Colpodaspis pusilla M. Sars 1870

Ohnheiser, Lena Tina & Malaquias, Manuel António E., 2014, The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species C olobocephalus costellatus M. Sars, 1870, Zootaxa 3774 (6), pp. 501-522 : 514-515

Colpodaspis pusilla M. Sars 1870

( Fig. 10 A–H)

Colpodaspis pusilla M. Sars 1870: 182 , tab. 11, figs 1–6. Garstang 1894:664 –669, pl. XLIV. Odhner 1939: 10. Brown 1979: 202 –217, figs 1–6, pl. I b, c. Høisaeter 1986: 100. Thompson 1988: 30, fig. 6. Burn & Thompson 1998: 948. Høisaeter et al. 2001: 249. Templado 2011: 402, 403.

Diagnosis. Shell internal, whitish transparent, almost smooth, keeled. Body whitish translucent with white dots. Foot anteriorly lobed, cephalic shield with tentacular lobes. Rachidian tooth absent, one smooth inner lateral tooth, two smooth outer lateral teeth. Elongate penial sheath with short, flat, folded prostate.

Type locality. Drøbak, Oslofjorden, Norway.

Material examined. Mausundvaer, Norway, 2 spcs (dissected), NTNU 11101, H = 2.6, 3.3 mm. Ellingsøya, Norway, 1 spc., NTNU 62589, H = 2.4 mm. Risnesfjorden, Norway, 1 spc, ZMBN 90606, H =?.

Shell ( Fig. 10 D, E, G, H): Maximum H = 2.6 mm. Internal, thin; whitish transparent; globose in shape, keeled, angulated shoulder, aperture wide with thin parietal callus, spire elevated but apex slightly sunken, umbilicate; shell surface with irregular sculpture on inner whorls, last whorl with shallow spiral lines and faint growth lines.

Animal ( Fig. 10 A–C): Body transparent with white dots, foot anteriorly lobed, cephalic shield with long thin tentacles, mantle tissue forms exhalant siphon ( Brown 1979).

Radula: Radular formula 34 x 2.1.0.1.2. Rachidian tooth absent. Inner lateral teeth curved with broad base, inner edge smooth. Outer lateral teeth with broad base, curved, smooth ( Brown 1979).

Male reproductive system ( Fig. 10 F): Elongate penial sheath with short, flat, folded prostate.

Ecology. The species occurs down to 230 m on stones and slag, on Laminaria stipes, red algae, polyzoan colonies and the tube-worm Filograna implexa ( Brown 1979; Thompson 1988; Høisaeter 2009; present study).

Distribution. Occurs in Norway from Trondheim southwards over the British Isles to the Mediterranean Sea ( Thompson 1988; Cervera et al. 2004; Templado 2011; present study).

Remarks. Fischer (1887), Thompson (1976, 1988), and Brown (1979), suggested the possibility of Colpodaspis pusilla being a damaged or juvenile philinid due to radula similarities and considered Colobocephalus costellatus to be a synonym of C. pusilla . Pilsbry (1895: 2) first considered members of both genera to belong to Philine , but later in the same work kept them distinct due to the lack of anatomical data ( Pilsbry 1895: 238).

Figures

FIGURE 10. Colpodaspis pusilla. A. dorsal view of complete animal (automontage picture). B. ventral view of complete animal (automontage picture). C. lateral view of complete animal (automontage picture). D. dorsal view of shell (automontage picture). E. ventral view of shell (automontage picture). F. male reproductive system. Abbreviations: es, exhalant siphon; f, foot; ga, genital aperture; ppl, posterior pallial lobe; pr, prostate; ps, penial sheath. G. detail of shell showing apex (SEM). H. sculpture on dorsal surface of outer whorl of shell (SEM). Scale bars: A - E = 0.5 mm; F = 200 Μm; G = 50 µm; H = 100 Μm.