Cuffeyella arachnoidea

Classification
Phylum: Bryozoa
Class: Stenolaemata
Order:  Cyclostomata
Genus: Cuffeyella
Species: Cuffeyella arachnoidea (Hall, 1847)

Taxonomic Details

Originally: Aulopora arachnoidea
Includes:Stomatopora arachnoidea, Aulopora frondosa James, 1873, Alecto frondosa, Proboscina frondosa, Stomatopora frondosa, Alecto auloporoides Nicholson, 1875, Proboscina auloporoides, Alecto confusa Nicholson, 1875, and Proboscina confusa (UGA)
History: (Under Stomatopora arachnoidea, Nickles & Bassler, 1900)

  • 1847 Aulopora arachnoidea Hall, Pal. New York, I, p. 76, pl. xxvi, 6a-c, and woodcut on p. 76.
  • 1875 Aulopora archnoidea Nicholson, Pal. Ohio, II, p. 216, pl. xxiii, 1, 1b.
  • Trenton and Cincinnati (Utica, Lorraine, and Richmond): Various localities in New York, Ohio, Indiana, and Kentucky.

Stratigraphic Occurrences

C.aracnoidea_strat

Geographic Occurrences

		
Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations: Members)

  • C5 Sequence (Lower Whitewater, Waynesville)
  • C4 Sequence (Arnheim)
  • C3 Sequence (Mt. Auburn, Corryville)
  • C2 Sequence (Bellevue, Fairview: Fairmount, Mount Hope)
  • C1 Sequence (Clays Ferry/Kope: McMicken, Southgate, Economy, Fulton)

Identification in Hand Sample

  • Zoarium Morphology: Completely encrusting colonies
  • Zoecia: Rounded proximally, pierced by one to four pseudopores
  • Monticules: None visible
  • Wall Morphology: Exterior frontal walls are perforated by large and conspicuous pseudopores, 17-21 micrometers in external diameter and spaced 35-50 micrometers apart
Cuffeyella_arachnoidea800px

Cuffeyella arachnoidea from McMillan Formation of Brown County, Ohio (OUIP 2232)

Published Description

Taylor & Wilson (1996):

