Recluzia Petit de la Saussaye 1853
Creators: name: Beu, Alan G.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Janthinidae
Recluzia

description: Recluzia Petit de la Saussaye, 1853
Recluzia Petit de la Saussaye, 1853: 117. Type species (by subsequent designation, Cossmann, 1925: 159): Recluzia jehennei Petit de la Saussaye, 1853 (= Janthina lutea Bennett, 1840); Recent, cosmopolitan.
Remarks. Iredale & McMichael (1962: 49) stated that the type species of Recluzia was selected originally by Petit de la Saussaye (1853), but Petit de la Saussaye named two species of Recluzia without designating a type species.A type species was not designated by most subsequent authors, and the earliest designation the writer is aware of is by Cossmann (1925: 159). However, this is of little consequence, as the two species included by Petit de la Saussaye are rendered absolute synonyms here.
The teleoconch of Recluzia is markedly to greatly taller and narrower than that of the tallest Janthina species, with a smooth, pale brownish-yellow shell (i.e., natural calcite colour), lightly polished in some specimens, and bears an obvious, slightly darker, thin, smooth periostracum that does not occur (or at least, is not obvious) on Janthina species. It also has evenly and strongly convex whorls, a deeply impressed suture, a straight, simple, acline outer lip without a sinus, and no obvious sculpture. The radulae of Janthina and Recluzia are indistinguishable. The protoconch (Churchill et al., 2011b: figs 1D–E; Figs 37A–G) also is closely similar to that of Janthina and all other planktotrophic Epitoniinae, pupiform, with a weakly impressed suture and sculpture of fine, low, closely spaced axial ridges on protoconch 2, although that of Recluzia lutea (Bennett, 1840) has one fewer whorls in protoconch 2 than those of Janthina species (2.2 whorls in R. lutea, 3.2 whorls in Janthina species). Recluzia differs from Janthina also by having simple rather than forked cephalic tentacles, no epipodia or purple gland, stylets in the inner salivary glands that are lacking in Janthina, adult statocysts that are lacking in Janthina, and small juvenile post-larval specimens riding on the adult’s shell or float, rather than forming a float of their own as in Janthina (Table 1). Recluzia lutea was also said by Abbott (1968: 92) to have yellow egg capsules and brownish mucus bubbles, in contrast to the white to slightly purplish, pink or pale blue egg capsules and transparent colourless to faintly bluish mucus bubbles of all Janthina species. This is confirmed by Tony Healy’s and Denis Riek’s photographs of living specimens (Figs 6–7); the egg capsules of Recluzia species are a similar colour to the shell, whereas the head and foot are a paler, brighter yellow than the shell, and the float bubbles have a brown tinge. The float bubbles also have a much more irregular appearance than those of Janthina species.
Putative fossil record
The one sample of fossils the writer is aware of that has been identified as a species of Recluzia is in NMB, labelled as “? Recluzia rollandiana Petit ”. It is from NMB locality 17516, Cantaure Formation, lower shellbed, 300 m south of Casa Cantaure, 10 km west of Pueblo Nuevo, near San José, central Paraguaná Peninsula, northern Venezuela (Burdigalian, late early Miocene; six small shells, largest 6.5 mm high). The fauna from this locality was monographed by Jung (1965). However, the “? Recluzia ” material is from a much larger and more diverse collection than Jung’s, gathered subsequently during many visits by Win and Jack Gibson-Smith, and recently monographed by Landau et al. (2016). The teleoconch of these specimens indeed closely resembles that of Recluzia lutea in thinness and shape, its lack of sculpture other than faint growth lines, its inner lip being narrowly reflected over a very narrow umbilicus, and its straight, acline outer lip. However, the protoconch is present on two of the smallest shells (Figs 36A, C) and is significantly larger, taller, of c. 3.5 whorls, and with a more stepped outline than the pupiform one of 2.2 whorls in Recluzia lutea (Churchill et al., 2011b: figs 1D–E; Figs 37A–G). The Recluzia protoconch has almost flush sutures. It also has an almost smooth surface with weak sculpture of narrow, shallow, closely spaced axial grooves, but fainter spiral sculpture than that of Janthina species. The protoconch of the Casa Cantaure fossil has an even smoother surface with still weaker axial sculpture than that of Recluzia species and no spiral sculpture discernible at all, and has a much more deeply impressed suture than the protoconch of Recluzia, forming a narrow subsutural platform. These specimens evidently belong in Epitoniidae, and probably represent a benthic species of Epitoniinae with lecithotrophic development. They tentatively were referred to “ Alexania aff. floridana Pilsbry, 1945 ” by Landau et al. (2016: 102, pl. 87, figs 1–2). Comparison with the protoconch of presentday specimens of Alexania natalensis would help identify these specimens.
