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Family: Echinoderidae
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Bocas Species Database Habitat: Mixed mud at 20 m depth Distribution: The species has been reported in Twin Cays, Belize and in the region of Bocas del Toro, Panama. Natural History Notes: The specimens of E. truncatus collected in Panama presented an interesting morphological characteristic, the presence of ventrolateral tubules on segment 4, that had not been mentioned in the original description made by Higgins, 1983. It remains uncertain whether these tubules are unique for the Panamanian specimens or whether they were overlooked in the original species description. Characteristics: The species is recognized by its spine formula (short middorsal spines on trunk segments 4 to 8, and lateroventral spines on trunk segments 5 to 10), the prominent perforation sites and the characteristic truncate tergal extensions. The species also possesses nine oral styles in the mouth cone. There is also the presence of sensory dots and peculiar fringed tubules on most of the trunk segments. The sensory dots are very numerous on the trunk; they present an ovoid shape, one central pore, and numerous small papillae. The tubules are 2.5 µm long, have a thick base and emerge from cuticular perforations. However, their function is not known yet but it is hypothesized to be secretory. The tergal plates and some lateral sternal plates are covered with cuticular hairs that Sørensen describes as “bracteate cuticular hairs”. Notes: Observations were based on three specimens and refer to female morphology only. |