Chondrocyclus amathole, 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 : 26-30

Chondrocyclus amathole sp. nov.

urn:lsid:zoobank.org:act:2B4E9251-C68B-450D-9EC6-820CCF66433E

Figs 9 , 10 D–E, 14

Chondrocyclus alabastris – Connolly 1939: 539 .

Diagnosis

Shell small, very depressed, discoidal to lenticular; protoconch mammillate; periostracum with dense transverse costae developing at periphery broad quadrangular flanges; lamellate axial costae with dense axial riblets, rendering upper edge of each costa scalloped along its length; operculum duplex, exterior portion very shallowly concave to almost flat, multispiral lamella with fringe of very long bristles, fused at their tips, below main fringe is a second shorter fringe of loose bristles; umbilicus wide, exposing all the whorls; radula with two large cusps on second lateral tooth.

Etymology

Named after the Amathole Mountains, Eastern Cape, an area of natural and historic interest.

Type material examined

Holotype

SOUTH AFRICA – Eastern Cape • Amathole Mountains, Hogsback, downstream of Madonna and Child Waterfall , Southern Mistbelt forest ; 32.6068°S, 26.9622°E; 1061 m a.s.l.; 6 Apr. 2014; M. Cole, D. Herbert and L. Davis leg.; NMSA P0640 /T4157. ( Fig. 10 D–E)

Paratypes

SOUTH AFRICA – Eastern Cape • 18 specimens; same collection data as for holotype; ELM W3812 / T59 • 21 specimens; Hogsback, downstream of Madonna and Child Waterfall ; 32.6068°S, 26.9622°E; 1061 m a.s.l.; 31 Dec. 2008; M. Bursey leg.; ELM D16944/T55 • 9 specimens; same collection data as for preceding; ELM W3629 /T56 • 22 specimens; same collection data as for preceding; M. Cole leg., 13 Sep. 2012; ELM D17014/T57 • 6 specimens; same collection data as for preceding; ELM W3665 / T58 • 4 specimens; same collection data as for preceding; NMSA P0601 /T4115 • 2 specimens; same collection data as for preceding; NHMUK 20120278 • 3 specimens; same collection data as for preceding; NMW.Z.2012.065.00008 • 3 specimens; same collection data as for preceding; RMNH MOL.33050 • 3 specimens; Hogsback, forest above Hobbiton Camp, Southern Mistbelt forest ; 32.5958°S, 26.9617°E; 1253 m a.s.l.; 1 Dec. 2005; M. Bursey and V. Ndibo leg.; ELM W02966/T54 • 13 specimens; same collection data as for preceding; 13 Sep. 2012; ELM D17013/T60 • 13 specimens; same collection data as for preceding; ELM W3662 /T61 • 28 specimens; same collection data as for preceding; 10 Jun. 2013; M. Cole leg.; ELM D17338/T63 • 7 specimens; same collection data as for preceding; 6 Apr. 2014; M. Cole, D. Herbert and L. Davis leg.; ELM W3811 /T62 • 1 specimen; Kologha Forest, Evelyn valley, north side of Maden Dam , Murray’s Krantz ; 32.7257°S, 27.3078°E; 25 Apr. 1998; M. Bursey and N. Smith leg.; alive under a log; ELM D14417/T76 • 1 specimen; same collection data as for preceding; ELM W3693 /T77 • 13 specimens; Isidenge , SE of Mount Kemp, harvested site, south-facing forest; 32.6885° S, 27.2783°E; 1159 m a.s.l.; 5Apr. 2016; M. Cole leg.; ELM D18082/T198 • 4 specimens; same collection data as for preceding; ELM W03915/T196 • 23 specimens; Isidenge, Sandile’s Rest, small patch of forest near base of Mount Kemp ; 32.6614° S, 27.3004° E; 900 m a.s.l.; 7 Apr. 2016; M. Cole leg.; ELM D18077/T200 • 8 specimens; same collection data as for preceding; ELM W03914/T195 • 3 specimens; Stutterheim, Kologha Forest , waterfall walk from picnic site; 32.5339°S, 27.4308°E; 18 Jan. 2009; M. Cole leg.; ELM W3633 /T64 • 5 specimens; same collection data as for preceding; 22 Dec. 2009; M. Cole and T. Pretorius leg.; ELM D16942/T65 • 1 specimen; same collection data as for preceding; ELM W03628/T66 • 2 specimens; same collection data as for preceding; 11 Dec. 2010; M. Cole leg.; ELM W3634 /T67 • 4 specimens; Qacu forest ; 32.4031°S, 27.4486° E; 6 Apr. 2016; M. Cole leg.; ELM D18126/T201 • 5 specimens; same collection data as for preceding; ELM W03917/T197 • 5 specimens; Patchwood Farm, forest at source of Quanti River ; 32.3924°S, 27.4470°E; 1238 m a.s.l.; 18 Dec. 2012; M. and K. Cole leg.; ELM D17100/T80 • 3 specimens; Patchwood Farm , forest below (north of) house; 32.3875° S, 27.4501° E; 1196 m a.s.l.; 6 Apr. 2016; M. Cole leg.; ELM D18140/T199 • 8 specimens; Fort Fordyce , south facing slope near top of pass; 32.6843° S, 26.4956° E; 1110 m a.s.l.; 29 Dec. 2008; M. Cole leg.; ELM D16946/T68 • 19 specimens; same collection data as for preceding; ELM W3630 /T69 • 36 specimens; same collection data as for preceding; 3 Jan. 2010; M. Cole leg.; ELM D16947/T70 • 12 specimens; same collection data as for preceding; ELM W3632 /T71 • 1 specimen; same collection data as for preceding; 31 Dec. 2011; ELM D17005/T72 • 7 specimens; same collection data as for preceding; ELM W3631 /T73 • 4 specimens; same collection data as for preceding; NHMUK 20120279 • 4 specimens; same collection data as for preceding; NMSA P0600 /T4111 • 10 specimens; Fort Fordyce , south facing slope behind lookout; 32.6956°S, 26.4857°E; 1120 m a.s.l.; 30 Dec. 2008; M. Cole leg.; ELM D16950/T74 • 5 specimens; same collection data as for preceding; 17 Jan. 2015; ELM D17860/T75 • 10 specimens; same collection data as for preceding; 1 Apr. 2016; ELM D18116/ T202 • 3 specimens; Kapp River , north bank, indigenous riverine forest on shady, south-facing slope; 33.4830° S, 27.0807°E; 30 Dec. 2002; M. Bursey; ELM W3694 /T78 • 2 specimens; Beggars’ Bush , 15 km E of Grahamstown, south facing slope; 33.2871°E, 26.6885°E; 25 Feb. 2013; M. Cole, G. Godfrey and S. Ritcher leg.; ELM D17289/T79 .

