Caecum superbum de Folin, 1867

Figures 72 A–F, 73A–L, 74A–B, 127B

Caecum superbum de Folin, 1867a: 44, 8 syntypes MNHN-IM-2000-4584, Panama.

Caecum superbum — Kisch, 1959a: 34.

Micranellum lohri Strong & Hertlein, 1939: 225, pl. 20, figs. 12 – 13, holotype CAS 065684, 1 paratype LACM 1714, Panama. (syn. nov.).

Micranellum lohri — Keen, 1971: 400, fig. 489.

Caecum (Micranellum) lohri — Skoglund, 1992: 28; Kaiser, 1997: 29.

Caecum lohri — Lightfoot, 1993a: 21, fig. 11.

Material examined. In addition to the type material the following lots were examined. NHMLAC: LACM 1935 - 170.15, Port Utria, Choco Dept., Colombia, 24 m, 2 sh; LACM 1938 - 25.17, Port San Jose, Escuintla Dept., Guatemala, 37 m, 1 sh; LACM 1934 - 126.14, Secas Islands, Chiriqui Prov., Panama, 1 m, 1 sh; LACM 1965 - 21.73, Otoque Island, Panama Prov., Panama Bay, Panama, 9–37 m, 85 sh; LACM 1965 - 25.61, Taboga Island, Panama Prov., Panama Bay, Panama, 9–37 m, 25 sh; LACM 1965 - 22.42, Tortola Island, Panama Bay, Panama, 18–37 m, 1 sh; LACM 1972 - 54.60, Herradura Bay, Puntarenas Prov., Costa Rica, 37 m, 7 sh; LACM 1972 - 53.38, Herradura Bay, Puntarenas Prov., Costa Rica, 21 m, 1 sh; LACM 1972 - 64.23, Cano Island, Puntarenas Prov., Costa Rica, 13 m, 10 sh; LACM 1935 - 122.22, Salinas Bay, Guanacaste Prov., Costa Rica, 10 m, 38 sh; LACM 1972 - 19.52, El Jobo, Salinas Bay, Guanacaste Prov., Costa Rica, 2–6 m, 70 sh; LACM 1967 - 70.31, Magdalena Island, Magdalena Bay, Baja California Sur, Mexico, 8–10 m, 4 sh; LACM 1967 - 71.11, Magdalena Island, Magdalena Bay, Baja California Sur, Mexico, 8–10 m, 1 sh; LACM 1936 - 126.10, Magdalena Bay, Baja California Sur, Mexico, 31 m, 2 sh; LACM 1965 - 16.101, Banderas Bay, Jalisco, Mexico, 18–27 m, 1 sh; LACM 1967 - 15.22, Banderas Bay, Jalisco, Mexico, 9–20 m, 1 sh; LACM 1937 - 212.1, San Pedro Nolasco Island, Sonora, Mexico, 15 m, 1 sh; LACM 1971 - 17.22, Arroyo Conejo, Baja California Sur, Mexico, 25 m, 1 sh; LACM 1960 - 20.15, 40 miles S of Mazatlan, Sinaloa, Mexico, 31–36 m, 6 sh. SBMNH: SBMNH 621422, Isla Smith, NW, Baja California [Norte], Mexico, 120–183 m, 4 sh; SBMNH 619711, Playa Tamarindo, Guanacaste, Costa Rica, 6–15 m, 12 sh; SBMNH 619704, Playas del Coco Islands, east side, Guanacaste, Costa Rica, 20–30 m, 2 sh; SBMNH 620526, Bahia Cuastecomate, Jalisco, Mexico, 12–30 m, 8 sh; SBMNH 110187, Acapulco, Guerrero, Mexico, 11–18 m, 5 sh; SBMNH 619705, Balboa, Panama Prov., Panama, 3 sh; SBMNH 619706, Balboa, Panama Prov., Panama, 2 sh; SBMNH 127126, Chacala, Nayarit, Mexico, 3 m, 3 sh; SBMNH 619708, Isla Jaltemba, Nayarit, Mexico, 10–25 m, 30 sh; SBMNH 128457, Bahia Salinas, Baja California Sur, Mexico, 5–9 m, 3 sh; SBMNH 619709, Bahia Ballena, Puntarenas, Costa Rica, 13–15 m, 1 sh; SBMNH 619718, Balboa, Panama Prov., Panama, 2 sh; SBMNH 619905, Bahia Jaltemba, Nayarit, Mexico, 13–20 m, 50 sh; SBMNH 620695, Golfo de Tehuantepec, Oaxaca, Mexico, 45–63 m, 1 sh; SBMNH 620696, Isla Perico, Panama Prov., Panama, intertidal, 1 sh; SBMNH 620803, Bahia Tenacatita, Cabo Tamarino, Jalisco, Mexico, 8–10 m, 1 sh; SBMNH 620804, La Cruz de Huanacaxtle, Nayarit, Mexico, 9–13 m, 2 sh; SBMNH 620809, Mazatlan, Mazatlan, Sinaloa, Mexico, intertidal, 1 sh; SBMNH 621370, Playa Kobbe, Panama Prov., Panama, 1 sh; SBMNH 621506, Bahia de Salinas, Guanacaste, Costa Rica, 10–30 m, 4 sh; SBMNH 622324, Isla Taboga, Panama Prov., Panama, 15 sh; SBMNH 622494, La Cruz de Huanacaxtle, Nayarit, Mexico, intertidal, 1 sh. BCD: Navidad Bar, Colima, Mexico, 17–30 m, 7 sh.

