Caecum skoglundae Pizzini, Raines & Nofroni, 2007

Raines, Bret K., 2020, A Rosetta Stone for eastern Pacific Caecidae (Gastropoda: Caenogastropoda), Zootaxa 4827 (1), pp. 1-146 : 120-122

publication ID	https://doi.org/ 10.11646/zootaxa.4827.1.1
publication LSID	lsid:zoobank.org:pub:2CE528C2-DE07-4155-B37D-BE2C342A3901
DOI	https://doi.org/10.5281/zenodo.4402336
persistent identifier	https://treatment.plazi.org/id/03A3DF49-FF95-FFF8-FF44-FEF0FD6239CA
treatment provided by	Plazi
scientific name	Caecum skoglundae Pizzini, Raines & Nofroni, 2007
status

Treatment

Caecum skoglundae Pizzini, Raines & Nofroni, 2007 View in CoL

Figures 99 View FIGURE 99 A–F, 100A–G, 101A–B, 126L

Caecum skoglundae Pizzini et al. 2007: 2 View in CoL , figs. 1A–F, holotype LACM 3063 About LACM and 6 paratypes LACM 3064 About LACM , MZB 14140, MNHN-IM-2000-20869, NHMUK, Panama Bay, Panama.

Caecum View in CoL species #3— Lightfoot, 1993a: 25, fig. 18.

Material examined. In addition to the type material the following lots were examined. NHMLAC: LACM 1977 About LACM - 144.15 About LACM , Chame Point , Panama Bay, Panama Prov., Panama, 11 sh . SBMNH: SBMNH 617116 About SBMNH , Balboa , Panama Prov., Panama, 100 sh ; SBMNH 619728 About SBMNH , Bahia Audiencia , Manzanillo, Colima, Mexico, 7–13 m, 1 sh ; SBMNH 619907 About SBMNH , Balboa , Panama Prov., Panama, 30 sh ; SBMNH 619910 About SBMNH , Balboa , Panama Prov., Panama, 80 sh ; SBMNH 620562 About SBMNH , Balboa , Panama Prov., Panama, 2 sh ; SBMNH 620563 About SBMNH , Punta Chame , Panama Prov., Panama, 10 m, 3 sh ; SBMNH 622347 About SBMNH , Punta Chame , Panama Prov., Panama, 15 sh ; SBMNH 622520 About SBMNH , 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 View FIGURE 1 ). Microsculpture exclusively consisting of a very fine growth striation, visible only with very strong optical enlargement ( Fig. 1C View FIGURE 1 ). 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 View FIGURE 1 , 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 View FIGURE 1 ). 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 View FIGURE 100 ), surface smooth ( Fig. 100C View FIGURE 100 ), transition to teleoconch III marked by slight incised axial line followed by distinct change in coloration ( Fig. 100B View FIGURE 100 ). Teleoconch III surface smooth and glossy with very fine axial growth striae ( Figs. 100B, D, G View FIGURE 100 ), mucro finger-like, rounded, positioned along dorsal margin ( Figs. 100 View FIGURE 100 A–B), transition to teleoconch IV marked by slight axial constriction ( Fig. 100D View FIGURE 100 ). Teleoconch IV with identical characters as previous stage, transition to teleoconch V marked by suture ( Fig. 100E View FIGURE 100 ). 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 View FIGURE 100 ). Surface smooth and glossy with very fine axial growth striae ( Figs. 100 View FIGURE 100 F–G). Posterior [Dpe: 0.40–0.45 mm] with simple rounded shoulder ( Fig. 99E View FIGURE 99 ). Septum mucronate, slightly inflated ( Fig. 99E View FIGURE 99 ). Mucro lamelliform, rounded top, positioned centrally, oriented at an oblique angle ( Fig. 99E View FIGURE 99 ). Aperture weakly constricted [Da: 0.59–0.60 mm] ( Fig. 99C View FIGURE 99 ). No varix. Lip smooth, weak, with slightly deflected peristome ( Fig. 99C View FIGURE 99 ). Periostracum thin, smooth, yellowish brown ( Fig. 99A View FIGURE 99 ). Operculum thin, light brown; exterior surface with 5–7 concentric rings ( Fig. 99F View FIGURE 99 ). Conceptual reconstruction of growth stages shown in Fig. 101A View FIGURE 101 .

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 View FIGURE 99 ). It is often misidentified as C. reversum , but can be easily separated by its rounded blade-like mucro ( Fig. 100E View FIGURE 100 ) and smooth teleoconch.