Physa acuta Draparnaud, 1805 (Gastropoda: Physidae): a study of topotypic specimens

Abstract

Habite dans la Garonne et les rivières qui s'y jettent. MATERIALS AND METHODSThe snails were collected from four places in the Garonne basin: Saint Léger (on Garonne river), Viale (on Baïse river), Clairac (on Lot river), tank at Saint Étienne de Fougères. Additional samples were collected from an artificial pond at Montpellier and a canal at Perpignan.The specimens to be dissected were relaxed for 8 h in a 0.05% solution of nembutal. Then they were immersed for 40 sec in water heated at 70 o C, from which they were transferred to water at room temperature. The animals (under water) were drawn from the shell with a small forceps applied to the cephalopedal mass, and fixed in slightly modified Railliet-Henry's fluid (distilled water 930 ml, sodium chloride 6 g, formalin 50 ml, glacial acetic acid 20 ml).Voucher specimens were deposited in the Museum National d'Histoire Naturelle (Fig. 1) elongate-ovate, thin, smooth, moderately lustrous and translucent, light fawn colored; fine, closeset lines of growth, non-perceptible spiral lines. Protoconch distinct, rounded exserted. Whorls 5, regularly and rapidly increasing, the first minute, the last very large, roundly shouldered. Spire short. Suture slightly impressed. Aperture large, ear-shaped, about ¾ total length of shell; outer lip thin, sharp; inner lip closely appressed to the columellar region completely closing the umbilical region; columellar plait somewhat twisted; parietal callus wide, columellar fold well marked. Largest shell 16 mm in length, 9 mm in width.Cephalopedal mass uniformly dark gray. Fig. 2 shows some features of a crawling specimen: labial palps fanlike, slightly bilobed anteriorly, roundly angled laterally; foot tapering to a pointed caudal tip that does not overreach the shell apex. Roof of pulmonary cavity deeply pigmented and flecked with small circular to oval unpigmented spots. Renal tube (Fig. 3, rt), as usual in physids, tightly folded into a zig-zag course, ending by a short ureter which opens through a subterminal meatus just behind the pneumostome. Mantle collar (Fig. 3, mc) with about 3-5 digitations on the apical (ad) and 5-10 on the columellar (cd) region, reflected -the latter more extendedly -over the edge of the shell. By the way, in the original description of P. acuta it is stated that "the animal has no mantle digitations at all", whereas seven digitations over the columella are mentioned by Moquin-Tandon (1855).Reproductive system (Fig. 4) -Ovotestis (ot) embedded in the digestive gland. Ovotestis follicles (about 80 in a minutely dissected specimen) emptying into a collecting canal which continues into the ovispermiduct. Between the proximal (od 1 ) and distal (od 2 ) segments of the latter are the seminal vesicles (sv). The ovispermiduct empties into the carrefour, as well as the albumen gland (removed in the figured specimen).From the carrefour the oviduct (ov) emerges as a narrow tube which runs leftwards, gradually widens, becomes

Planorbidae, Lymnaeidae and Physidae of Peru (Mollusca: Basommatophora)

“…1965. Remark -Physa acuta is considered a senior synonym of P. cubensis Pfeiffer, 1839 (see Paraense & Pointier 2003).…”

Diversity and distribution of mollusks along the Contas River in a tropical semiarid region (Caatinga), Northeastern Brazil

“…According to Santos et al (2012), the occurrence of this species is restricted to the small eastern and southeastern Atlantic river basins. However, P. acuta has been recorded in other regions of Brazil (Simone 2006, Fernandez 2011, which concords with its wide geographic range, including other continents; Paraense & Pointier (2003). The specimens from this basin have a smaller maximum size (10 mm) and fewer spire whorls (3) than recorded by other authors (ca.…”

“…The specimens from this basin have a smaller maximum size (10 mm) and fewer spire whorls (3) than recorded by other authors (ca. 16 mm × 9 mm, and five whorls, according to Paraense & Pointier 2003, Núñez 2011. The parietal callus of most specimens (Figure 2q) is also straighter and less developed (e.g., Simone 2006, page 101, figure 298B; Núñez 2011, page 104, figure B; Santos et al 2012, page 48, figure 28).…”

The distinction between retractor and protractor muscles of the freshwater snail's male organ has no physiological basis

“…Although the terms protractor and retractor given by Holm (Holm, 1946) seemed reasonable from a morphological point of view and are still in use (e.g. Paraense and Pointier, 2003;Paraense, 2006), our results indicate that these muscle bands are not used for eversion. Rather, all of the muscle bands that are attached to the preputium are involved in retraction of the preputium.…”

“…For freshwater snails both protractor and retractor muscles have been described (Holm, 1946) and both terms are used by taxonomists (e.g. Paraense and Pointier, 2003;Paraense, 2006), while for brackish water, marine and terrestrial molluscs only retractor muscles have been described (e.g. Berry et al, 1967;Blankenship et al, 1977;Gittenberger, 1979;Jaeger, 1963;Wabnitz, 1976).…”