Caecum leilae, 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 : 112-114

Caecum leilae sp. n.

Figs 10A–N , 11 , 22P, Q , 23P, Q , 24E, F , 26M–P

Etymology: Named after the late Leila Zitelli, second author’s mother.

Description: Tube rather large, cylindrical, colourless and glossy, semitransparent, evenly arched, sculptured by very fine, slightly oblique rings, more evident in the abapical half, separated by narrower interspaces. Aperture simple, contracted, slightly oblique toward the ventral side. Surface grooved by gross, shallow, worm-like incisions visible at low magnifications especially in the adapical half. Septum dome­shaped, opaque, smooth, very protruding. Mucro ear-like, of variable height with respect to the septum, positioned at a variable angle between the dorsal and the right side. Surface of the septum with orange-peel aspect. Sparse, irregular grooves arranged like waves coming from the mucro are often visible on the septum. Macula small, heart-shaped, hardly visible, transparent, slightly displaced to the left side. Periostracum light brown, dull, easily lost, sculptured by fine longitudinal worm­like grooves. Juveniles quite similar to the adults, having the same morphology of the aperture, sculpture and microsculpture and are distinguished by the smaller diameter, the more curved tube, the less defined rings and by the slightly less protruding septum. Larval stage unknown. Operculum thin, corneous, circular, multispiral, composed by a small central nucleus surrounded by an initially tight spiral of 7–8 whorls. External side slightly concave, internal side with a slightly convex nucleus.

Length: 2.5–3.2 mm.

Type locality: SOUTH AFRICA: Eastern Cape: Mzamba.

Holotype ( Figs 10A–C , 22P , 23P ): SOUTH AFRICA: Eastern Cape: sh, Mzamba, beach drift, leg. R. Kilburn & D. Herbert 12–30.v.1986 ( NMSA D3032 /T3374), length 3.1 mm, min. diam. (posterior end) 0.51 mm, diam. in the middle of the tube 0.6 mm, max. diam. (apertural end) 0.62 mm.

Paratypes: SOUTH AFRICA: Eastern Cape: 7 lv and 26 sh, Mzamba, near Natal border, vii.1976 ( JPM 2119 ) ; 2 lv and 6 sh, same data as holotype ( NMSA W9674 /T3375) ; 1 lv, Mbotyi, beach drift, leg. R. Kilburn, D. Herbert v-vi.1985 ( NMSA C8454 /T3885); KwaZulu-Natal : 2 lv, Mapelane, S of St. Lucia, iv.1981 ( JPM 2116 ) ; 1 lv, off Richards bay , shallow dredgings, viii.1986 ( JPM) ; 2 sh, off Durban Bluff, ­ 18–22 m, fine sand, leg. RK, RF 1983 ( NMSA E981 /T3883) ; 1 lv and 3 sh (1 broken), Mission Rocks, N of St. Lucia, v.1989 ( JPM) ; 1 lv and 2 sh (1 broken, 1 with two attached growth stages), Mapelane, leg J. Marais iv.1981 ( NMSA B4607 /T3882) ; 1 lv, Umtamvuna R. mouth, beach-drift, leg. J.P. Marais vi.1996 ( NMSA V3999 /T3884) .

Comparative material examined: C. inflatum de Folin, 1869 , lectotype (MNHN-IM-2000-24915) selected by Pizzini et al. (2013: 30, fig. 12P–R); C. attenuatum de Folin, 1880 , lectotype (NHMUK 1887.2.9.2315) selected by Pizzini et al. (2013: 3, fig. 9O, P); C. cooki Pizzini & Raines, 2011 , holotype (MNHNIM-2000-23124); C. incisum sp. n.; C. inhacaense Albano & Pizzini, 2011 , holotype (MZB 15000).

Distribution: Eastern coast of South Africa from Mbotyi (south of Port Edward) to St. Lucia ( Fig. 11 ).

Remarks: Caecum leilae resembles C. inflatum de Folin, 1869 and C. attenuatum de Folin, 1880 which show a similar annulated sculpture, but the septum is different, with a larger and ill­defined mucro in C. inflatum and with a triangular outline in C. attenuatum .

