Exechonella catalinae, Cáceres-Chamizo & Sanner & Tilbrook & Ostrovsky, 2017

Cáceres-Chamizo, Julia P., Sanner, Joann, Tilbrook, Kevin J. & Ostrovsky, Andrew N., 2017, Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology, Zootaxa 4305 (1), pp. 1-79 : 47-50

Exechonella catalinae n. sp.

( Fig. 19 , Table 18)

Material examined. Holotype: DPUV 2012-0002-0001 , on coral rubble. Red Sea, the Northern Bay of Safaga, south of Ras Abu Soma , depth 1–20 m, September 1992 . Paratypes: DPUV 2012-0002-0002 , DPUV 2012-0002- 0 0 0 3, DPUV 2012-0002-0004 , on coral rubble. Red Sea, the Northern Bay of Safaga, south of Ras Abu Soma , depth 1–20 m, September 1992 . Mounted on the SEM stubs and coated with gold: DPUV 2012-0002-0005 , DPUV 2012-0002-0006 , DPUV 2012-0002-0007, on coral rubble. Red Sea, the Northern Bay of Safaga, south of Ras Abu Soma , depth 1–20 m, September 1992 . Other material examined: IPUW 7014 (zooidal fragments mounted on SEM stub, coated with gold). Red Sea, the Northern Bay of Safaga , station B 3/2, depth 4 m, sand between coral patches, 16 July 1987 ; IPUW 7015 , on coral rubble. Red Sea, the Northern Bay of Safaga, south of Ras Abu Soma , depth 1– 20 m, September 1992 ; IPUW 7016 , on coral (mounted on SEM stub, uncoated). Red Sea, Jeddah.

Etymology. Named after the first author’s daughter Catalina López –Cáceres.

Description. Colonies encrusting, unilaminar, multiserial. Autozooids pentagonal, hexagonal or oval in shape, separated by a narrow groove. Primary orifice oval, wider than long, with both anter (two-thirds) and poster (onethird) rounded. Poster sometimes bears tiny central elevation. Anter wall underlain by an inner lamina that is hardly seen in a frontal view. Lamina ends in the proximal one third of the orifice with a pair of small, predominantly triangular condyles, pointed to the midline of the orifice (or slightly proximally). Proximal part of primary orifice is limited by a flat calcified shelf that is a distalmost part of the zooidal frontal shield proximally surrounded by a wall of the peristome. Shelf is smooth centrally and with fine wrinkles laterally in most zooids. Peristome tubular, low, with pustulose surface and smooth, sometimes swelled, rim. Frontal shield smooth or pustulose, evenly perforated by 37–59 (Safaga) and 61–83 (Jeddah) closely-spaced, circular to subcircular foramina, each with wide and smooth gymnocystal rim; fusions of the rims of 2–6 foramina are frequent. Marginal pores small and rounded, easily observed around the autozooidal periphery. Vertical zooidal walls wide, represented by multiporous mural septula with 1–3 rows of communication pores. Two (sometimes one, rarely none) lateral avicularia are present in each zooid, being situated on the external edge of the rim of larger lateralmost foramina (sometimes also occuring in the proximal part of zooid). This part of the rim is often raised having a shape of pointed or blunt projection, and these foramina are the largest in a zooid. Avicularium consists of a shallow depression, sometimes surrounded by a low denticulate rim, with a central nipple-like (low cylindrical or conical) structure with a central pore. Oval or triangular adventitious kenozooids are frequently developed, being recognized by a 3–6 small pores with a centrally perforated cuticular plate. These are often associated with avicularia, but also present in the colonies when the avicularia are absent, and sometimes bud from the ancestrula. Ancestrula autozooidal, having the same size as the rest of autozooids.

Northern Bay of Safaga, Red Sea Jeddah, Red Sea Remarks. E. catalinae n. sp. differs from all other species described in this paper as having the largest zooidal size with the average zooidal length 1.05 mm (Safaga) and 1.20 (Jeddah), and reaching maximal length up to 1.23 mm in some zooids. Except E. elegantissima n. sp., E. nikitai n. sp. and E. kleemanni n. sp. (see below), all other species have the average zooidal length less than 1 mm, although some of them have maximal zooidal size 1 mm or more. To note, the species of Exechonella with the largest zooidal size are E. gigantea Cook, 1967 and E. loslosensis Tilbrook, 2006 having zooidal length 1.2‒1.6 mm and 1.4‒1.7 mm correspondingly.

E. catalinae n. sp. has tubular peristome, primary orifice with flat shelf proximally surrounded by a wall of the peristome, small, predominantly triangular condyles and no step-like curved area below a condyle in the outline of the primary orifice. Together with large zooidal size all these characters are in common with the E. albilitus - complex (see below). However, the appearance of the foramina in E. catalinae n. sp. is more like some species of E. brasiliensis and E. antillea species-complexes.

Other distinctive characters of E. catalinae n. sp. are a dentate (uneven) rim surrounding the nipple-like central structure and raised lateral rim with a blunt or pointed projection in avicularia-bearing foramina, seen in the most of autozooids. Similar projections we observed only in one colony of E. azeezi n. sp. ( E. brasiliensis -complex) that otherwise have simple rim with raised lateralmost part.

We suggest that some numerical differences between colonies from Safaga and Jeddah observed should be attributed to the ecophenotypic variability. Additional material from Jeddah is needed for making this suggestion more precise.

Distribution. Colonies of E. catalinae n. sp. is found in the Red Sea, in Northern Bay of Safaga (western coast) and Jeddah (eastern coast).

Figures

FIGURE 19. Exechonella catalinae n. sp. Red Sea (A, C, F: paratype DPUV 2012 - 0002 - 0006, Northern Bay of Safaga; B, D: E, paratype DPUV 2012 - 0002 - 0007, Northern Bay of Safaga; G, H: IPUW 7016, Jeddah). A, G, general colony view from above. B, close-up of two zooids showing details of primary orifice and peristomes. Three lateralmost foramina shown by arrows. C, D, lateral view of peripheral colony part showing shape of peristomes and multiporous mural septula. E, close-up of lateralmost foramen with avicularium associated with kenozooid in cleaned colony. Central nipple-like structure is surrounded by denticulate rim. Pores of kenozooid have centrally perforated cuticular plates. F, H, details of primary orifice and peristome. Scale bars: A, C = 1 mm; B, D ‒ F = 100 µm; G = 2 mm; H = 400 µm.