Carditella naviformis Reeve 1843
Creators: name: Güller, Marina
name: Zelaya, Diego G.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Bivalvia
Carditoida
Condylocardiidae
Carditella
Carditella naviformis

description: Carditella naviformis (Reeve, 1843)
Figs. 6 A–M, 9D, Appendix 6
Cardita naviformis Reeve, 1843: pl. 9, fig. 45.
Cardita naviformis— Reeve, 1844: 194; Hupé, 1854: 319.
Mytilicardia (Glans) naviformis Reeve—Adams & Adams, 1857: 489.
Cardita australis Philippi, 1858: 23 (non Lamarck, 1819).
Actinobolus philippi Tryon, 1872: 254.
Cardita naviformis Reeve—Clessin, 1888: 34, pl. 13, fig. 10; Melvill & Standen, 1914: 130.
Cardita (Glans) naviformis Reeve, 1843 — Dall, 1903: 707.
Cardita (Glans) naviformis Reeve—Lamy, 1922: 269 (in part).
Glans naviformis (Reeve) 1843 [sic]— Carcelles & Williamson, 1951: 334.
Carditella naviformis (Reeve, 1843) — Powell, 1960: 177; Dell, 1964: 194, texfig. 3, no 1; Ramorino, 1968: 202, pl. 2, figs. 3, 4, pl. 6, figs. 1, 4.
Carditella tegulata Reeve, 1843 — Cárdenas et al., 2008: 230 (in part) (only fig. 7.91) (non Reeve, 1843).
Type localities: Valparaíso, South America [Chile], 25 fathoms [46 m] (Cardita naviformis); Archipiélago de los Chonos (Cardita australis = Actinobolus philippi).
Material examined: 3 syntypes of Cardita naviformis (NHMUK 1967584), and 75 lots (Appendix 6, Table 1).
Other published records: Malvinas / Falkland Islands (Melvill & Standen, 1914); Magellan Strait (Lamy, 1922); Chile (Ramorino, 1968) (Appendix 6, Table 2).
Known distribution: Valparaíso [33ºS], Chile to Malvinas / Falkland Islands [51°S]. Living specimens: 0– 137 m.
Description: Shell small (maximum observed L = 7.1 mm), trapezoidal (H/L = 0.74 ± 0.05, n = 42), markedly inequilateral, somewhat inflated (W/H = 0.67 ± 0.05, n = 42), solid (Figs. 6 A–F, K). Anterior end shorter and lower than posterior end. Antero-dorsal margin straight, abruptly sloping, forming a well-marked angle at the junction with anterior margin. Anterior margin extremely short, continuous with ventral margin, which is obliquely straight and projecting posteriorly. Posterior margin arched, twice the height of the anterior margin, insensibly connected with ventral margin, and forming angle at the junction with dorsal margin (Figs. 6 A, C, E, F). Postero-dorsal margin straight, parallel to ventral margin, slightly sloping; longer than the antero-dorsal margin in larger specimens (Figs. 6 A, C); smaller specimens usually triangular, nearly equilateral, with ventral margin markedly curved (Fig. 6 I). Lunule short, wide and deep; escutcheon narrow, elongated (Fig. 6 K). Beaks small, low, anteriorly located, anteriorly directed (Figs. 6 A–F, K). Prodissoconch large (about 520 µm in length); P-1 rough, mamillate, with central depression; P-2 separated from teleoconch by a bulging rim, somewhat enlarged posteriorly (Figs. 6 L, M). Shell surface sculptured with 10–14 strong, rounded radial ribs, with rectangular, juxtaposed, flat scales; interspaces narrower than rib width, with fine commarginal lines (Figs. 6 A–D, I, J). Periostracum thick, brownish (Figs. 6 A, C). Inner shell surface porcelaneous, evenly white, coincident with outer shell sculpture, more evident at posterior part; inner margin crenulated (Figs. 6 E, F). Pallial line continuous.
Hinge plate narrow; dorsal margin, between beaks and laterals, finely granulated (Figs. 6 G, H). Right valve (Fig. 6 G): anterior cardinal tooth (CA3) forming a prominent hook, with anterior (CA3a) and posterior (CA3b) parts similar in length; CA3a elongated, close to or fused with dorsal margin, CA3b massive, triangular at the base. Posterior cardinal tooth (CP5b) narrow, elongated, parallel to the nymph. Anterior lateral (LAI) relatively narrow and high, with distal cusp. Posterior lateral tooth (LPI) elongated, low, poorly differentiated from margin. Left valve (Fig. 6 H): with two small, divergent cardinal teeth; the anterior (CA2) triangular at the base, ventrally directed, the posterior (CA4b) obliquely directed. Anterior lateral tooth (LAII) low, ill defined. Posterior lateral tooth (LPII) delicate, elongated, narrow. External ligament short and wide, located in a nymph which extends for one-third the length of postero-dorsal margin (Figs. 6 E, F, L). Internal ligament small but strong, on a resilifer located in the dorsal half of hinge plate, above CA4b in left valve and behind CA 3 in right valve (Figs. 6 G, H).
Anatomy (Fig. 9D): Mantle margin with a large inhalant-pedal aperture, and a small posterior exhalant opening. Transverse section of anterior adductor muscle reniform; transverse section of posterior muscle ovate, larger than the anterior one. Inner and outer demibranchs fused posteriorly to each other and to mantle margin. Outer demibranch large, nearly rectangular, showing 40 filaments in a 4 mm length specimen; ascending and descending lamellae equally developed. Inner demibranch small (one-fourth the size of outer demibranch), with 52 filaments in the above mentioned specimen; ascending lamella as high as descending lamella. Labial palps small.
Remarks: Carditella naviformis has been frequently confused with C. semen. D’Orbigny (1845) first identified specimens from Arica, Chile as C. naviformis; the study of this material (NHMUK 1854.12.4.762) (Fig. 7 C) reveals that these specimens actually correspond to C. semen. The specimen figured as Carditella tegulata by Cárdenas et al. (2008: fig. 7.91) proves to correspond to C. naviformis; however, the other specimens from that same lot (MZUC 32641) actually do correspond to C. tegulata.
Actinobolus philippi Tryon, 1872, is the replacement name for Cardita australis Philippi, 1858 (non Lamarck, 1819), a species described from the Archipiélago de los Chonos and erroneously reported from “ Philippines ” by Tryon (1872). The original description of this species is quite short and lacks illustrations; the types were not found at the MNHNCL or ZMB. Philippi (1858) described his species as having a trapezoidal shell outline, with the posterior part of the dorsal margin and the ventral margin parallel, the anterior “end” (i.e.: the antero-dorsal margin) obliquely truncated, and sculptured with 11–12 radial ribs, paved with strong, juxtaposed scales. According to Philippi (1858), his species differs from C. naviformis by having a shorter and not vertically truncated posterior end, less prominent beaks, and white color. However, we found no arguments for distinguishing these two species. The posterior end of C. naviformis is more or less projected in accordance with the size of the specimens (see Figs. 6 A, B, I); the beaks are more or less prominent depending on the state of erosion; and the shell is actually posteriorly rounded, and whitish in color. Coan (2003) and Huber (2012) previously regarded Actinobolus philippi as a synonym of Carditella semen. Although the latter also has a trapezoidal shell outline, it lacks juxtaposed scales, and the anterior part of the dorsal margin is concave rather than “obliquely truncated”, as described by Philippi (1858).
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 214-216, DOI: 10.11646/zootaxa.3682.2.1, http://zenodo.org/record/217328