Schizoretepora aviculifera ( Canu & Bassler, 1930 )

Madurell, Teresa, Jones, Mary Spencer & Zabala, Mikel, 2019, Revision of the Genus Schizoretepora (Bryozoa, Cheilostomatida) from the Atlantic-Mediterranean region, European Journal of Taxonomy 536, pp. 1-33 : 14-17

Schizoretepora aviculifera ( Canu & Bassler, 1930)

Fig. 7 , Table 3

Schizellozoon aviculiferum Canu & Bassler, 1930: 60–62 , pl. VIII, figs 1–13.

Schizellozoon granulosum Canu & Bassler, 1930: 62–63 , pl. VII, figs 6–8.

Material examined

Holotype (by original designation)

TUNISIA • 3 fragments; Kerkennah Is.; Canu coll.; labelled Schizellozoon aviculiferum (specimen figured in original publication); MNHN-IB- 2014-24.

Other material

TUNISIA • 3 fragments; Sfax; Canu coll.; labelled Schizellozoon granulosum (syntype specimen figured in original publication); MNHN-IB- 2014-21 • 1 colony; Golfe de Gabés, st. 17; Nov. 1953; Y.V Gautier and J. Picard leg.; labelled Schizellozoon aviculiferum ; MNHN-IB- 2008-11126 • 2 colonies; same collection data as for preceding; Gautier leg.; labelled Schizellozoon longisetae ; MNHN-IB- 2008-11127 .

Description

Colony erect, regularly fenestrate (reteporiform) ( Fig. 7A ); frontal faces bearing autozooids, abfrontal faces consisting of sheets of kenozooids. Color not noted in live material. Old colonies strongly calcified, branches thick, trabeculae with 3–6 longitudinal rows of autozooids arranged quincuncially ( Fig. 7D, F ). Fenestrae oval, small, often equal or smaller in width than trabeculae ( Fig. 7A, D ).

Autozooids longer than wide, convex, separated by distinct raised sutures. Frontal shield notably nodular, with 6–8 conspicuous areolae ( Fig. 7E ).

Primary orifice semi-elliptical, as long as wide, distal rim with 16–18 blunt denticles, proximal border with U-shaped sinus (wider than long), framed by two acute denticles that form a gutter on the proximal peristomial rim, and flanked by smooth condyles, sloping towards the edges of the sinus ( Fig. 7B ).

Peristome relatively low, variably developed following ontogeny, with proximal lateral flanges distinctly rounded (when compared with S. longisetae and S. imperati ) on younger zooids ( Fig. 7C ), smothered in older zooids ( Fig. 7F ).

Two to six long oral spines, commonly 4–5 in young zooids, articulated (i.e., telescopic) and carinated ( Fig. 7C ), with basal parts thickly fused in distal zooids, one of them particularly large and thick, clublike ( Fig. 7E ). Spines fragile and easily broken off, only two bases remaining in older zooids ( Fig. 7B ).

Two types of frontal avicularia. Adventitious avicularia almond-like, with triangular hooked tip, typically proximo-lateral to orifice and directed disto-laterally ( Fig. 7E ), with slender crossbar and without columella. Giant avicularia on raised cystid (with 2–5 pores) ( Fig. 7F ); orientated perpendicular to frontal plane and directed proximo-laterally; similar in shape to almond-like adventitious avicularia, triangular but with straight borders and a strongly hooked tip; crossbar robust, without columella. Giant and almond-like adventitious avicularia rarely occur in same zooid, the former being more abundant on the central part of branches.

Ovicell typically globular, non-cleithral ( Fig. 7F ), slightly wider than long, hyperstomial in young zooids, subimmersed with secondary calcification; surface rugose imperforate, with large central fissure, widening at the base.

Abfrontal convex and notably nodular ( Fig. 7H ), with large polygonal kenozooids separated by raised sutures, and numerous pores (2 to 8). Abfrontal avicularia always triangular, with straight margins, hooked, variable in number but occasionally very numerous ( Fig. 7G ), of two different sizes, larger on the basis of the fenestrae; with slender crossbar, wide triangular lacuna and without columella. Base of the colonies with numerous kenozooids bearing small oval avicularia.

