Pseudococculinidae Hickman, 1983
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publication ID |
https://doi.org/10.4202/app.01179.2024 |
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persistent identifier |
https://treatment.plazi.org/id/4019EF34-4E69-FF9D-CC7F-FBDB751733B6 |
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treatment provided by |
Felipe |
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scientific name |
Pseudococculinidae Hickman, 1983 |
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Family Pseudococculinidae Hickman, 1983 View in CoL Genus Mesopelex Marshall, 1986
Type species: Mesopelex zelandica Marshall, 1986 ; Recent , New Zealand .
Mesopelex godavariensis Hoffman & Little sp. nov. Fig. 4 View Fig .
Zoobank LCID: urn:lsid:zoobank.org:act:13902726-1A3C-49F9-864E-98E4D1E3C46B .
Etymology: After the type locality in the Krishna-Godavari Basin.
Type material: Holotype, SMF373138 About SMF , relatively well preserved limpet shell with protoconch . Paratype, SMF373139 About SMF , relatively well preserved limpet shell with protoconch .
Type locality: Northern Indian Ocean, Krishna-Godavari Basin , Bay of Bengal, offshore eastern India, 15°51.6335’ N, 81°50.2274’ E, 1046 m water depth GoogleMaps .
Type horizon: 16.28–16.48 mbsf level, core NGHP-01-12A; Upper Pleistocene .
Material. — Type material and several additional specimens from core NGHP-01-12A (for details see Table 1).
Diagnosis.—Small, thin, fragile, patelliform shell, oval apertural outline, apex posterior of midline. Protoconch simple exposed whorl with pitted sculpture.
Dimensions.— Holotype height 2.0 mm, length 2.4 mm, width 0.8 mm.
Description.—Protoconch single stage only, network of spirally and axial line segments, spirally aligned pitted sculpture, planispiral aligned along major height and length axes, 40% from posterior margin, shell leaning posteriorly, fused with teleoconch. Transition to teleoconch clear by change in sculpture, margin indistinct. Length 150 μm. Teleoconch convex sub-elliptical in dorsal view; anterior margin highest convexity. In side view, weakly convex anterior and posterior margins; apical angle high (approximately 160°). Sculpture smooth with fine irregular growth lines. Margin smooth, sharp. Internally smooth, glossy.
Remarks.—A single species has been described in Mesopelex Marshall, 1986 (MolluscaBase 2024). The type species Mesopelex zelandica Marshall, 1986 , was found off New Zealand on muddy sediment ( Marshall 1986: 535–536, fig. 10a–d). Its apex is more raised and its protoconch is less elongated than in Mesopelex godavariensis Hoffman & Little sp. nov. The dorsal outline, protoconch shape and sculpture are very similar to Mesopelex godavariensis Hoffman & Little sp. nov. Pseudococculinid species in other genera have a strong sculpture (for example in the genera Copulabyssia Haszprunar, 1988 , Kaikarapelta Marshall, 1986, Notocrater Finley, 1926 ), a raised shell (for example in the genera Pseudococculina Schepman, 1908 , Pterodacna Herbert, 2024 , Tentaoculus Marshall, 1986 ) or a pointed conical outline ( Punctabyssia McLean, 1991 ).
Stratigraphic and geographic range.— Type locality and horizon only.
Family Fissurellidae Fleming, 1822 View in CoL
Fissurellidae View in CoL gen. et sp. indet.
Fig. 5 View Fig .
Material.— One shell ( SMF373112 About SMF ) from Northern Indian Ocean, Krishna-Godavari Basin , Bay of Bengal, offshore eastern India, 15°51.6335’ N, 81°50.2274’ E, 1046 m water depth, 16.38 mbsf level, core NGHP-01-12A; Upper Pleistocene GoogleMaps .
Description.—Small cap-shaped shell, planispiral coiling. Protoconch paucispiral, three-quarters whorl, smooth, large nucleus, diameter 200 µm. Teleoconch in two stages. First stage half whorl, without selenizone, sculpture with fine radial bifurcating riblets, diameter about 600 µm. Second stage with about 15 radial ribs and commarginal somewhat regular growth margins, weak blunt nodules are formed at the crossings. Shell fragment length about 1 mm, width about 1 mm, thickness about 600 µm.
Remarks.—The shell is too fragmentary to identify below family level.
Family Anatomidae McLean, 1989 View in CoL
Genus Anatoma Woodward, 1859 View in CoL
Type species: Scissurella crispata J. Fleming, 1828 , by monotypy; Recent, NE Atlantic and Mediterranean.
