Celleporella hyalina (Linnaeus, 1767)

(Fig. 3A–C, Table 4)

Cellepora hyalina Linnaeus, 1767: 1286 .

Celleporella hyalina: Gray 1848: 128; Hayward & Ryland 1999: 94, fig. 21; Florence et al. 2007: 29, figs. 10D–F.

Schizoporella hyalina: Hincks 1880: 271, pl.18, fig. 1.

Hippothoa hyalina: O’Donoghue 1924: 41; O’Donoghue & de Watteville 1937: 15; O’Donoghue & de Watteville 1944: 424; O’Donoghue 1957: 84; Ryland & Gordon 1977: 38.

Material examined. SAMC-A094507, Morgan Bay (32°42′41.1″S, 28°20′21.7″E), 10 December 2019 . SAMC- A094508-09, Kei Mouth (32°41′03.4″S, 28°22′59.3″E), 10–11 December 2019 . SAMC-A094510, Mazeppa Bay (32°28′25.0″S, 28°39′25.5″E), 28 January 2020 . SAMC-A094518 (on the same substratum as C. atypica n. sp.) (dry), Kidds Beach (33°08′57.3″S, 27°42′09.2″E), 7 March 2020 . SAMC-A094526-27, SAMC-A094528 (on the same substratum as C. atypica n. sp.), St. Francis Bay (34°10′15.7″S, 24°50′06.2″E), 4 August 2020 . SAMC- A094519, Mossel Bay (34°10′52.4″S, 22°09′29.1″E), 26 March 2020 . All material was collected by K.C.K. Ma and is kept dry .

Additional comparative material examined: Celleporella hyalina, SAMC-A073500 (preserved in ethanol), False Bay, rock dredge, collected by J. Gilchrist, 31 January 1959 .

Remarks. Celleporella hyalina has been reported to be widely distributed throughout the northern and southern hemispheres (e.g. Hincks 1880; Morris 1980; Moyano 1986). In South Africa, C. hyalina has been reported from Saldanha Bay on the west coast to Durban on the east coast (O’Donoghue 1924, 1957; O’Donoghue & de Watteville 1937, 1944; Florence et al. 2007).

This species can typically be identified by its elongated, transversely striated frontal wall, often with a lunate umbo below the orifice, orifice of the female zooid wide and short, bearing a porous globular ovicell (Florence et al. 2007). The orifice shape of non-ovicelled zooids shown by Florence et al. (2007, p. 28, fig. 10E, F) differs from the present material in having a deep U-shaped sinus as opposed to a broad shallow sinus (as seen in Fig. 3B). These differences may reflect inter-lineage or interspecific variation. Morris (1980) also described variation in orifice shape for C. hyalina from the Pacific Coast of North America.

Previous reports of C. hyalina from South Africa lack morphological measurements useful to quantify intraspecific variation of South African populations. Therefore, re-examining specimens from previous collections would be necessary for this purpose. In the present material, ovicelled zooids (N T = 5; mean length 0.28 mm by mean width 0.18 mm, Table 4) are smaller than non-ovicelled zooids (N T = 20; mean length 0.42 mm by mean width 0.22 mm, Table 4). The ovicells are prominent, globose and irregular in shape, with 5–11 conspicuous pores (N T = 10; mean number of pores = 8 ± 1) distributed over the entire surface as seen in colony SAMC-A094526.

Some studies have shown that C. hyalina can be considered as a species complex comprising significant morphological variation (e.g. Morris 1980; Navarrete et al. 2005; Grischenko et al. 2007). Integrated morphological, molecular, and reproductive-compatibility studies are required to better understand the C. hyalina species complex (Dick et al. 2005) and to establish species- and population-level diversity within this species complex in South Africa.

Celleporella hyalina forms encrusting patches on mussels (this study), the fronds of kelp, and sometimes pelagic plastic debris in shallow waters (<30 m) from Saldanha Bay on the west coast to Durban on the east coast (Florence et al. 2007).