Tetraclitella purpurascens purpurascens ( Wood, 1815 )

Buckeridge, John S., 2008, Two new species and a new subspecies of Tetraclitella (Cirripedia: Thoracica) from the Cainozoic of Australia and New Zealand and a consideration of the significance of tubiferous walls, Zootaxa 1897, pp. 43-52 : 44-45

Tetraclitella purpurascens purpurascens ( Wood, 1815)

Figure 1 F

1815: Lepas purpurascens Wood, General Conchology, 55.

1854: Tetraclita purpurascens: Darwin, Ray Soc. London,

1971: Tetraclitella purpurascens: Ross, Trans. San Diego Soc. Nat. Hist. 15(15): 237. 1986: Tetraclitella purpurascens: Foster and Anderson Jour. Roy. Soc. NZ 15: 64–66.

Diagnosis: Tetraclitella with low to moderately high conic shell, paries externally with narrow ridges separated by approximately their own width; exterior rugose when eroded, with secondarily-filled pores; base membranous; radii with internal tubes parallel to the base of shell, and growth lines parallel to articular margin; radii thick and elevated over adjacent parietal surface; scutum elongate.

Distribution: Australia – temperate waters, from below 26°S. See Foster and Anderson (1986: 65) for a full list of supposed occurrences outside this region.

Comments: Recognition of a new subspecies (below), on the basis of morphology and temporal separation, is a cautious move that nonetheless provides a useful mechanism to help envisage the evolution of the Tetraclitella group in the region.

Figures

FIGURE 1. Tetraclitella spp. A – E: Tetraclitella judiciae sp. nov. A: RM 318 – latus (exterior); B: RM 318 – latus (interior), the central, large, ellipsoidal structure is a grain of calcite, that if removed may have damaged the plate. It is not part of the barnacle; C: P 313914 – detail showing eroded radius of left latus (central cavity on image), and ellipsoidal pattern produced by eroded parietal pores intersecting the exterior surface; D: P 313914 – detail showing basal section through the shell wall, with inner row of large, elongate pores and outer multi-porous zone; E: P 313914 – detail showing parietal pores that have been apically infilled; F: Tetraclitella purpurascens purpurascens (Wood, 1815): Basal view of parietes exposing edge of sheath (upper, unpatterned zone) and multi-porous zone that lacks a distinct inner row or larger, elongate pores.