Anatoma sahlingi Hoffman & Little sp. nov. Fig. 6 View Fig .
Zoobank LCID: urn:lsid:zoobank.org:act:C51A4420-6F20-4CF1-9748-8C5B3489F090 .
Etymology: After Heiko Sahling (1969–2018), to celebrate his pioneering work on hydrocarbon seep community ecology.
Type material: Holotype, SMF373130 About SMF . Paratypes, five shells, SMF 373124 About SMF ; one shell, SMF373125 About SMF ; one shell, SMF373126 About SMF ; one shell, SMF373127 About SMF ; 12 shells, SMF373128 About SMF ; four shells, SMF373129 About SMF .
Type locality: Northern Indian Ocean, Krishna-Godavari Basin , Bay of Bengal, offshore eastern India, 15°51.6335’ N, 81°50.2274’ E, 1046 m water depth GoogleMaps .
Type horizon: 16.18–16.68 mbsf level, core NGHP-01-12A; Upper Pleistocene .
Material.— Type material and several additional specimens from core NGHP-01-12A (for details see Table 1).
Diagnosis.—Small, thin, fragile, globose elevated shell, apertural wide anal slit, strong sculpture with spirals and ribs on shoulder, weak spiral sculpture below selenizone, selenizone sculpture weak.
Dimensions.—Maximum length 2.5 mm, height 2.3 mm.
Description.—Protoconch single stage only, three quarters flattened whorl. Sculpture rough, grooved network of dominating spirals and short axial line segments. Transition to protoconch clear by terminating smooth rim and change in sculpture. Length 200 μm. Teleoconch with two stages. First stage without selenizone three quarters whorl, convex, sculpture worn; suture to protoconch deep. Second stage one and three quarters globose whorls, spirals and dominating raised prosocline ribs above selenizone; 50 ribs, 15 spirals on body whorl; ribs extending on margin above selenizone, rib frequency increased near lip. Outline raised with early development of area below selenizone and suture. Very broad selenizone at periphery; sculpture reverse-arched ribs, frequency twice of axial ribs above; extended margins above and below eroded. Lower half whorl evenly convex; sculpture fine spiral lines and fine growth lines, flexuous near base. Deep open umbilicus with spiral lines, near vertical umbilical keel ending on columellar callus. Aperture circular, smooth internally with sharp lip; peripheral slit one fifth whorl deep. Union of parietal lip and shoulder area at 90°. Parietal and columellar lip united, concave, ending in pointed extended lip area.
Remarks.—Anatomids in the Indian Ocean were reviewed by Geiger (2012) and Hoffman et al. (2022). Hoffman et al. (2022) identified 17 species in the Indian Ocean of which six species were found alive in the lower (> 2000 m) bathyal depth range; four species were associated with hydrothermal vents on the Central Indian Ridge and the SE Indian Ridge. The combination of strong ribs and spirals on the shoulder, weak spirals on the lower whorl and very wide selenizone in the specimens here is different from all known species in the Indian Ocean. The strong sculpture on the shoulder is common in anatomids, but this is commonly combined with ribs and occasionally spirals at the base. The lack of basal ribs is unique. For example, Anatoma paucisculpta Hoffman et al., 2022 , has a weak basal rib and spiral sculpture but lacks the rib sculpture on the shoulder ( Hoffman et al. 2022: 155–156, fig. 11). Anatoma sagamiana ( Okutani, 1964) from the Western Pacific has a similar outline and wide selenizone with thin margins like Anatoma sahlingi Hoffman & Little sp. nov., but it has a weak reticulated sculpture above and below the selenizone and its umbilicus is closed ( Geiger 2012: 1075–1081, figs. 875–880); Anatoma sahlingi Hoffman & Little sp. nov. has a stronger sculpture on the shoulder and a weak spiral sculpture below, and its umbilicus is open. The similar Anatoma soyoae ( Habe, 1951) is found off NW Honshu, Japan. It has a similar wide selenizone with thin margins and its umbilicus is open, but its upper sculpture is finer and the outline is more compressed ( Geiger 2012: 1095–1097, figs. 895–896).
Stratigraphic and geographic range.— Type locality and horizon only.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Pseudococculinidae Hickman, 1983
| Little, Crispin T. S., Kumar, Rajendar, Johnson, Joel E. & Hoffman, Leon 2025 |
Anatomidae
| McLean 1989 |
Anatoma
| Woodward 1859 |
Fissurellidae
| Fleming 1822 |
Fissurellidae
| Fleming 1822 |