Cyclocardia compressa Reeve 1843
Creators: name: Güller, Marina
name: Zelaya, Diego G.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Bivalvia
Carditoida
Carditidae
Cyclocardia
Cyclocardia compressa

description: Cyclocardia compressa (Reeve, 1843)
Figs. 1 A −M, 9A, Appendix 1
Cardita compressa Reeve, 1843: pl. 9, fig. 46.
Cardita compressa— Reeve, 1844: 194; Hupé, 1854: 319.
Cardita compressa Reeve—d’Orbigny, 1845: 580; Martínez y Saez, 1870: 47; Clessin, 1888: 11, pl. 5, figs. 14, 15; Rochebrune & Mabille, 1889: H111.
Cardita (Actinobolus) procera Gould, 1850: 276.
Cardita procera (Gould) —Gould, 1852: 416.
Actinobolus compressus [sic] [recte compressa], Reeve—Adams & Adams, 1857: 487.
Actinobolus procerus [sic] [recte procera], Gould—Adams & Adams, 1857: 487.
Cardita procera G.—Gould, 1860: pl. 36, fig. 533.
Cardita (Actinobolus) procera — Gould, 1862: 83.
Cardita (Actinobolus) compressus [sic] [recte compressa] Reeve—Smith, 1881: 42.
Venericardia (Cyclocardia) compressa Reeve, 1843 — Dall, 1903: 708.
Venericardia (Cyclocardia) procera Gould, 1850 — Dall, 1903: 704.
Venericardia compressa Reeve—Dall, 1909: 261.
Venericardia (Cyclocardia) compressa Reeve—Lamy, 1922: 340.
Cyclocardia compressa Reeve, 1843 — Soot-Ryen, 1959: 39; Osorio & Reid, 2004: 82; Cárdenas et al., 2008: 230, figs. 7.85– 87.
Cyclocardia procera Gould, 1850 — Soot-Ryen, 1959: 39.
Cyclocardia compressa (Reeve, 1843) — Dell, 1964: 190; Ramorino, 1968: 198, pl. 2, fig. 1, pl. 5, figs. 1, 3; Osorio & Reid, 2004: fig. 3e.
Type localities: Valparaíso, South America [Chile], 20 to 60 fathoms [36–109 m] (Cardita compressa); “Río Negro, Patagonia” [~ 41–42ºS] (Cardita (Actinobolus) procera).
Material examined: 3 syntypes of Cardita compressa (NHMUK 1967582); 77 lots (Appendix 1, Table 1).
Other published records: Chile (Martínez y Saez, 1870; Smith, 1881; Ramorino, 1968; Osorio & Reid, 2004; Cárdenas et al., 2008); Magellan Strait (Smith, 1881); Cape Horn (Dell, 1964) (Appendix 1, Table 2).
Known distribution: Valparaíso [33°S], Chile to Burdwood Bank [54°S]. Also mentioned from “Río Negro, Patagonia” (type locality of Cardita procera). Living specimens: 12– 272 m.
Description: Shell medium in size (maximum observed L = 15.1 mm), triangular to subcircular (H/L = 0.98 ± 0.04, n = 18), flat (W/H = 0.54 ± 0.03, n = 18), solid (Figs. 1 A–D, K). Anterior end slightly to moderately produced. Antero-dorsal margin short, concave, sloping, insensibly connected with anterior margin. Anterior, ventral and posterior margins evenly rounded; posterior end sometimes truncated, almost vertical. Postero-dorsal margin convex, sloping, longer than the antero-dorsal margin (Figs. 1 A–H). Lunule short, wide, moderately deep; escutcheon elongated, narrow (Figs. 1 K, L). Beaks pointed, subcentrally located, anteriorly directed (Figs. 1 A–J). Prodissoconch small (about 240 µm in length); prodissoconch-1 (P-1) smooth, prodissoconch-2 (P-2) with commarginal lines (Fig. 1 M). Shell surface white, sculptured with 11–18 wide, low, rounded in section radial ribs, which are evenly developed along all shell surface or stronger at posterior part; low and irregular growth lines crossing over radial sculpture, present; interspaces relatively wide (Figs. 1 A–D). Periostracum thick, yellow to brownish, forming narrow commarginal folds, particularly evident towards the margin (Figs. 1 A–D). Inner margin crenulated, coincident with outer shell sculpture (Figs. 1 E–H). Inner shell surface evenly white, or with brown stains at the margins.
