Neolepadidae, Yamaguchi, Newman & Hashimoto, 2004

Gale, Andy S., Little, Crispin T. S., Johnson, Joel E. & Giosan, Liviu, 2020, A new neolepadid cirripede from a Pleistocene cold seep, Krishna-Godavari Basin, offshore India, Acta Palaeontologica Polonica 65 (2), pp. 351-362 : 353

Family Neolepadidae Yamaguchi, Newman, and Hashimoto, 2004

Included genera: Neolepas Newman, 1979 , Ashinkailepas Yamaguchi, Newman, and Hashimoto, 2004, Vulcanolepas Southward and Jones, 2003 , Leucolepas Southward and Jones, 2003 , Stipilepas Carriol in Carriol et al., 2016.

Diagnosis. —Pedunculate calcareous forms which possess an 8 plated capitulum comprising two scuta, two terga, two upper latera, a carina and a rostrum. The large rostrum articulates with the rostral margin of the scutum, and the carina with the lower carinal margin of the tergum.

Remarks.—As demonstrated by X-ray diffractometry analysis, Ashinkailepas has shell plates composed of calcite. The Neolepidinae Yamaguchi, Newman, and Hashimoto, 2004, is therefore raised to family status, because the family Eolepadidae Buckeridge, 1983 , to which it was previously assigned, has been shown to have a phosphatic shell ( Høeg et al. 1999; Gale 2014b; Gale and Schweigert 2015), and includes only the genera Eolepas and Toarcolepas . Living forms are exclusively associated with hydrothermal vents and methane seeps ( Watanabe et al. 2018), but the Eocene Stipilepas is found in open marine clay sediments deposited under dysoxic conditions ( Carriol et al. 2016).There have been three records of fossil neolepadids, of which only Stipilepas appears to me to belong to the family. The other records are described below.

? Neolepas augurata Buckeridge and Grant-Mackie, 1985

Fig. 2A, B .

Material.—UoA A291a, b, A292a, b; two mouldic valves from the Sinemurian–Pliensbachian (Lower Jurassic), New Caledonia.

Remarks.—This species is based upon a single scutum and a fragmentary tergum from the Lower Jurassic of New Caledonia ( Fig. 2A, B ). The scutum is asymmetrically triangular, with a broad basal margin and an acuminate umbo, and somewhat resembles in outline the scutum of Toarcolepas mutans Gale and Schweigert, 2015 ( Fig. 2C ). This phosphatic taxon from the Lower Jurassic of Germany is now known from articulated individuals ( Gale et al. 2019: fig. 7A–C). However, the basal margin in? N. augurata is more convex than in T. mutans , and the external surface of the valve appears to be swollen. The tergum of? N. augurata appears similar in shape and sculpture (curved apicobasal line, moderately strong co-marginal ridges, weaker radial ridges) with those of Eolepas bathonica Withers, 1928 (compare Withers 1928: pl. 2: 7–9). The species is tentatively interpreted as a possible eolepadid, but the material requires further study.

Figures

Fig. 2. Fossil taxa assigned to Neolepadidae. A, B.?Neolepas augurata Buckeridge and Grant-Mackie, 1885 (original of Buckeridge and Grant-Mackie 1985: figs. 2, 3); Sinemurian–Pliensbachian (Lower Jurassic), New Caledonia. A. University of Auckland Geology Department UoA A291a, b, external mould of tergum. B. University of Auckland Geology Department UoA A292a, b, external mould of scutum. This is here tentatively interpreted as an eolepadid. C. Toarcolepas mutans Gale and Schweigert, 2015 (SMNS 26029); Toarcian (Jurassic), Harpoceras falciferum Zone, Zell u. Aichelberg, Germany; reconstruction based upon type material (Gale and Schweigert 2015: fig. 5). D. Litholepas klausreschi Nagler, Haug, Glenner, and Buckeridge, 2017; Tithonian (Upper Jurassic), Hybernoticeras hybernotum Zone, Eichstatt, Germany; D2, SMNS 70388/5 (decolourised original of Nagler et al. 2017: fig. 5B). I am unable to identify the upper latus, marked “l” in their figure; D1, reconstruction (mirrored for comparison with C). E. Concinnalepas costata (Withers, 1928) (NHMUK IC 1103); Kimmeridge Clay, 2 m beneath Freshwater Stone Band, Pectinatites pectinatus Zone, Tithonian (Upper Jurassic), Kimmeridge, Dorset, UK; fragmentary capitulum, showing scutum, tergum, and two lateral plates (based on original of Gale 2014: fig. 6l).Abbreviations: c, carina; l, upper latus; p, peduncle; r, rostrum; s, scutum;; t, tergum.