Gephyrotes moissettei, Martino, Emanuela Di & Rosso, Antonietta, 2015

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 (2), pp. 261-283 : 267-270

Gephyrotes moissettei n. sp.

( Figs 13–22 , 26; Table 3 )

Gephyrotes sp. Moissette 1988: 112, pl. 18, figs 8, 11.

Gephyrotes cf. fortunensis Zágoršek 2010: 140 , pl. 71, figs 1–3.

Material examined. Holotype: PMC.B18.6.9.2006a late Tortonian, Calabria, Italy. Paratype: PMC.B18.6.9.2006b, same details as holotype; FSL 119799 late Tortonian, Fortuna (Murcie, Spain).

Etymology. Named after Dr Pierre Moissette (Université Claude Bernard, Lyon) for his contribution to the knowledge of Miocene bryozoans.

Description. Colony encrusting unilaminar, multiserial ( Figs 13 , 18 ). Ancestrula tatiform. Periancestrular zooids similar to later autozooids but smaller ( Fig. 18 ). Autozooids distinct, with deep interzooidal furrows, arranged quincuncially, oval to irregularly polygonal, almost twice as long as wide (mean L/W = 1.92). Gymnocyst smooth, forming steeply inclined marginal portions of frontal shield ( Fig. 20 ), usually narrow laterally, more extensive proximally, often hidden in frontal view by adjacent zooids ( Figs 14 , 18–19, 22 ). Frontal shield moderately convex, formed by 11–15 costae, more often 13, not including the 2 distalmost pairs participating in the proximal peristomial rim. Costae 30–50 µm broad, separated by 3 large subquadrangular intercostal pores, except for proximalmost pairs in which only 1–2 pores are present. Costal fusion evident, marked by thin slits along entire costal length, enlarged in places, probably corresponding to original position of pelmatidia. 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 second pair originating lateral to orifice as continuations of avicularian rostra, if present ( Figs 17 , 19, 22 ); this collar-like rim with semicircular intercostal lacuna centrally that is smaller than the two elliptical lateral lacunae ( Figs 14–15 , 22 ). Primary orifice broader than long, semicircular with straight or slightly concave proximal margin ( Fig. 16 ); secondary orifice subcircular, bean-shaped in zooids with ooecia. Oral spines absent. Ooecium prominent, subglobular, wider than long, with less-calcified irregularly shaped patches ( Figs 19, 22 ), becoming deeply immersed in distal zooid in late ontogeny by encroaching secondary calcification ( Fig. 15 ). Adventitious avicularia large, usually paired, lateral to orifice, proximomedially directed, sickle-shaped, slender if associated with ordinary autozooids ( Fig. 14 ), squatter if associated with ooecia ( Fig. 15 ); sometimes absent in autozooids. Pivot bar complete ( Figs 20, 22 ) but rarely preserved. Small irregularly shaped or tubular hollow structures, interpreted as kenozooids, frequent along zooidal margins, more often placed lateral and distal to orifice ( Figs 14 , 19 ). Uniporous mural septula in inner vertical walls ( Fig. 21 ).

Remarks. Within-colony variability is mostly related to zooid size and shape, with some of the zooids distinctly shorter than average ( Figs 13 , 18 ). The lace-like appearance of the frontal shield renders G. moissettei n. sp. similar to G. spectabilis (see below) but readily distinguishable from other species of the genus. Gephyrotes moissettei differs from the other Mediterranean species, G. f o r t u n e n s i s Pouyet, 2000 in having more numerous costae, a less extensive gymnocyst and much larger intercostal pores. Further differences are related to the collarlike peristomial complex, which exhibits three transversally aligned intercostal lacunae, with the central one smaller in G. moissettei but more proximal and larger than the two lateral lacunae in G. fortunensis , as figured by N, Number of colonies and number of zooids measured; SD, standard deviation.

Berning (2006, figs 48–49). As mentioned above, we disagree with the original description of G. fortunensis regarding the presence of distally directed avicularia, oral spines, and an ooecium characterized by a median ridge and two fenestrae. Specimens assigned to Gephyrotes sp. by Moissette (1988, pl. 18, figs 8, 11), catalogue numbers FSL119779 and FSL119849, are here synonymized with G. moissettei , as well as with G. cf. fortunensis , specimen P01606, of Zágoršek (2010). Berning (2006, p. 54) already highlighted the differences between Moissette's specimens and typical G. fortunensis . The ancestrula has not been figured, having been accidentally detached during preparation of the specimen for SEM.

Distribution. Langhian of the Czech Republic; late Tortonian of Calabria, southern Italy, and SE Spain; Messinian of Algeria ( Fig. 1 ).

Figures

FIGURE 1. Map showing the spatial and temporal distribution of all the studied species. 1, Gephyrotes nitidopunctatus (Smitt, 1868); 2, Gephyrotes fortunensis Pouyet, 2000; 3, Gephyrotes moissettei n. sp.; 4, Gephyrotes spectabilis Canu & Bassler, 1920; 5, Gephyrotes quadriserialis Canu & Bassler, 1920; 6, Gephyrotes convexus Canu & Bassler, 1920; 7, Tricephalopora saillans (Canu & Bassler, 1920); 8, Tricephalopora levigata (Canu & Bassler, 1920); 9, Spiniflabellum spinosum Canu & Bassler, 1928. Open circles, Recent; solid circles, Miocene; diamond, Oligocene; stars, Eocene; triangles, Danian.

FIGURES 13 – 17. Gephyrotes moissettei n. sp., holotype, PMC. B 18.6.9.2006 a, late Tortonian, Calabria, Italy: 13, part of colony showing the lacy appearance of zooidal frontal shields; 14, close-up of an autozooid bordered by broken tubular kenozooids and exhibiting a secondary orifice with associated, long, proximally directed, convergent avicularia; 15, a zooid with an ooecium and adjacent squat sickle-shaped avicularian chambers; 16, primary orifice; 17, proximolateral view of the collar-like orificial structures and associated avicularia; note the aligned lacunae, the central one smallest. Scale bars: Fig. 13, 500 Μm; Figs 14, 15, 17, 200 Μm; Fig. 16, 100 Μm.

FIGURES 18 – 22. Gephyrotes moissettei n. sp., figs 18 – 21 of paratype, PMC. B 18.6.9.2006 b, late Tortonian, Calabria, Italy; fig. 22 of FLS 119799, late Tortonian, Fortuna (Murcie, Spain): 18, periancestrular area, with smaller autozooids showing a flabellate budding pattern; 19, reproductive zooids; note ooecia with areas of thinner calcification, and associated avicularia and well-developed tubular kenozooids; 20, autozooids and associated peristomial avicularia, one exhibiting a complete pivot bar; 21, zooidal vertical walls showing uniporous septula; 22, several zooids, those with ooecia showing how avicularia contribute to peristomial structure. Scale bars: Figs 18, 19, 22, 500 Μm; Figs 20, 21, 200 Μm.

Tables

TABLE 3. Measurements (in Μm) of Gephyrotes moissettei n. sp., holotype, PMC. B 18.6.9.2006 a.

	N (colonies, zooids)	Mean	SD	Range
Zooid length	1, 15	760	68	737–866
Zooid width	1, 15	411	79	364–502
Orifice length	1, 10	126	4	122–130
Orifice width	1, 10	191	19	171–209
Ovicell length	1, 6	267	10	260–274
Ovicell width	1, 6	321	24	304–339
Avicularia length	1, 10	190	9	182–202
Avicularia width	1, 10	83	7	73–89