Turritelladuplicata ( Linnaeus, 1758 )

Waite, Richard & Allmon, Warren D., 2016, Observations on the Biology and Sclerochronology of “ Turritella ” Duplicata (Linnaeus, 1758) (Cerithioidea, Turritellidae) from Southern Thailand, Malacologia 59 (2), pp. 247-269 : 248-250

Turritelladuplicata ( Linnaeus, 1758)

1758 Turbo duplicatus Linnaeus : 766.

1758 Turbo acutangulus Linnaeus : 766.

1758 Turbo replicatus Linnaeus : 766.

1822 Turritelladuplicata (Linnaeus) – Lamarck, 1822: 56.

1843 Turritelladuplicata “Lamarck ” – Deshayes & Milne-Edwards, 1843: 251.

1847 Zaria duplicata (Linnaeus) – Gray, 1847: 155.

1849 Turritelladuplicata (Linnaeus) – Reeve, 1849: 571, pl. 1, fig. 2.

1879 Turritelladuplicata “Lamarck ” – Martin, 1879: 69, pl. 11, fig. 13.

1883 Turritella (Zaria) duplicata (Linnaeus) – Tryon, 1883: 224, pl. 67, fig. 59.

1957 Zaria duplicata (Linnaeus) – Marwick, 1957: 165, figs. 40, 47.

2009 Zaria duplicata (Linnaeus) – Harzhauser etal., 2009: 343.

DESCRIPTION AND GEOGRAPHIC DISTRIBUTION

Description

Turritella duplicata , the two-keeled screw shell, for full descriptions of the shell, see Reeve (1849) and Kiener (1873).

Shells can reach at least 160 mm in length and about 40 mm in basal diameter, with at least 25 whorls. Our observations on the soft part anatomy confirm the description provided by Allmon (2011: fig. 2), and the illustrations of Kiener (1873), reproduced here in Figs. 2–6 . The head-foot has a short, wide snout, and a pair of long cephalic tentacles, each with an eye situated near the base. The foot itself is relatively small, with a ciliated groove on the right side. The aperture is fringed by two rows of non-branching papillae or tentacles, which prevent the entrance of large particles. The operculum is small, permitting the animal to retreat into the shell far enough to vacate the lowest two whorls. Ratios between the diameters of opercula and the respective shell apertures range between 1.8 and 2.3.

Geographic Distribution

Indo-West Pacific: from Madagascar to Indonesia; north to the Gujarat coast of India and the Philippines and south to northern Queensland ( Poutiers, 1998; Saravanakumar et al., 2007; Fig. 7 ). It is known to occur in intertidal waters but maximum depth range is unknown.

Temporal Distribution

It was reported from the Upper Miocene ( Martin, 1879), where it was only known from one fossil locality on Java. According to Hoek Ostende et al. (2002), however, that is a misidentification. There is no other published fossil record.

Geographical and Geological Setting of the Nopparat Thara Tidal Flat

The Nopparat Tharabeach is situated onthe Phang Nga Bay coast and forms the extension of the Ao Nang beach. It lies west of Ao Nang in the district of Krabi, southern Thailand ( Fig. 1 ). Along the Phang Nga coast, sand flats and mud flats alternate with steep cliffs, the mud flats predominantly facing east and the sand flats west. The region’s climateis dominated by the reversing monsoon, which is responsible for a rainy season and south-westerly winds from April to October and a cooler dry season with north-easterly winds from November until March. Rainfall averages around 300 mm / month in the wet season and 50 mm /month in the dry season. Sea surface temperatures range from 27–31°C and salinities are generally between 32 and 33‰ (Tudhope & Scofin, 1994).

The Nopparat Thara beach is separated from the Ao Nang beach by a small cliff that defines the eastern end of the studied tidal flat ( Fig. 1 ). The western termination of the tidal flat is an estuary that drains a low-lying swamp area, and forms a busy harbour for long-tail and tourist boats. Tides are semidiurnaland tidalrange during the study period varied between about 3.2 m at spring tide to about 1.0 m at neap tide. Winds during the surveyingperiod were weak, but consistently from the southeast. In the east, the beach is relatively narrow (~ 15 m wide) and the flat is steep, so during low tide a rather narrow expanse of tidal flat is exposed. The beach is narrowest in the central part and then broadens out towards the west. A sand-spit is formed at the estuary mouth due to longshore currents and sediment transport ( Fig. 1 ). Here, a broad expanse of the flat is ex- posed at low tide.

Figures

FIGS. 2–6. Anatomical features of T. duplicata. FIG. 2. Underwater photograph of T. duplicata burying itself. Visible elements of soft part anatomy include: a = outer rim of papillae, b = tentacle with eye, c = snout, d = food groove; FIGS. 3, 4: Sketches of shells of T. duplicata copied from Kiener (1873); FIG. 5: Sketch of the corresponding operculum to the specimen figured in Fig. 4; FIG. 6: Sketch of hard- and soft part anatomy of T. duplicata: a = outer rim of papillae, b = tentacle with eye, c = snout, d = food groove.

FIG. 7. Known distribution of T. duplicata (hatched area) modified form Poutiers (1998) (Caramagna, 1875; Sundaram et al., 1969; Purchon & Purchon, 1981; Rajagopal et al., 1990; Saravanakumar et al., 2007).

FIG. 1. Map of the study area depicting the Nopparat Thara tidal flat and its position on the Andaman Sea coast. (1) Beach, (2) Near shore or ocypode zone, (3) Intermediate zone, (4) Turritellid zone, (5) Firmground zone; a–c refer to the positions of the transects described in Fig. 3; D1–D4 refer to the positions of the excavations on the tidal flat (Modified from Waite & Strasser, 2011, p. 226, fig. 1, © Springer-Verlag 2010; with kind permission from Springer Science & Business Media B. V.).