Salicornaria stokesii, EDWARDS, 1838

D’Hondt, J. - L., 2006, The Henri Milne EDWARDS’ (1800 - 1885) collection of recent and fossil bryozoa, Linzer biologische Beiträge 38 (1), pp. 25-38 : 34

4. Salicornaria stokesii : Thalamoporella stokesii (MILNE- EDWARDS 1838b)

The jar labelled Salicornaria stokesii (Galapagos Islands, Cuming coll., gift H. Milne EDWARDS) contains two different species. We identified the first (two minute specimens) as Cellaria diffusa ROBERTSON 1905 (species very close to the European C. fistulosa (LINNAEUS 1758) . The second, consisting of many big specimens of a Thalamoporella , constitutes in all probability the true EDWARDS’ species and corresponds to a taxon later redescribed by HASWELL (1880) from Torres Strait under the name of T. novaehollandae, and later found in Indonesia ( HARMER 1926). Neither of these two genera was mentioned from Galapagos Archipelago by CANU & BASSLER (1929) but, according the further researchs of BANTA & REDDEN (1990), both are here respectively represented in fact by two ( C. diffusa ROBERTSON 1905 and C. veleronis OSBURN 1950 ) and one ( T. californica (LEVINSEN 1909)) species.

A – Cellaria diffusa ROBERTSON 1905 . The thin zoarium presents an areolation normally rhomboidal, becoming hexagonal in the areas of the internodes being in reproduction. The autozoecial aperture is situated in the distal half of the zooid; its shape is hemicircular with forewards a convex proximal edge, without lateral incision, containing a lateroproximal tooth at each side, but without opposite distal tooth. The avicularia are few; they measure about 1/3 of the autozoecial length and are approximatively rectangular in shape, a little longer than wide, and bearing a hemicircular mandible, with the free edge distally oriented. The ovicellian pore is wide, in shape of crescent in the peripheral regions of the reproductive part of the zoarium, circular in the middle of it.

B – Thalamoporella . The zoarium is ramified dichotomiously and constituted by claviform branches, enlarged at their distal extremity, quadrangular at the lower part, octogonal in transversal section at the apex. The autozoecial length varies from 0,64 to 0,75 mm, the distal wide being 0,40 mm. A sort of chitinous joint exists at the level of the ramifications, some rhizoids being shortly obvious on the surface. The aperture measures 0,20-0,24 mm in length and 0,20 mm in width, and presents a proximal sinus in shape of very open V. The ovicell is 0,60 mm in diameter, and is incised by a groove of 0,24 mm deepth and 0,28 mm of opening, V-shaped with a round top. The frontal surface (cryptocyst), thinly perforated, is depressed and presents two antero-lateral opesiulae, rather regular in shape, 0,19 mm wide and 0,16 mm long. The avicularian zooid measures 0,60 mm in length; the mandible, generally truncated and much more rarely round at it distal extremity, fall back upon a notch, itself distally curved. A large calcified and mamilliform tubercle exists on the both sides of the aperture.

This form corresponds perfectly to the HASWELL’ S description (1880) and to the illustrated redescription published by HARMER (1926), with a single difference – but bearing nevertheless on a very obvious and significant character –, the presence of the two lateroapertural tubercles. According my own experience of the degrees of intraspecific variability amongst the Bryozoa, I regard this character having only a subspecific value, despite the geographic distance existing between the two regions where this species has been collected. The binomen T. stokesii (senior synonym) has the priority, by anteriority, over T. novaehollandiae (junior synonym) ones. Consequently, the Galapagos specimens must be designated as T. stokesii (EDWARDS 1838) , typical form,and the material from Torres strait and Indonesia becomes T. stokesii (EDWARDS 1838) subsp. novaehollandiae (HASWELL 1880) .