Caecum leilae can also be compared with the Indo­West Pacific species C. cooki Pizzini & Raines, 2011 with which it shares the shape of the ear-like mucro, but shows no sculpture and a different shape of the aperture as well.

Juveniles of C. leilae can be confused with C. incisum and C. inhacaense . However, C. leilae can be distinguished by the different sculpture (obsolete rings in leilae , incised collabral grooves defining flat rings in incisum ) and by the mucro (broader in C. incisum and by the presence of the longitudinal microsculpture, while the latter shows a different shape of the mucro and lacks the regular annular sculpture crossed by the longitudinal microsculpture occurring throughout the tube that is typical of C. leilae ). Moreover, the maculae in C. leilae and C. inhacaense are different in both shape and colour (heartshaped and transparent in the former, roundish to chevron-shaped and opaque white in the latter) ( Fig. 24E–G ).

Figures

Fig. 10. Caecum leilae sp. n., South Africa: (A–C) holotype, Mzamba (NMSA D3032/T3374) — (A) right side, (B) ventral side, (C) microsculpture; (D–G) paratype, Umtamvuna R. mouth (NMSA V3999/ T3884) — (D) right side, (E) ventral side, (F) operculum (outer side), (G) microsculpture; (H–K) paratype (juv), Mission Rocks, N of St.Lucia (JPM) — (H) right side, (I) ventral side, (J) operculum (inner side), (K) microsculpture; (L–N) paratype (two attached growth stages), Mapelane (NMSA B4607/T3882) — (L) right side, (M) ventral side, (N) microsculpture. Scale bar = 1 mm (A, B, D, E, H, I, L, M); 250 µm (C, G, K, N); 200 µm (F, J).

Fig.11. Distribution map of Caecum leilae sp. n. (■), C.incisum sp.n. (▲) and C. maraisi sp. n. (▼).White symbol indicates the type locality.

Fig. 22. Detail of the septum of South and western African Caecum species (right side): (A–C) C. subquadratum Carpenter, 1859 — (A) Walker’s Point, W of Knysna (NMSA S3729), (B) Walker’s Point, W of Knysna (JPM), (C) juv, Langebaan Lagoon, Saldanha Bay (JPM); (D, E) C. morgan sp. n., Cape Morgan Lighthouse — (D) holotype (NMSA B7132/T3377), (E) paratype (NMSA W9676/ T3378); (F–H) C. austrafricanum sp. n., Algoa Bay — (F) holotype (NMSA W9655/T3349), (G) paratype (JPM),(H) paratype (juv) (JPM); (I) C. knysnaense sp.n., holotype, Knysna, Gericke Point, Sedgefield (NMSA S7625/T3362); (J) C. intortum sp. n., holotype, Walker’s Point, W of Knysna (NMSA W9668/T3358); (K) C. inhacaense Albano & Pizzini, 2011, Aliwal Shoal, off Umkomaas area (JPM); (L, M) C. incisum sp. n. — (L) holotype, Walker’s Point, W of Knysna (NMSA S3728/ T3355), (M) paratype, Knysna,Gericke Point, Sedgefield (NMSA W9661/T3357);(N, O) C.maraisi sp.n.—(N) holotype, Knysna, GerickePoint,Sedgefield (NMSA W9765/T3376),(O) paratype (juv), Fish R. mouth (between Port Alfred and East London) (JPM 2117); (P, Q) C. leilae sp. n. — (P) holotype, Mzamba (NMSA D3032/T3374), (Q) paratype, Umtamvuna R. mouth (NMSA V3999/ T3884); (R) C. cf. glabrum (Montagu, 1803), Knysna, Gericke Point, Sedgefield (NMSA W9658); (S, T) C. glabrum (Montagu, 1803) — (S) Porto Mindelo, Ilha de São Vicente, Cape Verde (MP), (T) St. Malo, France (MP). Scale bar = 100 µm.

