Caecum quadratum Carpenter, 1857

Raines, Bret K., 2020, A Rosetta Stone for eastern Pacific Caecidae (Gastropoda: Caenogastropoda), Zootaxa 4827 (1), pp. 1-146 : 57-61

Caecum quadratum Carpenter, 1857

Figures 39 A–E, 40A–I, 41A–B, 127K

Caecum (Anellum) quadratum Carpenter, 1857: 322 , 7 syntypes NHMUK 1857.6 .4.1529, Mazatlan.

Caecum (Anellum) compactum Carpenter, 1857: 322 , 7 syntypes NHMUK 1857.6 .4.1530, Mazatlan.

Caecum (Anellum) quadratum — Carpenter, 1858: 428.

Caecum dalli Bartsch, 1920: 568 , holotype USNM 340724 , San Diego , California.

Caecum grippi Bartsch, 1920: 568 , holotype USNM 206961 , San Diego , California.

Caecum licalum Bartsch, 1920: 568 , holotype USNM 340725 , San Diego , California.

Caecum diegense Bartsch, 1920: 568 , holotype USNM 340726 , San Diego , California. (Lost)

Caecum quadratum — Carpenter, 1860: 32; Tryon, 1886: 217, pl. 67, fig. 67; Palmer, 1951: 43; Brann, 1966: pl. 34, fig. 370; Keen, 1968: 419, fig. 79; Keen, 1971: 397; Hertz, 1979a: 2; Skoglund, 1992: 28; Lightfoot, 1993a: 15, fig. 2; Raines, 2019: 98, figs. 1C–D, [non Shasky, 1984: 27; non Kaiser, 1997: 29; non Finet et al. 2016: 28].

Caecum compactum — Tryon, 1886: 217, pl. 67, fig. 68; Keen, 1968: 418, fig. 76; Keen, 1971: 397; Lightfoot, 1993a: 16, fig 3.

Caecum dalli —Abbott, 1974: 91, fig. 872; McLean, 1978: 29, fig. 14.2.

