Rhynchozoon larreyi ( Audouin, 1826 )

Harmelin, Jean-Georges, 2014, Alien bryozoans in the eastern Mediterranean Sea — new records from the coast of Lebanon, Zootaxa 3893 (3), pp. 301-338 : 329-331

Rhynchozoon larreyi ( Audouin, 1826)

( Fig. 15 A–D; Table 13 )

Cellepora (?) larreyi Audouin, 1826: 239 [ Savigny 1817: pl. 8, fig. 5.].

“ Cellepora ” lareyi (sic): Balavoine 1959: 277, pl. 6, figs 3–4.

Rhynchozoon larreyi: Harmer 1957: 1074 (part), pl. 70, figs 12, 16–20;? Powell 1969b: 361; Dumont 1981: 636 (list); d’Hondt 1988: 194 (list); d’Hondt 2006: 33.

Rhynchozoon lareyi (sic): Ünsal & d’Hondt 1978: 624.

Rhynchozoon globosum: Powell 1967a (fide Powell 1969b). Non Rhynchozoon globosum Harmer, 1957: 1072 .

Non Rhynchozoon larreyi: Ristedt & Schuhmacher 1985: 167 , figs 1–3; Gordon 1989: 74, pl. 43B–D; Gordon & Mawatari 1992: 35, pls 3B, 10C.

Material examined. Specimens from Lebanon: 1) Stn 2A, 2 colonies; 2) Stn 3A, 1 colony on biogenic concretion; 3) Stn 4A, 1 colony; 4) Stn 5A, 1 colony on Phyllangia mouchezi ; 5) Stn 5B, 2 colonies on Spondylus spinosus shell; 6) Stn 5D, 1 colony; 7) Stn 11A, 2 colonies on dead Reteporella sp. and Spondylus shell; 8) Stn 16An 3 colonies on Spondylus shell. Other material examined: 1) MNHN, specimens recorded as Cellepora lareyi (sic) by Balavoine (1959), Dollfus coll., Al Sayad survey in Gulf of Suez: No. 7836, Stn XI, 8 December 1928; No. 7849, Stn XII, 28 December 1928, on scleractinian (colony figured by Balavoine 1959, pl. 6, fig. 3–4); 2) SEM photos of Rhynchozoon NSP03, northern Bay of Safaga, Red Sea, posted by Ostrovsky et al. (2011).

Description. Colony encrusting, unilamellar, well calcified. Autozooids disposed in files, frontal shield distinctly nodular, 4–6 large areolae on each side, separated by ridges. Primary orifice frontally exposed in newly formed zooids at growing edge, deeply immersed in older zooids, around 10% wider than long; anter denticulate with 10–14 small, widely spaced beads; condyles medium-sized, step-shaped; proximal sinus broad, shallow, rounded. Peristome lacking pseudosinus, typically with raised median process, variably sized, conical when short, cylindrical when long, with tapered tip or sometimes a little inflated with a granular surface, often flanked by shorter, irregularly shaped and sized mucros. Two oral spines occasionally present in young zooids. Large suboral avicularium visible frontally in zooids near growing edge, in raised, swollen chamber replacing median umbo; mandible long, triangular; rostrum hooked, raised obliquely and directed laterally; crossbar complete. In older zooids, suboral avicularium immersed in inner side of peristome, not visible frontally. Frontal avicularium occasionally present, smaller than suboral avicularium, with narrow triangular rostrum directed proximally. Ooecium with thick, nodular rim of ectooecium and large, semicircular frontal exposure of smooth endooecium.

