Miniacina Galloway 1933

Miniacina es un género de foraminífero bentónico de la familia Homotrematidae, de la superfamilia Acervulinoidea, del suborden Rotaliina​ y del orden Rotaliida.​ Su especie tipo es Millepora miniacea. Su rango cronoestratigráfico abarca desde el Aquitaniense (Mioceno inferior) hasta la Actualidad.

Megalospheric generation with raspberrylike cluster of globular chambers, consisting of proloculus, gradually enlarging second globular chamber, and third larger, ovoid chamber forming a free-living early stage, numerous stolons radiating from the third chamber connect to the surrounding tubular to reniform chambers, microspheric generation with five to nine chambers in an early trochospire of about one and a half whorls; following the juvenile three-chambered or trochospiral stage, the test attaches to a substrate, commonly to other shells, the attached base varying from narrow to spreading, and up to 5 mm in diameter, from this base arise vertical conical to irregularly branching structures up to 7 mm in height, the central core of the branches formed by irregular and bifurcating but nonseptate imperforate and double-walled cylindrical vertical tubes that expand at the open ends, the core surrounded by encrusting compartments termed pillar-pore chambers with tubelike infoldings of the wall at the base, normal chambers occur between the pillarpore chambers and may utilize their walls, successive chambers overlap both the earlier true chambers and pillar-pore chambers; wall of proloculus thick and proteinaceous, succeeding chambers with thick organic layer that is progressively thinner in later chambers, and an outer calcareous layer that may have numerous irregular channels against the organic layer, finally with calcareous layers on both sides of the very thin organic layer, wall light pink to red in color, rarely white, hyaline, of optically radial calcite, small pores of 3 µm to 4 µm in diameter, and larger interspersed pillar-pores up to 50 µm in diameter that open into the pillar-pore chambers and result in a pock-marked surface, wall of pillar-pore tubes imperforate, lamellae may obscure the pores of earlier parts of the wall as new layers of chambers are added; chambers of early stage with one or more apertures at the peripheral margin, adult with one to multiple rounded apertures with phialine bordering lip at the ends of the branches, chambers near the multiple apertures may be subdivided into tubular chamberlets or apertural tubes by intertubular partitions, chambers and pillar-pore chambers interconnected only by the fine wall perforations and not by foramina, large openings at the ends of the branches not involved in later chamber formation. L. Miocene (Aquitanian) to Holocene; cosmopolitan in warm waters. (Loeblich & Tappan, 1987, Foraminiferal Genera and Their Classification)