Caecum limnetes Long, 1972

Raines, Bret K., 2020, A Rosetta Stone for eastern Pacific Caecidae (Gastropoda: Caenogastropoda), Zootaxa 4827 (1), pp. 1-146 : 112-115

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.4457827

persistent identifier

https://treatment.plazi.org/id/03A3DF49-FF8D-FFF3-FF44-FB6EFAB638CE

treatment provided by

Plazi

scientific name

Caecum limnetes Long, 1972
status

 

Caecum limnetes Long, 1972 View in CoL

Figures 90 View FIGURE 90 A–G, 91A–I, 92A–B, 127N

Caecum (Micranellum) limnetes Long, 1972: 291 , figs. 1–2, holotype CAS 088040 About CAS and 6 paratypes CAS 088041 About CAS , AMNH 162063 About AMNH , SDMNH 55551 , FMNH 172334 About FMNH , NHMUK 197012 About NHMUK , LACM 1446 About LACM , Estuaries of Bahia de Adair , Sonora, Mexico.

Caecum (Micranellum) limnetes View in CoL — Skoglund, 1992: 28.

Brochina limnetes — Lightfoot, 1993b: 81, fig. 28.

Fartulum limnetes — Hertz et al. 1994: 93, figs. 7a–c.

Material examined. In addition to the type material the following lots were examined. NHMLAC: LACM 1961 About LACM - 2.12 About LACM , San Carlos Bay , Guaymas, Sonora, Mexico, intertidal, 2 sh ; LACM 1968 About LACM - 14.31 About LACM , Estero Soldado, NW of Guaymas , Sonora, Mexico, intertidal to 3 m, 110 sh ; LACM 1968 About LACM - 12.10 About LACM , Guasimas Bay , Guaymas, Sonora, Mexico, intertidal, 32 sh ; LACM 1973 About LACM - 5.51 About LACM , Estero Soldado, NW of Guaymas , Sonora, Mexico, intertidal, 75 sh ; LACM 1969 About LACM - 21.25 About LACM , El Muerto Island , Puertecitos, Baja California, Mexico, 15–27 m, 1 sh ; LACM 1965 About LACM - 34.53 About LACM , Puertecitos, Baja California, Mexico, intertidal to 10 m, 3 sh . SBMNH: SBMNH 620189 About SBMNH , Estero Morua , Sonora, Mexico, intertidal, 1 sh ; SBMNH 114904 About SBMNH , Bahia La Choya , Sonora, Mexico, intertidal, 30 sh ; SBMNH 118949 About SBMNH , Empalme, Empalme, Sonora, Mexico, intertidal, 2 sh ; SBMNH 114906 About SBMNH , Bahia La Choya , Sonora, Mexico, intertidal, 3 sh ; SBMNH 619738 About SBMNH , Bahia La Choya , Sonora, Mexico, 8 sh ; SBMNH 619784 About SBMNH , Estero Morua, Sonora, Mexico, intertidal, 4 sh ; SBMNH 619785 About SBMNH , Estero Morua, Sonora, Mexico, 10–25 m, 5 sh ; SBMNH 129779 About SBMNH , Agua de Chale , Baja California [Norte], Mexico, intertidal, 5 sh ; SBMNH 126596 About SBMNH , Playa Las Almejas, San Felipe, Baja California [ Norte ], Mexico, intertidal, 2 sh ; SBMNH 118496 About SBMNH , Playa Las Almejas, San Felipe, Baja California [ Norte ], Mexico, intertidal, 20 sh ; SBMNH 620165 About SBMNH , Puerto Penasco, Sonora, Mexico, 1 sh ; SBMNH 620591 About SBMNH , Santa Clara, Sonora, Mexico, intertidal, 10 sh ; SBMNH 116670 About SBMNH , Miramar, Sonora, Mexico, intertidal, 10 sh ; SBMNH 621308 About SBMNH , Estero Morua, Sonora, Mexico, intertidal, 12 sh ; SBMNH 621410 About SBMNH , Puerto Lobos, Sonora, Mexico, intertidal, 1 sh ; SBMNH 621502 About SBMNH , Estero Morua, Sonora, Mexico, intertidal, 25 sh ; SBMNH 116243 About SBMNH , Bahia Tortugas, Baja California Sur, Mexico, 5 m, 1 sh. BCD: Marua Estero , SE of Penasco Point, Sonora, Mexico, intertidal, 26 sh; Pelican Pt. , Cholla Bay , Sonora, Mexico, intertidal, 4 sh; San Felipe , Baja California, Mexico, intertidal, 8 sh; 25 miles S of Guaymas, Sonora, Mexico, intertidal, 1 sh; San Carlos Bay, Guaymas, Sonora, Mexico, intertidal, 9 sh .

