Dietotenhosen remondi (R. A. Philippi, 1887)
PHILIPPI, R. A. 1887. Die tertiären und quartärem Versteinerungen Chiles. 266 p., pls. 1-58. F. A. Brockhauss. Leizpig. [p. 211, pl. 45, fig. 6]
1887 Pecten remondi R. A. Philippi, 1887
1896 Pecten coquimbensis Möricke, 1896
1896 Pecten coquimbensis Möricke, 1896
R. A. Philippi, 1887, plate 45.
|
«Testa majuscula, subaequivalvis, suborbicularis, aequilatera, modice convexa, costata; costae circa viginti sex, asperae, in valva superiore undato-rotundatae et sicut interstitia lineis radiantibus elevatis ornatae, in valva inferiore sulco profundo bipartitae, rarins tripartitae, costulis minoribus saepe interstitia ornantibus; auriculae inaequales, multicostatae. — Longit. 75, altit. 76, crass. 25 mm.
Von den Ufern der Küste von Mejillones del Sur, D. Ramon Vidal Gormaz.
Die obere Schale ist etwas gewölbter als die untere. Diese Art nähert sich dem P. tenuicostatus, aber die Muschel ist weit stärker und dickschaliger, gleichseitiger, die Rippen stärker, die Ohren grösser.» RUDOLPH AMANDUS PHILIPPI, 1887
|
«Type specimens.— Holotype of Pecten remondi Philippi, 1887, SGO.PI 222, a right valve, syntypes of P. coquimbensis Möricke, 1896 UNISTRA 52731, 52732, a right valve and a left valve, all of them from “Coquimbo” (Coquimbo Region), Coquimbo Formation.
Diagnosis.— Shell thin and subcircular in outline with a right anterior auricle narrow and dorsally smooth. Plicae rounded and bearing primary and secondary ribs from early ontogeny. Shagreen microsculpture developed on interspaces of the left valve 7–19 mm from beaks, being ventrally replaced by antimarginal ridgelets. Auricles on both valves and right disc sculptured with antimarginal microsculpture.
Occurrence.— Middle Miocene–earliest early Pliocene from La Piña, Caldera, quebrada blanca (Atacama Region, Bahía Inglesa Formation); quebrada Herradura, estancia Tangue (bahía de Tongoy), quebrada Honda, punta Teatinos (Coquimbo Region, Coquimbo Formation).
Description.— Shell thin, large-sized, attaining up to 116 mm in height, subcircular in outline and slightly higher than long, or equidimensional, acline or slightly opisthocline and posteriorly elongate with postero-dorsal margin of discs straight, antero-dorsal one very concave, and both moderately inclined; left valve much more convex than the right. Hinge dorsal margin straight, 58–63% of total disc length. Umbonal angle 99–101°. Resilifer deep, triangular-isosceles and vertical. Auricles large, anterior ones slightly longer than posterior auricles, auricles with free margins sloping anteriorly, posterior ones with free margin convex, left anterior one markedly convex; right anterior auricle narrow, projected upwards, with dorsal and free margins straight;
byssal notch rounded or rectangular, moderately deep and wide, with functional ctenolium throughout ontogeny, with 4–6 strong teeth; byssal fasciole with corrugations convex towards umbo; byssal sinus absent. Right anterior auricle sculptured with six radial ribs, right posterior one with 9–14 ribs, left anterior auricle with 14–16 ribs, left posterior one with 8–10 ribs. Disc sculptured with high, moderately wide, ventrally flattened, rounded radial plicae, top plicae covered with one rib from early ontogeny in both valves and two secondary ribs that appear at 30–55 mm from beaks on plicae flanks, all ribs bearing ventrally directed low scales and small from 4–7 mm. Interspaces narrower than plicae and covered with two orders of ribs, central rib appearing at 3–10 mm and two flanks ribs at 25–40 mm height from beaks. Right valve sculptured with 18–26 plicae and left valve ornamented with 17–21 plicae. Shagreen microsculpture restricted to a band between 7 mm and 19 mm from beaks on left valve. Antimarginal microsculpture on plicae, interspaces, and auricles, well developed on entire surface on right valves, while appearing beyond the shagreen microsculpture on left ones. Commarginal corrugations on right anterior auricle. Materials.— Seven right valves and seven left valves: SGO.PI 1024a, b, 1109, 1100, 17186–17188, GNS WM 9616, SNSBBSPG 1966 IV 14–15, 167–169, and 183.
