Caecum shaskyi Raines 2020, species novum
Creators: name: Raines, Bret K.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Caecidae
Caecum
Caecum shaskyi

description: Caecum shaskyi species novum
Figures 114 A–I, 115A–E, 116A–B, 128E
Fartulum farcimen — Shasky, 1984: 27, [non Carpenter, 1857].
Type material. Holotype, SBMNH 637732; paratypes, SBMNH 637733 (4 figured).
Additional material examined. NHMLAC: LACM 1938 - 218.5, 18 miles SE of Foca Island, Piura Dept., Peru, 21 m, 2 sh. SBMNH: SBMNH 637731, Salango Island, Manabí Province, Ecuador 11–27 m, 1 sh. BCD: N. side of La Plata Island, Ecuador, 12–30 m, 1 sh.
Type locality. La Plata Island, Manabí Province, Ecuador.
Diagnosis. Teleoconch subcylindrical, with increase in diameter from posterior end to aperture. Surface smooth and glossy, yellowish-orange to orange in color. Septum mucronate, with pronounced finger-like, blunt mucro. Aperture with slight swelling and pronounced axial rings. Periostracum sculptured with dense, sinuous striae.
Description. Protoconch and teleoconchs I, II unknown. Teleoconch III surface smooth with weak axial growth lines (Fig. 115B), transition to teleoconch IV marked by slight axial constriction (Fig. 115A). Teleoconch IV surface smooth, glossy, with occasional axial growth lines (Fig. 115C), transition to teleoconch V marked by slight axial constriction (Fig. 115A). Teleoconch V with identical characters as previous stage, transition to teleoconch VI marked by axial constriction (Fig. 115D). Teleoconch VI (last growth stage) large for genus [Tol 3.41–3.60 mm], tubular, thick, robust, moderately and regularly arched [Larc: 1.22–1.41 mm; Arc: 0.30–0.35 mm], subcylindrical with increase in diameter from posterior to aperture, yellowish-orange to orange (Fig. 114B). Surface smooth, glossy (Fig. 115C). Posterior [Dpe: 0.60–0.61 mm] with thick edge, squared shoulder (Fig. 114E). Septum mucronate, deeply recessed (Fig. 114E). Mucro finger-like, conical, blunt, positioned near dorsal margin, straight to slightly curved toward dorsal margin (Fig. 114E). Aperture [Da: 0.72–0.79 mm] with slight swelling followed by rapid constriction, with 4–5 distally spaced axial rings, interspace narrowing with constriction (Figs. 114E, 115E). No varix. Lip smooth, with deflected peristome (Fig. 114E). Periostracum rather thick, with dense, sinuous striae, yellow-orange (Figs. 114A, C, F). Operculum thin, light brown; exterior surface with 5–6 concentric rings (Figs. 114 H–I). Conceptual reconstruction of growth stages shown in Fig. 116A.
Etymology. The species is named in honor of the late Donald R. Shasky (1925–2002), for his work on eastern Pacific molluscs.
Distribution and Habitat. Known from La Plata Island, Manabí Province, Ecuador to Foca Island, Piura Dept., Peru. Subtidal, 11– 30 m. Uncommon on sandy substrates.
Remarks. Caecum shaskyi cannot be mistaken for any other eastern Pacific caecid. Its robust, glossy, yelloworange teleoconch along with its blunt finger-like mucro has no contenders. While several western Atlantic species such as C. floridanum Stimpson, 1851, C. lineicinctum de Folin, 1880, and C. carolinianum Dall, 1892 also have recessed, blunt, finger-like mucros, only C. carolinianum is comparable. Both C. shaskyi and C. carolinianum have smooth, glossy teleoconchs with longitudinal striae on the periostracum. Both species are rather robust with apertural swelling. Where C. shaskyi differs from C. carolinianum is in microsculpture, size and coloration. Caecum shaskyi lacks surface microsculpture, while C. carolinianum has both axial growth lines and longitudinal striae. The only axial rings present on C. shaskyi are those on the apertural swelling. Caecum shaskyi has a yellow-orange teleoconch with an average size of 3.5 mm. Caecum carolinianum is creamy white with a larger average size teleoconch of 4.2 mm.
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 131-133, DOI: 10.11646/zootaxa.4827.1.1, http://zenodo.org/record/4402308