Bostrycapulus aculeatus, (GMELIN, 1791)

Collin, Rachel, 2005, Development, phylogeny, and taxonomy of Bostrycapulus (Caenogastropoda: Calyptraeidae), an ancient cryptic radiation, Zoological Journal of the Linnean Society 144 (1), pp. 75-101 : 92-93

BOSTRYCAPULUS ACULEATUS ( GMELIN, 1791)

Synonymy

Patella aculeata Gmelin, 1791: 3693 .

Crepidula aculeata - Lamarck, 1822: 25. Reeve, 1859. Sowerby, 1883 [in part]: 67, sp. 9., figs 124, 125; Sowerby, 1887 [in part]: 67, figs 39, 40. Parodiz, 1939 [in part]: 695. Hoagland, 1977 [in part]: 364. Collin, 2003a: 541–593. Collin, 2003b: 618–640.

C. intorta var. Say, 1822: 227 [in part].

C. costata Morton, 1829: 115 , pl. 7, figs 2, 3. Maryland Tertiary [non C. costata Sowerby, 1824 nec C. costata Deshayes, 1830 ].

C. spinosa Conrad, 1843: 307 . Miocene Virginia.

C. ponderosa H. C. Lea, 1846: 249 . Virginia Tertiary.

Crypta aculeata - Mörch, 1877: 93–123.

Bostrycapulus aculeatus - Olsson & Harbison, 1953 [in part]: 280. Simone, 2002 [in part]: 18.

Original description: ‘ Patella aculeata . Shell oval, brown, with prickly striae: crown recurved. Chemn. Conch. 10, tab. 168, 624, 1625. Da Costa Conch. tab. 6, fig. 1, Elements t 2, f 2. Favann. Conch. 1, tab. 4, fig. 3. Walch. Naturs. 10 tab. 1, fig. 5. 2. Inhabits American Islands. resembles the last shell small, chestnut or white with longitudinal striae, lip white dividing the cavity into equal parts’.

Fate of original type material: the types of B. aculeatus have previously been referred to as ‘lost’ ( Hoagland, 1977). Fates of most of the shells figured in the works referred to by Gmelin are unknown. However, the material Chemnitz cited as ‘Ex Museo Nostro’ was sold at public auction and the catalogue ‘Enumeratio Systematica Conchyliorum beat J. H. Chemnitzii’ by Havniae 1802 lists Patella aculeata as number 1144 ( Martynov, 2002). A shell with the number 1144 attached to it and matching the figure in Chemnitz is housed in the Zoological Museum in St. Petersburg, Russia. There are two other shells in the lot with the figured specimen, and notes in the margin of the auction catalogue in St. Petersburg mention 1144 as containing three shells ( Martynov, 2002). Specimens of Patella aculeata described by Favanne from the Cabinet Royal cannot be found in the Museum National d’Histoire Naturelle (P. Bouchet pers. comm.), and C. aculeata attributable to da Costa are not in the Natural History London (pers. observ. and D. Reid pers. comm.). Finally, inquiries about material of C. aculeata that may be attributable to any of these four authors suggests that possible types do not exist in London, Paris, Leiden, Berlin, Hamburg, Vienna, Copenhagen, Frankfurt, or Stockholm. It is therefore probable that the shell in St. Petersburg figured by Chemnitz is the only remaining type of B. aculeatus .

Original type locality: Gmelin states the habitat of B. aculeatus to be ‘Islands of the Americas’. This is most likely following ‘Westindischen’ from Chemnitz.

Diagnosis: This species can be distinguished from other Bostrycapulus species by features of development and mitochondrial DNA sequences. Development is direct from large, 380 Mm eggs. Embryos develop characteristic larval features but reabsorb them prior to hatching. The globose protoconch is 900 Mm in diameter and has less than a single whorl. Diagnostic DNA sequence differences, distinguishing B. aculeatus from all other Bostrycapulus species are in the following positions in the COI sequences submitted to GenBank (position 1 = position 1537 of the Drosophila yakuba mitochondrial genome, GenBank # X03240 ): 28 (c), 33 (g), 186 (g), 282 (t), 468 (g), 511(c).

