands, south of Agattu Island; 52°13.50'N, 173°27.80'E; 166 m; 6 August 1997; R/ V Dominator stn 23-971-229; RN Clark leg.; LACM 1997-165.20 (Fig. 1I View Figure 1 ) GoogleMaps .
Description.
Shell. Shell narrowly turreted, spire angle ca. 30°, ~ 18 mm in adult shell length, consisting of approximately eight, thin, convex whorls, separated by deeply impressed suture (Fig. 1E-I View Figure 1 ); growth indeterminate. Shell whitish, with thick, velvety periostracum. Larval shell non-planktotrophic, ~ 3 elevated, constricted whorls, with smooth, blunt nucleus; well-defined opisthocyrt riblets and spiral threads producing cancellate sculpture on subsequent whorls. Prominent thread at shoulder and flattened subsutural ramp producing angulate appearance of first 1-1.5 whorls; gradually becoming more convex. Axial elements becoming more closely spaced toward teleoconch transition. Inferred transition to teleoconch marked by change in orientation of axial sculpture and slight expansion in whorl diameter (Fig. 3C, D View Figure 3 ). Teleoconch with seven to eight distinct, flattened spiral cords, somewhat irregular in width and spacing, and which extend onto base but may be less distinct. Spiral ornament crossed by variably developed, well separated, weakly prosocline axial threads and growth increments; axial threads obsolete on base. Aperture broad, outer lip thin, sharp. Axis weakly gyrate, pervious; columellar plait lacking. Anterior canal short, slightly recurved.
Operculum [Holotype]. Operculum thin, corneous, honey in color, thinning toward edges; paucispiral, nucleus eccentric, occupying ca. 38% of operculum length (Fig. 3F View Figure 3 ).
Radula [Holotype and LACM 1997-163.21]. Radular ribbon long, comprising 40 rows, ~ 3.7 mm in length, to 51 rows, ~ 4.4 mm in length (holotype). Radula taenioglossate (Fig. 6A View Figure 6 ). Rachidian small, concave, with sharp constriction below broad cutting edge, tapering to flat or pointed, narrow base. Cutting edge straight, bearing single, prominent, sharply pointed, triangular cusp and zero to four smaller, irregular, occasionally bifid denticles on each side (Fig. 6B, C View Figure 6 ). Radular membrane diagonally creased between rachidian and lateral teeth of each row. Lateral teeth robust, broad, with undulating inner edge of shaft curving posteriorly; cutting edge with prominent, dagger-like, pointed cusp, rarely with small, rounded accessory denticle at inner base, and with small, blunt inner cusp (Fig. 6A, B, D View Figure 6 ). Marginal teeth long, slender, with cylindrical shafts and constriction below claw-like tips; cutting edges of inner and outer marginal teeth bearing three to six elongate, curving, pointed cusps (Fig. 6E View Figure 6 ).
Anatomy [Holotype and LACM 1997-163.21]. Jaws large, robust, oval-rectangular to L-shaped (holotype; Fig. 6F View Figure 6 ), partially connected across posterior midline via thin membrane, comprised of rectangular rods. Rectum filled with sponge spicules.
Etymology.
In honor of Roger N Clark, Associate in Malacology at the LACM, who collected the type material during a fishery monitoring cruise conducted by NOAA in the Aleutian Islands in 1997.
Distribution and ecology.
Known only from the Aleutian Islands (Fig. 2 View Figure 2 ) in 114-166 m, feeding on sponges.
Remarks.
This species differs from Pseudomohnia kurilana in having constricted and elevated early whorls with an early angulation that is somewhat variable among available specimens. The shell is more turreted, with a narrower spire angle, and the operculum has a slightly larger nucleus. The radula is distinguished by the multicuspid rachidian and a greater number of cusps on the marginal teeth.
A radula preparation showing the distinctive multicuspid rachidian that was photographed in July 2006 could not be located in the collections of the LACM (L Groves, pers. comm.). Notes in an unpublished draft for the Northeast Pacific Gastropod volume indicate that LACM 1997-165.20 was used for a radula preparation. This lot (Fig. 1I View Figure 1 ) contains a damaged shell with a broken operculum and dried soft parts lacking a head.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Triphoroidea |
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