Family CALLIODENTALIIDAE

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Introduction

This small, recently recognised family currently consists of only four species, three of which occur in the Indo-West Pacific and one of which is limited to the Western Atlantic and Caribbean regions (Scarabino 1995).

The shells are well curved, glossy, white, yellow or sometimes orange, with only fine growth striae as sculpture; a notch and pipe may be present apically and the anterior aperture is usually slightly compressed dorso-ventrally (Habe 1964; Scarabino 1995).

Calliodentalium was originally erected by Habe (1964) as a genus in the Dentaliidae, expressly for C. crocinum (Dall), then known only from Japanese waters. Palmer (1974) regarded Calliodentalium as a subgenus of Laevidentalium in the Laevidentaliidae (in his original sense, a very broad family now split into a number of discrete families). Later, Chistikov (1975) included both Calliodentalium and Laevidentalium in his newly created subfamily in Dentaliidae, the Calliodentaliinae. Scarabino (1995) included four species within Calliodentalium and elevated Chistikov's Calliodentaliinae (but minus the genus Laevidentalium) to full family status based on the important observation that the central radular tooth (rachidian) of all Calliodentalium species is flanked on each side by an extra abutting tooth which he termed the subrachidian, thus producing a radular tooth row formula at present unique among scaphopods (1.1.1.1.1.1.1; that is: marginal.lateral.subrachidian.central / rachidian.subrachidian.lateral.marginal). Due to infolding of the laterals over the edges of the central tooth in SEM radular preparations of Calliodentalium crocinum, the edges of the central tooth and hence the subrachidian teeth were not observed by Lamprell & Healy (1998). Consequently they placed Calliodentalium crocinum in the genus Laevidentalium, but noted the marked difference between the rugose, heavily mineralised radula of 'Laevidentalium crocinum' and radulae of other Laevidentalium species. The unique radular formula combined with certain anatomical features including the size differences in the pedal retractor muscles, shape of epipodial collar and mantle lobes (cited by Chistikov 1975) strongly support Scarabino's recognition of a separate family to accommodate Calliodentalium.

The Calliodentaliidae is represented in Australian waters by only a single species, the Western Pacific C. crocinum (Dall).

General References

Chistikov, S.D. 1975. Some problems in the classification of the order Dentaliida (Mollusca; Scaphopoda). pp. 18-21 in Likharev, I.M. (ed.). U.S.S.R. Academy of Sciences Zoological Institute, Fifth Meeting on the Investigation of Molluscs. Molluscs: their system, evolution and significance in nature. Theses of communications. Leningrad : Academy of Sciences USSR, Institute of Zoology. Izdatel'stvo `Nauka'. [in Russian; English abstract printed in Malacological Review 11: 71–73]

Habe, T. 1964. Fauna Japonica. Scaphopoda (Mollusca). Tokyo : Biogeographical Society of Japan 59 pp. 5 pls.

Lamprell, K.L. & Healy, J.M. 1998. A revision of the Scaphopoda from Australian waters (Mollusca). Records of the Australian Museum Suppl. 24: 1-189

Palmer, C.P. 1974. A supraspecific classification of the scaphopod Mollusca. Veliger 17: 115-123

Scarabino, V. 1995. Scaphopoda of the tropical Pacific and Indian Oceans, with description of 3 new genera and 42 new species. In Bouchet, P. (ed.) Résultats des Campagnes MUSORSTOM. Vol 14. Mém. Mus. Natl. Hist. Nat. Paris 167: 189–379.

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