Caecum magellanicum (di Geronimo, Privitera & Valdovinos, 1995 )

Raines, Bret K., 2020, A Rosetta Stone for eastern Pacific Caecidae (Gastropoda: Caenogastropoda), Zootaxa 4827 (1), pp. 1-146 : 118-120

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.4402326

persistent identifier

https://treatment.plazi.org/id/03A3DF49-FF97-FFF6-FF44-FE0CFAB138CE

treatment provided by

Plazi

scientific name

Caecum magellanicum (di Geronimo, Privitera & Valdovinos, 1995 )
status

 

Caecum magellanicum (di Geronimo, Privitera & Valdovinos, 1995) View in CoL

Figures 96 View FIGURE 96 A–E, 97A–F, 98A–B, 126F

Fartulum magellanicum di Geronimo et al. 1995: 114 View in CoL , figs. 1–5, holotype IPOP M1.8.8.95, Cabo Deseado , Strait of Magellan, Chile.

Fartulum magellanicum View in CoL — Linse 2002: 85, pl. VII, figs. 54–56; Mattano & Zelaya 2013: 170.

Material examined. In addition to the type material the following lots were examined. NHMLAC: LACM 1973 About LACM - 75.4 About LACM , Westhoff Island , Los Lagos Prov., Chile, 23 m , 8 sh; LACM 1973 About LACM - 74.5 About LACM , Darwin Channel , Aysen, Prov., Chile, 8 m , 5 sh. FS: Stanley , near Yorke Point, East Falkland, Falkland Islands, 9 m.

Original diagnosis. “Teleoconch cylindrical, moderately curved, vitreous or lightly opaque in less fresh shells. Under the optical microscope, surface seems entirely smooth, with less distinct annular growth striae. Using the SEM these striae are rather thick, irregularly distanced and little engraved. Apertural end circular with a thin lip folded outwards. Septum well developed, oblique angled to the back of the shell. Maximum diameter, at aperture, is constant to middle of the teleoconch while the posterior diameter is always smaller. Operculum and soft parts not known.” di Geronimo et al. (1995: 114).

Description. Protoconch paucispiral (about 1.4 whorls), planispiral, smooth ( Fig. 97A View FIGURE 97 ), transition to teleoconch I marked by very slight axial line ( Fig. 97A View FIGURE 97 ). Teleoconchs I and II short, no sculpture observed, transition to teleoconch III marked by very slight axial line ( Fig. 97A View FIGURE 97 ). Teleoconch III sculpture smooth with occasional axial growth striae ( Fig. 97C View FIGURE 97 ), transition to teleoconch IV marked by incised axial line ( Fig. 97B View FIGURE 97 ). Teleoconch IV with identical characters as previous stage, transition to teleoconch V marked by incised axial line ( Fig. 97B View FIGURE 97 ). Teleoconch V (last growth stage) small for genus [Tol 1.26–1.45 mm], tubular, thin, very narrow, mildly to moderately and regularly arched [Larc: 0.45–0.55 mm; Arc: 0.13–0.14 mm], subcylindrical, semi-translucent to opaque white ( Figs. 96 View FIGURE 96 A–B). Surface smooth with numerous weak annuli ( Fig. 97E View FIGURE 97 ). Posterior [Dpe: 0.20–0.22 mm] with squared shoulder ( Fig. 97D View FIGURE 97 ). Septum mucronate ( Fig. 97D View FIGURE 97 ). Mucro heel-like, positioned along dorsal margin, usually covered by septum in adult stage ( Fig. 97D View FIGURE 97 ). Aperture [Da: 0.24–0.25 mm] thin ( Fig. 97F View FIGURE 97 ). No varix. Lip smooth, with deflected peristome ( Fig. 97F View FIGURE 97 ). Periostracum not observed. Operculum thin, light brown; exterior surface with 5–6 concentric rings ( Fig. 97D View FIGURE 97 ). Conceptual reconstruction of growth stages shown in Fig. 98A View FIGURE 98 .

Distribution and Habitat. From Westhoff Island, Chile to Stanley, East Falkland, Falkland Islands. Subtidal, 8– 245 m. Uncommon on organogenic sand substrates.

Remarks. The type material of Caecum magellanicum is comprised of three late subadult stages and nine adult specimens (holotype IPOP M1.8.8.95, Fig. 96E View FIGURE 96 ). Caecum magellanicum is the southern-most caecid known in the eastern Pacific and has also been found in the southern Atlantic.

Despite repeated attempts to obtain better images, the figures shown of the type material ( Figs. 96E View FIGURE 96 ; 97A View FIGURE 97 ) are from di Geronimo et al. (1995). Hence it was not possible to observe the sculpture of teleoconchs I and II.

Kingdom

Animalia

Phylum

Mollusca

Class

Gastropoda

SubClass

Caenogastropoda

Order

Littorinimorpha

Family

Caecidae

SubFamily

Caecinae

Genus

Caecum

Loc

Caecum magellanicum (di Geronimo, Privitera & Valdovinos, 1995 )

Raines, Bret K. 2020
2020
Loc

Fartulum magellanicum

Mattano, N. & Zelaya, D. G. 2013: 170
Linse, K. 2002: 85
2002
Loc

Fartulum magellanicum di Geronimo et al. 1995: 114

Geronimo, I. di & Privitera, S. & Valdovinos, C. 1995: 114
1995
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