Cribrilaria cf. harmeri Ristedt, 1985

Cribrilaria cf. harmeri Ristedt, 1985

( Fig. 8.1–4 View FIGURE 8 )

Material examined. SMF 40794 (St. 283 KU; Fig. 8.1–4 View FIGURE 8 ).

Description. Colonies encrusting, multiserial, unilamellar ( Fig. 8.1 View FIGURE 8 ). Zooids arranged quincuncially, separated by broad and distinct furrows ( Fig. 8.2 View FIGURE 8 ); 14–20 communication pores within vertical walls of each autozooid (one proximal, 2 × 3–4 proximolateral, 2 × 3–4 distolateral, one distal), circular to transversely elliptical ( Fig. 8.3 View FIGURE 8 ). Ancestrula and early astogeny not observed.

Autozooids rounded subhexagonal, 291–443 μm (ẋ = 352 ± 42 µm; CV = 12; N = 15 on 1 specimen) long by 226–313 μm (ẋ = 281 ± 25 µm; CV = 9; N = 15 on 1 specimen) wide ( Fig. 8.2 View FIGURE 8 ). Gymnocyst surrounding costate shield, smooth, usually with proximal or lateral extensions between adjacent autozooids. Frontal shield moderately convex, consisting of 14–18 costae; 1–2 suboral pores, distalmost suboral pore transversely elliptical, second suboral pore circular ( Fig. 8.4 View FIGURE 8 ). Costae converging and fused at zooidal midline, separated by 6–8 regularly-spaced, longitudinally elliptical costal pores, distalmost pair of costae undifferentiated; pelmatidia on costae not observed. Orifice semicircular, 42–61 μm (ẋ = 49 ± 5 µm; CV = 10; N = 15 on 1 specimen) long by 61–73 μm (ẋ = 68 ± 4 µm; CV = 5; N = 15 on 1 specimen) wide. Oral spine bases numbering six in non-ovicellate and four in ovicellate autozooids, placed lateral and distal to the orifice in non-ovicellate and lateral to the orifice in ovicellate autozooids. Ovicells hyperstomial, globular, 92–110 μm (ẋ = 102 ± 6 µm; CV = 6; N = 15 on 1 specimen) long by 122–140 μm (ẋ = 131 ± 6 µm; CV = 5; N = 15 on 1 specimen) wide; ectooecia completely calcified, smooth, with median longitudinally elongate, elevated ridge proximally ( Fig. 8.2–3 View FIGURE 8 ) .

Avicularia monomorphic, interzooidal, interspersed among autozooids, rare, rounded proximally, elongate distally, bilaterally symmetrical ( Fig. 8.3–4 View FIGURE 8 ).Avicularian aperture proximal, teardrop-shaped; crossbar not observed. Rostrum acute, directed distally.

Kenozooids not observed.

Remarks. Cribrilaria harmeri Ristedt, 1985 , originally described from the Philippines, is a widespread species in the western and central Indo-Pacific, with additional records from Mauritius ( Hayward 1988a). The number of oral spine bases and spines surrounding the ancestrula are generally used as key diagnostic features to distinguish Cribrilaria species (see Ristedt 1985). In Cribrilaria harmeri , non-ovicellate autozooids consistently possess seven oral spine bases, whereas our specimen from the Gulf of Aden has only six ( Fig. 8.2 View FIGURE 8 ). This difference may indicate that our specimen is likely not conspecific with Cribrilaria harmeri . Unfortunately, the ancestrular region in our specimen is damaged, preventing further comparison. Furthermore, the avicularia in our specimen from the Gulf of Aden were broken during bleaching and are only incompletely preserved ( Fig. 8.3–4 View FIGURE 8 ).

Several Cribrilaria species with six oral spine bases are known, including some from the Indian Ocean. Cribrilaria flabellifera ( Kirkpatrick, 1888) from Mauritius differs from our species in having distinct, proximally broad avicularia with a short rostrum (see Ristedt 1985). Cribrilaria africana Hayward & Cook, 1983 , from off East London, South Africa, is more comparable, as it appears to have six oral spines. However, this species has been inadequately imaged, and its avicularia were described as “semi-pedunculate”. Additionally, it possesses up to five large suboral pores.

The assignment of these species to Cribrilaria rather than Puellina Jullien, 1886 , follows Rosso et al. (2018), who differentiated the two genera based on interzooidal avicularia and an imperforate ooecium in Cribrilaria , whereas Puellina (including its type species) lacks avicularia and has a perforate ooecium.