Caecum lightfootanum, Raines, 2020
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publication ID |
https://doi.org/ 10.11646/zootaxa.4827.1.1 |
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publication LSID |
lsid:zoobank.org:pub:2CE528C2-DE07-4155-B37D-BE2C342A3901 |
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DOI |
https://doi.org/10.5281/zenodo.4453332 |
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persistent identifier |
https://treatment.plazi.org/id/03A3DF49-FF9F-FFFE-FF44-FB6EFD713A7A |
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treatment provided by |
Plazi |
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scientific name |
Caecum lightfootanum |
| status |
sp. nov. |
Caecum lightfootanum View in CoL species novum
Figures 108 View FIGURE 108 A–F, 109A–G, 110A–B, 126J
Type material. Holotype: SBMNH 637734 View Materials ; paratypes: SBMNH 637735 View Materials (3 figured); SBMNH 637736 View Materials (3 unfigured).
Additional material examined. SBMNH: SBMNH 637737 View Materials , Playa Pocoma , Peru, intertidal, 30 sh ; SBMNH 100339 View Materials , San Pedro, Guayas, Ecuador, 6 sh .
Type locality. Playa Pocoma , Peru .
Diagnosis. Teleoconch subcylindrical, with increase in diameter from posterior end to aperture. Surface smooth, semi-translucent white in color. Septum mucronate, pronounced, but flattened and angled away from dorsal margin. Mucro low, heel-like, and usually covered by septum. Aperture rather ovate and oblique. No varix. Periostracum thin, smooth, translucent.
Description. Protoconch multispiral (about 2.2 whorls), planispiral, smooth ( Fig. 109A View FIGURE 109 ), transition to teleoconch I marked by well-defined apertural varix ( Fig. 109A View FIGURE 109 ). Teleoconch I short, sculptured with axial growth marks ( Fig. 109C View FIGURE 109 ), transition to teleoconch II marked by incised axial line ( Fig. 109A View FIGURE 109 ). Teleoconch II about two times length of teleoconch I, sculptured with numerous, very weak, thin growth lines ( Fig. 109E View FIGURE 109 ), transition to teleoconch III marked by incised axial line, followed by increase in diameter ( Fig. 109A View FIGURE 109 ). Teleoconch III with identical characters as previous stage, transition to teleoconch IV marked by slight incised axial line, followed by increase in diameter ( Fig. 109B View FIGURE 109 ). Teleoconch IV smooth ( Fig. 109F View FIGURE 109 ), transition to teleoconch V marked by slight incised axial line, followed by increase in diameter ( Figs. 109B View FIGURE 109 , 110A View FIGURE 110 ). Teleoconch V with identical characters as previous stage, transition to teleoconch VI marked by suture, followed by increase in diameter ( Fig. 110A View FIGURE 110 ). Teleoconch VI (last growth stage) small for genus [Tol 1.45–1.80 mm], larger than previous stage, tubular, mildly and regularly arched [Larc: 0.43–0.60 mm; Arc: 0.09–0.10 mm], with increase in diameter from posterior to aperture, semi-translucent white ( Figs. 108 View FIGURE 108 A–C). Surface smooth ( Fig. 109F View FIGURE 109 ). Posterior [Dpe: 0.35–0.44 mm] with thick edge, squared shoulder ( Fig. 108D View FIGURE 108 ). Septum mucronate, pronounced with flattened top, angled away from dorsal margin ( Fig. 108C View FIGURE 108 ). Mucro low, heel-like, positioned on dorsal margin, usually covered by septum.Aperture rather ovate [Da: 0.40–0.50 mm], oblique, slightly constricted ( Fig. 108D View FIGURE 108 ). No varix. Lip smooth ( Fig. 108D View FIGURE 108 ). Periostracum thin, smooth, translucent ( Fig. 108A View FIGURE 108 ). Operculum thin, light brown; exterior surface with 5–7 concentric rings ( Fig. 108F View FIGURE 108 ). Conceptual reconstruction of growth stages shown in Fig. 110A View FIGURE 110 .
Etymology. The species is named in honor of the late Joanne Lightfoot (1930 – 1993), for her lifelong work on Caecidae .
Distribution and Habitat. From Playa Pocoma, Peru to San Pedro, Guayas, Ecuador. Intertidal. Common on coarse sand substrates near the type locality, less so farther north.
Remarks. The apertural end of Caecum lightfootanum is rather ovate, and is especially noticeable in early stages and subadults. There is no doubt that with only casual observation C. lightfootanum could be mistaken for its most similar congener C. orcutti . However, the smoother sculpture, ovate aperture shape, and growth morphology of C. lightfootanum is quite different. Furthermore, the closest population of C. orcutti is over 4,800 km away and ocean currents do not support its dispersal or distribution to South America. There are also no fossil records that would suggest an earlier connection.
Cruz (2007) reported a species he referred to as Caecum cf. orcutti from Ecuador. However, his description is more consistent with the smoother form of C. chilense . It could also be a subadult C. lightfootanum , but the illustration is not detailed enough to make that determination.
| SBMNH |
Santa Barbara Museum of Natural History |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.