E . Schwabe 1 & F. J . A . S l i e ker 2 1Zoologische Staatssammlung München 2N a t u u r museum Rotterd a m

A new species of C a l l o c h i t o n G r ay, 1847 (: Po lyplacophora) from Western Samoa

Schwabe, E. & Slieker, F.J.A., 2001 - A new species of C a l l o c h i t o n G r a y, 1847 (Mollusca: Polyplacophora) from Western Samoa - DEINSEA 8: 225-228 [ISSN 0923-9308]. Published 09 November 2001

Among molluscan material from Western Samoa collected by H. Bayer and sent to the first author an unknown species of was found. It is here described as Callochiton mumuena spec. nov. The new taxon is only known from the holotype, collected on Savaii Island under coral slab at a depth of one metre.

Keywords: Mollusca, Polyplacophora, Callochiton, new species, Western Samoa

Correspondence: Enrico Schwabe, Zoologische Staatssammlung München, Münchhausenstraße 21, 81247 München, Germany, e-mail [email protected]; Frans J. A. Slieker, Natuurmuseum Rotterdam, P.O. Box 23452, 3001 KL Rotterdam, T h e Netherlands, e-mail natuurmuseum@nmr. n l

I N T RO D U C T I O N M ATERIAL EXAMINED R e c e n t l y, Mr H. Bayer (Savaii Island, For direct comparison the following material Western Samoa) has sent many molluscan was studied: Callochiton empleurus (HU T TO N, specimens to the first author. This material 1872) from New Zealand (National Museum included several different chiton species, of of New Zealand, Wellington: lectotype which the following could be identified: NMNZ M279); Callochiton klemi AS H B Y, To n i c i a (L u c i l i n a) lamellosa (QU O Y & 1926 from Yorke Peninsula, South A u s t r a l i a GA I M A R D , 1835) (Schwabe 1997); (South Australian Museum, Adelaide: holo- Callistochiton granifer HU L L, 1923; type SAMA D 11703, only a single median Squamopleura araucariana (HE D L E Y , 1898) valve) Callochiton bayeri SC H WA B E , 1998 (first record from this locality); Chiton subas - from Savaii, Western Samoa (Zoologische s i m i l i s SO U V E R B I E, 1866 (first record, apart Staatssammlung München: holotype ZSM from the holotype) and Callochiton bayeri 1 9 9 8 1 7 1 5 ) . SC H WA B E , 1998. One specimen defied identi- fication and is described here as a species new to science.

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Figures 1-3. Callochiton mumuena s p e c. n ov. , h o l o t y p e , collection Nationaal Natuurhistorisch Museum, L e i d e n , r e g . n r. R M N H . 5 9 3 8 7 ; 1 d o r sal view of the complete specimen (length 12.1 mm) now disart i c u l a t e d ; 2 v a l ve I, d o r sal view; 3 v a l ve V, d o r sal view. Scale bar (for Figs. 2-3) 1 µ m. [ p h o t o ' s : F. J . A . S l i e ker (1), Nationaal Natuurhistorisch Museum (2-3)]

S YS T E M AT I C S also preserved dry. No other type material.

Family D i ff e rential diagnosis A typical member of Subfamily Callochitoninae the C a l l o c h i t o n as defined by Gray Genus C a l l o c h i t o n GR AY, 1847 (1847). Differs from C. empleuru s (HU T TO N , 1872) by the greater number of pits in the Callochiton mumuena s p e c . n ov. pleural areas of the intermediate valves, the Figures 1-6 more keeled valves and the form of the dorsal girdle spicules which are broader and more H o l o t y p e Nationaal Natuurhistorisch sharpened in C. empleuru s. C. klemi AS H B Y , Museum, Leiden, reg. nr. RMNH 59387. 1926 (although only known from the holo- Western Samoa, Savaii Island, Va i s a l a type, a single median valve) differs from lagoon, under coral slab at about 1m depth, C. mumuena spec. nov. by the number of slits collected February 1999 by H. Bayer. in the insertion plates, which are 2-3 in Specimen slightly curved, length 12.1 mm, C. klemi and one in C. mumuena spec. nov. , width 6.9 mm; now disarticulated and pre- by the more beaked apex in C. klemi and in served dry, valves III-VIII medially broken; having a stronger sculpture. C. mumuena slides of perinotum and part of the radula spec. nov. differs from the recently described

226 SCHWABE & SLIEKER: a new Callochiton

Callochiton bayeri SC H WA B E , 1998 by the shape of the postmucronal slope in the tail valve which is straight and steep in C. bayeri instead of concave as in C. mumuena s p e c . n o v. Furthermore the grooves in C. bayeri a r e more numerous and larg e r.

