Powellitheca , Emanuela Di Martino, Paul D. Taylor, Dennis P. Gordon & Lee Hsiang Liow, 2016

Emanuela Di Martino, Paul D. Taylor, Dennis P. Gordon & Lee Hsiang Liow, 2016, On Powellithecidae fam. nov., a new Pliocene to Recent bryozoan family endemic to New Zealand, with the description of Powellitheca gen. nov. (Bryozoa, Cheilostomata), European Journal of Taxonomy 207, pp. 1-17: 4-5

publication ID

10.5852/ejt.2016.207

publication LSID

lsid:zoobank.org:pub:E16CAFB9-F553-4D91-9761-BBBE4E3B3278

persistent identifier

http://treatment.plazi.org/id/43B95C9D-F5C5-4802-B508-A952DA9020A6

taxon LSID

lsid:zoobank.org:act:43B95C9D-F5C5-4802-B508-A952DA9020A6

treatment provided by

Plazi

scientific name

Powellitheca
status

gen. nov.

Powellitheca  gen. nov.

urn:lsid:zoobank.org:act: 43 B 95 C 9 D-F 5 C 5-4802 -B 508 -A 952 DA 9020 A 6

Type species

Powellitheca terranovae  gen. et sp. nov.

Diagnosis

Colony encrusting, with zooids arranged in well-defined longitudinal rows. Zooids with convex, lepralioid frontal shield, regularly and evenly perforated. Lateral zooidal communication through small number of multiporous septula in vertical walls. Orifice dimorphic, wider in maternal zooids. Primary orifice with convex proximal rim and small condyles; not cormidial. Suboral umbo and lyrula present or absent; oral spines lacking. Ovicells hyperstomial. Ooecia of the microporelliform type, large, globular, occupying most of the frontal shield of the next distal zooid. Ectooecium uncalcified. Endooecium thick, granular with deep oval and round pits. Avicularia present or absent, uncommon when present.

Etymology

Named after Neil A. Powell who first described Recent specimens now attributed to this genus in the ‘Terra Nova’ Collection from the Three Kings Islands area, northern tip of New Zealand.

Remarks

The new genus Powellitheca  gen. nov. is introduced for three species of cheilostomes from New Zealand, one of which was previously placed in the Australian genus Emballotheca  . After comparing these species with a specimen of the type species of Emballotheca  , E. quadrata  ( Fig. 1View Fig. 1), it is clear that they differ in several respects, particularly with regard to the morphology of the orifice, ooecium and avicularia. Although both Emballotheca  and Powellitheca  gen. nov. have enlarged orifices in maternal zooids and a similar orificial shape with a convex proximal lip, Powellitheca  gen. nov. lacks the cormidial orifice seen in Emballotheca  , as well as the long and robust condyles with very characteristic downwardly directed, scaled tips ( Fig. 1View Fig. 1 B–C). Ovicells in Emballotheca  are hyperstomial and cleithral. The ooecium is of the lepralielliform type, large, formed by the next distal zooid and occupying its entire frontal shield. The globular ectooecium is calcified, thick-walled, with numerous oval and round pseudopores, in most cases covered by the secondary calcification formed by the four or five distal and distolateral neighboring zooids and separated by thin raised sutures ( Fig. 1View Fig. 1 A, D). Secondary calcification corresponds structurally to the zooidal frontal shield and bears pseudopores that are coincident in position with those of the ectooecium. The endooecium is thin and uncalcified (A. Ostrovsky, pers. comm. 2016). Although Powellitheca  gen. nov. also has hyperstomial ovicells and the ooecium is similarly large and granular, the ooecia are totally different as they have an uncalcified ectooecium and a calcified endooecium typical of the microporelliform type.

Avicularia in the type species of Emballotheca  have a complete crossbar and are directed proximally and towards the midline of the autozooid ( Fig. 1View Fig. 1 B, D–E), whereas in Powellitheca  gen. nov., when present, they have an incomplete crossbar with short condyles and are distally and outwardly directed. In E. quadrata  , avicularia occur constantly paired in female zooids ( Fig. 1View Fig. 1 A, D), but in Powellitheca  gen. nov. they are uncommon and less regularly placed. Another difference concerns the arrangement of zooidal communication pores in the lateral walls, with numerous, small, oval pore chamber windows in Emballotheca  ( Fig. 1View Fig. 1 E), but only a few large and consequently more distantly spaced multiporous septula in Powellitheca  gen. nov.