  • REMARKS: This species is usually referred to in the modern literature (e.g., Brood, 1975; Dzik, 1981; Anstey, 1986; Bodenbender et al., 1989; Taylor & Wilson, 1994)as ‘Proboscina’ auloporoides (Nicholson, 1875a). Nicholson (1875a, p. 127) remarked on the ‘very considerable superficial resemblance’ between his Alecto auloporoides and Aulopora arachnoidea Hall, 1847. We can find no clear morphologic grounds for separating the two species, both originally described from the Cincinnatian. Similary, two other Nicholson (1875a) species from the Cincinnatiain – Alecto confusa and A. frondosa – are also placed in synonymy with Aulopora arachnoidea Hall, 1847. Alecto confusa was named for irregular colonies encrusting crinoid stems, and A frondosa for colonies with anastomosing branches. Both are interpreted here as ecophenotypic variants.
  • DISTRIBUTION: Cuffeyella arachnoidea is a common, although inconspicuous, fossil found encrusting shells and other hard substrates throughout the North American Cincinnatian Series (Edenian, Maysvillian, and Richmondian Stages, equivalent to the upper part of the Caradocian and the Ashgillian Stages). There are possible occurrences of Cuffeyella in the Upper Ordovician of the Baltic (Bassler, 1911), but these require further investigation. Most specimens of C. arachnoidea have been found in the tri-state region surrounding Cincinnati (southwestern Ohio, northern Kentucky, and southeastern Indiana). Cuffeyella arachnoidea (as “Proboscina”) has also been reported from Cincinnatian rocks in Manitoba (Ulrich, 1889), Wisconsin (Chamberlin, 1883), Illinois (Grabau & Shimer, 1909), and Tennessee (Shimer & Shrock, 1944).
  • COLONY MORPHOLOGY: Colonies are entirely encrusting, generally with narrow multiserial branches (‘ribbon-like’ or ‘probosciniform’), two to four zooids in width. However, parts of colonies may be uniserial (‘stromatoporiform’) or more broadly multiserial. The latter condition results from flabellate branch expansions and /or frequent branch anastomoses which are seen particularly well in Nicholson’s (1875a) figured specimen of Alecto frondosa. Broader branches often include large numbers of kenozooids intercalating between the autozooids. Colonies may attain diameters of at least 40 mm. Branch multiplication is achieved mainly by bifurcation which is dichotomous or asymmetrical, sometimes with one of the two daughter branches significantly narrower than the other, and occurs at variable intervals. Angles of bifurcation are generally higher in early than in later astogeny but the pattern of decrease during astogeny is inexact; most angles in late astogeny range between 60° and 90°. Lateral ramifications are rare in some colonies, common in others. In all colonies preserving the ancestrula, a lateral branch arises from either the left or right side of the distal ancestrular tube opposite the aperture and grows proximally. Therefore, young colonies are ‘bipolar’, with two primary branches growing in almost opposite directions. Subsequent lateral ramifications are distributed through colonies without apparent pattern, and diverge from the parent branch at angles of 40° – 90°. They usually develop opposite apertures but sometimes short and stout, sometimes even rotund. Branch intersections are of three types: abutment, overgrowth and anastomosis. Proximal regenerations from broken branches have not been observed.
  • ZOOID MORPHOLOGY: The ancestrula, frequently preserved is short with a protoecium that is rounded proximally, pierced by one to four pseudopores, passing gradually into the distal ancestrular tube. Post-ancestrular autozooids increase in size through a primary zone of astogenetic change. Autozooidal frontal walls are slightly convex, particularly distally. In zooids with clearly defined outlines, frontal walls are 2-3 times longer than wide; however, in the majority of cases zooidal boundaries are not apparent and it is impossible to determine the frontal dimensions or proportions of autozooids. Uniserial branches occasionally include elongate zooids exceeding 1 mm in length. Septal traces visible in abraded branches show that the basal outlines of medial autozooids vary from rounded rhomboidal to elongate elliptical; autozooids at the edges of branches may be highly irregular. Apertures are small and longitudinally elongate when peristomes are lacking. Peristomes, which are occasionally preserved up to a length of 0.13 mm, taper distally and have circular apertures about 0.06 mm in diameter. A terminal diaphragm may occlude the aperture at a level just beneath the rim of the broken-off peristome. Many terminal diaphragms have one central perforation (?pseudopore), whereas others appear to have several perforations or are imperforate.
  • WALL MORPHOLOGY: Calcified walls comprise the exterior basal wall (basal lamina), exterior frontal walls (including peristomes and terminal diaphragms), and interior vertical walls. Exterior frontal walls are perforated by large and conspicuous pseudopores, 17-21 micrometers in external diameter and spaced 35-50 micrometers apart (centre-to-centre). Pseudopore diameter appears constant through the thickness of the wall. Surfaces of frontal walls consist of a mosaic of sub-equidimensional flattened crystallites, each on average about 5 micrometers in diameter, often fractured along calcite cleavage planes; this fabric may be diagenetic rather than biological in origin as it is very different from the fabric of frontal exterior walls in recent cyclostomates. Abraded zooids stripped of frontal walls show occasional holes in interior vertical walls which are probably interzooidal pores rather than microborings. In tangential thin section, vertical interior walls and peristomes have a laminated microstructure, and both are about 30 micrometers thick. Interior walls include a medial zooecial boundary layer which is up to 5 micrometers thick, and is darker and apparently finer grained than the succeeding calcification.
  • DIMENSIONS: Ancestrula (n=3): protoecium width: 0.07-0.08 mm; frontal length: 0.18 – 0.19; aperture length: 0.05 – 0.06 mm; aperture width 0.05 mm. Autozooids from zone of repetition (n = 10; AUGD 9854 a): frontal length: mean = 0.54 mm (range = 0.45-0.68 mm): frontal width: mean = 0.21 mm (range = 0.20-0.24 mm) apertural length: mean = 0.11 mm (range = 0.09-0.12 mm); apertural width: mean = 0.08 mm (range = 0.08-0.09 mm).

Taylor & Wilson (1994):

  • Encrusting, uniserial or narrowly multiserial zooecia; Distinguished from Coryontrypa inflata: zooids not distinct tear-drop shaped
  • This is the only species of the genus in the Cincinnatian