Sonarina Taylor and Di Martino, 2018

Taylor, Paul D., Martha, Silviu O. & Gordon, Dennis P., 2018, Synopsis of ‘ onychocellid’ cheilostome bryozoan genera, Journal of Natural History (J. Nat. Hist.) 52 (25 - 26), pp. 1657-1721 : 1704-1705

Genus Sonarina Taylor and Di Martino, 2018

( Figure 31 )

Type species

Sonarina tamilensis Taylor and Di Martino, 2018 , by original designation. Cretaceous (late Campanian or early Maastrichtian), Trichinopoly District , Tamil Nadu, India .

Diagnosis

Colony encrusting. Autozooids hexagonal ( Figure 31 (a); boundary walls raised with a medial groove. Cryptocyst extensive, slightly convex, ornamented by a reticulate pattern of polygonal ridges. Gymnocyst lacking. Opesia terminal, occupying one-third to one-half of frontal length, rounded rectangular, longer than wide, the proximal edge slightly flatter than the distal edge, a narrow distal shelf evident in some zooids; oral spine bases lacking. Ovicell hyperstomial ( Figure 31 (b)), wider than long; ooecium cryptocyst-like, continuous with the frontal wall of the distal zooid and covered with the same polygonal ridges; proximal margin concave. Avicularia interzooidal ( Figure 31 (a)), located at row bifurcations as one of the two sibling zooids, oriented proximolaterally, drop shaped, symmetrical or slightly asymmetrical; opesiae elongate elliptical; cryptocyst developed proximally, crescent shaped, depressed, pustulose but not reticulated; no condyles or calcified pivotal bar; rostrum acuminate, resting on the opesial rim of the proximal zooid ( Figure 31 (c)).

Remarks

This monospecific genus from the Late Cretaceous Kallankurichchi Formation of southern India has two distinctive features: reticulate ornamentation covering the cryptocyst and ooecium, and proximolaterally oriented avicularia at row bifurcations. Reticulation occurs in some other Cretaceous onychocellids (PDT pers. obs.) but the proximolaterally oriented avicularia at row bifurcations may be unique to Sonarina among onychocellds.

Range

Cretaceous (Campanian and/or Maastrichtian).

Figures

Figure 31. Sonarina tamilensis Taylor and Di Martino, holotype, NHMUK BZ7849; Cretaceous, late Campanian or early Maastrichtian, Kallankurichchi Limestone No. 3mine Trichinopoly District, Tamil Nadu, India; (a) autozooids and an avicularium (arrowed) at a row bifurcation; (b) ovicellate autozooid; (c) avicularium with rostrum touching the distal end of an autozooidal opesia. Scale bars = 200 µm.