Fig. 23. Detail of the septum of South and western African Caecum species (ventral side): (A–C) C. subquadratum Carpenter, 1859 — (A) Walker’s Point, W of Knysna (NMSA S3729), (B) Walker’s Point, W of Knysna (JPM), (C) juv, Langebaan Lagoon, Saldanha Bay (JPM); (D, E) C. morgan sp. n., Cape Morgan Lighthouse — (D) holotype (NMSA B7132/T3377), (E) paratype (NMSA W9676/ T3378); (F–H) C. austrafricanum sp. n., Algoa Bay — (F) holotype (NMSA W9655/T3349), (G) paratype (JPM); (H)paratype (juv) (JPM); (I) C. knysnaense sp.n., holotype, Knysna, Gericke Point, Sedgefield (NMSA S7625/T3362); (J) C. intortum sp. n., holotype, Walker’s Point, W of Knysna (NMSA W9668/T3358); (K) C. inhacaense Albano & Pizzini, 2011, Aliwal Shoal, off Umkomaas area (JPM); (L, M) C. incisum sp. n. — (L) holotype, Walker’s Point, W of Knysna (NMSA S3728/ T3355), (M) paratype, Knysna, Gericke Point, Sedgefield (NMSA W9661/T3357);(N, O) C. maraisi sp.n.— (N) holotype, Knysna, Gericke Point,Sedgefield (NMSA W9765/T3376), (O) paratype (juv), Fish R. mouth (between Port Alfred and East London) (JPM 2117); (P, Q) C. leilae sp. n. — (P) holotype, Mzamba (NMSA D3032/T3374), (Q) paratype, Umtamvuna R. mouth (NMSA V3999/ T3884); (R) C. cf. glabrum (Montagu, 1803), Knysna, Gericke Point, Sedgefield (NMSA W9658); (S, T) C. glabrum (Montagu, 1803) — (S) Porto Mindelo, Ilha de São Vicente, Cape Verde (MP), (T) St. Malo, France (MP). Scale bar = 100 µm.

Fig. 24. Ventral side of South and western African Caecum species: (A) C. austrafricanum sp. n., paratype, Walker’s Point, W of Knysna (NMSA W9656/T3351); (B) C. knysnaense sp. n., paratype, Knysna, Gericke Point,Sedgefield (NMSA W9673/T3364);(C, D) C. intortum sp.n.— (C)paratype,Walker’s Point, W of Knysna (NMSA W9669/T3360), (D) the same specimen slightly rotated, detail of the macula; (E, F) C. leilae sp. n. — (E) paratype, Mzamba, near Natal border (JPM 2119), (F) the same specimen, detail of the macula; (G) C. inhacaense Albano & Pizzini, 2011, Mzamba, near Natal border (JPM 2119); (H) C. macrum van der Linden & Moolenbeek, 2000, Charbonnier, Senegal (MP); (I) C. crassum de Folin, 1870, Banc d’Arguin, Mauritania (MP). Scale bar = 1 mm (A–C, E, G–I); 300 µm (D, F).

Fig. 26. South African Caecum species: (A, B) C. inhacaense Albano & Pizzini, 2011 — (A) Aliwal Shoal, off Umkomaas area (JPM), (B) Mzamba, near Natal border (JPM 2119); (C, D) C. incisum sp. n. — (C) paratype, Walker’s Point, W of Knysna (NMSA W9660/T3356), (D) paratype, Knysna, Gericke Point, Sedgefield (NMSA W9661/T3357); (E, F) C. maraisi sp. n. — (E) holotype, Knysna, Gericke Point, Sedgefield (NMSA W9765/T3376), (F) paratype (juv) Fish R. mouth (between Port Alfred and East London) (JPM 2117); (G–I) C. subquadratum Carpenter, 1859 — (G) Walker’s Point,W of Knysna (NMSA S3729); (H, I) Langebaan Lagoon, Saldanha Bay (JPM): (H) adult, (I) juvenile; (J, K) C. morgan sp. n., paratypes, Cape Morgan Lighthouse (NMSA W9676/T3378); (L) C. chinense de Folin, 1868, Durban (MP); (M–P) C. leilae sp. n., paratypes, Mzamba, near Natal border (JPM 2119); (Q, R) C. neocaledonicum de Folin, 1868, Ilot Fourneau, Mauritius (NMSA K9346) — (Q) specimen with periostracum, (R) specimen without periostracum. Scale bar = 1 mm.