Protozoa - Nassellaria - Hsuidae

Original description: Original description: Test multisegmented, exact number of chambers unknown, possibly less than 8 or 9. Outline of test gourd-shaped with a weak to strong stricture in proximal 1/3 portion. Cephalis hemispherical with an apical horn; horn solid and mostly polygonal in cross-section. The proximal portion of test, above stricture, possessing irregularly arranged pores and circular to polygonal pore frames; surfaces of pore frames smooth to rough, occasionally spiny (Pl. 1, Fig. 1c). The distal portion below stricture inflated and having longitudinally and transversally aligned pores and 14 to 19 longitudinal continuous costae; longitudinal costae mostly long, developed at an interval of 2 or 3 rows of pores, and frequently having branches. Immediately below stricture, some discontinuous costae occasionally observed. In complete specimens, costae disappeared at the distal end of test (Pl. 1, Figs. 3a, b, 5).

Original remarks: Hsuum altile sp. nov. is very similar to Hsuum matsuokai Isozaki and Matsuda, 1985b on its form and costal arrangement. The former, however, differs from the latter by lacking robust massive apical horn which is tetraradiate cruciform in cross section and possessing irregular arranged pores on proximal portion of test. On the basis of morphological resemblances and stratigraphic positions, H. sp. "alpha" ( the provisional name of H. altile) is regarded as the ancestor of H. matsuokai. This species also resembles Hsuum sp. B of Takemura (1986) and Hsuum parvulum Yeh, 1987 but differs in having irregular pore frames on proximal part of test and in being larger and gourd-shaped. Hsuum sp. aff. H. mirabundum of Pessagno and Whalen (1982) and Hsuum sp. A of Carter in Carter et al. (1988) are similar to H. altile. However, the former two species can be distinguished from the latter by possessing costae on proximal portion of test.

Etymology: The name is derived from the Latin adjective altilis, meaning stout.

Full reference: R. S. Hori and T. Otsuka. 1989. Early Jurassic Radiolarians from the Mt. Norikuradake Area, Mino Terrane, Central Japan. Journal of Geosciences, Osaka City University 32(6):175-199

Belongs to Hsuum according to R. S. Hori and T. Otsuka 1989

Sister taxa: Hsuum acutum, Hsuum amabile, Hsuum arabicum, Hsuum arenaense, Hsuum belliatulum, Hsuum brevicostatum, Hsuum cuestaense, Hsuum feliformis, Hsuum gratum, Hsuum lucidum, Hsuum lupheri, Hsuum matsuokai, Hsuum maxwelli, Hsuum mclaughlini, Hsuum medium, Hsuum mirabundum, Hsuum modicum, Hsuum mulleri, Hsuum optimum, Hsuum parasolense, Hsuum parvulum, Hsuum plectocostatum, Hsuum robustum, Hsuum rosebudense, Hsuum rutogense, Hsuum tamanense

Type specimen: OCU MR 4020

Ecology: passively mobile planktonic omnivore

Distribution:

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Specimen images are retrieved through the ePANDDA API.