Material examined. In addition to the type material the following lots were examined. NHMLAC: LACM 1963 - 42.37 , Banda Point, Baja California, Mexico, 3–10 m, 30 sh ; LACM 1963 - 11.81 , Mazatlan, Sinaloa, Mexico, intertidal to 6 m, 1 sh ; LACM 1934 - 257.10 , Braithwaite Bay , Socorro Island, Revillagigedo Islands, Mexico, 25 m, 1 sh ; LACM 1940 - 64.33 , San Carlos Bay , Guaymas, Sonora, Mexico, intertidal, 1 sh ; LACM 1973 - 6.48 , Juan Venado Island , Guaymas, Sonora, Mexico, intertidal, 5 sh ; LACM 1967 - 44.26 , Banda Point, Baja California, Mexico, 3–10 m, 15 sh ; LACM 1967 - 47.43 , Banda Point, Baja California, Mexico, 20–24 m, 100+ sh ; LACM 1967 - 48.16 , Banda Point, Baja California, Mexico, 13 m, 75 sh ; LACM 1968 - 14.29 , Estero Soldado, NW of Guaymas , Sonora, Mexico, intertidal to 3 m, 33 sh ; LACM 1967 - 1.51 , Santo Tomas Port, Baja California, Mexico, 3–8 m, 500+ sh ; LACM 1946 - 12.9 , Barra de Navidad , Jalisco, Mexico, intertidal, 1 sh ; LACM 1968 - 45.54 , Cuastecomate Bay , Jalisco, Mexico, 18–37 m, 3 sh ; LACM 1968 - 41.90 , Cuastecomate Bay , Jalisco, Mexico, 5–31 m, 2 sh ; LACM 1940 - 42.10 , San Felipe Bay , Baja California, Mexico, 5 m, 2 sh ; LACM 1967 - 60.40 , San Martin Island , Baja California, Mexico, 18 m, 100+ sh ; LACM 1969 - 14.30 , San Nicholas Island , California, 8–13 m, 24 sh ; LACM 1969 - 29.57 , San Clemente Island , Ventura Co., California, 20–27 m, 75 sh ; LACM 1969 - 31.54 , Santa Catalina Island , Los Angeles Co., California, 10–24 m, 75 sh ; LACM 1969 - 32.55 , Santa Cruz Island , Santa Barbara Co., California, 13–20 m, 100+ sh ; LACM 1971 - 98.36 , Coronado Islands , California, 22–24 m, 100+ sh ; LACM 1960 - 24.104 , off N end of San Jose Creek Beach, Monterey Co., California, 13–42 m, 80 sh ; LACM 1968 - 199.8 , off N end of Monastery Beach, Monterey Co., California , 13–17 m, 20 sh ; LACM 1968 - 37.37 , Avila Beach, San Luis Obispo Co., California , intertidal, 30 sh ; LACM 1972 - 97.37 , Santa Barbara Island , Santa Barbara Co., California, 10–23 m, 100+ sh ; LACM 1972 - 98.25 , Pt. Mugu, Ventura Co., California , 3–6 m, 8 sh ; LACM 1973 - 11.40 , Santa Cruz Island , Santa Barbara Co., California, 11–13 m, 100+ sh ; LACM 1936 - 41.2 , Coronado Islands , California, 7–13 m, 100+ sh ; LACM 1974 - 80.15 , Crescent Bay , Laguna Beach, Orange Co., California, 10 m, 75 sh ; LACM 1965 - 18.17 , Farnsworth Bank, Santa Catalina Island , California, 28–40 m, 20 sh ; LACM 1960 - 32.65 , Ensenada Carrizal, W of Guaymas , Sonora, Mexico, intertidal– 30 m, 4 sh ; LACM 1977 - 107.15 , Diablo Cove, San Luis Obispo Co., California , 9–12 m, 100+ sh ; LACM 1973 - 3.16 , Coyote Bay , Baja California Sur, Mexico, 9–22 m, 4 sh ; LACM 1965 - 12.45 , Maria Cleofas Island , Tres Marias Islands, Mexico, 5–10 m, 30 sh ; LACM 1968 - 18.19 , Banderas Bay , Jalisco, Mexico, intertidal, 10 sh ; LACM 1964 - 36.53 , San Carlos Bay , Guaymas, Sonora, Mexico, 3–6 m, 7 sh ; LACM 1962 - 22.36 , Cholla Bay , Port Penasco, Sonora, Mexico, intertidal, 23 sh ; LACM 1965 - 34.52 , Puertecitos, Baja California, Mexico, intertidal to 10 m, 66 sh ; LACM 1973 - 9.31 , Santa Rosa Island , Santa Barbara Co., California, 11–13 m, 100+ sh ; LACM 1980 - 67.14 , Anacapa Island , Ventura Co., California, 11–12 m, 40 sh ; LACM 1969 - 35.33 , Tanner Bank, Los Angeles Co., California , 33–40 m, 75 sh ; LACM 1982 - 59.55 , San Miguel Island , Santa Barbara Co., California, 9–14 m, 100+ sh ; LACM 1982 - 59.32 , San Miguel Island , Santa Barbara Co., California, 23–27 m, 100+ sh ; LACM 1972 - 101.36 , San Nicolas Island , Ventura Co., California, 23 m, 50 sh ; LACM 1972 - 100.32 , San Nicolas Island , Ventura Co., California, 13 m, 100+ sh ; LACM 1972 - 99.40 , San Nicolas Island , Ventura Co., California, 23–33 m, 75 sh ; LACM 1966 - 12.51 , Cape San Lucas, Baja California Sur, Mexico, 8–35 m, 1 sh ; LACM 1966 - 16.35 , El Tule, Canelo Bay , Baja California Sur, Mexico, intertidal, 14 sh ; LACM 1965 - 82.7 , Cerralvo Island , Baja California Sur, Mexico, 9 m, 1 sh ; LACM 1966 - 19.66 , Pulmo Bay , Baja California Sur, Mexico, 2–7 m, 34 sh ; LACM 1937 - 181.5 , Carmen Island , Baja California Sur, Mexico, 15 m, 33 sh . SBMNH: SBMNH 214940 , Isla Maria Madre, SE Cabo Alto, Nayarit, Mexico, 15–20 m, 2 sh ; SBMNH 452454 , Playa Tamarindo, Guanacaste, Costa Rica, 5–15 m, 1 sh ; SBMNH 620161 , Punta la Gringa , Bahia de los Angeles, Baja California [Norte], Mexico, 20–40 m, 12 sh ; SBMNH 620477 , Bahia Ballena , Puntarenas, Costa Rica, 10–25 m, 2 sh ; SBMNH 141299 , Forney’s Point, Santa Barbara County, California, USA, intertidal, 26 sh ; SBMNH 622336 , Isla Salango, N side, Manabi, Ecuador, 8 m, 1 sh ; SBMNH 620160 , Cabo Tepoca, Sonora, Mexico, 20–30 m, 25 sh ; SBMNH 215008 , Point Loma, San Diego County, California, USA, 