Parvamussium, Sacco, 1897

Dijkstra, Henk H. & Beu, Alan G., 2018, Living Scallops of Australia and Adjacent Waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae), Records of the Australian Museum (Rec. Aust. Mus.) 70 (2), pp. 113-330 : 130-131

Key to species of Parvamussium from Australia

1 Shell small, c. 9 mm high, circular, almost opaque, whitish, auricles unequal, byssal notch small, lv with radial and commarginal sculpture, 3 rudimentary internal riblets ............................................ P. araneum

—— Shell small, subcircular, translucent white, auricles unequal, byssal notch shallow, lv with commarginal and interstitial radial scupture, 11–13 internal riblets ................................................................................................. 2

2 Shell c. 7 mm high, whitish, left valve more convex than right valve, equivalve, almost equilateral, auricles dissimilar in shape, lv with commarginal lamellae and weak interstital radial riblets, rv with regularly spaced commarginal lirae, lv with 12–13 internal riblets, rv with 11 internal riblets ........................................................... P. cancellorum

—— Shell small, circular, hyaline, both valves smooth, 12–13 internal riblets ......................................................................................................................................... 3

3 Shell c. 9 mm high, whitish, both valves weakly inflated, almost equally convex, inequivalve, equilateral, 12–13 narrow internal riblets ........................................................................................................... P. lamprelli

—— Shell small, oblong, hyaline, lv delicate sculptured, 10 internal riblets ......................................................................................................................................... 4

4 Shell c. 14 mm high, slightly posteriorly oblique, whitish, lv delicately radially sculptured, central part almost smooth, commarginal lamellae near ventral margin, 10 or 11 internal riblets, most specimens with 10 ............................................................................... P. maorium

—— Shell small, fragile, circular, hyaline, lv commarginally sculptured, 14 internal riblets .................................................................................................... 5

5 Shell c. 9 mm high, flattened, lv with widely spaced prominent commarginal lamellae, 14 internal riblets plus a few rudimentary ones ................................................................................................. P. multiliratum

—— Shell small, circular, hyaline or opaque, auricles almost equal, a few rudimentary internal riblets ................................................................................................ 6

6 Shell c. 8 mm high, both valves almost smooth, lv flattened, 1–3 rudimentary internal riblets ................................................................................ P. pauciliratum

—— Shell small, oblong, posteriorly oblique, lv with delicate reticulate sculpture, 10 internal riblets ...................................................................................... 7

7 Shell c. 16 mm high, opaque, whitish, lv with fine radial and commarginal sculpture, 10 prominent internal riblets with a few rudimentary ............................................................................................................... P. retiolum

—— Shell small, almost circular, lv flattened, delicately radially sculptured, 9–10 internal riblets ................................................................................................ 8

8 Shell c. 10 mm high, lv stained and opaque, weakly radially and commarginally sculptured, rv almost smooth, whitish, 9–10 internal riblets, with a few rudimentary in some specimens ..................................... P. scitulum

—— Shell small, circular, hyaline, valves equally convex, smooth, auricles almost equal, internal riblets rudimentary ................................................................... 9

9 Shell c. 6 mm high, valves smooth and glossy, with white maculations, internal riblets rudimentary, 2 anteriorly and 2 posteriorly ........................................................................................................... P. slacksmithae

—— Shell small, almost circular, lv sculptured with fine scaly radial riblets, 10 internal riblets ......................................................................................................... 10

10 Shell c. 11 mm high, lv stained and opaque, sculptured with fine unevenly spaced scaly radial riblets, rv whitish, 10 internal riblets, with a few rudimentary ones in some specimens .................................... P. squalidulum

—— Shell small, almost circular, opaque, lv heavily sculptured, 10 internal riblets .......................................................................................................................... 11

11 Shell c. 10 mm high, creamy with white spots, lv with unevenly set prominent radial sculpture and close-set commarginal lamellae, 8–10 internal riblets, 10 in most specimens ................................................. P. thetidis

—— Shell small, almost circular, lv smooth and glossy, 10 internal riblets ....................................................................................................................................... 12

12 Shell c. 9 mm high, lv opaque and whitish, lv sculptured with only delicate commarginal lamellae near ventral margin, 10 internal riblets, with a few rudimentary in some specimens ................................... P. torresi

—— Shell small, almost circular, lv coarsely sculptured with vesicles, few rudimentary internal riblets .............................................................................................. 13

13 Shell c. 6 mm high, lv with commarginal lirae and radially arranged vesicles, few rudimentary internal riblets anteriorly and posteriorly .............................................................................................................. P. vesiculatus