Scaphander amygdalus, Siegwald & Malaquias, 2025

Siegwald, Justine & Malaquias, Manuel António E., 2025, Bringing light into deep-sea biodiversity: a systematic revision and molecular phylogeny of the genus Scaphander Montfort, 1810 (Gastropoda: Cephalaspidea), with a focus on the Indo-Pacific, Zoological Journal of the Linnean Society 203, pp. 1-60 : 42-45

Scaphander amygdalus sp. nov.

( Figs 8 , 28 , 29 ; Table 2)

Scaphander cf. otagoensis 3— Siegwald et al. 2022.

ZooBank LSID: urn:lsid:zoobank.org:act:77914A80-336C-4D73-9155-1E7782C0D529

Etymology: Latin, amygdalum; almond. Named after its almondshaped shell.

Type material: Australia: New South Wales, Hunter Commonwealth Marine Reserve , holotype,dissected and sequenced, AMC.563070 , H = 29 mm . New Zealand: between the South Island and the Chatham Islands , 43°58’55.2”S, 179°37’40.8”E, one paratype, sequenced, NIWA 48567 , H = 13 mm .

Other material examined: Australia: New South Wales, Hunter Commonwealth Marine Reserve, one spc., AM C.590965, H = 27 mm; three spcs, AM C.519357, H = 17–21 mm; one spc., AM C.600442, H = 32 mm; Central Eastern Commonwealth Marine Reserve, one spc., dissected and sequenced, AM C.519351, H = 27 mm. New Zealand: west of the North Island, one spc., sequenced, NIWA 30512, H = 9 mm; off Kahurangi, three spcs, one sequenced, NIWA 30374, H = 10–13 mm; one spc., sequenced, NIWA 30469, H = 9 mm; northeast of Christchurch, one spc., sequenced, NIWA 30258, H = 20 mm; one spc., sequenced, NIWA 30235, H = 8 mm; one spc., sequenced, NIWA 30291, H = 8.5 mm.

Diagnosis: Shell elongate to oval, covered by thin, cream-coloured periostracum. Spiral sculpture composed of ovoid punctations in rows. Spire concealed; posterior edge of outer lip rising slightly above apex. Rachidian teeth sub-rectangular. Prostate short, cylindrical. Penial papilla absent. Penial chamber bulged and lined with soft warts around prostatic duct entrance.

Shell ( Fig. 28 ): Maximum H observed = 29 mm. Shell elongate to oval, widest around centre, only one whorl visible. Aperture wide, as long as shell, narrowing posteriorly. Spire concealed. Posterior edge of outer lip rising slightly above apex. Parietal wall covered with thick, smooth white callus. Spiral sculpture composed of punctuated striations. Punctations ovoid, separate. Periostracum thin, translucent to cream coloured. Shell dirty white to pale yellow.

Radula ( Fig. 29A–C ): Radular formula 19 × 1.1.1 (H = 29 mm). Lateral teeth curved, with weak denticulation on inner edge. Rachidianteethsub-rectangular,withcuspsacutelycurvedinwards.

Digestive tract ( Fig.29D, E ): Salivary glands medium long, surface uneven. Paired gizzard plates sub-triangular to kidney-shaped.

Male reproductive system ( Fig. 29F, G ): Penial chamber cylindrical, lined with soft longitudinal ridges towards genital opening, bulged around prostatic duct entrance, lined with soft warts. Muscular papilla absent. Penial chamber separated from prostate by thin prostatic duct. Prostate short, cylindrical, rounded at end.

Ecology: Found between 531 and 1257 m depth. Feeds on foraminifera (present study).

Distribution ( Fig. 8 ): Southeastern Australia to Western and Eastern New Zealand.

Remarks: This species showed higher than average intraspecific variability for COI, with uncorrected p -distances of 0.18%– 3.22%. However, no significant conchological or anatomical differences were noticed when studying the morphology of these sequenced specimens.

The shell of this species is similar in shape to the shell of S. otagoensis and S. interruptus , two sympatric species. However, p -distances between those species were unquestionably high (10.14%–11.76% between S. amygdalus and S. interruptus , 11.91%–13.39% between S. amygdalus and S. otagoensis , and 9.01%–10.03% between S. otagoensis and S. interruptus ), and S. amygdalus is wider and more centrally rounded, with the rachidian teeth of S. amygdalus being noticeably wider and more indented than those of the other two. The shell of S. amygdalus is also similar to elongate forms of S. mundus but has a more oval shape and pronounced narrowing at both anterior and posterior ends.

Figures

Figure 8. Geographical distribution of Scaphander amygdalus, Scaphander interroptos, and Scaphander otagoensis. Geographical records are based on studied material and reliable literature records.

Figure 28. Shell and SEM image of the shell sculpture of Scaphander amygdalus. A, Australia, New South Wales, Hunter Commonwealth Marine Reserve (holotype, AM C.563070, H = 29 mm). B, New Zealand (paratype, NIWA 48567, H = 13 mm). C, Australia, New South Wales, Central Eastern Commonwealth Marine Reserve (AM C.519351, H = 27 mm). D, New Zealand (NIWA 30258, H = 20 mm). E, Australia, New South Wales, Hunter Commonwealth Marine Reserve (AM C.590965, H = 27 mm). F, New Zealand (NIWA 30469, H = 9 mm). G, Australia, New South Wales, Hunter Commonwealth Marine Reserve (holotype, AM C.563070, H = 29 mm). H, New Zealand (NIWA 30258, H = 20 mm). I, New Zealand (NIWA 30469, H = 9 mm). J, Australia, New South Wales, Central Eastern Commonwealth Marine Reserve (AM C.519351, H = 27 mm). Scale bar: J = 200 µm.

Figure 29. Anatomical details of Scaphander amygdalus. A, radula, Australia, New South Wales, Central Eastern Commonwealth Marine Reserve (holotype, AM C.563070, H = 29 mm).B, rachidian teeth (holotype, AM C.563070, H = 29 mm). C, detail of lateral teeth (holotype, AM C.563070, H = 29 mm). D, anterior part of digestive tract, Australia, New South Wales, Central Eastern Commonwealth Marine Reserve (AM C.519351, H = 27 mm). E, gizzard plates (AM C.519351, H = 27 mm). F, male reproductive system (holotype, AM C.563070, H = 29 mm). G, lining of penial chamber (holotype, AM C.563070, H = 29 mm). Scale bars: A = 200 µm; B = 20 µm; C = 10 µm; D, F = 1 mm; E = 2 mm; G = 500 µm.