Dimensions (mm).— SGO.PI 222 holotype of Pecten remondi, L = 35.2, H = 41.6; SGO.PI 1024b, L = 75.0, H = 80.0; SGO.PI 1024a, L = 80.3, H = 85.2; SGO.PI 1100, L = 70.7, H = 78.4.
Remarks.— Dietotenhosen remondi n. comb. is distributed from La Piña southwards to the area of Caleta Horcón. It is recorded in the fossiliferous beds of the Bahía Inglesa Formation exposed at Caldera and quebrada Blanca, considered by Marchant et al. (2000) to be late Miocene and middle Miocene–late Miocene, respectively. This species is represented in the area of Bahía Tongoy, where it was found at Quebrada Herradura and estancia Tangue (Coquimbo Formation) deposits that, according to Le Roux et al. (2006), should be placed in the latest late Miocene–earliest early Pliocene.
Many other localities, such as Barranquilla, Cerro Lecheros (Bahía Inglesa Formation), Carretera Panamericana km. 480 (area of La Serena), Quebrada Culebrón, Tierras Blancas (surroundings of Coquimbo), Quebrada Pachingo and Quebrada Salina (Bahía Tongoy), (Coquimbo Formation), and Horcón (Horcón Formation) were pointed out by Herm (1969), but the repository of the material from these sites remains unknown. Philippi (1887) described Pecten remondi on a small right valve from Coquimbo. Based on one right and one left valve from the same locality, Möricke (1896) described P. coquimbensis, herein synonymized with P. remondi because both species display the same diagnostic characters: development of subcircular shells, symmetrical auricles, with the right anterior one very low and free margin inclined anteriorly, high and wide byssal notch, free margin of posterior auricles prominently convex, and discs ornamented with antimarginal microsculpture and with rounded, plicae with crests bearing a fine rib from early ontogeny. Jonkers (2003) stated that the type material of P. coquimbensis had been lost. However, it was recently located at UNISTRA and it is herein illustrated (Fig. 5.2, 5.4). Dietotenhosen remondi n. comb. is included in this new genus because it has equidimensional adult valves, with the right valve very flat, the left one convex, an umbonal angle between 99° and 116°, with slightly asymmetrical auricles, posterior auricles with convex free margin, and an elongated hinge margin. Also, the right valve is sculptured with 18–26 plicae and the left valve with 17–21 plicae, all of them of equal width, bearing up to two orders of ribbing and with secondary ribs appearing at 40–60 mm from the umbo. Herm (1969) provided a short diagnosis, stating that Chlamys remondi should be synonymized with C. vidali (Philippi, 1887) (= Dietotenhosen hupeanus n. comb.). However, both taxa are different enough to be considered as distinct species. Dietotenhosen remondi n. comb. can be differentiated from D. hupeanus n. comb. In having sub-circular and thinner shells with a remarkably narrower and more anteriorly inclined right anterior auricle, and being ornamented with commarginal corrugations. In D. remondi n. comb., the byssal notch is deeper and wider and the free margins of posterior and left anterior auricles are strongly convex. Also, valves are sculptured with nongrooved, rounded plicae (Fig. 5.1–5.4, 5.6, 5.7, 5.9–5.11), which are narrower on the right valve and hardly ever bifurcated, bearing scaly primary ribs from early ontogeny and secondary ribs covering the flanks of plicae, instead of the equal-width ribs that cover plicae crest in D. hupeanus n. comb. (Fig. 3.2, 3.5–3.7, 3.9, 3.10). In contrast with D. hupeanus n. comb., which has shagreen microsculpture covering both valves, the shagreen microsculpture in D. remondi n. comb. is present only on the left valve and it is replaced by antimarginal ridges beyond the umbonal zone (Fig. 4.4). Moreover, antimarginal microsculpture covers entire auricles in D. remondi n. comb., instead of the shagreen as is the case in D. hupeanus (Table 2).» SANTELLI, M. B. & C. J. DEL RÍO. 2019. New Neogene taxa of the tribe Chlamydini Teppner, 1922 (Pectinidae, Bivalvia) of southern South America. Journal of Paleontology, 93 (6): 1088-1104, figs. 1-7. [p. 1096, 1098]
|
Dietotenhosen remondi (Philippi, 1887); M. B. Santelli & C. J. del Río, 2019, New Neogene taxa of the tribe Chlamydini Teppner, 1922 (Pectinidae, Bivalvia) of southern South America, figures 4.4, 4.5; 5.1, and 5.11 (holotype of Pecten remondi Philippi, 1887), 5.2 and 5.4 (syntypes of P. coquimbensis Möricke, 1896), 5.3, 5.5-5.10.
|