Excentroconchidae Hollande & Enjumet, 1960 sensu Dumitrica 2014
Creators: name: Suzuki, Noritoshi
name: Caulet, Jean-Pierre
name: Dumitrica, Paulian
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Excentroconchidae

description: Family EXCENTROCONCHIDAE Hollande & Enjumet, 1960 sensu Dumitrica (2014a)
Excentroconchidae Hollande & Enjumet, 1960: 68, 86. — Dumitrica 1979: 18; 1984: 94; 2001: 193-194 (sensu emend.); 2014a: 59-60 [in Entactinaria]. — Petrushevskaya 1979: 105. — Kozur & Mostler 1979: 33. — Anderson 1983: 50. — Cachon & Cachon 1985: 288 [in the Order Periaxoplastida].
TYPE GENUS. — Excentroconcha Mast, 1910: 64 [type species by subsequent designation (Campbell 1954: D67): Excentroconcha minor Mast, 1910: 64].
INCLUDED GENERA. — Excentroconcha Mast, 1910: 64. — Gonosphaera JØrgensen, 1905: 132. — Lonchosphaera Popofsky, 1908: 217 (= Arachnostylus synonymized by Dumitrica 1984: 94).
DIAGNOSIS. — The central structure consists of an MB, two A-rays, four B-rays (rarely two), one to three AA-rays, and a central frame. The MB is also a part of the central frame. A-rays, B-rays and AArays are oriented towards upper, lateral (equatorial) and lower directions, respectively, from the central frame. A-rays emerge from both ends of MB. Four B-rays extend laterally from each corner of the central frame at the equatorial plane. The central frame is vertically subdivided into upper and lower hemispheres by the height level of the central frame where B-rays are joined. The upper hemisphere of the central frame is constructed by the MB and four to three downward rays. The lower hemisphere is variable but two sets of the four downward rays are joined near the opposite side of MB, respectively. The junction point is visible from a view parallel to MB. These two joint points are connected by a small arch at the antapical end of the central frame (named the antapical arch). The plane of the antapical arch is perpendicularly oriented to the length of MB. One to three AA-rays extend from the end of the antapical arch towards the opposite direction of the double A-rays. Some members develop an additional equatorial ring that is also connected by four B-rays and, or, other arches in the lower hemisphere of the central frame. One latticed, one spongy layered cortical shell, or a spherical structure made of coarse spongy meshwork is present. Short to long radial spines directly connected to the internal rays or beams are visible. The by-spine may be present or absent.
Regarding the axopodial system of periaxoplastid-type; the axoplast is located at the center of the protoplasm and a bundle of axonemes radiates from the center. The nucleus is independent of the axopodial system and has an arch shape. No axoflagellum was recognized. The central structure is attached to the capsular wall, placing it at the center of the skeleton. The arched nucleus is placed on the opposite side of the central structure.
STRATIGRAPHIC OCCURRENCE. — early Early Miocene-Living.
REMARKS
This family is specified by reference to fig. 3 in Dumitrica (2014a). Some undescribed species remain. The internal skeletal structure for Lonchosphaera (Helmcke & Bach 1990: 75; Matsuoka 2009: fig. 3.12; Dumitrica 2014a: figs 3.a-3.h) was illustrated. The fine protoplasmic structure was illustrated for Excentroconcha (Hollande & Enjumet 1960: pl. 1, fig. 7; pl. 19, fig. 5; pl. 43, fig. 1) and Lonchosphaera (Hollande & Enjumet 1960: pl. 1, figs 8, 9).
description: Published as part of Suzuki, Noritoshi, Caulet, Jean-Pierre & Dumitrica, Paulian, 2021, A new integrated morpho- and molecular systematic classification of Cenozoic radiolarians (Class Polycystinea) - suprageneric taxonomy and logical nomenclatorial acts, pp. 405-573 in Geodiversitas 43 (15) on page 464, DOI: 10.5252/geodiversitas2021v43a15, http://zenodo.org/record/5101757