Parastrophia ornata, Vannozzi & Pizzini & Raines, 2015

Vannozzi, Angelo, Pizzini, Mauro & Raines, Bret, 2015, Revision of South African Caecidae (Mollusca: Gastropoda), African Invertebrates 56 (1), pp. 99-99 : 123

Parastrophia ornata sp. n.

Figs 18A–H , 20 , 25B, C

Etymology: Derived from the Latin adjective ornatus (= adorned), referring to the longitudinal microsculpture that adorns the teleoconch.

Description: Tube bisinuous, semitransparent, vitreous. Coiled protoconch formed by about 1.1 whorls; uncoiled protoconch conical, about 0.5 mm long, ending in a clear varix. The varix is asymmetrical, flange­like in the adapical side, shaped into a ring in the abapical side. Teleoconch smooth, with only some growth lines, especially close to the aperture, defining irregular rings. Microsculpture composed by fine longitudinal threads, slightly dextrally wound around the tube, rather sparse adapically, finer and denser abapically. The threads are interrupted by the growth lines, producing a wavy appearance. Operculum unknown.

Length: 2.5–2.7 mm.

Type locality: SOUTH AFRICA: Eastern Cape: Mzamba.

Holotype ( Fig. 25B ): SOUTH AFRICA: Eastern Cape: sh, Mzamba , near KwaZulu-Natal border, vii.1976 ( W9677 / T3379 ), length 2.71 mm, protoconch diam.0.14 mm, max. diam. (apertural end) 0.46 mm.

Paratypes: SOUTH AFRICA: Eastern Cape: 1 sh, same data as holotype ( JPM 2119 ); 1 sh (broken), Mzamba, beach, leg. J.P. Marais vii.1976 ( NMSA W9678 / T3380 ) .

Additional material examined: SOUTH AFRICA: KwaZulu-Natal: 2 sh, off Richards bay , shallow dredgings, viii.1986 ( JPM) (lost) .

Distribution: Eastern coast of South Africa ( Fig. 20 ).

Remarks: This species can be compared with the Australian Parastrophia cygnicollis (Hedley, 1904) and P. erseusi Hughes, 1993 . It differs from the former by the different shape of the tube, which is longer and more slender in P. cygnicollis , by the shape of the adapical side of the varix, smoothly flaring in cygnicollis , flange­like in ornata , and by the presence of a microsculpture composed of fine longitudinal threads, whereas in cygnicollis a microsculpture composed of a few longitudinal wavy grooves is sometimes visible ( Pizzini et al. 2013: fig. 16O). Conversely, Parastrophia erseusi differs by the more or less symmetrical, evenly rounded varix and by the absence of microsculpture (Hughes 1993). Parastrophia ornata sp. n. is also similar to P. melanesiana Pizzini, Raines & Vannozzi, 2013 , which shares a similar microsculpture, but differs from it by the paucispiral coiled protoconch and by the different shape of the separation varix.

Figures

Fig. 18. Parastrophia ornata sp. n., South Africa: (A–C) paratype, Mzamba (JPM 2119) — (A) whole specimen, (B) detail of the protoconch, (C) microsculpture; (D, E) specimen from off Richards bay (JPM) — (D) whole specimen, (E) detail of protoconch and varix; (F–H) another specimen from off Richards bay (JPM) — (F) whole specimen, (G) detail of the separation varix, (H) detail of the aperture. Scale bar = 1 mm (A, D, F); 500 µm (B); 250 µm (H); 100 µm (E, G); 50 µm (C).

Fig. 20. Distribution map of Parastrophia ornata sp. n. (■) and P. avaricosa sp. n. (▲). White symbol indicates the type locality.

Fig. 25. South and western African Caecum and Parastrophia species: (A) P. avaricosa sp. n., holotype, Mzamba (NMSA E1665/T3354); (B, C) P.ornata sp. n., Mzamba,near Natal border — (B) holotype (NMSA W9677/T3379), (C) paratype (JPM 2119); (D) C. sepimentum de Folin, 1868, Kosi Bay (NMSA S2010); (E) C. cf. oahuense Pilsbry, 1921, Aliwal Shoal, off Umkomaas area (JPM); (F) Caecum cf. gulosum Hedley, 1899, Kosi Bay (NMSA S2869); (G, H) C. succineum de Folin, 1880 — (G) between Bhanga Nek andKosi Bay (NMSAS1586), (H)Aliwal Shoal, off Scottburgh (NMSA W9684); (I) C. cf. glabrum (Montagu, 1803), Knysna, Gericke Point, Sedgefield (NMSA W9658); (J) C. glabrum (Montagu, 1803), Rabat, Morocco (MP); (K) C.lindae sp. n., holotype, Cape Morgan Lighthouse (NMSA W9682/T3924); (L, M) C. cf. musorstomi Pizzini, Raines & Vannozzi, 2013, Landers reef (JPM); (N, O) C.austrafricanum sp.n., paratypes,Walker’s Point,W of Knysna (NMSA W9656/T3351);(P) C.knysnaense sp.n., paratype,Knysna,Gericke Point,Sedgefield (NMSAW9673/ T3364); (Q) C. intortum sp. n., paratype, Walker’s Point, W of Knysna (NMSA W9669/T3360); (R) C. macrum van der Linden & Moolenbeek, 2000, Charbonnier, Senegal (MP); (S, T) C. crassum de Folin, 1870, Gabon (MP): (S) adult; (T) juvenile. Scale bar = 1 mm.