Watersipora subtorquata (d'Orbigny, 1852)

Harmelin, Jean-Georges, 2014, Alien bryozoans in the eastern Mediterranean Sea — new records from the coast of Lebanon, Zootaxa 3893 (3), pp. 301-338 : 314-315

Watersipora subtorquata (d'Orbigny, 1852)

( Fig. 5 A–C; Table 6 )

Cellepora subtorquata d’Orbigny, 1852: 399 .

Watersipora subtorquata: d’Hondt 1988: 199 , figs 6.1–2; Taylor & Gordon 2002: 536, fig. 1; Chimenz Gusso et al. 2004: 101, figs 9–13; Abdel Salam & Ramadan 2008: 9, fig. 3; Vieira et al. 2014: 155 , figs 1–5, 12–16, 18–24, 67, 70. Non Watersipora subtorquata: Gordon 1989: 40 , pl. 20B–H; Gordon & Mawatari 1992: 31, fig. 8E; Ryland et al. 2009: 55 , figs 1, 3, 4A, B, E, F, 5. (More complete synonymy in Vieira et al. 2014).

Watersipora subovoidea: Ryland et al. 2009: 54 , figs 4C, D, G, H. Non Cellepora subovoidea d’Orbigny, 1852: 402 (nomen dubium).

Material examined. Specimens from Lebanon: 1) Stn 2A, 3 colonies on rock fragment and pottery; 2) Stn 5A, small colonies on concretions from cavities; 3) Stn 6A, 1 colony on Dictyopteris ; 4) Stn 6C, 2 colonies on coralline alga; 5) Stn 7A, 5 colonies on Pinctada shell; 6) Stn 8A, 2 colonies; 7) Stn 11A, 1 small colony on rocky fragment; 8) Stn 12C, several colonies on rocks; 9) Stn 13B, several colonies on shells, concretions and pebbles; 10) Stn 14A, 2 colonies on Spondylus shell; 11) Stn 15A, several colonies on various substrata. Other material examined: 1) France, Marseille, commercial harbour, Pinede, 3 February 1971, on mussels; same station, 11 December 1982, 6 m, on barnacles; 2) Spain, Tarifa, port, 3 July 1982, 5 m, on Cladocora ; 3) Italy, Savona, port, October 1972, 5 m, on barnacles.

Description. Colonies small in the collected material, encrusting, unilamellar, moderately pigmented (not observed alive), except for opercula (see below). Zooids subrectangular to hexagonal, relatively short (average L/ W ratio = 1.6) but ranging widely in size (coefficient of variation SD*100/X: 14.1% for Az L, 16.1% for Az W). Frontal shield perforated by numerous, evenly distributed, large pseudopores. Orifice distal, large, wider than long ( Table 6 ), with rounded anter developed on about three-quarters of a circle, poster indented by a broad sinus, rounded or sometimes slightly ogival; condyles narrow in frontal view, corresponding to slight bulging of internal arch of anter, superposed to upper side of ‘shoulders’ of sinus, with tip angular or more rounded. Operculum with dark-brown to black thickening in shape of a broad column with slightly arched sides defining a pair of round to oval fenestrae. Tentacles not observed.

Remarks. According to the recent revision by Vieira et al. (2014), at least four Watersipora species occur in the Mediterranean Sea. Three of them are relatively common: Watersipora complanata ( Norman, 1864) , an Atlanto-Mediterranean species lacking a sinus the generic status of which is open to question ( Ryland et al. 2009), W. cucullata ( Busk, 1854) , apparently endemic to the Mediterranean, and W. subtorquata , a non-indigenous species originally described from Brazil but now spread worldwide in tropical and warm-temperate areas ( Taylor & Gordon 2002; Vieira et al. 2014). The occurrence in the Mediterranean of the fourth species, W. souleorum Vieira, Spencer Jones & Taylor, 2014 , based on type material from the Cape Verde Islands, is attested by specimens collected in the early 20th century at Naples ( Vieira et al. 2014) and recorded by Waters (1909) as Lepralia ? cucullata . Therefore, the current presence of this species in the Mediterranean needs to be confirmed. Identification at species-level of Watersipora colonies having a U-shaped sinus has long been a taxonomic challenge, repeatedly discussed (e.g. Ryland 1974; Soule & Soule 1975). Examination of the types of W. subtorquata and W. cucullata has made possible to specify the diagnostic value of several morphological and morphometric characters, to better characterize these species and to correct previous records ( Taylor & Gordon 2002; Chimenz Gusso et al. 2004; Vieira et al. 2014). Genetic studies have shown that cryptic diversity is remarkably high in Watersipora ( Ryland et al. 2009; Mackie et al. 2006, 2012), obviously in relation with human-mediated dispersal on a wide geographic scale. Particularly in this genus, molecular approaches must be conducted jointly with precise examination of morphological characters.

The Lebanese specimens of Watersipora were ascribed to W. subtorquata based on orificial criteria ( Chimenz Gusso et al. 2004; Vieira et al. 2014)—a rounded sinus (more quadrangular in W. cucullata ), small condyles and a mean width/length ratio of the orifice up to 1.14 in the Lebanese material, i.e. a value close to that of the type specimen (1.18: data from Soule & Soule 1975). The validity of this attribution was confirmed by L.M. Vieira (pers. comm., 19 February 2014).

The distribution of W. subtorquata in the Mediterranean based on published literature and examination of museum specimens ( Soule & Soule 1975; Chimenz Gusso et al. 2004; Abdel Salam & Ramadan 2008; Vieira et al. 2014) includes the eastern basin ( Turkey, Israel, Egypt), the Central Mediterranean ( Malta), the Western Mediterranean (Tyrrhenian and Ligurian seas: Civitavecchia, Naples, Genoa, Savona), and the Strait of Gibraltar (Tangiers). The features of specimens from Marseille stored at the Station Marine d’Endoume attest that W. subtorquata was established in the commercial port before the 1970s, presumably introduced by vessels with fouled hulls.

Figures

FIGURE 5. Watersipora subtorquata (d'Orbigny, 1852), Lebanon; A, C from Stn 2 A; B from Stn 8 A: A, four autozooids at edge of colony; B, orifice; C, distal part of autozooid (angled view) showing a low orificial collar and communication pores. Scale bars: A, 400 µm; B, C, 100 µm.

Tables

TABLE 6. Watersipora subtorquata, morphometrics of five colonies from Stns 5 A, 7 A, 12 C and 13 B.

W. subtorquata	X	SD	Range	N
Az L	825	116	600–1165	50
Az W	520	84	350–680	50
Or L	193	12	170–220	50
Or W	219	130	180–240	50
Or W/L	1.14	0.07	1.00–1.28	50