LOWER CARBONIFEROUS BRYOZOA 
| 
Fig. 25 Rhombopora cylindrica: sp. nov. Line drawing of external 
| features of BMNH PD9507; scale bar = 1 mm. 
] 
some but not all zoaria. 20 to 24 heterostyles (0.01—0.03mm wide) in 
ne or two rows flank autozooecial apertures on all zoaria A 
longitudinal groove frequently occurs between heterostyle rows 
which probably marks the position of the zooecial boundary. 
Acanthostyles have a thick granular core and develop from the base 
pf the exozone. Heterostyles have a thinner granular core and grow 
from within the exozone. Skeletal lamellae are bent around 
hcanthostyles. 
{able 7 Measurements of Rhombopora cylindrica (in mm). N=23. 
xe Mn Mx CVw CVb 
0.76 0.54 1.15 4.40 7.11 
8.75 8 10 10.94 - 
v2 155 4.26 3 6 9.56 10.57 
ADI 219 0.19 0.10 0.35 12222) 7.21 
AD2 219 0.11 0.07 0.18 12.18 8.56 
WT! 219 0.25 0.12 0.55 18.87 6.80 
WT2 219 0.15 0.09 0.32 24.78 6.55 
AD 1 Pil 0.04 0.01 0.13 32.17 2.04 
AD2 21 0.04 0.02 0.10‘ 24.85 2.10 
\H 34 0.04 0.01 0.10 27.86 1.79 
\W 63 0.02 0.01 0.07 20.64 2.01 
fE 18 0.15 0.10 0.20 13.53 5.66 
DISCUSSION. Rhombopora cylindrica is quite distinctive and may 
€ easily distinguished by the presence of oval-circular autozooecial 
pertures, a central axis, a thin exozone, and structurally varied 
canthostyles. 
Coefficients of variation for both zoarial (ZW) and zooecial 
AD1, AD2, IWT1, and IWT2) parameters within colonies are low. 
‘Vw values for metapore diameter (MD1 and MD2) as well as 
ee height (AH) and width (AW) are large. They are due to 
€ space-filling function of metapores, abrasion of acanthostyles, 
nd poor replacement by silica of small skeletal elements. This is 
eflected by examining autozooecia aperture dimensions which 
yere more varied in silicified specimens than in calcified specimens. 
‘oefficients of variation between colonies are all extremely low. 
Millepora similis was first described by Phillips (1841) as a 
pposed coral from the Devonian of south-west England. Phillips 
131 
collected specimens from two localities: Cannington Park, north 
Devon, and Hope, near Torquay, south Devon. M‘Coy (1844) noted 
Millepora similis from the Lower Carboniferous of Ireland (the 
Courceyan of St. Doulagh’s, County Dublin and the Courceyan/ 
Chadian of Gort, County Galway). This identification was the first 
of many that confused two distinct taxa of Devonian and Carbonif- 
erous age. It is unfortunate that of the two slabs labelled Millepora 
similis from the Griffith Collection (NMING F7081, 7082) exam- 
ined by M‘Coy neither contains specimens referable to either taxa; 
but it is evident that M‘Coy described a taxon that is different from 
the Devonian Millepora similis of Phillips (M‘Coy, 1844: 196). 
Subsequently Morris (1854) classified Millepora as a zoophyte 
and transferred M. similis into the genus Ceriopora, considered then 
to be a coral, but now known to be a cyclostome bryozoan. 
Later still, Young & Robertson (1877) described some Carbonif- 
erous bryozoans from the Carboniferous of Scotland, which they 
regarded as being conspecific with Ceriopora similis. Vine (1881) 
followed this description but later (1885) deciding that the former 
generic assignment was incorrect, placed all Carboniferous mate- 
rial, as well as Phillips’ Devonian taxon, into the newly erected 
genus Rhombopora Meek, 1872. 
Rhombopora similis (Phillips, 1841) sensu Vine 1885 has only 
been found in strata of Carboniferous age. It is clear that M‘Coy 
(1844) misassigned a new undescribed Lower Carboniferous 
bryozoan and that this mistake was compounded and reinforced in 
later descriptions of Lower Carboniferous material. 
Phillips’ figured and only extant Millepora similis specimen 
(GSM 7110, ?Hope’s Nose Limestone, Middle Devonian (Eifelian), 
Hope, near Torquay, Devon, England) has been examined. It is a 
poorly preserved specimen which displays both rhomboporid and 
ptilodictyid affinities. The zoarium is composed of dendroid, mod- 
erately delicate, flattened lense-shaped straight bifurcating branches 
1.35—1.80mm in diameter. Autozooecia are developed in eight to ten 
longitudinal rows. Autozooecial apertures are moderately large, 
0.28 x 0.13mm, distinctly rhombic in shape, and closely packed less 
than one diameter apart. Interapertural walls are thin and appear to 
be smooth. A single proximal acanthostyle may be associated with 
autozooecial apertures. These features contrast with the cylindrical 
branches and oval to circular-shaped autozooecial apertures devel- 
oped in R. cylindrica. 
Vine’s figured material (BMNH D294-5: Vine 1887, pl.1, figs 7— 
8) in the collections of the Natural History Museum, London, and 
some Vine material in National Museum of Wales, Cardiff has been 
examined, and all specimens are correctly assigned to the genus 
Rhombopora. They are not conspecific with Phillips’ Devonian 
taxon. 
The Carboniferous material represents a new taxon which is 
described and named here as Rhombopora cylindrica. A new epithet 
is required; similis of M‘Coy cannot be used on account of original 
misapplication of the name through misidentification (Article 49 — 
Code of Zoological Nomenclature, 1985). 
A holotype for Rhombopora cylindrica sp. nov. is designated 
from the Lower Carboniferous of Carrick Lough, County Ferman- 
agh, Ireland. 
STRATIGRAPHICAL RANGE. Carboniferous (Asbian—Pendleian). 
The range of Rhombopora cylindrica has been increased down- 
wards into the Asbian by its discovery in County Fermanagh and 
Nant-y-Gamar, north Wales, where the taxon is quite uncommon. 
DISTRIBUTION. Carrick Lough and Sillees River, County Ferman- 
agh and Nant-y-Gamar, north Wales. Previously recorded and 
described (see discussion) from the Brigantian of the Midland Valley 
of Scotland (Young & Armstrong 1871, Young & Robertson 1877) 
