Smittina cf. smittiella Osburn, 1947

Smittina cf. smittiella Osburn, 1947 View in CoL

( Fig. 19.1–4 View FIGURE 19 )

Smittina smittiella View in CoL : Sanjay et al. 2020: 39, fig. 19 (non Smittina smittiella Osburn, 1947 View in CoL ).

Material examined. SMF 40785 About SMF (St. 283 KU; Fig. 19.1, 19.3 View FIGURE 19 ) , SMF 10731 About SMF ( 2 specimens; St. 283 KU; A = Fig. 19.4 View FIGURE 19 , B = Fig. 19.2 View FIGURE 19 ) .

Description. Colonies encrusting, multiserial, unilamellar ( Fig. 19.1 View FIGURE 19 ). Zooids arranged quincuncially, separated by salient rims. Septula inside vertical walls monoporous, circular. Ancestrula and early astogeny not observed.

Autozooids irregularly polygonal to subhexagonal, 360–547 μm (ẋ = 447 ± 46 µm; CV = 10; N = 45 on 3 specimens) long by 232–493 μm (ẋ = 327 ± 46 µm; CV = 14; N = 45 on 3 specimens) wide ( Fig. 19.2 View FIGURE 19 ). Frontal shield cryptocystidean, flat, evenly pierced by> 50 circular pores. Primary orifice horseshoe-shaped, cormidial, with bifurcated, anvil-shaped lyrula located proximally ( Fig. 19.3 View FIGURE 19 ); condyles not observed. Peristome salient, terminal, non-porous, pustulose. Secondary orifice squircle-shaped, 96–171 μm (ẋ = 124 ± 15 µm; CV = 12; N = 45 on 3 specimens) long by 98–144 μm (ẋ = 117 ± 10 µm; CV = 9; N = 45 on 3 specimens) wide. Spine bases not observed. Ovicells hyperstomial, globular, 112–194 μm (ẋ = 144 ± 18 µm; CV = 12; N = 42 on 3 specimens) long by 179–238 μm (ẋ = 206 ± 15 µm; CV = 7; N = 42 on 3 specimens) wide; ectooecia evenly pierced by 20–30 circular pores, indistinct from frontal shield pores .

Avicularia monomorphic, peristomial, located within secondary orifice vertically above the lyrula, rectangular with rounded corners, serrated proximally with approximately six triangular denticles, 30–51 μm (ẋ = 41 ± 5 µm; CV = 12; N = 42 on 3 specimens) wide, bilaterally symmetrical ( Fig. 19.4 View FIGURE 19 ). Avicularian aperture centrally located, rectangular, occupying most of avicularian frontal; crossbar complete, at about one-third the avicularian length .

Kenozooids polymorphous, irregularly interspersed among autozooids, pierced by circular pores proximally and centrally, non-porous distally ( Fig. 19.2 View FIGURE 19 ).

Remarks. Our material of Smittina cf. smittiella from the Gulf of Aden closely resembles the specimen illustrated by Sanjay et al. (2020) as Smittina smittiella Osburn, 1947 , from Rathnagiri, Maharashtra, India. In this species, there is only one type of avicularium that is confined to the secondary orifice, located vertically above the lyrula ( Fig. 19.4 View FIGURE 19 ). This contrasts with most other species of Smittina , in which additional adventitious avicularia may be present in the (proximo)lateral corners of the secondary orifice or on the frontal shield.

The true Smittina smittiella was originally described from the Caribbean Sea ( Osburn 1947), and subsequently revised and re-illustrated from Brazilian material by Farias et al. (2020). Compared to the northwestern Indian Ocean specimens, the pseudopores in Smittina smittiella are located inside depressions that are typically overlain by a nodular network of secondary calcification. Additionally, one (or rarely two) small avicularia may occasionally occur in the proximolateral corners of the secondary orifice. Due to these morphological differences, we prefer to refer our material to open nomenclature.

A further comparable species is Smittina nitidissima ( Hincks, 1880a) , originally described from Madeira, Portugal, but also reported from the Red Sea ( Ostrovsky et al. 2011). Smittina nitidissima and Smittina smittiella are morphologically very similar and have been considered part of a species complex that includes also Smittina malleolus ( Hincks, 1884) (see Farias et al. 2020).According to these authors, Smittina nitidissima typically possesses a greater number of additional avicularia around the secondary orifice than Smittina smittiella . Other distinguishing features include differences in the shape of the primary orifice and in the number of denticles associated with the avicularium above the lyrula. Ultimately, only a re-examination of the type material will allow the establishment of more robust species concepts. In light of such a revision, the material from the Gulf of Aden and the Arabian Sea may well represent a distinct, as-yet undescribed species.