Hinge plate wide, solid, oblique, higher posteriorly. Right valve (Fig. 1 J): anterior cardinal CA3 markedly hooked, dorsally fused with shell margin; composed by a small, extremely thin, ventrally directed anterior part (CA3a), and a prominent posterior part (CA3b), high, triangular at the base. Posterior cardinal (CP5b) long, strong, slightly arched, parallel to the nymph, with a distal cusp. Anterior and posterior lateral teeth (LAI and LPI) minute, knob-like, the posterior close to shell margin. Left valve (Fig. 1 I): two solid, elongated, slightly arched, diverging cardinal teeth, dorsally fused with shell margin; anterior cardinal (CA2a) ventrally directed, one-third to one half the size of the posterior one, with subcentral cusp. Posterior cardinal (CP4b) gradually widening distally, with cusp located in anterior third. Anterior and posterior lateral teeth (LAII, LPII) minute, knob-like. Ligament completely external, located in a nymph, which extends for about one half the length of the posterior dorsal margin (Figs. 1 I– L).
Anatomy (Fig. 9A): Mantle margin with a large inhalant-pedal aperture, extending for about 85% mantle margin length, separated from a small posterior exhalant opening by a short suture. Transverse section of anterior adductor muscle large, reniform; transverse section of posterior muscle ovate, smaller than the anterior one. Both inner and outer demibranchs, present, posteriorly fused with each other and to mantle margin. Outer demibranch one third the size of inner one, showing up to 120 filaments in larger specimens; ascending and descending lamellae equally developed. Inner demibranch with 145 obliquely directed filaments in larger specimens; ascending lamella as high as descending lamella. Labial palps with 5 sorting ridges. Foot with posterior byssal gland.
Remarks: The molluscs from the United States Exploring Expedition are housed at the Museum of Comparative Zoology (MCZ), Harvard and in the United States National Museum, Smithsonian Institution (USNM), Washington. However, according to Johnson (1964), Baldinger, A. (in. litt. May, 2012), and Strong, E. (in. litt. June, 2012), the types of Cardita (Actinobolus) procera are missing. Gould (1850) described this species as having an oval-triangular shell, with subcentrally located beaks, sculptured with 15 radial ribs, and yellow periostracum. This set of characters, figured by Gould (1860), agrees with those present in Cyclodardia compressa; in fact Dell (1964) regarded the two species as synonymous.
Cardita (Actinobolus) procera was described from “Río Negro, Patagonia”, and subsequently reported by the same author (Gould, 1852) as coming from “mouth of Río Negro, Patagonia”. Pastorino (2000) reported Cyclocardia compressa from Quaternary raised beaches in the vicinities of this area. However, there is no published information that allows confirming that the species actually lives at present in the area.
Two specimens from Payta, Perú (MACN-In 13926) appear closely similar in shell morphology to Cyclocardia compressa. However, these specimens have flatter ribs with square cross section, separated by narrower interspaces, and a narrower hinge plate, with more delicate teeth. These facts, together with the absence of intermediate records between Payta and Valparaíso, suggest that these specimens could correspond to a different species. The absence of additional material, precludes describing it as new. Guzmán et al. (1998) reported a Cyclocardia cf. compressa from Antofagasta (northern Chile). Their illustrations show an extremely large specimen (about 5.6 cm long), with low and inflated beaks, flat radial ribs, and narrow hinge plate. The identity of this material must be further investigated.
description: Published as part of Güller, Marina & Zelaya, Diego G., 2013, The Families Carditidae and Condylocardiidae in the Magellan and Perú – Chile provinces (Bivalvia: Carditoidea), pp. 201-239 in Zootaxa 3682 (2) on pages 203-205, DOI: 10.11646/zootaxa.3682.2.1, http://zenodo.org/record/217328