Chondrocyclus, Cole, 2019

Cole, Mary L., 2019, Revision of Chondrocyclus s. l. (Mollusca: Cyclophoridae), with description of a new genus and twelve new species, European Journal of Taxonomy 569, pp. 1-92 : 7-8

Genus Chondrocyclus sensu stricto Ancey, 1898

Diagnosis

Shell dextral, small (~ 4.5–6.5 mm), depressed, lenticular; aperture circular, last whorl descending near aperture, peristome not thickened, continuous and free; umbilicus wide and deep, exposing all the whorls; periostracum glossy and lacquer-like with lamellate axial costae at regular intervals, expanded into spiral rows of hairs or flanges; operculum duplex, corneous; inner portion consists of a thin disc which grows outwards in a tight spiral, smooth on inside where it attaches to foot; fused to disc on its outer surface is a multispiral, elevated horny blade-like lamella formed by fused bristles; height of lamella increases as it spirals outwards forming a concave exterior element; lamella not vertical, but stepped or flared, so that diameter of each whorl larger at proximal edge of lamellar blade; a fringe of fused bristles emanates from outer surface of each lamellar whorl; fringe reflexed over peristome but operculum can be withdrawn into aperture; radula taenioglossate; penis lies dorsally immediately behind right tentacle and consists of a stout, muscular shaft, cylindrical or dorsoventrally flattened and wrinkled along most of its length due to annular rugae, and a terminal, tapering intromittent organ without flagellum; seminal tube completely enclosed without seminal groove.

Key to species of Chondrocyclus

1. Periostracum bears spiral rows of hairs arising from axial lamellae ................................................. 2 – Axial lamellae of periostracum expanded into pointed or rounded flanges ...................................... 3

2. Distinct spiral grooves on shell corresponding to rows of periostracal hairs .... C. kevincolei sp. nov. – Spiral grooves weak if present................................................................... C. langebergensis sp. nov.

3. Protoconch mammillate and tilted ..................................................................................................... 4 – Protoconch not mammillate or tilted ................................................................................................. 8

4. Axial lamellae expanded into broadly rounded flanges at periphery; lamellae with numerous ridges perpendicular to shell surface ............................................................................. C. amathole sp. nov.

– Periostracal flanges taper towards their proximal ends ..................................................................... 5

5. Flanges taper to rounded point .......................................................................................................... 6 – Flanges taper to acute tip ................................................................................................................... 7

6. Axial lamellae widely spaced; approx. 45 on body whorl.................................... C. herberti sp. nov. – Axial lamellae less widely space, approx. 70 on body whorl............................. C. silvicolus sp. nov.

7. Flanges taper from broad base into a long spine; second lateral tooth of radula with three large cusps; Western Cape ................................................................................ C. convexiusculus ( Pfeiffer, 1855)

– Flanges taper gradually towards tips; if spine-tipped, spine short; second lateral tooth of radula with two large cusps; Eastern Cape ................................................................ C. alabastris ( Craven, 1880)

8. Operculum deeply or shallowly cup-shaped in side view ................................................................. 9

– Operculum more or less flattened in side view with outer portion parallel to disc surface and appears attached to disc by pedestal ..............................................................................................................11

9. Body whorl with at least six spiral rows of broadly rounded flanges.................. C. cooperae sp. nov. – Body whorl with three spiral rows of broadly rounded flanges....................................................... 10

10. Operculum deeply cup-shaped; southern Kwazulu-Natal and northern Transkei............................... .................................................................................................................. C. putealis Connolly, 1939

– Operculum cup-shaped; Albany area and southern Transkei ....... C. bathrolophodes Connolly, 1929

11. Operculum with spiral lamella of outer portion raised above level of fringe in side view; southern KwaZulu-Natal and Transkei........................................................................... C. pondoensis sp. nov.

– Operculum with spiral lamella not raised above fringe................................................................... 12

12. Body whorl with only one row of broadly rounded flanges at periphery........... C. devilliersi sp. nov. – Body whorl with multiple spiral rows of rounded or paddle-shaped flanges .................................. 13

13. Body whorl with 12 spiral rows of flanges; spire almost flat ...................... C. pulcherrimus sp. nov. – Body whorl with five spiral rows of flanges..................................... C. trifimbriatus Connolly, 1929