BRYOZOANS FROM CHATHAM ISLAND 
unknown owing to loss through breakage, but apparently not crossed 
by the angles of adjacent zooids, the opening separate from the 
opesia-orifice. 
REMARKS. This striking species represents a new genus of 
Cellariidae. It appears closest to Melicerita Edwards sensu stricto 
from which it differs, however, in the occurrence of elongate vicari- 
ous avicularia with separate rostral and opesial foramina, and much 
larger combined female zooid and ovicell. As presently constituted, 
the genus Melicerita appears to need splitting. The Pliocene type 
species, M. charlesworthii Morris, 1843, has vicarious avicularia, 
with a large longitudinally oval foramen and no pivots, scattered 
throughout the colony; the ovicell is relatively small with no elabo- 
ration of calcification either side of the opening, and the 
opesia-orifices are not dimorphic (see Bishop 1987). Recent Tierra 
del Fuegian M. temaukeli Moyano, 1997 shares a number of charac- 
ters with the type species. Antarctic Melicerita latilaminata Rogick, 
1956 and M. flabellifera Hayward & Winston, 1994 have similar 
features, except that the avicularian foramen in both species has a 
proximal sinus either side of which is a shoulder for pivoting of the 
mandible. These latter two species could possibly be regarded as 
constituting a subgeneric clade within Melicerita. Several Australa- 
sian species (M. angustiloba Tenison-Woods, 1862, M. chathamensis 
Uttley & Bullivant, 1972, M. knoxi Uttley & Bullivant, 1972, M. 
ejuncida Gordon, 1986) have smaller, interzooidal avicularia con- 
fined to the lateral margins of the colony and the fertile zooids have 
dimorphic orifices with a complex pattern of surface calcification 
adjacent to the opening, sometimes with perforations. These species 
may constitute another subgeneric clade, to which should be added 
Antarctic M. obliqua (Thornely, 1924) and M. hlancoae Lopez 
Gappa, 1981 (which lack avicularia), and M. digeronimoi Rosso, 
1992, all three of which lack dimorphic orifices but have the 
complex surface calcification. Melicerita atlantica Busk, 1884 and 
M. antarctica d’ Hondt, 1984 (which may be conspecific — see Rosso 
1992) differ in too many features to be included in Melicerita sensu 
stricto. 
Suborder ASCOPHORINA Levinsen, 1909 
Family ARACHNOPUSIIDAE Jullien, 1888 
Genus ARACHNOPUSIA Jullien, 1888 
TYPE SPECIES. Lepralia monoceros Busk, 1854, by original desig- 
nation; Recent, Patagonia. 
Arachnopusia gracilis sp. nov. Fig. 93 
HOLotyPe. IGNS BZ 198, from Pukekio, Chatham Island. No 
paratypes. 
NAME. From the Latin gracilis, slender, alluding to the narrow 
bilamellar stem. 
DESCRIPTION. Colony erect, gracile, with thin bilamellar stem 
0.93—1.22 mm wide. Autozooids arranged more or less quincuncially, 
each being surrounded by 5-7 others; length = 0.37—0.60 mm, width 
= 0.14-0.24 mm; interzooidal boundaries merging and not clearly 
defined. Frontal shield more-or-less evenly perforated by 15-20 
small, simple, circular to subcircular or oval foramina. Orifice 0.09 
mm wide, somewhat bean-shaped owing to a median convexity of 
the proximal rim; peristome low (or eroded), the entire colony 
surface being relatively flat. No trace of distal or intraoral spines or 
spine bases. In interzooidal areas and/or distal to some orifices are 
small polymorphs; these appear to be kenozooids, but some may 
35 
correspond to avicularia; of variable shape from oval to distally 
acute, with an inwardly sloping shelf of uniform width surrounding 
the central opesia, also of varying shape. Ovicells not apparent. 
REMARKS. Only two other species attributed to Arachnopusia are 
known from the New Zealand Tertiary: A. unicornis (Hutton, 1873), 
ranging from Otaian (Lower Burdigalian) to Recent, and A. bugei 
Brown, 1952, occurring only in the Waiauan (Serravallian), Southland 
Series (Gordon et al., 1994). Arachnopusia unicornis is known to 
produce erect bilamellar colonies from an encrusting base but they 
are broad and foliaceous, the zooids have fewer, larger foramina, and 
the aviculiferous proximal rim of the peristome is less convex 
(Gordon 1989b). From SEM examination of the holotype specimen, 
Arachnopusia bugei appears not to belong to this genus at all — it 
lacks foramina in the centre of the shield. The combined characters 
of the shield and proximal 1-2 intraoral avicularia (not spine bases 
as interpreted by Brown) suggest inclusion in the Desmacystidae or 
Rhamphostomellidae (see Gordon & Grischenko 1994). 
Family KLEIDIONELLIDAE Vigneaux, 1949 
Genus PAVOBEISSELINA Voigt, 1964 
TYPE SPECIES. Eschara oblita Kade, 1852, by original designa- 
tion; Paleocene, Germany. 
?Pavobeisselina sp. Figs 94, 95 
MATERIAL. IGNS BZ 216, a unique specimen from Pukekio, 
Chatham Island. 
DESCRIPTION. Colony small, fan-shaped, bilamellar, evidently at- 
tached by rootlets in life; height of incomplete colony 3.6 mm; 
maximum width 4.1 mm; thickness 0.48-0.56 mm, being thicker 
towards base. Zooids appear to be arranged quincuncially based on 
the distribution of peristomial orifices but there are no zooidal 
boundaries at the colony surface; length = 0.41—0.47 mm (measured 
in longitudinal section on fractured part of colony), width not readily 
determinable. Peristomial orifices circular or subcircular, 0.14—0.17 
mm in diameter, flush with colony surface. Other perforations 
comprise areolar pores (variable diameter); possible avicularia, 
lacking a crossbar but with a narrow concentric shelf below the 
surface; and the openings of possible spiraminal tubes, but, as is 
typical of this and related genera, the identity of the perforations is 
difficult to determine from their surface distribution alone. 
REMARKS. The family and genus attributions are uncertain. One of 
us (DPG) has examined by SEM external and internal colony 
surfaces in the type species of Kleidionella Canu & Bassler, Beisselina 
Canu, and related genera of equivalent age. Kleidionella and 
Beisselina form erect colonies, often quite robust, from an encrust- 
ing base. Both genera have planar-spherulitic microstructure on the 
inner surface of the frontal shield; Beisselina has a characteristic 
suboral spiraminal pore and tube, lacking in K/eidionella. Beisselina, 
Pavobeisselina, Pseudobeisselina Wiesemann, Beisselinopsis Voigt, 
and a number of other Late Cretaceous-Paleogene genera have 
traditionally been attributed to the family Porinidae, but, based on an 
examination of the frontal shield of the Recent type species P. 
gracilis (Lamarck), Porina is characterised by a lepralioid 
(‘cryptocystidean’) frontal shield. Thus the so-called ascopore in 
Beisselina (see Wiesemann, 1963) is technically a spiramen since it 
does not open into a compensation sac. As indicated by Pouyet 
(1973), Kleidionella has some of the characters of several 
celleporiform genera (umbonuloid shield, large avicularia with cross- 
