Tonicia atrata (G.B.Sowerby II, 1839)
- Dataset
- GBIF Backbone Taxonomy
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Mollusca
- class
- Polyplacophora
- order
- Chitonida
- family
- Chitonidae
- genus
- Tonicia
- species
- Tonicia chilensis
distribution
Distribution. WTSP: between Punta Pingueral and Cape Tirua (Aldea and Valdovinos 2005) and Valdivia (Zagal and Hermosilla 2001). Magellanic: Comau Fjord (Schwabe et al. 2006), Punta Pulga (Dell 1971), Gulf of Ancud (Leloup 1956), Chonos Archipelago (Leloup 1956), Estero Elefantes (Reid and Osorio 2000), and Puerto Eden (Dell 1971); Strait of Magellan (Sirenko 2006): eastern micro-basin of the Strait of Magellan (Rios et al. 2003), Laredo Bay (Mutschke et al. 1998), Punta Arenas (Thiele 1908), Rio de los Ciervos (Leloup 1956), Porvenir (Thiele 1908), Punta Santa Maria (this study), Punta Santa Ana (Rios et al. 2007), and Carlos III Island (Aldea et al. 2011 a); Smyth Channel (Thiele 1908), London Island (Pelseneer 1903), Beagle Channel (Pelseneer 1903), Ushuaia (Thiele 1908), Puerto Williams (Dell 1971), Robalo Bay (Dell 1971, Ojeda et al. 2010), Bertrand Island (Dell 1971), and Seno Grandi (Dell 1971); Malvinas / Falkland Islands (Sowerby 1840, Tryon and Pilsbry 1892, Melvill and Standen 1914, Sirenko 2006).
materials_examined
Material examined. 7 spm (17 x 8 - 50 x 26 mm).
description
Description. Animal of medium to large size, reaching 51 mm in examined specimens. Shell elongate-oval, moderately elevated, subcarinated dorsum. Color reddish brown to blackish purple. Head valve semicircular, with straight posterior valve margin unnotched in middle; intermediate valves broadly rectangular, with distinct protruding apex and concave posterior valve margins. Lateral area hardly elevated, but clearly indicated by faint depression in front of diagonal ridge. Jugal area weakly developed, but showing partly a more or less distinct keel, especially in the more posterior intermediate valves. Tail valve with centrally situated, forward-directed, and slightly elevated mucro, straight antemucronal area and rather steep, straight postmucronal slope. Jugal area of tail valve extending towards anterior. Tegmentum without sculpture, except for growth marks and faint radial striations on terminal valves and lateral areas. Perinotum wide and fleshy (After Schwabe et al. 2006).
distribution
Distribution. According to Reid and Osorio (2000), this species distributes in Chile between 40 ° S and 54 ° S, at Tierra del Fuego and around the Falkland Islands. The species ranges in depth from the low eulittoral to a depth of 36 m (Schwabe et al. 2006). The record presented here (at 27 ° S) is now the northernmost record for this species.
description
Size: Maximum length 85 mm (Reid & Osorio 2000). Body outline: Elongate oval, moderately high elevated, subcarinated dorsum. Color: Variable but generally greyish, or blackish purple. Valves: Head valve semicircular, with straight posterior valve margin unnotched in middle. Intermediate valves broadly rectangular, with distinct protruding apex and concave posterior valve margins. Lateral area hardly elevated, but clearly indicated by faint depression in front of diagonal ridge. Jugal area weakly developed, but showing partly a more or less distinct keel, especially in the more posterior intermediate valves. Tail valve with centrally situated, forwarddirected, and slightly elevated mucro, straight antemucronal area and rather steep, straight postmucronal slope. Jugal area of tail valve extending towards anterior. Tegmentum without sculpture, except for growth marks and faint radial striations on terminal valves and lateral areas. Radial rows of ocelli situated on terminal valves, as well as on anterior region of lateral zones. Articulamentum: Solid, thickened, white with a hue of brown or red under mucro or apical regions. Apophyses rather long, rectangular (in intermediate valves), to trapezoidal in tail valve. Apophyses connected by welldeveloped, strongly serrated jugal plate. Insertion plates long, with pectinated outside. Slit formula: 8 / 1 / 11 – 12. Slits deep, teeth with rather sharp edges. Slit rays present in all valves. Perinotum: Wide and fleshy, appears naked. Dorsally with small elongate oval calcareous spicules showing fine striation at distal end, minute smooth and slender spicules, and corneous processes occurring randomly. Ventrally short rectangular to squarish scales, arranged in radial rows; theses scales, slightly bent and showing distinct radial sculpture. Marginal short fringe of minute scale – like spicules. Ctenidia (ZSM Moll 20040973, specimen measuring 15.4 x 8.6 mm): 39 ctenidia on each side of foot, arranged holobranchially and adanally. Radula (same specimen): 5.6 mm long, 2.4 mm of which taken up by radula cartilages. 62 teeth rows, 49 of them mineralized. Extremely slender central tooth showing forwardbent, obtuse, simple cutting edge. First lateral tooth noticeably longer than central one, with deeply notched distal end. Base of first lateral moderately extended, with winglike extension covering lowermost part of central tooth. Second lateral tooth long with sharply keeled shaft and having discoidal unicuspid head with sharp edge. Major uncinal tooth spoonlike.
discussion
Remarks: Plate (1901) described Tonicia atrata as hosting the simple unicellular parasite Chitonicum simplex Plate, 1898. Unfortunately, the systematic position of this parasite is unknown and no further work has been done to evaluate Plate’s findings.
distribution
Distribution: Tonicia atrata occurs between 40 ° and 54 ° S along the Chilean coast, at Tierra del Fuego, and around the Falkland Islands (Reid and Osorio 2000, and material from ZSM).
materials_examined
Material: Tonicia atrata is commonly found within the fjord at virtually all stations (see Table 1). According to Reid and Osorio (2000), the species ranges bathymetrically from the low eulittoral to a depth of 10 m. The specimens reported here were found between 1.5 – 36 m depth.
Name
Bibliographic References
- Hutton, F. W. (1880). Manual of the New Zealand Mollusca. A systematic and descriptive catalogue of the marine and land shells, and of the soft Polyzoa of New Zealand and the adjacent islands. <em>Wellington: Colonial Museum and Geological Survey Department.</em> xvi, iv, 224.
- Ibáñez, C. M., Eernisse, D. J., Méndez, M. A., Valladares, M., Sellanes, J., Sirenko, B. I. & Pardo-Gandarillas, M. C. (2019). Phylogeny, divergence times and species delimitation of Tonicia (Polyplacophora: Chitonidae) from the eastern Pacific Ocean. <em>Zoological Journal of the Linnean Society.</em> 186: 915-933.
- Ibáñez, C. M., Eernisse, D. J., Méndez, M. A., Valladares, M., Sellanes, J., Sirenko, B. I. & Pardo-Gandarillas, M. C. (2019). Phylogeny, divergence times and species delimitation of Tonicia (Polyplacophora: Chitonidae) from the eastern Pacific Ocean. <em>Zoological Journal of the Linnean Society.</em> 186: 915-933.
- Kaas P. & Van Belle R. A. (1994). Monograph of living Chitons (Mollusca: Polyplacophora). Vol. 5. Suborder Ischnochitonina. Ischnochitonidae: Ischnochitoninae (concluded), Callistoplacinae; Mopaliidae. Additions to Volumes 1-4. <em>E. J. Brill, Leiden.</em> 402 pp.
- Kaas et al. 2006