Diaphana globosa ( Lovén, 1846 ), Loven, 1846

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 : 503-505

Diaphana globosa ( Lovén, 1846)

( Figs 1 A–H, 2 A–D)

Amphisphyra expansa Lovén 1846: 143 .

Diaphana expansa — G. O. Sars 1878: pl. XI fig. 11; Thompson 1988: 28 –29. Diaphana globosa — Schiøtte 1998: 114, figs 21, 22 B. Høisaeter et al. 2001: 250. Sneli et al. 2005: 95. Høisaeter 2009: 78. Diaphana minuta — Lemche 1948, in part.

Diagnosis. Shell external, transparent, smooth. Body whitish translucent with black dots in live animals. Foot posteriorly bifurcated, cephalic shield with tentacular lobes. Rachidian tooth denticulate, not asymmetrical, lateral teeth with minute denticulation, teeth on left side smaller than on the right.

Type locality. Trondheimfjorden, Norway.

Material examined. Hauglandsosen, Norway, 2 spcs (dissected), ZMBN 88019, H = 3.6,? mm. Hauglandsosen, Norway, 5 spcs (dissected), ZMBN 88018, H = 2.5–3.6 mm. Kristiansund, 63°09’40’’ N, 0 7°44’ E, Norway, 1 spc (dissected), ZMBN 82175, H =?. Bodø, Norway, 1 spc (dissected), ZMBN 82187, H = 3.8 mm. Nesna, 66°12’20’’ N, 13°04’ E, Norway, 1 spc (dissected), ZMBN 82188, H = 3.9 mm.

Shell ( Fig. 1 D–H): Maximum H = 3.9 mm. External, thin; transparent; globose in shape, shoulders rounded, narrowing from widest point in middle of shell towards apex, aperture wide without parietal callus, apex obtuse, protoconch brownish transparent, mammillate, but protoconch not protruding top of last whorl, umbilicated; shell surface smooth, faint spiral lines visible under SEM.

Animal ( Fig. 1 A–C): Body whitish translucent with black dots (in live animals only) on cephalic shield and foot. Foot posteriorly bifurcated, anteriorly widened into two lobes. Broad short cephalic shield with tentacular lobes posteriorly, tips turned upwards in live animal.

Radula ( Fig. 2 A–C): Radular formula 11–12 x 1.1.1. Rachidian tooth with two flat denticulate lobes separated by gap, right lobe slightly larger than left lobe. Lateral teeth long, inner edge denticulate. Radula asymmetrical with left laterals much smaller than the right laterals, one large denticle on tip of left laterals only.

Male reproductive system ( Fig. 2 D): Consisting of two thick branches lying together to form a lump, internal transparent duct on anterior lobe.

Ecology. Between 25–2644 m on mud, stones, sand, fine sand and silt, pebbles, silty sand, shell gravel, gravel, clay and foraminifera ( Schiøtte 1998; Høisaeter 2009; present study).

Distribution. Along the entire Norwegian coastline to northern Portugal ( Schiøtte 1998; Høisaeter 2009), the Faroes ( Sneli et al. 2005).

Remarks. Diaphana globosa was recently redescribed by Schiøtte (1998) and given species status again after being synonymised with D. minuta by Lemche (1948). The species clearly differ in their reproductive systems, radula, and shape of the shell. In the diagnosis of Diaphana we refer that species in this genus have an armed penis ( Schiøtte 1998) but this character was not investigated in this work.

Figures

FIGURE 1. Diaphana globosa. A. dorsal view of live animal (H ~ 3.3 mm). B. ventral view of live animal. C. right lateral view of live animal. D. dorsal view of shell (automontage picture). E. ventral view of shell (automontage picture). F. ventral view of shell (SEM). G. apex of shell (SEM). H. protoconch. Abbreviations: cs, cephalic shield; f, foot; sh, shell. Scale bars: D, E = 250 µm; F, G = 200 Μm; H = 100 Μm.

FIGURE 2. Diaphana globosa. A. radula (SEM). B. detail of lateral tooth (SEM). C. rachidian tooth. D. male reproductive system (drawing). Abbreviations: d, duct, ga, genital aperture, pr, prostate, ps, penial sheath. Scale bars: A = 20 Μm; B = 3 Μm; C = 10 Μm; D = 200 Μm.