taxonID	type	description	language	source
3E1DC918FFF2810E7842FC2AFED2BEE0.taxon	discussion	Remarks. Heteractinids are a group of Palaeozoic sponges with anomalous spicules containing a non-actualistic number of rays (de Laubenfels, 1955; Rigby and Nitecki, 1975; Kozur et al., 2008). In almost all cases, the spicules are based on a hexaradiate pattern, sometimes with an additional pair of rays in the perpendicular plane (octactins), or additional radial rays (Kozur et al., 2008). The triradiate or hexaradiate symmetry mirrors that of calcite crystals, which appears to influence the growth form (Jones, 1970), although there is some evidence for the existence of a mineralogically distinct core, as in certain other early sponge groups (Botting and Butterfield, 2005). They are historically and currently regarded as representing the early stem group of Calcarea (Botting and Muir, 2018).	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810E7A8CFC2CFC2CB9DC.taxon	diagnosis	Diagnosis. As for the species, by monotypy.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810E7A8CFC2CFC2CB9DC.taxon	etymology	Etymology. After the Niquivil locality, San Juan Province, Argentina.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810E7A8CFC2CFC2CB9DC.taxon	discussion	Remarks. The closest similarity of the new genus is to Ensiferites Reimann, 1945. Niquivilispongia gen. nov. has comparable body morphology and both genera have fine monaxon-like spicules in addition to octactins. However, the new genus is differentiated by the absence of hypertrophied gastral rays in dermal-layer spicules and the presence of a conspicuous array of long, irregular, hypertrophied heteractinid rays and undulating monaxons, which may constitute a root tuft. The unusual feature of an apparent root tuft may have helped in anchoring the sponge to the substrate. Such a feature is rare among heteractinids, with only Eiffelospongia Rigby and Collins, 2004, possessing a root tuft of sub-vertically aligned monaxons. However, Eiffelospongia requires a careful revision, for it shows so many cross-laid spicules that these could be in fact diagonal stauractins overlaid by longitudinal monaxons, as in Diagoniella (JB personal observation of the type material).	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810D7AF7F9CBFC5BBB3F.taxon	description	Figures 3 - 4 zoobank. org / 3 E 1 D 53 E 0 - 0 F 1 D- 4 D 04 - A 84 C- 6 FE 47 D 989146	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810D7AF7F9CBFC5BBB3F.taxon	diagnosis	Diagnosis. Domal to mound-shaped, encrusting heteractinid sponge with homogeneous, dense spicular net, mainly composed of hexaradiate heteractins (six rays in one plane) and small monaxons. A complex root tuft of irregular undulating monaxon-like spicules and hypertrophied heteractinid rays emerge from the base of the sponge body.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810D7AF7F9CBFC5BBB3F.taxon	etymology	Etymology. From Greek, asteria, meaning stars, referring to the star-like appearance of the heteractinid spicules.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810D7AF7F9CBFC5BBB3F.taxon	materials_examined	Holotype. CEGH-UNC 27593, a section through the sponge in a thin section. Paratypes. CEGH-UNC 27594 - 27595; additional thin sections cutting through sponges, from the type locality. Type locality. Niquivil, Precordillera of Argentina; Middle Ordovician (early Dapingian; T laevis - B navis Conodont zones, Monorthis cumillangoensis Brachiopod Zone).	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810D7AF7F9CBFC5BBB3F.taxon	description	Description. Domal to mound-shaped encrusting heteractinid sponge 4 to 5 cm in maximum diameter (measured at the base). No evidence of central cavity or canals are seen within the homogeneous, dense spicular net, which is mainly composed of hexaradiate heteractins (six rays in one plane) and small monaxons. The heteractine spicules are 1 to 1.5 mm in maximum diameter, and typically 60 – 80 μm in basal ray diameter. No size ranks are observed, although traces of numerous finer spicules are visible in the background. The heteractins are octactine where visible, with six horizontal (in one plane) slightly curved rays and two perpendicular rays, arising from the axis. All rays equal in size and thickness. At a first glance the thin sections appear to show a small number of hexactin-type spicules, with four equal rays in one plane, of the same size as the heteractine spicules, and with similar morphology of evenly tapered, sometimes curved rays. Rays in one plane are generally orthogonal, but some show deviations, including possibly interposed rays bisecting the space between two others (Figure 3 G). However, this is almost certainly an artefact of the angle of section through standard octactins (see remarks). Internal structure of the spicules is generally replaced by coarse calcite cement showing typical drusy texture with increasing crystallite size towards the center. Some spicules show an axial hollow, either irregular (typical of incomplete infill of cavity following spicule dissolution) or with a sharp, circular boundary. In the latter case, the hollow is approximately 100 μm in diameter. In some of the entirely calcitized spicules, there is a circular, axial discontinuity within the structure, of similar dimensions (Figure 4 J-K). A complex root tuft or similar structure emerges from the base of the sponge body in one paratype, the spicules protruding from the base of the sponge either as a continuation or extension of the main spicule rays, or as simple juxtaposed monaxon-like spicules (Figure 3 I-K; Figure 4 C). Some of the spicules included in this skeletal base appear to be fine-rayed heteractins or similar, with shortened lateral rays and extended, undulating basal rays.