Exechonella azeezi, 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 : 40-43

Exechonella azeezi n. sp.

( Fig. 16 , Table 15)

? Exechonella brasiliensis: Winston & Heimberg 1986 , p. 15, figs 26–27.

Material examined. Holotype: DPUV 2012-0001-0001 , on coral rubble. Red Sea, the Northern Bay of Safaga , south to Ras Abu Soma , depth 1–20 m, September 1992 . Paratypes: DPUV 2012-0001-0002 , DPUV 2012-0001- 0 0 0 3, DPUV 2012-0001-0004 , DPUV 2012-0001-0005 , DPUV 2012-0001-0006 , DPUV 2012-0001-0007 , DPUV 2012-0001-0008 (two last specimens mounted on the SEM stubs and coated with gold), 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 7010 , on coral, Red Sea, the Northern Bay of Safaga , south of Ras Abu Soma , depth 1–20 m, September 1992 ; IPUW 7011 , on living coral. Red Sea, the Northern Bay of Safaga, Sandy Island , 1 November 1984 ; IPUW 7012 , five colony fragments. Red Sea, the Northern Bay of Safaga , 2 August 1987 ; IPUW 7013 , on coral rubble (mounted on the SEM stub and coated with gold). Indian Ocean , Maldive Islands, North Male Atoll, Vabbinfaru Island, depth 10 m, 3 August 2009 ; IPUW 7543 , on coral (mounted on the SEM stub and coated with gold). Red Sea, the Northern Bay of Safaga, west part of Safaga Island , transect A 5, depth 1–2 m, September 1992 ; IPUW 7544 , IPUW 7545, on coral (mounted on the SEM stub and coated with gold). Red Sea, the Northern Bay of Safaga, south of Ras Abu Soma , depth 1–20 m, September 1992 ; IPUW 7546 , on bivalve shell (mounted on the SEM stub, uncoated). Indian Ocean, Maldive Islands, North Male Atoll, Vabbinfaru Island, House Reef , depth 5– 19 m, 12–13 January 2008 .

Etymology. Named after Mr. Abdul Azeez Abdul Hakeem, a prominent local environmentalist and educator, who has generously provided help to many scientists visiting the Maldives.

Description. Colonies encrusting, unilaminar, multiserial. Zooids pentagonal, sometimes hexagonal or oval, separated by a narrow groove. Primary orifice subcircular, wider than long, poster narrower (one-third) than the anter (two-thirds), predominantly of rounded outline, but angular in some zooids. Anter wall underlain by an inner lamina the ends of which form triangular or oval elongated condyles, with pointed or rounded tips pointing medially and typically extending beyond a step-like curved area below. Peristome is low, collar-like, slightly flared, with a pustulose external surface, sometimes bearing low, pointed projections (seen in one colony), rounded or oval in outline, more often narrowing proximally or can be with parallel lateral sides; the proximal edge normally with a prominent central fold-like projection, with a blunt tip, frontally-directed. Frontal shield convex, predominantly pustulose, evenly covered with 13–35 circular or oval, well separated foramina, with a relatively narrow raised rim with a peripheral inner wall surface and smooth or slightly wrinkled gymnocystal sloping walls, surrounding a central lumen. Fusions between foraminal rims not common. Small round or oval marginal pores are obvious. Lateral avicularia are frequent, developing in either or both lateralmost foramina, which are larger than the rest of the foramina; each avicularium is situated on the outer (often raised) edge of a foramen obvious as a shallow depression (sometimes surrounded by a low rim) with a central button-like elevation with thick walls (sometimes cylindrical with thinner walls) and a central pore. In non-cleaned specimens the entire structure is covered with a thin oval operculum. Oval or triangular kenozooids are frequent (even budding from the ancestrula), often associated with avicularia, with a frontal surface bearing 6–8 small pores with centrally perforated cuticular plate. Ancestrula autozooidal, smaller than subsequent autozooids. Vertical zooidal walls wide, with multiporous mural septula with 1–3 rows of communication pores.

Northern Bay of Safaga, Red Sea Maldive Islands, Indian Ocean Remarks. It is worth noting that the colonies of Exechonella azeezi n. sp. from Safaga and Maldives differ slightly in the size of the orifice; it is larger in the Red Sea specimens (average 204×220 µm) than those from the Maldives (178×188 µm); also, although the frontal foramina have the same shape and distribution in both sets of material they are larger, on average, in the Red Sea than in Maldives (77 versus 50 µm).

Exechonella azeezi n. sp. is very reminiscent the specimens described as E. brasiliensis by Winston and Heimberg (1986) from Indonesia, Komodo Island, by Tilbrook et al. (2001) from Vanuatu, and E. similis n. sp. from the Lizard Island, Great Barrier Reef (see below), in several major characters. These are pustulose texture of the frontal shield bearing similar number of foramina of the same shape and distribution pattern, as well as the shape of avicularia and their close association with kenozooids. The differences are (1) primary orifice is subcircular with poster of the same width as anter and rounded outline in all specimens above mentioned, except E. azeezi n. sp. where the poster is narrower than the anter and angular in some zooids; (2) the number of frontal foramina that are less numerous on average in the Indonesian (17) and Vanuatu (19) material in comparison with the Red Sea (24), Maldives (28) and Lizard Island specimens (27); (3) the average size of the foraminal lumen is more similar in the Red Sea (29 µm), Maldives (24 µm) and Komodo (26 µm) material in comparison with the material from Vanuatu (39 µm) and Lizard (34 µm). To note the autozooidal length is quite variable in all localities, from 610–910 µm (Red Sea), 620–900 µm ( Maldives) and 620–760 µm (Komodo), 790–1010 ( Vanuatu) to 667– 877 µm (Lizard Island).

Tilbrook (2006, p. 115) mentioned two specimens—one from the Red Sea and another from the Seychelles, in the collection of the Natural History Museum, London, as “appears to be E. brasiliensis ”. Whether they belong to E. azeezi n. sp. should be checked.

Distribution. Being found encrusting both dead and living corals, Exechonella azeezi n. sp. has a distribution in the Red Sea (The Northern Bay of Safaga), and in the Indian Ocean ( Maldives).

Figures

FIGURE 16. Exechonella azeezi n. sp. (A ‒ G: A, IPUW 7544; B, G, paratype DPUV 2012 - 0001 - 0008; C, IPUW 7543; D, IPUW 7545, non-cleaned; E, F, paratype DPUV 2012 - 0001 - 0007 (all from Red Sea). H, I: D, IPUW 7546; I, D, IPUW 7013 (both from Maldive Islands )). A, general view of the part of colony from above. B, close-up of three zooids. Some lateralmost foramina with avicularia shown by arrows. C, lateral view of the peripheral part of the colony, showing peristome shape and multiporous mural septula. D, lateralmost foramen with avicularium. Arrowhead shows an edge of mandible. E, close-up of lateralmost foramen with avicularium associated with kenozooid (below). Pores of kenozooid have centrally perforated cuticular plates, larger marginal pores are seen laterally. F, G, close-up of two autozooids showing details of primary orifice and peristome. In F kenozooid (k) associated with avicularium (arrowhead) is visible to the left. H, general view of six peripheral autozooids from above. Some lateralmost foramina with avicularium shown by arrows. I, young colony of three autozooids and kenozooid (below). Supposed ancestrula is to the left. Scale bars: A = 1 mm; B, C, F, G, I = 100 µm; D, E = 10 µm; H = 500 µm.