33 m, 3 sh ; SBMNH 622325 , Isla Venado, Panama Prov., Panama, intertidal, 5 sh ; SBMNH 349188 , Forney’s Cove, Santa Barbara County, California, USA, 8 m, 5 sh ; SBMNH 349193 , Lions Rock, San Luis Obispo County, California, USA, 28 m, 2 sh ; SBMNH 149033 , Punta Ancon, Guayas, Ecuador, intertidal, 250 sh ; SBMNH 620584 , Bahia Cuastecomate , Jalisco, Mexico, 10–15 m, 4 sh ; SBMNH 214945 , Punta Penasco, Sonora, Mexico, intertidal, 5 sh ; SBMNH 214992 , Bahia El Dorado , Manzanillo, Colima, Mexico, 10–25 m, 11 sh ; SBMNH 215017 , Isla Candelero, Sonora, Mexico, 22 m, 50 sh ; SBMNH 132344 , Bahia de los Angeles, Baja California [Norte], Mexico, 11–31 m, 1 sh ; SBMNH 132337 , Bahia de los Angeles, Baja California [Norte], Mexico, 11–31 m, 2 sh ; SBMNH 133574 , Ship Rock, Los Angeles County, California, USA, 21 m, 4 sh ; SBMNH 133573 , Ship Rock, Los Angeles County, California, USA, 21 m, 27 sh ; SBMNH 133395 , Santa Barbara Island , Santa Barbara County, California, USA, 8 sh ; SBMNH 133394 , Santa Barbara Island , Santa Barbara County, California, USA, 7 sh ; SBMNH 119736 , Punta Colorado, Sonora, Mexico, intertidal, 45 sh ; SBMNH 119737 , Punta Colorado, Sonora, Mexico, intertidal, 35 sh ; SBMNH 101290 , Del Monte, Monterey County, California, USA, 22 m, 1 sh ; SBMNH 215025 , Del Monte, Monterey County, California, USA, 22 m, 12 sh ; SBMNH 215024 , Coronado, San Diego County, California, USA, 27 m, 21 sh ; SBMNH 214994 , Playa Cochorit, Sonora, Mexico, intertidal, 1 sh ; SBMNH 102422 , Point Vicente, Los Angeles County, California, USA, 22 m, 7 sh ; SBMNH 214999 , Laguna Beach, Orange County, California, USA, 12 sh ; SBMNH 103090 , Avalon, Los Angeles County, California, USA, 72 m, 2 sh ; SBMNH 101984 , San Diego, San Diego County, California, USA, 1 sh ; SBMNH 215020 , Playa Cochorit, Sonora, Mexico, intertidal, 1 sh ; SBMNH 452379 , Isla San Jorge [ Bird Island ], Sonora, Mexico, 10–25 m, 1 sh ; SBMNH 452380 , El Submarino, Sonora, Mexico, 10 m, 1 sh ; SBMNH 452381 , Punta Arena, Baja California Sur, Mexico, 17–33 m, 8 sh ; SBMNH 452382 , Bahia Santiago , Colima, Mexico, 27–40 m, 1 sh ; SBMNH 452383 , La Puntilla, Salinas, Guayas, Ecuador, intertidal, 20 sh ; SBMNH 15747 , Bahia Topolobampo , Sinaloa, Mexico, intertidal, 4 sh ; SBMNH 619729 , Playa Cochorit, Sonora, Mexico, intertidal, 3 sh ; SBMNH 128131 , Isla Lobos, Mazatlan, Sinaloa, Mexico, intertidal, 6 sh ; SBMNH 619730 , Isla Cleopha, Nayarit, Mexico, 12–15 m, 2 sh ; SBMNH 620171 , Tisate, Bahia Banderas , Jalisco, Mexico, intertidal, 3 sh ; SBMNH 131982 , Point Loma, San Diego County, California, USA, 33 m, 3 sh ; SBMNH 620185 , Bahia de los Angeles, Baja California [Norte], Mexico, intertidal, 12 sh ; SBMNH 124370 , Chester Rocks, 12.5 mi E of, Bahia Sebastian Vizcaino , Baja California [Norte], Mexico, 33 m, 1 sh ; SBMNH 115262 , Isla Coronado Sur, Baja California [Norte], Mexico, 14–18 m, 12 sh ; SBMNH 123196 , Bahia Sebastian Vizcaino , Baja California [Norte], Mexico, 35 m, 8 sh ; SBMNH 128586 , Isla San Marcos, Baja California Sur, Mexico, 9–12 m, 8 sh ; SBMNH 620293 , Bahia San Carlos , Sonora, Mexico, 31 m, 8 sh ; SBMNH 620294 , Estero Morua, Sonora, Mexico, intertidal, 40 sh ; SBMNH 620295 , Laguna Beach, Orange County, California, USA, intertidal, 6 sh ; SBMNH 124933 , Punta San Carlos, 4 mi SW of, Baja California [Norte], Mexico, 25 m, 1 sh ; SBMNH 620459 , Isla Maria Cleofas, Nayarit, Mexico, 12–15 m, 1 sh ; SBMNH 620460 , Playa Arenosa, Sonora, Mexico, intertidal, 8 sh ; SBMNH 620461 , Ensenada San Francisco, Sonora, Mexico, 1 sh ; SBMNH 620462 , Punta Mita, Nayarit, Mexico, intertidal, 1 sh ; SBMNH 620463 , Bahia San Carlos , San Carlos Nuevo Guaymas, Sonora, Mexico, 10–25 m, 20 sh ; SBMNH 620464 , Playa Venado, Panama Prov., Panama, 2 sh ; SBMNH 620583 , Estero Morua, Sonora, Mexico, intertidal, 6 sh ; SBMNH 620763 , Isla del Canal de Afuera , Montijo District, Veraguas, Panama, 10–25 m, 4 sh ; SBMNH 620859 , Bahia Bocochibampo , Sonora, Mexico, 15–17 m, 7 sh ; SBMNH 116332 , Isla Asuncion, Baja California Sur, Mexico, 12 m, 5 sh ; SBMNH 621301 , Punta Mita, Nayarit, Mexico, intertidal, 7 sh ; SBMNH 621312 , Point Loma, San Diego County, California, USA, 30–40 m, 5 sh ; SBMNH 621415 , Playa Cochorit, Sonora, Mexico, 6 sh ; SBMNH 132633 , Caleta Lalo, Sonora, Mexico, intertidal, 3 sh ; SBMNH 622354 , Punta San Felipe, San Felipe, Baja California [Norte], Mexico, intertidal, 20 sh. BCD: Marua Estero, SE of Penasco Point , Sonora, Mexico, intertidal, 13 sh ; San Carlos Bay , Guaymas, Sonora, Mexico, 32 m, 8 sh ; Cholla Bay , Penasco Point, Sonora, Mexico, intertidal, 10 sh ; Escondido Bay , Baja California, Mexico, 22 m, 1 sh ; Piedras Blancas , Nayarit, Mexico, 18 m, 5 sh ; Puertecitos, Baja California, Mexico, intertidal, 6 sh .

