Chitons (Mollusca: Polyplacophora) from the southern Chilean Comau Fjord, with reinstatement of Tonicia calbucensis Plate, 1897 Author Schwabe, Enrico Author Försterra, Günter Author Häussermann, Verena Author Melzer, Roland R. Author Schrödl, Michael text Zootaxa 2006 1341 1 27 journal article 10.5281/zenodo.174408 fbbcb2e5-d5ad-4c8b-af0e-22a30f852c15 1175­5326 174408 Ischnochiton ( Haploplax ) pusio (Sowerby in Broderip & Sowerby, 1832 ) (Figure 6) Chiton pusio Sowerby in Broderip & Sowerby, 1832 : 105 . Detailed bibliography and synonymy in Kaas & Van Belle (1994 : 67). Size: Maximum length 21 mm ( Kaas & Van Belle 1994 ). Body outline: Oval, rather elevated, dorsum subcarinated. Color: Usually olive­brown to blackish brown, with brighter spots. Valves: Rather solid; appear smooth (microgranulated) except for commarginal growth lines on terminal valves and lateral areas of intermediate valves; head valve less than semicircular, posteriorly widely V­shaped, slightly notched in middle; intermediate valves rectangular, posteriorly faintly convex on both sides of slightly protruding apex, lateral areas hardly raised; tail valve with mucro in anterior third, postmucronal slope nearly straight and rather steep. Articulamentum: Bluish white to greenish blue, sometimes with darker streaks in central part, apophyses subtrapezoidal and rather short, slit formula: 11–14 / 1 / 11 , slit rays present in all valves, teeth sharp and rather smooth at outside. Perinotum: Dorsally covered with smooth, solid, imbricated scales obtusely pointed; ventral side with radial rows of opaque rectangular to elongate scales. Ctenidia (ZSM Moll 20040966; 12 mm body length): 25 holobranchial ctenidia on each side of foot, posterior ctenidia longer than anterior ones. Radula ( 12 mm specimen): about 3.2 mm in length; radula cartilage 1.6 mm in length; 87 teeth rows, 72 showing mineralized teeth. Central tooth slender, extended at its base, with simple roundish blade; first lateral tooth twice length of central one, leaf­shaped, second lateral tooth with bicuspid head, inner denticle longer than outer. Material: Four specimens were collected at station 1, in a depth between 5 and 30 m and two additional specimens at station 4, between 5 and 20 m (see Table 1 ). Distribution: Ischnochiton pusio occurs from Tumbes, Perú , southwards to the Atlantic coast of Tierra del Fuego, Argentina . It is also known from offshore of the Chilean Juan Fernández Archipelago ( Kaas & Van Belle 1994 ). According to Reid & Osorio (2000) , I. pusio inhabits the underside of stones and other hard substrata from the intertidal zone down to 90 m , with a depth preference around 5–30 m in fjord areas. This is supported by our study and we speculate that Ischnochiton pusio is less tolerant of salinity fluctuations and therefore lives below the halocline.