Other material examined

SOUTH AFRICA – Eastern Cape • 5 specimens; Amathole Mountains: Hogsback, downstream of Madonna and Child Waterfall , Southern Mistbelt forest ; 32.6068° S, 26.9622°E; 1061 m a.s.l.; 25 Jan. 2002; M. Bursey leg.; ELM D13627 • 5 specimens; same collection data as for preceding; ELM W02834 • 6 specimens; Hogsback, forest above Hobbiton Camp, Southern Mistbelt forest ; 32.5958° S, 26.9617° E, 1253 m a.s.l.; 31 Dec. 2008; M. Bursey leg.; ELM D16945 • 14 specimens; Kologha Forest, near Stutterheim ; 32.5333°S, 27.3667° E; 27 Nov. 1993; R. Scott leg.; ELM D14405 • 5 specimens; Stutterheim, Kologha Forest, forest drive near Protea Hill ; 32.5558° S, 27.3175°E; 26 Jan. 2010; M. Cole leg.; ELM D16943 • 1 specimen; Stutterheim, Kologha Forest , waterfall walk from picnic site; 32.5339° S, 27.4308°E; 30 Dec. 2012; M. Cole leg.; ELM D17623 • 3 specimens; Fort Fordyce , kloof with watercourse, running eastwards; 32.6704° S, 26.4851° E; 1137 m a.s.l.; 29 Dec. 2008; M. Cole leg.; ELM D16949 • 3 specimens; Fort Fordyce , top of krantz near campsite; 32.6813° S, 26.4802°E; 1134 m a.s.l.; 30 Dec. 2011; M. Cole leg.; ELM D16948 • 7 specimens; same collection data as for preceding; ELM W3631 • 2 specimens; Patchwood Farm, forest at source of Quanti River ; 32.3924° S, 27.4470° E, 1238 m a.s.l.; 18 Dec. 2012; M and K Cole leg.; ELM W03695 • 3 specimens; Patchwood Farm , forest below (north of) house; 32.3875° S, 27.4501°E); 1196 m a.s.l.; M. Cole leg.; 18 Dec. 2012 ELM D17107 • 5 specimens; same collection data as for preceding; ELM W03699 .

