Onithochiton maillardi ( Deshayes, 1863 )

Schwabe, Enrico, 2004, The Polyplacophora (Mollusca) collected during the First International Marine Biodiversity Workshop for Rodrigues (western Indian Ocean), with the description of a new species, Journal of Natural History 38 (23), pp. 3143-3173: 3157-3160

publication ID

http://doi.org/ 10.1080/00222930410001695114

persistent identifier

http://treatment.plazi.org/id/03B187BA-FFA0-D62C-FE4A-FE1E4222FC8D

treatment provided by

Felipe

scientific name

Onithochiton maillardi ( Deshayes, 1863 )
status

 

Onithochiton maillardi ( Deshayes, 1863)  

( figures 9 View FIG , 10 View FIG , 17F View FIG )

Chiton maillardi Deshayes, 1863: 38   , pl. 5 figure 14 View FIG ; von Martens, 1880: 300 (as ‘ C. ( Tonicia   ?) maillardi   ’); Nierstrasz, 1905: 107; 1906: 513.

Toniciopsis maillardi: Thiele, 1893: 371   .

Tonicia (Onithoplax) maillardi: Thiele, 1929: 22   .

Onithochiton mailardi   [sic!]: Bergenhayn, 1933: 34.

Onithoplax maillardi: Cotton, 1964: 88   .

Onithochiton maillardi: Pilsbry, 1893: 250   , pl. 55, figure 20; Leloup, 1941: 9, text figures 5–8 View FIG View FIG View FIG View FIG ; 1960: 42, figure 11A View FIG ; 1974: 5; 1981a: 35; Kaas and Van Belle, 1980: 80; 1998: 117; Ferreira, 1983: 277 [as synonym of Onithochiton literatus (Krauss, 1848)   ]; Kaas, 1986: 18; Drivas and Jay, 1998: 33, figure 9 View FIG ; Slieker, 2000: 50,

pl. 13, figure 29.

Tonicia maillardi: Kaas, 1996: 374   .

Type. Syntypes ( MNHN)   .

Type locality. Réunion (Bourbon). Material examined. 1 spm, 15.7 6 7.2 mm: Pointe Coton, 19 ‡ 40.833 ’ S   ,

63 ‡ 29.548 ’ E, reef crest, 18 September 2001; 5 spms, 6.8 6 4.4 mm, ca 10.9 6 5.8 mm (curled), ca 9.5 6 6.7 mm (pd), 14.7 6 8.3 mm, 17.3 6 11 mm: RDS 15, Rivière Banane, 19 ‡ 40.261 ’ S, 63 ‡ 28.582 ’ E, reef crest.

Description

Animal elongate-oval with a broad ‘naked’ girdle ( figure 17F View FIG ). Tegmentum surface consists of concentric grooves in head valve, lateral areas and postmucronal area. Pleural areas and antemucronal area with longitudinal grooves. Large lenses arranged radially in lateral areas and within the grooves of the head valve.

Tegmentum. Valve surface smooth, except for openings of aesthetes. Head valve semicircular with distinct concentrically arranged, irregular grooves and a

shallow notched posterior margin ( figure 9A View FIG ). Intermediate valves with smooth jugum, and a beaked apex. Lateral areas concentrically grooved, not elevated, pleural areas longitudinally grooved ( figure 9C View FIG ). Mucro of triangular tail valve slightly elevated and situated terminally ( figure 9D, E View FIG ). Postmucronal area very small, concentrically grooved and with a steep slope. It is separated from antemucronal area by a slightly elevated, rather coarse diagonal ridge. Antemucronal

area sculptured as pleural areas of intermediate valves.

Ocelli arranged radially in diagonal ridge of tail valve, in lateral areas and within the grooves of head and tail valve, measuring about 30 M m in diameter ( figure 9B View FIG ).

Articulamentum. Thick and white, with large and triangular apophyses in second valve. They are connected by a shallow, pectinated jugal lamina. Apophyses of tail valve are trapezoid and connected by a shallow, deeply notched jugal lamina ( figure 9D View FIG ). Slit formula: 8/1/0 (callus), slits deep, resulting in rather long teeth, which are broad and pectinated on outside. Slit rays present in head and intermediate valves.

Perinotum. Rather wide and appears naked. Dorsally covered with short, straight, blunt spicules, 62.5 6 20.2 M m, with strong ribs in their upper half ( figures 9F View FIG , 10A–D View FIG ). Interspersed are short, broad, slightly curved spicules (64.5 6 12.2 M m) and slender, smooth needles, 97 6 10.4 M m ( figure 10A, D View FIG ). Margin bears long (117–146 6 21–25 M m), paddle-like spicules, and a fringe of scales, which measure approximately 35 6 21 M m ( figure 10A View FIG ). Ventrally, the girdle paved with radial rows of rectangular scales, grooved in their distal part, measuring 18.8–25 6 28–34.4 M m ( figure 10E View FIG ).

Radula. The partly disarticulated specimen has 52 tooth rows of which 46 are mineralized. The slender, nearly rectangular, central tooth has anteriorly a sharp keel and a single, rounded blade. First lateral tooth very large, wingshaped and the lower half is considerably extended. Major lateral tooth has a long keeled shaft and a four-cuspidated head. Innermost denticle smallest, the remaining denticles are larger and of equal size. The very large, spoon-like blade of the spatulate uncinal tooth supports the head of the major lateral tooth ( figure 10F View FIG ).

Ctenidia   . There are 27 abanal and holobranchial ctenidia on both sides of the foot in a 15.7 mm long specimen.

Comments

Although slightly inconsistent in sculpture, the examined material agrees well with two studied syntypes (dry, soft parts removed; 20.1 6 11 mm and 11.2 6 6.3 mm). At present the genus Onithochiton Gray, 1847   is in a state of taxonomic chaos. The validity of such species as O. erythraeus Thiele, 1910   , O. literatus (Krauss, 1848)   and O. lyellii   (Sowerby in Broderip and Sowerby, 1832) was debated in the past by several authors ( Kaas, 1979; Leloup, 1980; Ferreira, 1983; Strack, 1993). They are currently accepted as valid, but more material and a thorough revision of the genus is needed to get a better understanding of these taxa.

MNHN

Museum National d'Histoire Naturelle

Kingdom

Animalia

Phylum

Mollusca

Class

Polyplacophora

Order

Chitonida

Family

Chitonidae

Genus

Onithochiton

Loc

Onithochiton maillardi ( Deshayes, 1863 )

Schwabe, Enrico 2004
2004
Loc

Tonicia maillardi:

KAAS, P. 1996: 374
1996
Loc

Onithoplax maillardi:

COTTON, B. C. 1964: 88
1964
Loc

Onithochiton maillardi:

SLIEKER, F. J. A. 2000: 50
KAAS, P. & VAN BELLE, R. A. 1998: 117
DRIVAS, J. & JAY, M. 1998: 33
KAAS, P. 1986: 18
FERREIRA, A. J. 1983: 277
KAAS, P. & VAN BELLE, R. A. 1980: 80
LELOUP, E. 1941: 9
1941
Loc

Onithochiton mailardi

BERGENHAYN, J. R. M. 1933: 34
1933
Loc

Tonicia (Onithoplax) maillardi:

THIELE, J. 1929: 22
1929
Loc

Toniciopsis maillardi:

THIELE, J. 1893: 371
1893
Loc

Chiton maillardi

NIERSTRASZ, H. F. 1906: 513
NIERSTRASZ, H. F. 1905: 107
VON MARTENS, E. 1880: 300
DESHAYES, G. P. 1863: 38
1863