Gephyrotes fortunensis (Martino, Emanuela Di & Rosso, Antonietta 2015)
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Ordo: Cheilostomatida
Familia: Cribrilinidae
Genus: Gephyrotes
Name
Gephyrotes fortunensis Pouyet, 2000 – Wikispecies link – Pensoft Profile
- Gephyrotes fortunensis Martino, Emanuela Di, 2015, Zootaxa 3941: 265-267.
Materials Examined
Material examined.Holotype: FSL117925 late Tortonian, Fortuna (Murcie, Spain).
Description
Description. Colony encrusting unilaminar, multiserial (Fig. 9). Ancestrula and early astogeny not observed. Autozooids distinct, with deep interzooidal furrows, oval (mean L/W = 1.61). Gymnocyst smooth, forming steeply inclined marginal portions of frontal shield, usually visible only proximally. Frontal shield relatively flat, formed by 8–10 costae, more often 9, not including 2 distalmost pairs participating in proximal peristomial rim. Costae 55–75 µm broad, separated by 2–3 intercostal pores, 35–45 µm broad, with 2–4 pelmatidia on each costa, the marginal ones prominent, giving to central part of frontal shield a flatter appearance (Fig. 11). Proximal peristomial rim formed by conjunction of two pairs of raised costae, one pair originating from bifurcation of those most proximal to orifice and projecting upwards, the other pair rising distolateral to orifice; this collar-like structure having centrally a pointed-arch intercostal lacuna and 2 elongated lateral lacunae (Fig. 10, upper left side). Primary and secondary orifice broader than long, semicircular. Oral spines not observed. Tubular structures visible lateral to orifice (Fig. 10, upper part), either small and longitudinally elongate or large and transversely elongate, converging in midline and arching over orifice proximally; they probably correspond to distalmost part of broken costae. Presence of definite avicularia uncertain. Ooecium prominent, subglobular, wider than long, with irregularly shaped patches, possibly corresponding to weaker areas prone to breakage.
Discussion
Remarks. The holotype is characterized by several irregularly shaped zooids that have long 'tails' of gymnocyst as seen in G. nitidopunctatus, probably as an adaptive response to the irregularities of the encrusted substratum or as a result of regeneration after breakage. In the original description, Pouyet (2000) mentioned a large, curved avicularium on each side of the orifice, distally directed. We agree with Berning (2006) in interpreting their apparent presence as an artefact produced by the breakage of the distalmost pair of costae forming the collar-like structure. We similarly interpret the two hollow structures pointing across the orifice proximally in a few zooids (Fig. 10), as well as the two oral spine bases described by Pouyet (2000), located at the corners of the orifice, which exactly correspond to the raised points of the distalmost pair of costae (Figs 11–12). Pouyet (2000) described and figured an ooecium with a median ridge between two fenestrae. Again, we agree with Berning (2006) that these characters and other irregularities derive from mechanical breakage or partial dissolution of a normally subglobular ovicell (Figs 10–11). Specimens of G. fortunensis figured by Berning (2006) show a similar number of costae but a more extensive gymnocyst compared to the type specimen. In addition, Niebla material is better preserved than the holotype, allowing a more precise description of the frontal shield and of the collar-like construction associated with the orifice. Gephyrotes fortunensis differs from the type species G. nitidopunctatus in the appearance of the frontal shield, with a flat central area bordered by a raised rim formed by the prominent proximal portions of the costae. Further differences include the smaller extent of the kenozooidal network. The absence of avicularia cannot be effectively considered as a difference owing to the preservation of the specimens. Berning (2006) also cited peripheral papilla pores as a difference between G. nitidopunctatus and G. fortunensis; these have an elongated slit-like form, lie parallel to the costae and result from the absence of an outer row of costal fusions. This distinction is difficult to ascertain.
Distribution
Distribution. Late Tortonian of the Murcia and Guadalquivir Basins, SE and SW Spain (Fig. 1).
N (colonies, zooids)Mean SD Range Zooid length1, 10 636 72 538–741Zooid width1, 10 394 31 332–449Orifice length1, 5 137 9 130–143Orifice width1, 5 196 17 184–208Ovicell length1, 2 277 47 244–311Ovicell width1, 2 322 54 284–361Avicularia length1, 4 98 6 91–103Avicularia width1, 4 56 3 54–58 N, Number of colonies and number of zooids measured; SD, standard deviation.
Taxon Treatment
- Martino, Emanuela Di; Rosso, Antonietta; 2015: Revision of the bryozoan genus Gephyrotes Norman, 1903 (Cheilostomata, Cribrilinidae) with the description of two new taxa, Zootaxa 3941: 265-267. doi
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