Morphological variation in the shells ofPlacostylusspecies (Gastropoda: Bulimulidae) in New Zealand and implications for their conservation

Abstract

Shell morphologies of five extant populations of Placostylus bollonsi, 12 of P. ambagiosus, and one of P. hongii from three locations in the far north of New Zealand (Three Kings Islands, Te Paki, and Whangaruru North Head Scenic Reserve), were compared. Overall, little difference between populations could be detected within the species P. bollonsi and P. ambagiosus using a Principal Components Analysis on 10 or 14 shell characters. Only the West Island population of P. bollonsi seemed morphologically distinct from the remaining populations also endemic to the Three Kings Islands group. Although there were many differences between individual populations and subspecies of P. ambagiosus and P. hongii, taken collectively, there were only three coarse groups: (1) P. a. whareana; (2) P. a. michiei, P. a. pandora, P. a. paraspiritus; and (3) P. a. watti, P. a. annectens, P. a. keenorum, P. a. leslyae, P. a. consobrinus, P. a. ambagiosus, P. a. "nouvelle", P. hongii. The results agreed only in part with a study on the allozymes of many of the same populations, and differed in many respects from other studies on Placostylus she.ll morphology. It was concluded that investment into the conservation of the genus should take a conservative approach and reflect the greater array of geographically and genetically distinct forms rather than the fewer discrete morphological forms based on shell characters identified in this study.

Relationships of Placostylus from Lord Howe Island: an investigation using the mitochondrial cytochrome c oxidase 1 gene

“…Triggs and Sherley (1993) showed that there was a considerable level of genetic variation between populations of P. ambagiosus. In these cases, small but overlapping differences in shell morphology led to prior creation of several subspecies (Powell 1938(Powell , 1947(Powell , 1948(Powell , 1951bSherley 1996).…”

“…Species similar to Lord Howe Island Placostylus occur in northern New Zealand (Powell 1947(Powell , 1951bChoat and Schiel 1980;Triggs and Sherley 1993;Sherley 1996) and the Three Kings Islands (off northern-most New Zealand ;Powell 1951a;Brook and Laurenson 1992 Haas, 1935. In New Zealand, there are three main taxa. Placostylus hongii ( Fig.…”

“…The biota of these islands also includes many other endemics. All the New Zealand species of Placostylus have received considerable taxonomic (Powell 1938(Powell , 1947(Powell , 1948(Powell , 1951a(Powell , 1951bClimo 1973;Sherley 1996) and, more recently, conservation attention (Brook and Laurenson 1992;Triggs and Sherley 1993;Sherley 1996;Sherley et al 1998), including the publication of a Recovery Plan (Parrish et al 1995).…”

Conchology Variations in Species Identification of Pachychilidae (Mollusca, Gastropoda, Cerithiodea) through Multivariate Analysis

“…A total of 15 shell morphometrics was measured using Mitutoyo digital callipers at 0.00 ± mm following Sherely’s (1996) ( Fig. 2 , Table 1 ).…”

“… Shell characteristic used in the present study based on Sherely (1996) . Detail shell morphometrics and characteristics as shown in Table 1 .…”