Description

SHELL ( Fig. 14 A–C). Small, very depressed, discoidal to lenticular, adult diameter 5.09–7.4 mm, height 2.34–3.92 mm, diameter:height 1.52–2.54 (n = 68 measured in three populations spanning the Amathole Mountains). Spire little exserted, apex mammillate. Embryonic shell ( Fig. 14E ) 2.25 whorls, microscopically malleate, junction between embryonic shell and teleoconch evident with development of costae on teleoconch. Teleoconch comprising 2.5 whorls, convex, very rapidly increasing, suture deeply impressed. Aperture circular, last whorl descending near aperture, peristome simple, continuous and free. Umbilicus wide, exposing all the whorls. Periostracum glossy, honey-brown and lacquerlike with dense lamellate costae at regular intervals, 73–167 (n = 58) on last whorl, expanded into broad quadrangular flanges at periphery; lamellar blades ridged with dense axial riblets, rendering upper edge of each blade scalloped along its length; intervals between costae with about 6 microscopic axial threads. Shell translucent glossy honey-brown when fresh.

LIVING ANIMAL. Head, tentacles and snout dark grey, underside of foot creamy white.

OPERCULUM ( Fig. 14D, G ). Duplex, very shallowly concave to almost flat; outer portion consists of multispiral lamella with five–six whorls; each step-shaped; height of lamellar blade very low; fringe of very long bristles, fused at their tips but not along their entire length, below main fringe is a second shorter fringe of relatively loose bristles, long outer fringe of each whorl fused to lamella of following whorl, but due to its long length, fringe forms convex curve between one whorl and next, height of fringe of each whorl exceeds height of lamellar blade, outermost lamellar fringe very long and is reflexed over peristome in life, but operculum can be withdrawn into aperture.

RADULA ( Fig. 14F ). Rachidian with five cusps, central cusp approx. twice length of outer cusps; first lateral tooth usually with three large cusps, small fourth cusp and a vestigial fifth, third cusp (from centre) largest; second lateral with two large cusps, second cusp (from centre) longer and broader than first, a very small third cusp and a vestigial fourth.

PENIS ( Fig. 14 H–I). Shaft more or less cylindrical, slightly flattened, with prominent annular rugae, distal end smooth, intromittent organ short.

Distribution and habitat

Throughout the Amathole Mountains and extending eastwards towards the Kei River in isolated forest patches; also recorded at Beggars’ Bush near Grahamstown and at Kap River Nature Reserve near the mouth of the Great Fish River ( Fig. 9 ).

Amathole Mistbelt forest (Southern Mistbelt Forest group) ( von Maltitz et al. 2003) and Great Fish Thicket (Kap River) ( Hoare et al. 2006); in leaf-litter.

Remarks

The operculum of Chondrocyclus amathole sp. nov. is unique among all other Chondrocyclus species in its flatness, its long terminal fringe and relatively long secondary fringe below it and the low height of the multispiral lamellar blade. Chondrocyclus amathole sp. nov. was sister to C. alabastris and formed a well-supported clade (the Southern-Eastern Cape clade) with C. herberti sp. nov. and C. silvicolus sp. nov. ( Fig. 1 ). The periostracal flanges of C. amathole sp. nov. were broad and quadrangular while in the other three species in its clade, the flanges were pointed. In this feature, C. amathole sp. nov. resembled species in the Eastern Clade, but differed from species in the latter clade in all other diagnostic morphological features, i.e., single row of flanges at periphery, unique operculum, radula with two large cusps on second lateral tooth, cyclindrical penis ( Cole et al. 2019).