Distribution: the known distribution of this species includes both coasts of Florida, the Florida Keys, Yucatan, the Bahamas, and probably the northern Caribbean Sea. Shells from as far north as North Carolina also probably belong to this species, although this has not been verified by examination of development or DNA sequence data. It is common on rocks and debris in the shallow subtidal zone, and can also be found on the carapaces of horseshoe crabs. Ranges to a depth of at least 60 m.

Description

Shell: as described for all Bostrycapulus species above. Maximum length = 30 mm

Protoconch: globose, comprising a single whorl, c. 900 Mm across. No sculpture is retained in material available from juvenile shells. The protoconch–teleoconch boundary is not distinct ( Fig. 5H ).

Anatomy: as described for all Bostrycapulus spp. above.

Radula : as described for all Bostrycapulus spp. above ( Fig. 10 ).

Development: the egg capsules of B. aculeatus are typical of all calyptraeids. The stalks are wide, flattened ribbons and not thread-like as in some other species. The 20–30 large yolky eggs per capsule all develop directly into crawling juveniles. Embryos develop a small but distinct velum, an operculum ( Fig. 8B ), a small round yolk-free head vesicle, and a single round embryonic kidney on each side. The velum and tentacles have a few cream spots and a dark stripe develops along the mid-line of the foot late in development ( Fig. 8B ). Prior to hatching, the shell begins to turn brown and the granular sculpture can be seen clearly with a dissecting microscope. Despite the relatively large velum, excapsulated embryos are never able to swim free of the bottom of the container. Hoagland (1986) reports an egg size of 380 Mm and a hatching size of 840 Mm. I found an egg diameter of 378 Mm (SD = 9 Mm; N = 11) for a single female from Lido Key, Florida.

Notes: the type locality, ‘islands of the Americas’ is somewhat vague but most likely refers to a locality in the northern Caribbean. It is possible that Bostrycapulus from the southern Caribbean is a distinct species from the species described here as B. aculeatus ( Gmelin, 1791) . I have been unable to find Bostrycapulus in the Caribbean surrounding Panama, Cayman Islands, or Trinidad, despite finding ostensibly appropriate habitat. If an additional Caribbean species is discovered, nomenclatural stability would benefit from the description of the southern species as new.

Observations of embryos are limited because virtually all egg capsules collected in Lido Key, Florida in 1997 contained nothing but bacterially infected fluid. However, many of those collected in 2003 developed normally. Animals are often solitary or form pairs; they do not form large stacks. Fossil shells with this morphology date from the Miocene in Florida ( Hoagland, 1977).

Figures

Figure 5. Protoconchs. A, Bostrycapulus pritzkeri sp. nov. from Sydney. B, B. calyptraeformis from the Perlas Islands, Panama. C, B. cf. tegulicia from Cape Verde. D, B. gravispinosus from Minabe, Wakayama Prefecture, Japan. E, B. calyptraeformis from Paita, Peru. F, B. odities sp. nov. from Playa Orengo, Argentina. G, B. urraca sp. nov. from Isla Parida, Panama. H, B. aculeatus from Lido Key, Florida. I, B. odites sp. nov. from São Paulo, Brazil. All are to the same scale. Scale bar = 500 Mm.

Figure 8. A, 2-week-old larva of Bostrycapulus calyptraeformis showing the velar pigment, shell sculpture (on the top of the shell) and large foot. Scale bar = 300 Mm. B, intracapsular larva of B. aculeatus showing the welldeveloped velum with pigment spots and body pigmentation. Scale bar = 200 Mm.

Figure 10. Radula of Bostrycapulus aculeatus collected from Mote, Florida. Scale bar = 100 Mm.