Remarks

The descriptions by Canu & Bassler of S. aviculiferum and S. granulosum are unfortunate, because they are based on very old material, abraded and fragmented. In particular, they failed to observe the total number of spines and other details of young zooids. The specimens of S. aviculiferum collected by Gautier (MNHN-IB-2008-11126) are the best-preserved and show all the characters well. Gautier mistakenly ascribed the specimen MNHN-IB-2008-11127 to S. longisetae (see Fig. 7C ).

To date, S. aviculiferum has been considered a synonym of the former S. imperati (now S. pungens ), as suggested by Barrosso (1935), Zabala (1986), d’Hondt & Ben Ismail (2008) and Rosso & Di Martino (2016). Barroso (1935) noted that the differences between S. imperati and S. aviculiferum (and also S. pungens ) are limited and of “secondary order”, suggesting that they were probably the same species. Schizoretepora granulosa was never reported again after its description and it was recently considered an equivocal report by Rosso & Di Martino (2016). Canu & Bassler (1930) in their description of S. granulosum pointed out that this species is very similar to S. pungens , the only differences being the grainy frontal and the absence of abfrontal avicularia. Despite most fragments being very calcified, thus the abfrontal avicularia are probably embedded by secondary calcification, an accurate revision of Canu & Bassler’s material ( Fig. 7H ) reveals the presence of the characteristic triangular avicularia.

Overall, the descriptions of S. aviculiferum and S. granulosum were thus based on different parts of the colony and different growth stages that rendered equivocal characters to identify the species. The detailed examination of museum specimens together with the morphometric analysis presented here indicate that both species are the same, characterized by having only one type of frontal adventitious avicularia (triangular) and numerous abfrontal triangular avicularia.

Schizoretepora hassi ( Harmelin, Bitar & Zibrowius, 2007) shows great similarities with S. aviculifera , particularly with the presence of frequent abfrontal avicularia (more abundant at the base of the colony in S. hassi ), the adventitious avicularia typically located proximo-laterally to the orifice and the nodular aspect of the frontal. Differences between S. hassi and S. aviculifera are mainly based on the morphology of the colony and also on measurements, generally larger in S. hassi .

Schizoretepora aviculifera is very similar to S. pungens and differences between both species are very subtle. These differences are explained below (see remarks for S. longisetae ).

Figures

Fig. 7. Schizoretepora aviculifera (Canu & Bassler, 1930). A–B, F–G from Schizellozoon aviculiferum, holotype, coll. Canu (MNHN-IB-2014-24); C from specimen labelled as Schizellozoon longisetae (MNHN-IB-2008-11127); D, H from Schizellozoon granulosum, syntype, coll. Canu (MNHN- IB-2014-21); E from Schizellozoon aviculiferum (MNHN-IB-2008-11126). A. Frontal colony view. B. Primary orifice detail. C. Apical view of colony (note the articulated and carenated spines). D. Old ovicellate colony. E. Detail of young autozooids showing ovicells in formation and adventitiuos avicularia (note the giant club-like spine). F. Ovicellate zooids. G. Abfrontal view with avicularia. H. Abfrontal view showing triangular avicularia.

Tables

Table 3. Measurements of Schizoretepora aviculifera (Canu & Bassler, 1930).

	N	MEAN	SD	MIN	MAX
FL	55	1320	207	746	1774
FW	55	679	160	393	1056
TW	100	744	251	385	1632
Nz	93	4	1	2	6
AzL	142	411	51	278	542
AzW	143	261	35	167	386
OL	71	80	8	66	97
OW	71	80	8	60	97
ApL	48	109	10	89	130
ApW	48	109	9	94	129
AAL	80	88	15	46	127
AAW	80	45	9	29	73
VAL	71	174	48	106	296
VAW	71	90	25	51	159
OVL	40	200	29	132	252
OVW	40	230	22	189	279
AbAL	71	149	53	73	327
AbAW	71	74	25	35	140
AbVL	3	195	51	139	237
AbVW	3	75	6	68	79
Ns	92	3	1	2	6
Np	141	4	1	1	7
Np_Ab	51	3	1	1	6