Remarks. Cellepora (?) larreyi was introduced without description by Audouin (1826) for Savigny’s (1817) beautiful drawing of a colony of which the origin, Red Sea or Mediterranean, is unknown. As Savigny’s collection is lost (d’Hondt 2006), the only morphological traits offering a basis for defining this species are those provided by Savigny’s figure. This colony is unilaminar, small (<100 zooids), with recumbent zooids arranged in staggered files, presenting a frontal wall that nodular or seemingly costate; the orifices near the colony edge are rounded, but are hidden by a peristome with 2–4 conical or digitate processes in older zooids; ooecia are numerous and appear early in astogeny, many of them being either incompletely formed or partially broken; avicularia and oral spines are apparently absent. These features revealed by Savigny’s picture are insufficient for modern discrimination of Rhynchozoon species. In this genus, species may present large morphologic variations that may overlap those occurring between closely related species ( Dick & Mawatari 2005). However, the general appearance of the colony pictured by Savigny, particularly the shape of the peristome, recalls both the specimens from the Gulf of Suez reported as ' Cellepora ' lareyi (sic) by Balavoine (1959) and those from Lebanon presented here. Therefore, the decision to ascribe the Lebanese specimens to R. larreyi is in part arbitrary.

The Lebanese material of R. larreyi shows a broad range of morphological variation within- and between colonies. Features that appear to be diagnostic and relatively constant are supplied by the primary orifice, peristome, suboral avicularium (when present) and ooecium, particularly its endooecial frontal area. The two orificial spines in newly formed zooids are also a diagnostic feature, but they are rarely observed.

The occurrence of R. larreyi in the SE Mediterranean ( Turkey: Ünsal & d’Hondt 1979; Çinar et al. 2011; Lebanon: present records) results most probably from a Lessepsian migration. Several common features suggest that R. larreyi and Rhynchozoon sp. 1 Hayward (1974) from Chios (see also Zabala & Maluquer 1988) may be closely related. The migratory capacity of R. larreyi had been suggested by its presence in New Zealand according to Powell (1967b), who had encountered it in a Gulf of Suez sample ( Powell 1969b). Accepting Powell’s identification, Gordon & Mawatari (1992) reported it from New Zealand ports, but according to Gordon (2009), New Zealand records of R. larreyi correspond to R. zealandicum Gordon, 2009 , a widespread shelf and coastal species, and it is likely that most figures of R. larreyi given by Harmer (1957) also do not illustrate this species. It occurs in natural habitats of the Egyptian coast of the Red Sea as proven by SEM photos of specimens collected in the Northern Bay of Safaga and reported as Rhynchozoon NSP03 by A. Ostrovsky and J. P. Cáceres-Chamizo (http/ /palse2.pal.univie.ac.at/Bryozoa/Safaga_Bay/Safaga_Bay.html; pers. comm.). In contrast, the large pink colonies from Eilat recorded as R. larreyi by Ristedt & Schuhmacher (1985) belong to another species, which differs in the shape of the primary and secondary orifices and the suboral avicularium (J.P. Cáceres-Chamizo, pers. comm., based on SEM examination of Ristedt’s material). Obviously, records of Rhynchozoon need the support of a whole range of detailed images for adequate interpretation ( Dick & Mawatari 2005). A thorough revision of Rhynchozoon species from the whole of the Mediterranean and the Red Sea is obviously required. At several Lebanese stations, R. larreyi co-occurred with native Rhynchozoon pseudodigitatum Zabala & Maluquer, 1984 and Rhynchozoon neapolitanum Gautier, 1962 .

Figures

FIGURE 15. Rhynchozoon larreyi (Audouin, 1826), Lebanon; A from Stn 16 A; B – C from Stn 5 A: A, part of colony showing ovicelled zooids with raised granular processes; B, ovicelled zooids, one bearing a large, hooked, suboral avicularium; C, primary orifice with beaded anter. Scale bars: A, B, 200 µm; C, D, 100 µm.

Tables

TABLE 13. Rhynchozoon larreyi, measurement of the primary orifice in six colonies from Stns 2 A, 5 A, 5 D, 11 A and 16 A.

R. larreyi	X	SD	Range	X
Or L	110	6	100–125	22
Or W	121	5	115–135	22