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When I got this specimen, my first impression was a Toxopneustid-Temnopleurid-Hybrid because of the deep
buccal notches and the sculptured surface with prominent sutures or even
furrows. Later on I found in Shigei "The Sea Urchins of Sagami Bay"
a description (pages 85-86) and a picture (Plate 20, figure 1), which both
fit very well with the specimen above. I feel free to cite some parts of the
description:
- Ambulacra: The primary tubercles are of about the same size as the
interambulacral ones; they are set on every second plate
; there is usually another large tubercle on the admedian side of the primary tubercle. The plates
with the primary tubercle usually carry two large tubercles on the admedian side of the primary tubercle and near the midline.These tubercles form together with smaller
ones a conspicuous, though not very regular, horizontal series on each
plate of the aboral side. The horizontal sutures of the plates are
prominent. There are indistinct naked median spaces adapically.
- Interambulacra: The secondary tubercles reach the same size
as the primary tubercles, forming a very conspicuous regular horizontal
series on each plate. There is also a regular, horizontal series of
miliary tubercles on the adapical part of the plates. The naked median spaces are narrow and slightly
depressed.
- Apical system: The anal opening is near to Ocular I and Genital 5. The genital
plates carry each a distinctly large tubercle and a varying number of
miliary tubercles.
- Colour: The denuded test is in general somewhat light purplish to
pinkish grey; the pore zones and the median areas of both the ambulacra
and the interambulacra are olivaceous;
the tubercles are withish to slightly pinkish.
Shigei limits the distribution to Japanese seas from Sagami Bay to Kagoshima Bay; 2-20 m deep. H. Schultz in "Sea Urchins", page 269, reports this species from Sagami Bay to southern Kyushu, 2-20 m deep. Nevertheless, I got my specimen from Indonesia. For comparison another similar specimen from
Indonesia
, however,
matching Shigei´s description and figure not so
perfectly.
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