Redescription of Scalpellopsis Striatociliata Broch, 1922, with a Discussion on Its Phylogenetic Position and the Peduncular Plate Pattern in Scalpellids

Abstract

A B S T R A C TThe adult of Scalpellopsis striatociliata and the ontogeny of its capitular and peduncular plates are described. During ontogeny, S. striatociliata develops the carino-lateral (CL) and inframedian (L2) plates heterochronously after some peduncular plates (cl), which is unique. The position of Scalpellopsis as sister-group of the other scalpellids is reaffirmed. The Scalpellidae have diverse peduncular plate patterns, with the 8-plated pattern being ancestral and the most widespread among the genera. The peduncular plate patterns of several species of Scalpellidae are presented.

Origin and phylogeny of verrucomorph barnacles (Crustacea, Cirripedia, Thoracica)

“…Neoverruca is apparently unusual in that it adds new plates between the capitular valves and the inferred carinolatus and rostrolatus (Newman 1989, fig. 1) rather than at the junction between the peduncle and lateral plates as in all scalpelliforms (Young 2001). However, if the supposed latera in Neoverruca are actually just peduncular scales, the similarities with neolepadids are much closer; an upper latus is generated first, then peduncular scales are added at the base of the capitulum, exactly as in neolepadids ( Fig.…”

“…1C). The peduncle is armoured, with alternating rows and columns of peduncular scales, which are added at the contact with the capitulum (Young 2001). Verrucomorphs are highly modified and asymmetrical, having lost the peduncle and all lateral plates, and possess a wall formed of a fixed tergum, a fixed scutum, a carina and a rostrum; the moveable scutum and tergum form an opercular lid (Figs 2AÀE, 3;Darwin 1854;Newman et al 1969).…”

Phylogeny of the deep-sea cirripede family Scalpellidae (Crustacea, Thoracica) based on shell capitular plate morphology

“…The capitulum in scalpellids comprises 14 plates (paired scuta, terga, upper latera, inframedian latera, rostrolatera, carinolatera, plus an unpaired rostrum and an unpaired carina). The rostrum is lost in some scalpellids (Young, ) and, exceptionally, the rostrolatus is also lost in the aberrant Scalpellopsis Broch, (Young, ). The out‐group, Cretiscalpellum , additionally possesses paired subcarinolatera and a subcarina (Fig.…”

“…The peduncle of extant scalpellomorph cirripedes is made up of columns of plates that form at the boundary between the peduncle and the capitulum, usually after the full compliment of capitular plates have been added (Newman & Ross, ; Young, ). This is true in all taxa that have been studied, with the exception of the scalpellid Scalpellopsis (Young, ), in which peduncular plates are added before the final laterals. Thus, the youngest plates are usually found at the contact with the capitulum.…”

“…The plates in scalpellids are added alternately in two series, sc–l–sr and rl–cl, which correspond with the eponymous capitular plates. Plesiomorphically, eight columns of plates are present (Newman & Ross, ; Young, ), but some scalpellids have a reduced number, and calanticids and pollicipedids have generated a very large number of small plate rows (Young, ). In the taxa studied here, eight columns are present in all but Am.…”