Original diagnosis. “Teleoconch white, semitransparent, arcuation and diameter increasing only slightly toward the anterior. Annuli variable, consisting of about 40 or more raised, closely appressed rings, separated by fine incised grooves. Septum approximately hemispherical but with a right dorsal irregularity or protuberance rising in a straight line, apically, ending at the level of maximum elevation of mamillate portion of septum. Aperture never constricted. Operculum circular, horny, slightly concave, sinistral; composed of 6 to 8 rings plus a nucleus about 1/3 the total diameter of the operculum. In younger animals, diameter as well as degree of distinction between annuli increases with growth somewhat more than in older animals. Body of animal white, semitransparent, with concentrations of black pigment granules on head, beginning just dorsal to eyes and extending dorsally to edge of mantle. Mantle margin and dorsal surface of foot, beneath operculum, also with black pigment granules. Bolsters of radula black, visible through body surface. Both cephalic tentacles blunt, each with about 5 long stiff sensory cilia on tips. Tentacles with ciliated tracts along length. On right tentacle, dorsal tracts beats in a proximal direction while ventral tract beats in a distal direction. On left tentacle, the directions of beat for the tracts are reversed. Left tentacle sometimes with an undulated left lateral margin along proximal 1/2 of length.” Long (1972: 291).

Description. Protoconch unknown. No clear separation observed between teleoconchs I and II ( Fig. 91A View FIGURE 91 ), surface sculptured with rudimentary axial ribs covered by weak striae ( Fig. 91B View FIGURE 91 ), transition to teleoconch III marked by change in sculpture ( Fig. 91A View FIGURE 91 ). Teleoconch III sculptured with low rounded axial ribs covered by longitudinal striae ( Fig. 91C View FIGURE 91 ), transition to teleoconch IV marked by slight axial incised line ( Fig. 91A View FIGURE 91 ). Teleoconch IV sculptured with rounded axial ribs covered by numerous, overlapping, longitudinal striae ( Fig. 91E View FIGURE 91 ), transition to teleoconch V marked by rapid increase in diameter ( Fig. 91C View FIGURE 91 ). Teleoconch V sculptured with low, flattened axial ribs covered by dense, conspicuous, longitudinal striae ( Fig. 91F View FIGURE 91 ), transition to teleoconch VI marked by suture ( Fig. 91H View FIGURE 91 ). Teleoconch VI (last growth stage) small for genus [Tol 1.55–2.10 mm], larger than previous stage, tubular, mildly and regularly arched [Larc: 0.51–0.66 mm; Arc: 0.10–0.14 mm], subcylindrical with increase in diameter from posterior to aperture, semi-translucent to opaque white ( Figs. 90 View FIGURE 90 A–C). Axial sculpture of 30–40 low, wide ribs closely arranged and regularly spaced ( Fig. 91I View FIGURE 91 ). Axial interspaces shallow, narrower than ribs to nearly obsolete ( Fig. 91F View FIGURE 91 ). Surface sculptured with dense, conspicuous, longitudinal striae on axial ribs and interspaces ( Fig. 91F View FIGURE 91 ). Posterior [Dpe: 0.32–0.38 mm] with thin edge, squared to rounded shoulder ( Fig. 90D View FIGURE 90 ). Septum mucronate, pronounced ( Fig. 90 D View FIGURE 90 ). Mucro blunt, rather wedge-shaped, positioned on dorsal margin ( Fig. 90D View FIGURE 90 ). Aperture [Da: 0.38–0.50 mm] thick, simple ( Fig. 90D View FIGURE 90 ). No varix. Lip smooth, weakly developed, with slightly deflected peristome ( Fig. 90D View FIGURE 90 ). Periostracum thin, smooth, light brown ( Fig. 90A View FIGURE 90 ). Operculum thin, light brown; exterior surface with 6–8 concentric rings ( Figs. 90 View FIGURE 90 E–F). Conceptual reconstruction of growth stages shown in Fig. 92A View FIGURE 92 .

Distribution and Habitat. Restricted to the northern Gulf of California, from Cholla Bay to Guaymas, Mexico. Intertidal to 27 m. Common in estuaries on sand and mud substrates.

Remarks. The paratype at NHMLAC is a partial adult specimen (LACM 1446, Fig. 90G View FIGURE 90 ). Although the holotype (CAS 088040) was available for examination it was not figured, because it is broken into five pieces.

SBMNH

Santa Barbara Museum of Natural History

Kingdom

Animalia

Phylum

Mollusca

Class

Gastropoda

Order

Littorinimorpha

Family

Caecidae

Genus

Caecum

Loc

Caecum limnetes Long, 1972

Raines, Bret K. 2020
2020
Loc

Fartulum limnetes

Hertz, C. M. & Myers, B. W. & Gemmell, J. 1994: 93
1994
Loc

Brochina limnetes

Lightfoot, J. 1993: 81
1993
Loc

Caecum (Micranellum) limnetes

Skoglund, C. 1992: 28
1992
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