D e s c r i p t i o n small, elongate oval and broader towards the tail valve; back rather flat, dorsal elevation quotient 0.34 (valve II). Valves slightly beaked, lateral areas clearly 4 raised. Tegmentum sculptured with minute granules, arranged in many radial rows, shell eyes numerous, absent in the pleural areas of the intermediate valves. Girdle moderately wide, somewhat darker than the tegmentum, dorsally densely covered with conical, inward- ly directed spicules. Tegmentum reddish brown (for colour photograph see Slieker 2000: pl. 34, fig. 6); articulamentum pinkish white. Apophyses short, wide, and connected across the jugum by a small, slightly concave, lamina. Slit formula of insertion plates 5 13/1/c.13. Head valve semicircular, with a few fine growth lines; posterior margin straight, not notched in the middle. Intermediate valves broadly rectangular, posterior margins slightly concave, lateral areas clearly raised, side slopes straight, apices somewhat pointed. Pleural areas with short, broad and rather deep longitudinal grooves parallel to diagonal ridge, two grooves at both sides of jugum in valve II, four in valve III and five in valves IV- V I I I ; grooves become longer towards anterior mar- gin of valves. Tail valve semicircular, length 1 6 about /2 of width, mucro slightly anterior, postmucronal slope concave. Girdle moderate- ly wide, somewhat darker than tegmentum, Figures 4-6 Callochiton mumuena s p e c . n ov. , h o l o t y p e , c o l l e c- dorsally densely covered with conical, inward- tion Nationaal Natuurhistorisch Museum, L e i d e n , r e g . n r. ly directed spicules, which measure 140 x 36 µm. RMNH 59387; 4 v a l ve V, detail of tegmentum; 5 ve n t ral girdle Radula only partly known. Major lateral teeth s c a l e s ; 6 ra d u l a , c e n t r al and lateral teeth; (scale bars 100 with a strong tridentate cusp. Central teeth lar- µ m ) . [ p h o t o ' s : Nationaal Natuurhistorisch Museum] g e r, tulip-shaped, with a thin blade. Gills u n k n o w n .

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D i s t r i b u t i o n Only known from the type loca- R E F E R E N C E S l i t y, Savaii Island, Western Samoa. G r a y, J.E., 1847 - On the genera of the family Chitonidae - Proc. Zool. Soc. London 15:63-70 E t y m o l o g y C. mumuena is named after a M i l n e r, G.B., 1966 - Samoan dictionary - Oxford combination of the Samoan words 'mumu' University Press, New York, Melbourne (red) and 'ena' (brown), being the colour of Schwabe, E., 1997 - Ein ungewöhnlicher Fund von the tegmentum (Milner 1966). C a l l o c h i t o n cf. o l i g o s u l c u l a t u s Kaas & Van Belle, 1985 (Polyplacophora) von Western Samoa - Club AC K N OW L E D G E M E N T S Conchylia Informationen 29 (3-4): 22-24 Thanks are due to: Mr Helmut Bayer for send- Schwabe, E. 1998a - Description of a new species of the ing the material he collected at the request of genus Callochiton Gray, 1847 from the Southwest the first author; to Dr Bruce Marshall Pacific (Mollusca: Polyplacophora) - Club Conchylia (National Museum of New Zealand, Welling- Informationen 30 (4-6): 33-38 ton) for the loan of Callochiton empleurus; to Schwabe, E. 1998b - Callistochiton granifer Hull, 1923 Dr Thierry Laperousaz (South Australian (Mollusca: Polyplacophora) von Western Samoa - Museum, Adelaide) for the loan of Callochiton Club Conchylia Informationen 30 (1-3): 11 - 1 5 klemi; to Mr Jeroen Goud (Nationaal Natuur- S l i e k e r, F.J.A. 2000 - of the world, an illustrated historisch Museum, Leiden) for preparing the synopsis of recent Polyplacophora -L‘Informatore SEM photographs; to Dr Bernhard Ruthen- Piceno Ed., A n c o n a steiner for offering the first author the use of the facilities at the Zoological State Collection, re c e i ved 8 May 2000 Munich and to Mr Hermann L. Strack for criti- accepted 16 June 2000 cally reading the text.

DEINSEA - ANNUAL OF THE NATURAL HISTORY MUSEUM ROTTERDAM P. O . B o x 2 3 4 5 2 , N L - 3 0 0 1 K L R o t t e r d a m T h e N e t h e r l a n d s

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