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1 December 2007 Morphology and Development of a New Species of Balanoglossus (Hemichordata: Enteropneusta: Ptychoderidae) from Shimoda, Japan
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Abstract

The morphology and development of a new species of the genus Balanoglossus belonging to the family Ptychoderidae are described in detail. This acorn worm was collected from the sandy seashore in the cove near Shimoda Marine Research Center, University of Tsukuba (Shimoda, Shizuoka Prefecture, Japan). This acorn worm is easily distinguished from other balanoglossids by a characteristic hepatic region. There are two kinds of hepatic saccules: large, dark-colored saccules in the anterior region and small, light-colored saccules in the posterior region. Between the two subregions of the hepatic region, there is a small region that has no or tiny saccules. This species does not form distinct burrows or mounds of casts. The breeding season is in winter. The process of embryogenesis from fertilization to metamorphosis was observed. A shift in seawater temperature from about 13°C to about 9°C induced gamete release. Two days after fertilization, embryos hatched and became typical feeding tornaria larvae. Two months after fertilization these larvae metamorphosed into juveniles and began their benthic life.

Norio Miyamoto and Yasunori Saito "Morphology and Development of a New Species of Balanoglossus (Hemichordata: Enteropneusta: Ptychoderidae) from Shimoda, Japan," Zoological Science 24(12), 1278-1285, (1 December 2007). https://doi.org/10.2108/zsj.24.1278
Received: 16 February 2007; Accepted: 1 August 2007; Published: 1 December 2007
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