THE LARVAL STAGES OFLITHOTRYA DORSALIS(ELLIS & SOLANDER, 1786): A BURROWING THORACICAN BARNACLE

Abstract

Lithotrya dorsalis is a member of the only genus of thoracican barnacles known to burrow and is widely distributed throughout the tropical western Atlantic. It occurs primarily in high energy intertidal environments. L. dorsalis undergoes the typical thoracican larval sequence. Six naupliar stages are followed by the cyprid stage. These larvae were reared in the laboratory and their stages are described for the first time. Newly hatched stage I nauplii are typically 360 ^m in total length; larval size increases to 1100 urn by the 6th instar. The most distinguishing characteristic of Lihtolrya dorsalis nauplii is the presence of unusually long, spinulated posterior shield spines in stages IV through VI. Complete larval development (stage I nauplius to cyprid) averaged 18 days and ranged from 12 to 23 days. Scanning electron micrograph descriptions of the cyprid cuticle of this animal, showing a unique striated appearance, are also included.

Cypris Ultrastructure, Metamorphosis and Sex in Seven Families of Parasitic Barnacles (Crustacea: Cirripedia: Rhizocephala)

“…40 illustrates the antennules. The carapace is surprisingly smooth compared to cyprids of the Cirripedia Thoracica (Walker & Lee 1976;Dineen 1987) (Figs 16,17). The number of carapace setae differs considerably between species.…”

Larval development of Capitulum mitella (Cirripedia: Pedunculata) reared in the laboratory

“…The distal shield spine of C. mitella appearing in stages II and III is absent in the same early stages in balanomorphs and pedunculates. Dineen (1987) noted that rudimentary posterior shield spines occur in L. dorsalis, which appear around the caudal spine, as observed in C. mitella naupliar stages II and III. We do not know whether it is a rudimentary posterior shield spine or not, but its phylogenetic signi¢cance needs to be investigated through detailed ontogeny of other pedunculate barnacles.…”

“…However, the cephalic shield itself bears speci¢c distal shield spines, not found in the same stages of other pedunculate barnacle larvae, which appear around the caudal spine in stages II^III. Dineen (1987) suggests that the most striking similarity occurs between the cephalic shield outlines of Lithotrya dorsalis and C. mitella among the ¢ve scapellid species such as Calantica spinosa, Scalpellum scalpellum, Pollicipes polymerus, L. dorsalis and P. mitella. He also explains that the same basic shield shape, along with the elongated and spinulated thoracoabdominal process and dorsal thoracic spine, and the elongated posterior shield spines in larval stages IV^VI are present in both species, while the nauplii of other scalpellid species have relatively abbreviated thoraco-abdominal processes and dorsal thoracic spines and appear to lack posterior shield spines.…”

“…Early workers failed to rear the pedunculate larvae from hatching through the nauplius to the cyprid stage (Groom, 1894;Coker, 1902;Hoek, 1913). Lang (1979) reared the larvae of Lepas anserifera Linnaeus, 1767 to stage III and those of L. pectinata (Spengler, 1793) to stage V. The larvae of following species have been completely described and illustrated: Calantica spinosa (Quoy & Gaimard, 1834) from New Zealand ; Ibla idiotica from New Zealand ; Ibla quadrivalvis Cuvier, 1817 from Australia (Anderson, 1965); Scalpellum scalpellum Linnaeus, 1767, from Sweden (Kaufman, 1965); Ibla cumingii Darwin, 1851, from India (Karande, 1974); Pollicipes polymerus Sowerby, 1833, from North America (Lewis, 1975); Octolasmis mu« lleri (Coker, 1958), from North America (Lang, 1976); Conchoderma auritum Linnaeus, 1767, from England (Dalley, 1984); Lepas anatifera Linnaeus, 1767, and L. pectinata from England (Moyse, 1987); and Lithotrya dorsalis Ellis & Solander, 1786, from North America (Dineen, 1987). Larval development of Capitulum mitella is known only through Yasugi (1937) who only described the outline shape of ¢ve nauplius, a metanauplius and cyprid larvae, and did not draw the correct setal morphologies of appendages.…”