Original diagnosis. “ C. (Anellum) t. parva, curta, solida, annulis quadratis xii. –xx. cincta; interstitiis profundis, quadratis; apertura subcontracta, annulis concurrentibus; septo mucronato, margine laterali concavo, mucrone parvo, extante, angusta, subdextrorsum sita: operculo valde concavo, anfr. circiter x. linea spirali expressa.” Carpenter (1857: 322).

Description. Protoconch multispiral (about 2.0 whorls), planispiral, smooth ( Fig. 40A ), transition to teleoconch I marked by well-defined apertural varix ( Fig. 40A ). Teleoconch I short, with bands of reticular sculpture ( Fig. 40B ), transition to teleoconch II marked by change in sculpture ( Figs. 40A, D ). Teleoconch II about same length as teleoconch I, with irregular longitudinal sculpture, crossed by low axial annuli ( Fig. 40C ), transition to teleoconch III marked by change in sculpture ( Fig. 40D ). Teleoconch III sculptured with axial annuli, with short longitudinal striae between ( Fig. 40E ), transition to teleoconch IV marked by incised line immediately followed by change in sculpture ( Figs. 40D, G ). Teleoconch IV sculptured with axial annuli, crossed by short longitudinal striae; transition to teleoconch V marked by suture, immediately followed by change in sculpture ( Fig. 40G ). Teleoconch V (last growth stage) average size for genus [Tol 2.12–2.35 mm], tubular, rather thick, stout, moderately and regularly arched [Larc: 0.61–0.70 mm; Arc: 0.20–0.24 mm], subcylindrical with slight increase in diameter from posterior to aperture, cream to light tan ( Fig. 39A ). Axial sculpture of 16–24 angulate or squarish distally spaced axial ribs; ( Fig. 40I ), except last 3–4 preceding aperture, which are more close-set ( Fig. 40I ). Axial interspaces rather deep, as wide as ribs, except last 3–4 preceding aperture, which become narrower ( Fig. 40I ). Surface sculptured with longitudinal striae and axial ribs ( Figs. 40 H–I). Striae more pronounced in interspaces ( Fig. 40H ). Posterior [Dpe: 0.41–0.48 mm] with thick edge, squared shoulder ( Fig. 40I ). Septum mucronate, somewhat recessed. Mucro with low rounded point, positioned along dorsal margin ( Fig. 39B ). Aperture [Da: 0.59–0.69 mm]with weak to moderate sulcus prior to 3–4 close-set axial ribs, last 1–2 sharply reduced in width on ventral side ( Fig. 39I ). Lip smooth, with deflected peristome ( Fig. 39B ). Periostracum thin, light tan. Operculum thin, light brown; exterior surface with 7–9 concentric rings ( Figs. 39 C–D). Conceptual reconstruction of growth stages shown in Fig. 41A .