The Amathole Range is an outlier of the southern end of the Drakensberg, isolated by the valleys of the Great Fish and Great Kei Rivers ( Stuckenberg 1962) and is known for endemicity of many low-vagility forest-dependent taxa, including molluscs ( Connolly 1939; Herbert & Moussalli 2010; unpublished data), forest-floor spiders ( Griswold 1985), velvet worms ( Daniels & Ruhberg 2010), harvestmen ( de Bivort & Giribet 2010) and two frogs. Furthermore, populations of velvet worms in close geographic proximity are genetically discrete, suggesting that the historic contractions and expansions of forests in this region left a significant and complex impact on the phylogeography of low-vagility organisms ( Daniels et al. 2017).

Chondrocyclus amathole sp. nov. has been recorded in two localities geographically separated from the mistbelt forests of the Amatholes, indicative of past vegetation shifts. The population of C. amathole sp. nov. in the outlying forest patch, Beggars’ Bush near Grahamstown, was separated from populations of the sister species, C. alabastris on the opposite ridge, by a dry intervening valley. Beggars’ Bush is currently separated from the Amathole mountains by the dry Great Fish River basin although both regions are designated Amathole Mistbelt in certain classification systems and distinguished from other Southern Mistbelt forests ( von Maltitz et al. 2003). The presence of C. amathole sp. nov. near the mouth of the Great Fish River suggests a link between the coast and the Amathole Mountains, a pattern also demonstrated in other taxa (e.g., Streptocarpus ( Hughes et al. 2005)) . The Great Fish River basin has been identified as an area of persistence of thicket during the contractions of the LGM ( Potts et al. 2012). The distribution pattern in this eastern subclade of the Southern-Eastern Cape clade (i.e., C. alabastris and C. amathole sp. nov.) is mirrored by rhytidid snails ( Herbert & Moussalli 2010, 2016).

Figures

Fig. 9. Distribution map of Chondrocyclus species in the Southern-Eastern Cape clade in the southern Cape area of the Western Cape province and the western half of the Eastern Cape province. T indicates type localities. Major cities and rivers are labelled.

Fig. 10. Holotypes of species of Chondrocyclus Ancey, 1898. A–B. C. herberti sp. nov., diameter 3.70 mm (NMSA P1043/T4277). C, F. C. silvicolus sp. nov., diameter 5.82 mm (NMSA P0639/T4156). D–E. C. amathole sp. nov., diameter 6.01 mm (NMSA P0640/T4157). G–H. C. pondoensis sp. nov., diameter 5.92 mm (NMSA P0643/T4160). I, L. C. devilliersi sp. nov., diameter 5.23 mm (NMSA P1141/ T4312). J–K. C. pulcherrimus sp. nov., diameter 4.34 mm (NMSA W9272/T3075). M–N. C. cooperae sp. nov., diameter 4.93 mm (NMSA W9271/T3074). O, R. C. langebergensis sp. nov., diameter 5.13 mm (NMSA P0642/T4159). P–Q. C. kevincolei sp. nov., diameter 4.24 mm (NMSA P9270/T3073).

Fig. 14. Chondrocyclus amathole sp. nov. A. Aperture view (ELM W3629/T56). B. Dorsal view (ELM W3629/T56). C. Ventral view (ELM W2966/T54). D, G. Operculum (ELM W2966/T54). E. Protoconch (ELM W3812/T59). F. Portion of radula (ELM W3628/T66). H. Penis, dorsal view (ELM W3628/T66). I. Penis, lateral view (ELM W3632/T71). Scale bars: A–C = 2 mm; D, G–I = 1 mm; E = 500 µm; F = 50 µm.

Fig. 1. Bayesian Inference majority consensus tree of the “taxa complete” concatenated CO1-16S sequence dataset for Chondrocyclus s.l. Ancey, 1898 (84 sequences) and seven other caenogastropods with the tree rooted on Pomacea insularum (d’Orbigny, 1837) (modified from Cole et al. 2019). Colours indicate major clades of Chondrocyclus Ancey, 1898 and correspond with colours used in maps. Support values are given as posterior probabilities for Bayesian analysis above nodes (only values ≥ 0.95 are shown) and as bootstrap percentages for ML analysis below nodes (only values ≥ 65% are shown); maximal support (Bayesian = 1, ML = 100%) is indicated by an asterisk. Scale bar indicates substitutions per site.