Cetoconcha, DALL, 1886

Machado, Fabrizio Marcondes, Passos, Flávio Dias & Giribet, Gonzalo, 2019, The use of micro-computed tomography as a minimally invasive tool for anatomical study of bivalves (Mollusca: Bivalvia), Zoological Journal of the Linnean Society 186, pp. 46-75 : 62-64

publication ID	41CC8EA-67BE-4627-B941-C9E66E35972E
publication LSID	lsid:zoobank.org:pub:41CC8EA-67BE-4627-B941-C9E66E35972E
persistent identifier	https://treatment.plazi.org/id/039A8786-3A2A-B93A-FF52-F923697AF9CD
treatment provided by	Plazi
scientific name	Cetoconcha
status

Treatment

CETOCONCHA View in CoL AFF. SMITHII (DALL, 1808)

( FIGS 14, 15)

Description

Shell: Ovate-trigonal, thin, inflated, slightly translucid, with prominent umbones, inflated; sculpture of radial lines of micro-pustules for the entire ventral surface of the valves; without lithodesma.

Mantle: Ventral mantle margin with one anteriorly wide pedal gape extending from the anterior adductor until the inhalant siphon; without a fourth pallial aperture.

Siphons: Separated, different in size and outline; inhalant siphon, large, modified in a raptorial appendage, typically retracted into the infra-septal chamber; exhalant siphon short, cone-like and everted in our specimen; both surrounded at the base by a ring of siphonal tentacles, ~ten around the inhalant and ~three around exhalant.

Septum: Thin, perforated by three rows of grouped pores without interfilamental connections, the two anterior groups lie in a similar position to those of Cetoconcha spinosula comb. nov. and the third and smallest group lies behind the posterior septal muscles; bilobate hollow sac not observed in the posterior inner septal floor. With nine pairs of pores in the anterior group, five in the middle and three in the posterior group.

Labial palps: Non-lamellate and asymmetrical with anterior labial palps large, thin (probably contracted), cup-shaped and the posterior labial palps small.

Musculature: Posterior and anterior adductor muscles present and isomyarian; with posterior and anterior pedal and septal retractor muscles; prominent lateral septal muscles present; taenioid muscle absent.

Foot: Large, pedal groove not observed, without byssal thread.

Digestive system : The funnel-shaped mouth opens into a thick and muscular oesophagus that enters the anterodorsal portion of the stomach; stomach large, rounded, with longitudinal deep internal grooves in the dorsal wall, connected to the short and small crystalline style sac located in the median portion of the stomach floor; prey observed inside the stomach (ostracod: Fig. 14 A 2); stomach surrounded dorsally and

64 F. M. MACHADO ET AL .

anteriorly by gonads and digestive gland; crystalline style sac not visible in this specimen.

Reproductive system : May be dioecious, only ovary is visible in our specimen; ovary closely associated to the digestive gland, covers the roof of the stomach.

Nervous system : only the visceral ganglia were observed.