Parastrophia avaricosa, 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 : 123-125

Parastrophia avaricosa sp. n.

Figs 19A–C , 20 , 25A

Etymology: The name is composed by the Greek α (not) and the Latin adjective varicosus (= provided with a varix) due to the absence of the varix between the uncoiled protoconch and the teleoconch that occurs in all the other Parastrophia species.

Description: Tube slightly bisinuous, very thin, vitreous, tapered. Coiled protoconch small, ovoid, of half a whorl. Uncoiled protoconch smooth, conical in the adapical half, then subcylindrical, curved and with a slight constriction before the transition to the teleoconch, which is marked by a simple scar. Teleoconch gently curved and slowly growing, characterized by the presence of a microsculpture composed by shallow, irregularly set grooves spaced about 5 µm apart. Aperture rounded, simple, without any feature. Length 1.5 mm. Operculum unknown.

Type locality: SOUTH AFRICA: Eastern Cape: Mzamba.

Holotype ( Figs 19A–C , 25A ): SOUTH AFRICA: Eastern Cape: sh, Mzamba , beach, leg. J.P. Marais vii.1976 ( NMSA E1665 / T3354 ), length 1.47 mm, protoconch diam. 0.08 mm, max. diam. (apertural end) 0.26 mm .

Paratypes: MADAGASCAR: 9 sh, E of Cap Antsirabe, 25°02.8–03.0'S 47°01.3–02.0'E, sable vaso-sableux compact, - 49–52 m, 6.v.2010 ( MNHN-IM- 2012 - 2726 ); 1 sh, Phare Flacourt , 25°01.3'S, 47°00.5'E, fond rocheux avec dalle,- 18 m, 1.v.2010 ( MNHN-IM- 2012 - 2727 ); 1 sh, SW of CapAndavaka,chalutier “NosyBe II”, - 53–54 m, 25°16.9'S, 46°31.3'E, 4.v.2010 ( MNHN-IM- 2012 - 2728 ) .

Comparative material examined: P.cornucopiae de Folin, 1869 , lectotype (MNHN-IM-2000-24917) selected by Pizzini et al. 2013 ( 2013: 43, fig. 16F, G); P. filum Melvill, 1906 , holotype from Gulf of Oman, 156 fms (NHMUK 190610.23.47); P. japonica Hinoide & Habe, 1978 , holotype (NSMT-Mo 55474); P. melanesiana Pizzini, Raines & Vannozzi, 2013 , holotype (MNHN-IM-2000-24882).

Distribution: This species is known only from the eastern coast of South Africa (type locality, Fig. 20 ) and from the southern coast of Madagascar around Talanaro.

Remarks: Parastrophia avaricosa sp. n. is the only known Parastrophia species without a separation varix between protoconch and teleoconch, thus it is immediately distinguished from all the other congeners. The new species resembles P. cornucopiae de Folin, 1869 , P. japonica Hinoide & Habe, 1978 and P. melanesiana Pizzini, Raines & Vannozzi, 2013 (all figured in Pizzini et al. 2013) due to the paucispiral protoconch. Parastrophia cornucopiae is similar to P. avaricosa , having in common a similar shape of the protoconch, but the latter completely lacks the varix separating the uncoiled protoconch from teleoconch. Moreover, Parastrophia avaricosa shows a microsculpture composed by fine collabral grooves that is not observed in P. cornucopiae . Parastrophia avaricosa is also similar to P. japonica and P. melanesiana , but the latter two show a distinct separation varix and a longitudinal microsculpture ( Pizzini et al. 2013).

Figures

Fig. 19. Parastrophia avaricosa sp. n., South Africa, Mzamba: (A–C) holotype (NMSA E1665/T3354) — (A) left side, (B, C) microsculpture. Scale bar = 1 mm (A); 250 µm (B); 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.