Names proposed in Recluzia
As the species of Recluzia have not been revised previously, all names are listed here that the writer is aware of that have been referred to Recluzia, with comments on their status where necessary. Names are listed in chronological order of their proposal. The status of the 13 names that remain classified in Recluzia is clarified in the following sections.
1 Helix johnii Holten (1802: 76) (Jousseaume, 1872: 205; Winckworth, 1943: 148); refers to Chemnitz (1795: figs 2076–2077), i.e., the earliest reference making the non-binominal name Helix johnii Chemnitz available; probably northern Indian Ocean, locality unknown. Neotype designated below.
2 Janthina lutea Bennett (1840: 63, 298); taken at sea, 2°53'S 170°55'E, SW of the Phoenix Islands, Kiribati, central western Pacific Ocean. Discussed in detail below, with neotype designation.
3 Janthina turrita “von dem Busch ” Philippi (1849: 15); no illustration, no locality, no types found; its dimensions lie in the centre of variation of Recluzia specimens (Fig. 35, point identified by “T”), and it is assigned to the synonymy of the more common species, R. lutea. A neotype is designated below.
4 Recluzia jehennei Petit de la Saussaye (1853: 118, pl. 5, fig. 3); Arabian Gulf. Remaining syntype illustrated (Figs 36F–G).
5 Recluzia rollandiana Petit de la Saussaye (1853: 119, pl. 5, fig. 12); “environs de Mazatlan” [“later identified as actually from New Caledonia ” (Keen 1971: 903)]. Neotype designated below.
6 Recluzia aperta Jeffreys (1859: 114, pl. 3, figs 22a–c) = Torellia vestita Lovén ms Jeffreys (1867: 244, pl. 4, fig. 1); Britain; not Recluzia (Torellia, Family Capulidae).
7 Recluzia bensoni A. Adams (1861: 402); off Formosa; a small, narrow, juvenile Recluzia specimen. Holotype in NHMUK.
8 Recluzia hargravesi Cox (1870: 172, pl. 16, fig. 8); Port Stephens, New South Wales; extremely large as well as unusually tall and narrow. Holotype in NHMUK.
9 Recluzia montrouzieri Souverbie (1871: 334; 1872: 57, pl. 1, fig. 8); Art I., New Caledonia. Syntypes in MHNB.
10 Lymnaea? palmeri Dall (1871: 135; 1925: 25, pl. 17, fig. 8); delta of the Taqui River, head of the Gulf of California; holotype (in USNM) illustrated byAbbott & Dance (1982: 70, bottom right fig.) and here (Figs 36E, H).
11 Recluzia globosa E. A. Smith (1876: 551, pl. 30, fig. 8); Tarawa, Gilbert Islands. Holotype in NHMUK. Probably a juvenile specimen of R. lutea, but as it is unusually short and wide, also possibly an Alexania species, a benthic epitoniid. However, the dimensions (Table 12) fall within those of other small specimens of R. lutea, which are much shorter and wider than adults.
12 Recluzia erythraea Jickeli (1882: 367); Dahlak I., Red Sea; illustrated by Thiele (1928: fig. 6). Thiele gave no source for his figure, but it is assumed to be of the holotype; tall and narrow, resembling the holotype of R. hargravesi Cox, 1870 in proportions. Holotype in ZMB.
13 Recluzia rollandiana var. β annamitica Wattebled (1886: 67, pl. 3, figs 4a–b); Hué, Vietnam; “a considerable number of shells of this species was found thrown up on the beach of Thuan-an, at the end of a cyclone”. Syntypes in MNHN, one illustrated here (Fig. 36K–L).
14 Recluzia sp.: Murdoch & Suter (1906: 301, pl. 27, figs 55–56) illustrated a specimen dredged in 200 m off Great Barrier Island, NE New Zealand, identified as “ Recluzia sp.” Charles Hedley suggested verbally to Murdoch and Suter that it was either a larval shell or a new genus related to Janthina. It is small (H 3.83, D 3.29 mm), trochiform, with almost flat sides, a narrowly rounded periphery and a blunt, narrowly rounded apex with no distinguishable protoconch, and is essentially smooth. Its colour was described as “yellowish-horn, white underneath the epidermis” (Murdoch & Suter, 1906: 302). The specimen, in Suter’s collection in GNS (S3045) is a larval shell, probably of Cabestana spengleri (Perry, 1811) (Ranellidae).