Original diagnosis. “Testa (quoad genus) maxima, solida, arcuata, grisea; annulis plurimis (L–LV) planatis, ad apicem latioribus, cincta; apertura haud tumente, parum declivi, leviter contracta; septo parvo, submamillato, mucronato, mucrone dextrorsum sito; margine laterali primum convexo dein concavo; operculo?…” de Folin (1867a: 44).

Description. Protoconch unknown. Teleoconch I short, sculptured with fine longitudinal striae (Fig. 73B), transition to teleoconch II marked by change in sculpture (Fig. 73A). Teleoconch II about same length as teleoconch I, sculptured with stronger longitudinal striae, transition to teleoconch III marked by axial incised line or very slight constriction (Figs. 73A, D). Teleoconch III sculptured with short, dense longitudinal striae that alternate in strength (Fig. 73E), transition to teleoconch IV marked by change in sculpture (Figs. 73D, H). Teleoconch IV with well-developed, tightly spaced, flat annuli (Fig. 73F), transition to teleoconch V marked by suture (Fig. 74A). Teleoconch V with identical characters as previous stage (Fig. 73J), transition to teleoconch VI marked by slight constriction (Figs. 73 G–L). Teleoconch VI (last growth stage) large for genus [Tol 4.09–4.27 mm], tubular, thick, robust, moderately and regularly arched [Larc: 1.43–1.59 mm; Arc: 0.38–0.40 mm], subcylindrical with increase in diameter from posterior to aperture, white (Figs. 72 A–B, 73L). Axial sculpture of numerous, quadrangular (flattened at top) closely arranged and regularly spaced annuli (Figs. 73 K–L). Axial interspaces narrower than annuli (Fig. 73K). Surface sculptured with numerous, dense striae on annuli and interspaces (Fig. 73K). Posterior [Dpe: 0.65–0.74 mm] with thick edge, rounded to squared shoulder (Fig. 72C). Septum mucronate, somewhat inflated (Fig. 72C). Mucro wedge shaped, pronounced, positioned on dorsal margin (Figs. 72 A–C). Aperture [Da: 0.90–0.97 mm] thick (Fig. 72C). No varix. Lip smooth, with deflected peristome (Fig. 72C). Periostracum thin to obsolete, yellowish (Fig. 72A). Operculum thin, light brown; exterior surface with 7–9 concentric rings (Figs. 72 D–E). Conceptual reconstruction of growth stages shown in Fig. 74A.

Distribution and Habitat. From Magdalena Bay, Baja California, Mexico to Panama Bay, Panama, including the Gulf of California. Intertidal to 180 m. Common on sand and rubble substrates.

Remarks. The width of the ribs on Caecum superbum is quite variable even within a single specimen. It also tends to retain teleoconch stages V and VI attached, and there is a slight reduction in diameter at the transition (Figs. 73G, L). The periostracum when present is thin and easily rubbed off.

Strong & Hertlein (1939) overlooked Caecum superbum when describing C. lohri from the same locality. Although the type material of C. superbum (MNHN-IM-2000-4584, Fig. 72F) is in poor condition, the figured specimen provides enough detail to confirm that C. lohri (paratype, LACM 1714, Fig. 72G) is a junior synonym. Kisch (1959a), also suggested that C. occultum was a subadult of C. superbum. However, the sculpture and growth morphology does not support that position.