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFF2810D7AF7F9CBFC5BBB3F.taxon	discussion	Remarks. The possible presence of hexactins is a critical feature for the interpretation of the affinities of the new sponge (Botting and Butterfield, 2005) and needs to be considered carefully. Such features can be especially challenging in thin sections; thin-walled heteractinids like Eiffelia are preserved on rock surfaces, where orientations are consistent, and spicule morphology is easier to assess. For thick-walled heteractinids, there is much more scope for variability in orientation, leading to misleading appearance due to the angle of section. Unfortunately, the small size and the lack of mineralogical contrast of the spicules versus the host rock prevent the use of MicroCT to generate a three-dimensional view. To address this, we considered all possible sectioning planes through an octactine spicule, as some orientations can show the presence of four rays in a plane (appearing as a hexactin or derivative), and we compared this with the observed frequency of such spicules. If the spicules were all octactins, then there is only one orientation of section that would give six visible rays, but three (along each of the coplanar axes) that would make them appear as triaxons (i. e., hexactins / stauractins). Therefore, with random orientation of spicules, we would need to see significantly more than three times as many ‘ hexactins’ as hexaradiate spicules, in order to assume that genuine triaxons were present. Instead, we found that the proportion of apparent hexactins is very low, with at least 20 hexaradiate views for each four-rayed view within a given field of view. This is much lower than expected for a random orientation of octactins and indicates a preferred orientation with the six coplanar rays approximately parallel to the angle of section (which appears to be parallel to the body wall). Overall, it is most likely that the apparent four-rayed spicules are in fact octactins cut through one of three possible planes. Differentiation from other genera of the family was discussed under the genus heading. Distinction between species of the genus, if more are discovered, should be based on minor skeletal features, such as spicule net arrangement, types and proportions of spicules, or their size and arrangement. Development of canals could also be taken into account for species differentiation, together with any consistent difference in body form.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFFE81027842FFACFD00BB0E.taxon	discussion	Remarks. Rigby (1970) erected the genus Mattaspongia and the family Mattaspongiidae because there were no comparable genera within what he considered to be the closest family, the Dictyospongiidae Hall and Clarke, 1899. The visible characters of Mattaspongia did not fit well with the definition of the Dictyospongiidae, as the genus lacks a woven meshwork and the spicules are effectively loose within soft tissues (the lyssacine condition). However, Finks and Rigby (2004 b) refined the definition of the Dictyospongiidae to include six subfamilies, with the genus Mattaspongia included in the Subfamily Thysanodictyinae, Hall and Clarke, 1899, which involves “ Dictyospongids with coarse ridgelike, quadrate mesh that may represent radially erect lamellae, spicule bundles, coarse pentactins or a combination thereof ” (Finks and Rigby, 2004 b: 398). This still does not reasonably accommodate Mattaspongia, as it possesses a quadrate mesh but this reticulation lacked any coarse, ridge-like development, or even overlapping spicule rays. However, it is distinct from earlier reticulosans in being dominated by a single size of hexactin, rather than having subdivided quadrules. We therefore follow Rigby’s (1970) original interpretation, including Mattaspongia tentatively within its own family, and rejecting an assignment to the dictyosponges.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFFE81007A31F8E5FE26BFD9.taxon	description	(Figure 5 E-F)	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFFE81007A31F8E5FE26BFD9.taxon	materials_examined	Material. A single thin section from the San Juan reef mound block at Niquivil locality Middle Ordovician (Dapingian), CEGH-UNC 27597.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFFE81007A31F8E5FE26BFD9.taxon	description	Description. A single thin section from a reef mound slab shows a fragmented skeleton of a sponge composed of fused sphaeroclones that form an isodictyal net with triangular interspaces in all directions. The sphaeroclones are six-armed anapodal desmas (dichotriders) with terminal expansions (zygosis). The spicule net shows an open structure, at least as far as is visible in the small area preserved, with sphaeroclones being anaxial desmas with five to six ray-like arms extended from one side of a globular centrum and showing knobby or spiny terminations. The globular centrum of the sphaeroclones in the specimen is variable in size (0.4 to 0.8 mm) and formed by the fusion of the zygome endings of the rays (arms), which are generally slender and long (0.7 to 1.1 mm), forming an open triangular structure. In well-preserved sphaeroclones, or incompletely fused centra, the arms are composed of a cladome with a simple bifurcated zygome; the zygomes of multiple spicules interlock to form the globular center.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
3E1DC918FFFE81007A31F8E5FE26BFD9.taxon	discussion	Remarks. The characteristics exhibit by the spicular net seen in the thin section are not fully comparable with, or are difficult to relate to, described astylospongiids. Similar characteristics are seen in the Upper Ordovician and Silurian genera Astylostroma (Rigby and Webby, 1988) and Astylospongiella (Rigby and Lenz, 1978). In particular, Astylostroma has similar zygome junctions; however, the lack of fine detail in the spicule preservation, and the limited material, prevent a more comprehensive comparison. Most of the described genera of the family have a wide distribution but are restricted to the Upper Ordovician and Silurian, with only a few occurrences having been recorded from Middle Ordovician rocks (see Finks and Rigby, 2004 c). It therefore appears that the early Middle Ordovician (Dapingian) age of our material may represent the oldest record of the family.	en	Carrera, Marcelo G., Botting, Joseph P., Cañas, Fernando L. (2025): Heteractinid, hexactinellid and sphaeroclonid sponges as rare components of anthaspidellid-dominated reefs from the Ordovician of the Precordillera, western Argentina. Palaeontologia Electronica (a 17) 28 (1): 1-17, DOI: 10.26879/1351, URL: https://doi.org/10.26879/1351