15 Recluzia effusa [ex Martens ms] Thiele (1928: 78, footnote, fig. 2), has a diagnosis and apparently was not published elsewhere; from “chinesischen See”. No dimensions or illustrations of the shell were provided. Thiele (1928: 78, footnote) stated that the shell is not well preserved; he published a section through the foregut and radula of the presumed type, so it is evidently preserved in ethanol, with the shell corroded. The name must be attributed to Thiele (1928); assumed to be a synonym of R. lutea. Holotype in ZMB.
16 Recluzia insignis Pilsbry & Lowe (1932: 80, pl. 9, fig. 3); from Montijo Bay, western Panama; pale brown, but with prominent cancellate sculpture, not a Recluzia species; tentatively identified as a synonym of the type species of Alora, A. gouldii (A. Adams, 1857) by Keen (1969; 1971: 436, fig. 669). However, the spire of the holotype is markedly taller and narrower and the sculpture is considerably more prominent than those of illustrated specimens of A. gouldii (Weil et al., 1999: 145, fig. 439); possibly a distinct species of Alora or a similar genus; benthic Epitoniidae.
Dimensions and species of Recluzia
The only character that varies to any obvious extent in Recluzia is the spire height, a combined measure of the diameter and translation rate of the whorls. To try and understand this variation, some of the specimens available in AMS, GNS and NMNZ were measured (Tables 12, 13) and their height (H), diameter (D) and spire height (SH) compared in bivariate plots (Figs 35A–B). Initially this resulted in distinguishing two groups of shells, separated by spire height. If these are to be recognized as separate species, the earliest names for them are R. lutea for the more common, shorter, wider species and R. johnii for the much less common, taller, narrower one. As Bennett (1840) observed a large raft of specimens, he is very much more likely to have collected the more common, shorter Recluzia species than the rare, taller and narrower species.
The addition of a greater number of specimens made it seem more likely that the two groups intergrade in shape. A large lot in NMNZ (M155930, Great Exhibition Bay, Northland, New Zealand, Mar 1998; 59 specimens, of which 43 measured, Table 13) shows that (1) larger shells tend to have taller spires than smaller ones; i.e., height increases with growth; (2) many of the larger shells have a short, wide, shallow flare at the anterior end of the aperture, making their dimensions slightly taller and narrower than shells without the flare, although the whorls are actually no narrower than in specimens without the flare (e.g., see the illustration of Recluzia lutea by Habe & Tokioka, 1953: 57, fig. 12, identified as R. montrouzieri); and so (3) specimens identified as R. lutea largely intergrade in overall shape with specimens identified as R. johnii, although the spire outline of R. johnii is taller and straighter than in R. lutea. The majority of specimens in Fig. 35A assigned to R. lutea are included in the same field as specimens assigned to R. johnii, and the distinction between the two fields is slight. Comparisons of the height (H), width (diameter, D) and spire height (SH) of a number of specimens (Tables 12, 13) of the two species are summarized in Table 11. The overall shape is confirmed as similar, the means for H/D being 1.44 for R. lutea and 1.56 for R. johnii. Contrary to the conclusion about overall shape, the quite strongly distinct means of D/SH (1.51 for R. lutea, 1.20 for R. johnii) and the accompanying plot comparing diameter with spire height (Fig. 35B) show a clear distinction between the shorter-spired species R. lutea and the taller-spired species R. johnii. These fields overlap little (although the height of the spire was available for only nine of the 14 specimens of R. johnii). On average, diameter is 1.5 times spire height in R. lutea, whereas diameter is only slightly greater than spire height (1.2) in R. johnii.As seemed likely from visual estimation, R. johnii is considered here to be a rare, second Recluzia species with a taller, narrower and more straight-sided spire and narrower teleoconch whorls than R. lutea. Concomitant with the taller spire and narrower whorls, large specimens of R. johnii also have at least one more teleoconch whorl than R. lutea (6–7 compared with 4.5–5.5). Neotypes are provided here for some names to identify them unambiguously with one or the other species. Comparison of molecular sequences of Recluzia specimens obviously is desirable to confirm that two species exist.
description: Published as part of Beu, Alan G., 2017, Evolution of Janthina and Recluzia (Mollusca: Gastropoda: Epitoniidae), pp. 119-222 in Records of the Australian Museum (Rec. Aust. Mus.) (Rec. Aust. Mus.) 69 (3) on pages 198-199, DOI: 10.3853/j.2201-4349.69.2017.1666, http://zenodo.org/record/4677010