Distribution and Habitat. From Farallon Islands, California to Colima, Mexico, including the Gulf of California. Intertidal, down to 72 m. Abundant subtidally on coarse sand and gravel substrates.

Remarks. The type material of Caecum quadratum (NHMUK 1857.6.4.1529) is comprised of four adults and three subadults. The most similar congener is C. firmatum , and the two can be confused, especially when specimens are worn. As previously stated, both species are quite variable.

A comparison of the type material from both Caecum quadratum ( Fig. 39E ) and C. compactum (NHMUK 1857.6.4.1530, Fig. 39F ) has proven them to be conspecifics. Lightfoot (1993a) considered C. dalli Bartsch, 1920 ( Fig. 39G ) and C. richthofeni Strong & Hertlein, 1939 to be synonyms of C. quadratum , although she did have some reservations about C. richthofeni . After comparing the type material of each, Lightfoot’s position on C. dalli has been confirmed. However, C. richthofeni is actually a junior synonym of another species, which is discussed later.

Figures

FIGURE 39. Caecum quadratum. A. Profile view (LACM 1971-98.36). B. Ventral view (LACM 1969-29.57). C. Operculum, exterior surface (LACM 1971-98.36). D. Operculum, interior surface (LACM 1971-98.36).E. Syntype, NHMUK 1857.6.4.1529. F. C. compactum syntype, NHMUK 1857.6.4.1530. G. C. dalli, holotype USNM 340724.

FIGURE 40. Caecum quadratum shells at different growth stages: A. protoconch and teleoconchs I to II (LACM 1971-98.36). B. surface of teleoconch I (LACM 1971-98.36). C. surface of teleoconch II (LACM 1971-98.36). D. teleoconchs I to IV (LACM 1971-98.36). E. surface of teleoconch III (LACM 1971-98.36). F. surface of teleoconch IV (LACM 1971-98.36). G. teleoconchs III to V (LACM 1971-98.36). H. surface of teleoconch V (LACM 1971-98.36). I. teleoconch V (LACM 1969-29.57).

FIGURE 41. Caecum quadratum. A. Conceptual reconstruction of growth stages. B. Species distribution map.