16 
0.47 mm in the zone of astogenetic repetition. Zooidal margin 
somewhat thick-rimmed; the presence of marginal spine bases in the 
present material equivocal owing to inadequate preservation. Proxi- 
mal gymnocyst absent to infrequently present, occupying up to 20% 
of zooidal length, with the proximal ends of the lateral rim encroach- 
ing onto it; or the gymnocystal area slightly depressed, with the faint 
outline of the base of a broken ovicell on it. Avicularia not present. 
Complete ovicells absent, but the base of one broken ovicell (Fig. 
33) clearly indicates a disproportionately small, dependent 
hyperstomial ovicell not closed by the zooidal operculum in life. 
Ancestrula unknown, the ancestrular region missing. 
REMARKS. Better-preserved material is needed to determine if 
oral and marginal spines are truly lacking, and complete ovicells 
would give precise evidence of the relationship of the ovicell open- 
ing to the maternal zooid. 
This is a rare species. The sole colony encrusts a stylasterid 
(Sporadopora cf. marginata Tenison-Woods). 
Genus AKATOPORA Davis, 1934 
TYPE SPECIES. Akatopora clausentina Davis, 1934, by monotypy; 
Lutetian, Southampton, England. 
Akatopora chathamica sp. nov. Figs 34, 35 
IGNS BZ 185-1, from Pukekio Hill, Chatham Island. 
IGNS BZ 185-2; NHM BZ 4781. 
HOLOTYPE. 
PARATYPES. 
NAME. From the name of the main island in the Chathams group. 
DESCRIPTION. Colony encrusting, unilaminate, multiserial, with 
maximum diameter 13 mm. Zooids arranged quincuncially, more or 
less elongate-oval in shape; length = 0.41—0.49 mm, width = 0.24— 
0.28 mm in the zone of astogenetic repetition. Zooidal opesia oval, 
bordered on each side by a narrow lateral cryptocyst, probably 
originally granular, broadening to a sloping shelf proximally. Bounda- 
ries between zooids concealed by contiguous adventitious avicularia 
or kenozooids that occur along the rims; these heterozooids variable 
in shape, generally elongate on the lateral rims in the direction of 
zooid growth, or more subquadrangular to subtriangular at the 
proximal corners of the zooid where they are paired and partly cover 
the cryptocyst; the frontal chamber walls elongated along the mar- 
gins so that adjacent polymorphs are continuous. Heterozooid opesia 
oval; a cross-bar or distinct condylar pivots not evident. Ovicell 
hyperstomial, though somewhat recumbent on the proximal part of 
the cryptocyst of the succeeding zooid; the ectooecial surface smooth 
with a thin median suture line; becoming covered on both sides of 
the suture line by secondary calcification that may represent 
kenozooidal overgrowth. Ovicell probably closed by the zooidal 
operculum in life. Ancestrula unknown, the ancestrular region miss- 
ing. 
REMARKS. Preservation is generally poor but, because of the 
occurrence of ovicells and adventitious heterozooids, is adequate to 
show the distinctive characters of the genus and species. Akatopora 
was first described monotypically by Davis (1934) who interpreted 
the chambers of the interzooidal polymorphs as ‘lacunae’ in 
‘interoecial secondary tissue’, applying the terminology used by 
Lang (1916, 1921) for cribrimorph cheilostomes. Because of their 
variable size he concluded that the lacunae could not be avicularia. 
Subsequently, Gordon (1986) recognised Pleistocene-Recent 
Aplousina (?) circumsaepta Uttley, 1951 from New Zealand as 
congeneric with Akatopora. Study of fresh specimens (deep purple 
D.P. GORDON AND P.D. TAYLOR 
in life) and scanning electron micrographs make it clear that these 
variable-sized chambers are heterozooids comprising both avicularia 
and kenozooids. The avicularia are distinctly differentiated into a 
rostral area and opesia with proximal cryptocyst, whereas 
kenozooidal opesiae are entirely surrounded by a narrow granular 
cryptocyst (see Taylor et al., 1989, fig. 9A). The ovicells of A. 
circumsaepta become covered over by thin kenozooidal chambers, 
and this appears to be the case in A. chathamica. 
Akatopora circumsaepta has a much narrower proximal zooidal 
cryptocyst and lacks an ectooecial median suture, otherwise the two 
species are very similar. Additionally, A. circumsaepta has an obli- 
gate symbiotic relationship with hermit crabs in bryozoan-modified 
gastropod-shell extensions (Tayloretal., 1989;Taylor 1994), whereas 
A. chathamica (two specimens) encrusted what appears to have been 
dead (disarticulated and broken) bivalve shell. No other fossil 
Akatopora species is known in the New Zealand region and A. 
chathamica is the earliest record of the genus globally. 
Family CALESCHARIDAE Cook & Bock, in press 
Genus CALESCHARA MacGillivray, 1880 
TYPE SPECIES. FEschara denticulata MacGillivray, 1869, original 
designation; Recent, SE Australia. 
Caleschara sp. Figs 36, 37 
MATERIAL. IGNS BZ 207, asingle colony from Pukekio, Chatham 
Island. 
DESCRIPTION. Colony of unique specimen encrusting, in places 
multilamellar owing to self-overgrowth. Zooids large, dimorphic, 
arranged quincuncially, length = 0.65—0.97 mm, width = 0.52-0.71 
mm, with distinct interzooidal grooves. The cryptocystal shelf slopes 
inward from the proximal rim where it is highest to the mostly 
horizontal edge of the opesia where it appears to descend abruptly 
toward the zooidal interior; opesiae variable in shape depending on 
overall shape of zooid, ranging from a normally high-arched D 
shape to roundly triangular, widest proximally where it is 0.28—0.46 
mm wide. Brooding zooids larger than autozooids overall, although 
some dimensions may overlap; 0.89—1.03 mm long including ovicell, 
0.69-0.74 mm wide; easily distinguished not only by size but more 
especially by the distal ovicell chamber, which is not concealed by 
cryptocyst in the present material but, owing to poor preservation, it 
is not possible to say if this is because of breakage and loss of a 
cryptocystal cover; because there is no cryptocyst cover the opesiae 
appears very long; width of brooding zooids 0.46—0.50 mm. 
Avicularia not seen. 
REMARKS. Thanks to a recent revision of the genus Caleschara 
and a better appreciation of its characters (Cook & Bock, in press) it 
is now possible to compare the present material with the known 
living and fossil species. Recent Caleschara is mostly Indo-West 
Pacific in distribution, and fossil species are predominantly Austral- 
ian with the exception of the oldest-known species of the genus, C. 
squamosa Meunier & Pergens, from the Danian of Belgium. The 
present material thus constitutes the earliest occurrence of the genus 
in the Australasian region. 
Although preservation of the Red Bluff Tuff specimen is poor, the 
generic attribution appears reliable. Owing to the imperfect expres- 
sion of the characters of the brooding zooids, however, we prefer not 
to erect a new species name until better-preserved material is found. 
Pitting of the skeletal surface is pervasive and even gives the 
impression of holes where oral-spine bases might occur. This is 
