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Pectinodonta kapalae B. A. Marshall 1985

Description

provided by NMNH Antarctic Invertebrates

Pectinodonta kapalae, n. sp.

Fig. 3L, M, 4C, F; Table 3

Type data. Holotype AMS C. 141 469 (length 10.2 mm, width 7.65 mm, heights 3.80 mm (min.) and 4.60 mm (max.), anterior length 3.30 mm); 33 paratypes (AMS, LACM, MNHN, NMNZ, USNM): 35°31-28'S, 150°50-53'E, E of Ulladulla, New South Wales, alive on wood, 941-978 m, 8 Sep­tember 1983, FRV Kapala Stn K83/11/04.

Description. Shell up to 10.6 mm long, moder­ately arched, thick, white, exterior dull, interior porcellaneous. Anterior end occupying 21.98­-36.18% of shell length. Anterior slope flat or con­vex, posterior and lateral slopes convex. Aperture elliptical, rather deeply concave from side to side, ends narrowly rounded, sides broadly rounded. With increasing growth, shell gradually twisting up to 8° between juvenile and adult in a dorsally anti­clockwise direction.

Protoconch deciduous.

Teleoconch 1.3-1.6 mm in length, depressed, glossy and translucent, sculptured with fine concentric growth lines. Fine radial lines show through the shell but do not resolve as surface structures. Subsequent teleconch [sic] dull and opaque, with low rounded radial costae, and strong, rounded concentric ridges that gently undulate across the radi­als. Fine, crisp, crowded, concentric growth lines throughout. Myostracum clearly defined.

Animal white. Gill large, extending anterolaterally from left to right behind head. Mantle edge smooth. Muzzle lappets thin and broad. Cephalic tentacles long, narrow and parallel-sided, tips rounded, bases weakly swollen, without eyes.

Radula (Fig. 4C, F). Cross rows alternately skewed to the left and right so that one tooth set lies slightly before the other. Cutting area of each tooth set externally broadly convex in lateral and plan views. Each tooth set with 15 conical cusps, inner 4 largest and decreasing in size outwards, outer cusps small and similar. Lateral plates simi­lar to those in P. aupouria.

Remarks. Pectinodonta kapalae most closely resembles the Japanese P. rhyssa (Dall) in size, shape, and disposition of sculpture, and may be distinguished by its blunter more broadly angulate concentric ridges, weaker, less crisply defined radial riblets, and more numerous cusps on each radular tooth set (15 cf. 9-11). P. kapalae differs from P. aupouria in being relatively smaller, in having stronger concentric and weaker radial sculpture, and in having a smooth instead of serrate mantle edge. Compared with P. orientalis, P. kapalae and P. rhyssa differs in being smaller, in having weaker radial and stronger concentric sculpture, and in having a more strongly convex anterior slope.”

Table 3 Pectinodonta kapalae. Shell measurements (mm), n = 10.

Character

Range

Mean

SD

Length

9.25-10.6

9.90

0.39

Width

6.65-8.15

7.27

0.26

Height I (maximum)

4.00-5.20

4.48

0.24

Height II (less basal curvature)

3.25-4.35

3.77

0.25

Basal curvature depth/height I%

11.11-18.75

15.87

2.80

Length/Width

1.30-1.43

1.36

0.03

Length/Height II

2.44-2.95

2.63

0.15

(Anterior length/shell length) %

26.89-33.00

29.69

2.25

(Marshall, 1985: 280)