Tectonatica Sacco, 1890

Huelsken, Thomas, Marek, Carina, Schreiber, Stefan, Schmidt, Iris & Mann, Michael Holl-, 2008, The Naticidae (Mollusca: Gastropoda) of Giglio Island (Tuscany, Italy): Shell characters, live animals, and a molecular analysis of egg masses, Zootaxa 1770, pp. 1-40 : 23

The genus Tectonatica Sacco, 1890 on Giglio Island

So far, one species of the genus Tectonatica has been found alive on Giglio Island. T. sagraiana is common in sublittoral areas at depths of 10 m and below. It is well known for the Mediterranean Sea and lives infaunal directly under the sand surface. Specimens of T. sagraiana were found crawling in the sand in the Bay of Campese between 7 and 15 meters depths in large groups of 20 to 30 individuals. The specimens were collected both at day and night. The animals leave an easily observable trail on the sand surface. In contrast to other naticid species, T. sagraiana does not bury very deep in the sand.

Molecular analysis of larval stages of Naticidae indicated a related additional species to be present in the waters of Giglio Island. Four independent marker gene sequences obtained from randomly collected egg collars suggest a close relationship to T. sagraiana ( Figs. 1 , 11 B/b). One further species of the genus Tectonatica closely related to T. sagraiana is known from the Meditteranean: T. rizzae (Philippi, 1844) which has been described as a rare species in the Mediterranean Sea living at greater depth (> 10–100 m). Unfortunately, no shells were found on Giglio Island, so far, and no live-collected adult T. rizzae was available for sequencing. The sequences were obtained from larvae hatched from collected sand collars.

Figures

FIGURE 1: Phylogenetic tree based on an analysis of the entire data set (H 3, COI, 16 S, and 18 S sequences) of all specimens listed in Table 2. The phylogenetic model (GTR + I + G) was estimated by MrModeltest (Nylander 2004) performed with Paup * 4.0 b 10 (Swofford 2003). Protein coding data sets were coded as ” CODON ”. Based on different base compositions (chi-square test) in each of the single data sets, all parameters were defined as unlinked. Paup * 4.0 b 10 tree characteristics: RI = 0.851, CI = 0.579. 325 positions were parsimony-informative, 76 were parsimony-uninformative, and 1141 were constant (1542 bp). Tonna cerevisina (Hedley, 1919) and Cypraea annulus (Linnaeus, 1758) were used as outgroup.

FIGURE 11: Naticid egg masses collected on Giglio Island. A / a, Neverita josephinia (Campese Bay); B / b, probably Tectonatica rizzae (Pt. delle Secche); C / c, Notocochlis dillwynii (Pt. delle Secche); D / d, Notocochlis dillwynii (Cala dell´Allume); E / e, Notocochlis dillwynii (Fenaio); F / f, Tectonatica sagraiana (Campese Bay); G / g, Naticarius hebraeus (Pt. del Morto); H-I, egg capsules in egg masses of T. sagraiana (10 days old); J-K, egg capsules in egg masses of N. josephinia (1 day old).