Caecum skoglundae Pizzini, Raines & Nofroni 2007
Creators: name: Raines, Bret K.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Caecidae
Caecum
Caecum skoglundae

description: Caecum skoglundae Pizzini, Raines & Nofroni, 2007
Figures 99 A–F, 100A–G, 101A–B, 126L
Caecum skoglundae Pizzini et al. 2007: 2, figs. 1A–F, holotype LACM 3063 and 6 paratypes LACM 3064, MZB 14140, MNHN-IM-2000-20869, NHMUK, Panama Bay, Panama.
Caecum species #3— Lightfoot, 1993a: 25, fig. 18.
Material examined. In addition to the type material the following lots were examined. NHMLAC: LACM 1977 - 144.15, Chame Point, Panama Bay, Panama Prov., Panama, 11 sh. SBMNH: SBMNH 617116, Balboa, Panama Prov., Panama, 100 sh; SBMNH 619728, Bahia Audiencia, Manzanillo, Colima, Mexico, 7–13 m, 1 sh; SBMNH 619907, Balboa, Panama Prov., Panama, 30 sh; SBMNH 619910, Balboa, Panama Prov., Panama, 80 sh; SBMNH 620562, Balboa, Panama Prov., Panama, 2 sh; SBMNH 620563, Punta Chame, Panama Prov., Panama, 10 m, 3 sh; SBMNH 622347, Punta Chame, Panama Prov., Panama, 15 sh; SBMNH 622520, Punta Chame, Panama Prov., Panama, 10 m, 1 sh.
Original diagnosis. “Shell of medium size for the genus (dimensions of the holotype-length: 2.88 mm; width min: 0.45 mm; width max: 0.6 mm), less arched, smooth and glossy. The tube has a lesser diameter in its apical part, and has therefore a subcylindrical silhouette; the diameter gradually increases reaching its maximum near the aperture, then it tends to contract slowly, thus resulting in a simple, perfectly rounded aperture (Fig. 1A). Microsculpture exclusively consisting of a very fine growth striation, visible only with very strong optical enlargement (Fig. 1C). Septum slightly inflated, less protruded over the cutting plane, without any visible trace of a temporary septum (Pizzini et al. 1998). The mucro shows a particular shape, nearly lamelliform, unique in its kind, with a rounded top (Figs. 1B, D–F). While handling the tube with its concave side towards the observer and the mucro at the top, it is oriented at an oblique angle toward the right side with a range from about 0 o to 13 o (Figs. 1B, E). Color evenly whitish. Periostracum thin and yellowish brown. Operculum and soft parts unknown.” Pizzini et al. (2007: 2).
Description. Protoconch unknown. Teleoconchs I and II without obvious separation (Fig. 100A), surface smooth (Fig. 100C), transition to teleoconch III marked by slight incised axial line followed by distinct change in coloration (Fig. 100B). Teleoconch III surface smooth and glossy with very fine axial growth striae (Figs. 100B, D, G), mucro finger-like, rounded, positioned along dorsal margin (Figs. 100 A–B), transition to teleoconch IV marked by slight axial constriction (Fig. 100D). Teleoconch IV with identical characters as previous stage, transition to teleoconch V marked by suture (Fig. 100E). Teleoconch V (last growth stage) large for genus [Tol 2.73–3.15 mm], tubular, mildly to moderately and regularly arched [Larc: 1.01–1.21 mm; Arc: 0.16–0.21 mm], subcylindrical with slight increase in diameter from posterior to aperture, semi-translucent to opaque white (Fig. 100B). Surface smooth and glossy with very fine axial growth striae (Figs. 100 F–G). Posterior [Dpe: 0.40–0.45 mm] with simple rounded shoulder (Fig. 99E). Septum mucronate, slightly inflated (Fig. 99E). Mucro lamelliform, rounded top, positioned centrally, oriented at an oblique angle (Fig. 99E). Aperture weakly constricted [Da: 0.59–0.60 mm] (Fig. 99C). No varix. Lip smooth, weak, with slightly deflected peristome (Fig. 99C). Periostracum thin, smooth, yellowish brown (Fig. 99A). Operculum thin, light brown; exterior surface with 5–7 concentric rings (Fig. 99F). Conceptual reconstruction of growth stages shown in Fig. 101A.
Distribution and Habitat. From Jalisco, Mexico to Panama Bay. Panama. Intertidal to 60 m. Fairly common subtidally on sandy substrates.
Remarks. The type material of Caecum skoglundae is comprised of two late subadults and two adult specimens (holotype LACM 3063, Fig. 99D). It is often misidentified as C. reversum, but can be easily separated by its rounded blade-like mucro (Fig. 100E) and smooth teleoconch.
description: Published as part of Raines, Bret K., 2020, A Rosetta Stone for eastern Pacific Caecidae (Gastropoda: Caenogastropoda), pp. 1-146 in Zootaxa 4827 (1) on pages 120-122, DOI: 10.11646/zootaxa.4827.1.1, http://zenodo.org/record/4402308