Caecum morgan, 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 : 104-105

Caecum morgan sp. n.

Figs 2A–F , 3 , 22D, E , 23D, E , 26J, K

Etymology: Derived from the type locality (Cape Morgan) and used as a noun in apposition.

Description:Tube small, subcylindrical, proportionally thick, whitish, smooth.Aperture slightly oblique toward the ventral side, showing a well-developed swelling followed by a contraction and finally by a very small ring. Surface smooth, dull, without microsculpture. Septum opaque, slightly protruding over the cutting plane, with a sharp, nail-like mucro directed toward the right side, giving a dome-shaped outline to the septum when viewed from the side. Early stages and operculum unknown.

Length: 1.6–1.8 mm.

Type locality: SOUTH AFRICA: Eastern Cape: Agulhas Bank , off Cape Morgan Lighthouse , - 100 m.

Holotype ( Figs 2A–C , 22D , 23D ): SOUTH AFRICA: Eastern Cape: sh, Agulhas Bank , off Cape Morgan Lighthouse , - 100 m, broken coral + shell, don. A. Connell, 1977, ( NMSA B7132 / T3377 ), length 1.66 mm, min. diam. (posterior end) 0.22 mm, diam. in the middle of the tube 0.30 mm, max. diam. (apertural end) 0.34 mm.

Paratypes: 6 sh, same data as holotype ( NMSA W9676 / T3378 ) .

Comparative material examined: C. campanulatum Raines & Pizzini, 2005 , holotype (LACM 3027); C. chinense de Folin, 1868 , lectotype (MNHN-IM-2000-24905); C.dakuwaqa Pizzini, Raines & Vannozzi, 2013 , holotype (MNHN-IM-2000-24843); C. subquadratum Carpenter, 1859 , lectotype (NHMUK 1858.12.9.13, Fig. 21E ); C. fijiense Pizzini, Raines & Vannozzi, 2013 , holotype (MNHN-IM-2000-24857).

Distribution: Currently known only from the type locality, Cape Morgan, north of East London ( Fig. 3 ).

Remarks: Caecum morgan sp. n. strongly resembles C. subquadratum due to the lack of both sculpture and microsculpture, as well as a similar shape of the mucro. It can however be separated by the distinctly subcylindrical and more curved shape of the tube, and by the presence of a conspicuous swelling above the aperture, barely visible in C. subquadratum . In C. morgan sp. n. the septum is only somewhat emerging above the cutting plane. Conversely, in C. subquadratum the septum is more protruding, on the whole giving the mamillate-ungulate appearance pointed out by Carpenter (1859). Caecum morgan sp. n. resembles C. gofasi Pizzini & Nofroni, 2001 in general aspect, but the latter has a dorsal spatulate mucro and shows a distinct worm-like microsculpture absent in the new species. Moreover, C. morgan sp. n. is also similar to C. campanulatum Raines & Pizzini 2005 , C. dakuwaqa , and C. fijiense (both Pizzini, Raines & Vannozzi, 2013), having the same bell-shaped aperture, but in these species the septum is domeshaped without any mucro. Additionally, C. morgan sp. n. differs from C. dakuwaqa by the lack of the exasperate torsion of the tube occurring in the latter. Caecum morgan is also similar to C. musorstomi Pizzini, Raines & Vannozzi, 2013 , from which it can be separated by the smooth surface without sculpture, and microsculpture and by a different orientation and shape of the mucro.

Figures

Fig. 2. Caecum morgan sp. n., South Africa, Cape Morgan Lighthouse: (A–C) holotype (NMSA B7132/ T3377) — (A) right side,(B) ventralside, (C) microsculpture;(D–F) paratype(NMSA W9676/T3378) — (D) right side, (E) ventral side, (F) microsculpture. Scale bar = 1 mm (A, B, D, E); 250 µm (C, F).

Fig. 3. Distribution map of Caecum chinense de Folin, 1868 (■), C. subquadratum Carpenter, 1859 (▲) and C. morgan 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. 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.

Fig. 21. Type material of Caecum species: (A–D) Caecum variegatum de Folin, 1867, syntype (MNHN- IM-2000-25783) — (A) right side, (B) detail of theseptum, (C) ventral side,(D) detail of theseptum; (E, F) C. subquadratum Carpenter, 1859, lectotype (NHMUK 1858.12.9.13) — (E) left side, (F) original label. Scale bar = 1 mm (A, C, E); 100 µm (B, D).